EP1046780A1 - Method of enhanced hydrocarbon production by injection of a liquid and gaseous phase at least partially miscible with water - Google Patents

Method of enhanced hydrocarbon production by injection of a liquid and gaseous phase at least partially miscible with water Download PDF

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Publication number
EP1046780A1
EP1046780A1 EP00400945A EP00400945A EP1046780A1 EP 1046780 A1 EP1046780 A1 EP 1046780A1 EP 00400945 A EP00400945 A EP 00400945A EP 00400945 A EP00400945 A EP 00400945A EP 1046780 A1 EP1046780 A1 EP 1046780A1
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Prior art keywords
gas
aqueous phase
fluid
injection
deposit
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EP00400945A
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German (de)
French (fr)
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EP1046780B1 (en
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Nicole Doerler
Gérard Renard
Alexandre Rojey
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/20—Displacing by water
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
    • E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
    • E21B43/164—Injecting CO2 or carbonated water

Definitions

  • the present invention relates to an enhanced recovery method of hydrocarbons by the combined injection of water and gas into a deposit.
  • the method according to the invention finds applications in particular for improve the movement of petroleum fluids to producing wells and this increases the recovery rate of recoverable fluids, oil and gas, initially in place in the rock mass.
  • Recovery is said to be primary when petroleum fluids are produced under the sole action of the energy present in situ. This energy can result from the expansion of pressurized fluids in the deposit: expansion of oil saturated or not in gas, expansion of a gas cap above the oil deposit, or an active body of water. During this phase, if the pressure in the deposit drops below the oil bubble point, the gas phase from the oil will help increase the recovery rate. Recovery by natural drainage rarely exceeds 20% of fluids initially in place for light oils and is often less than this value for heavy oil deposits.
  • Secondary recovery methods are used to avoid excessive pressure drop in the deposit.
  • the principle of these methods is to bring external energy to the deposit.
  • fluids are injected into the deposit by one or more injector wells in order to move the recoverable petroleum fluids (hereinafter designated by "oil") to production wells.
  • Oil is frequently used as displacement fluid.
  • its effectiveness is limited. Much oil remains in place because in particular its viscosity is greater than that of water.
  • the oil remains trapped in the pore narrowing of training due to the large difference in interfacial tension between it and water.
  • the rock mass is frequently heterogeneous. In this context, the injected water will take the paths of greatest permeability to reach the producing wells, leaving large masses of oil not swept away. These phenomena induce a significant loss of recovery.
  • Pressurized gas can also be injected into a deposit at for secondary recovery, the gas has the well-known property of displacing significant amounts of oil.
  • the gas being much less viscous than the oil and water in place, it will cross the rocky massif using only a few of the most permeable and will arrive quickly at producing wells without having the effect of expected displacement.
  • WAG Water Alternate Gas
  • water and gas are injected successively as long as the fluids tankers are produced under economic conditions.
  • the role of water plugs is to reduce gas mobility and increase the swept area.
  • Many improvements of this technique are proposed: the addition of water surfactants in order to decrease the water-oil interfacial tension, adding foaming agent in water: the foam formed in the presence of the gas will reduce significantly the mobility of the latter.
  • One such method is by example described in US Patent No. 3,893,511.
  • patent FR 2,735,524 of the applicant there is also known an improved method consisting in add an agent to at least one of the water plugs injected alternately reducing the interfacial tension between water and gas. Under the influence of this agent, alcohol for example, the oil cannot spread on the film of water covering the rocky massif. The oil remains in the form of droplets which brake the displacement of gas.
  • patent FR 2 764 632 of the applicant we know also a process comprising the alternating injection of gas caps and water plugs in which at least one of the water plugs is added with pressurized gas both soluble in water and oil. The stage of production involves the release of the pressure prevailing in the deposit, so as to generate gas bubbles which will expel the hydrocarbons from pores of the rock mass.
  • Tertiary recovery aims to improve this rate of recovery, when the residual oil saturation is reached.
  • We regroup under this name the injection into the miscible gas tank, of micro emulsion, or steam or in situ combustion.
  • the process of enhanced recovery of a petroleum fluid produced by a deposit according to the invention aims, by a combined injection of a phase water and gas from an external source or, to the extent of possible, at least in part from acid gases from effluents from deposit itself, to increase the rate of recovery of hydrocarbons.
  • the method includes continuous injection through an injection well a sweeping fluid consisting of an aqueous phase with gas added to it less partially miscible in water and in petroleum fluid, with a permanent control at the top of the injection well, of the flow rate report for this aqueous and gas phase forming the sweeping fluid so that, at the bottom of the injection well, the gas is there in a saturation or supersaturation state
  • the sweeping fluid can be formed either at the bottom of the well with separate routing of the constituents to the injection zone, i.e. at the top well
  • a means arranged in the injection well to create a pressure drop such as a valve or a pipe restriction and so increase the rate of dissolution of gas in water.
  • a pump is used multiphase rotodynamic type for example to compress the gas, pressurize the aqueous phase and form an intimate mixture between this phase water and gas under pressure before injecting it into the injection well.
  • the gas in the sweeping fluid contains at least one acid gas such as than carbon dioxide and / or hydrogen sulfide and optionally, in varying proportions, other gas: methane, nitrogen, etc.
  • acid gas such as than carbon dioxide and / or hydrogen sulfide
  • other gas methane, nitrogen, etc.
  • gases can be taken from the effluents from a deposit, operation carried out by a processing unit adapted to separate them from other gases otherwise recoverable or come from chemical units or units thermal burning lignite, coal, fuel oil, natural gas etc.
  • the aqueous phase used to form the sweeping fluid can be for example water from an underground deposit (a water table by example or brine produced during the exploitation of a deposit) or any other readily available water (seawater).
  • the aqueous phase is added a surfactant additive to promote the dispersion of the gas therein and / or one or several additives to increase the solubility of the gas in the scanning.
  • the sweeping fluid is injected, for example, into one or more wells, horizontal or of complex geometry located for example at the base of the deposit .and the fluid tanker is produced for example by one or more deviated wells or complex geometry that can be located on the roof of the deposit.
  • the process can be implemented from the start of the operation of the deposit.
  • the aqueous phase preferably injected at the periphery of the producing area, sweeps the porous medium containing the hydrocarbons to recover.
  • carbon dioxide much more soluble in oil than in injected water, passes fluid sweeping with petroleum fluid causing it to swell and reducing its viscosity.
  • the invention also relates to an assisted recovery system. of a petroleum fluid extracted from a deposit, by continuous injection into the deposit of a sweeping fluid consisting of an added aqueous phase gas at least partially miscible in the aqueous phase and in the fluid tanker, which includes a set for conditioning the sweeping fluid and a permanent control unit for the packaging unit adapted to control the ratio of the flow rates of this aqueous phase and of the gases forming the sweeping fluid reached the bottom of the well, so that the gas is in a state of saturation or supersaturation.
  • the system includes status sensors arranged in the injection area to measure parameters thermodynamic and connected to the control unit.
  • the recovery process which is the subject of the present invention includes four steps:
  • the carbon dioxide mixed with the aqueous phase reacts according to the balanced reaction: CO 2 + H 2 O ⁇ H 2 CO 3 giving carbonic acid.
  • the solubility of carbon dioxide in water depends on the salinity of the water, the temperature and the pressure.
  • the CO 2 dissolution rate increases with pressure and decreases with temperature.
  • the effect of pressure is preponderant.
  • the rate of dissolution of carbon dioxide at the bottom of an injection well is higher than the rate of dissolution on the surface, despite the increase in temperature due to the geothermal gradient.
  • H 2 S For example, under a pressure of 150 bars and for a temperature of 70 ° C, the solubility of H 2 S will be approximately 8.3% by weight (83 kg of H 2 S are dissolved in 1 m 3 d 'water). Acid gases from petroleum production mainly contain carbon dioxide, it is the solubility of this gas which will be limiting when the mixture is dissolved in an aqueous fluid.
  • the volumes of acid gases and water likely to be reinjected into the deposit may be available in a ratio much higher than the ratio of solubility of acid gas in water. This ratio may change during exploitation or according to production constraints.
  • the increase in pressure at the bottom of the injection well is partially compensated by a increase in temperature linked to the geothermal gradient. However, the effect pressure is generally higher, especially as the fluid injected does not reach flow conditions of thermal equilibrium.
  • the fluid scanning is produced by a PA packaging unit and its constituents, brought separately to the injection area at the bottom of the well.
  • the gas is compressed by a compressor 1 and injected by an injection tube 2 to the bottom of the IW injection well, while the water from a pump 3 is injected into the annular space 4 between the casing and the injection tube 1.
  • the mixing between the two phases is carried out under the seal 5 at right of the injection area.
  • the injection pressures of compressor 1 and the pump 3 are determined by a control device 6.
  • the injection of gas requiring a high pressure at the wellhead we prefer to mix the surface before to inject it.
  • This simultaneous injection increases the weight of the liquid column in the injection well, and significantly reduce the pressure gas required.
  • the mixture produced in wellhead is strongly supersaturated with acid gases and particularly homogeneous, the gas being dispersed in the liquid phase.
  • a compression device can be used for this purpose (Fig. 2) and conventional pumping known to specialists, for injecting the scanning under saturation or supersaturation at the bottom of the well.
  • the acid gases are compressed in a compressor 1 in stages successive and cooled between two compression sections.
  • the water is pressurized by a pump 3 at a pressure equal to that applied by the compressor 1.
  • the gas and the liquid are then introduced into a mixer static or dynamic 7 having sufficient efficiency to allow the total dispersion of the gas in the liquid. Downstream of the mixer 7, the mixture can be compressed by an additional pump 8 to allow either dissolution of an additional quantity of gas, i.e. the injection of the scanning in the IW well.
  • Acid gases, heated during the compression can for example be cooled, by means of heat exchangers heat (not shown) before their introduction into the mixer 7 so to favor their dissolution.
  • a multiphase pump of the rotodynamic type can advantageously replace a conventional reinjection chain and fill the three functions: compress the gas, pressurize the liquid phase and mix intimately the two phases.
  • a rotodynamic multiphase pump suitable for this type of application is described in patents FR 2,665,224 (US 5,375,976) of the applicant or FR 2,771,024 of the applicant. By its design, this type of pump can inject a mixture into a well diphasic composed of saturated carbonated water and an excess of carbon gas without cavitation problem.
  • a pressure drop additional in the injection line in the form of a shut-off valve lamination or restriction of the injection pipe.
  • a lining is also placed in the well IW injection to improve the mixture of constituents while inducing an additional pressure drop, preferably in one and the other case of the state sensors (not shown) lowered to the bottom of well, in the injection area, to measure different parameters thermodynamics: pressures, temperatures etc., and linked to the control 6.
  • a transmission system adapted to transmit surface signals from permanent sensors permanently installed in wells to monitor a deposit, and in particular state sensors allowing know for example the temperatures and pressures prevailing at the bottom of the well, is described in particular in US patent 5,363,094 of the applicant.
  • the device control 6 adjusts the flow rates and their ratio in this case according to the conditions prevailing in situ.
  • the system is adapted to form a saturated or supersaturated mixture at least in part through controlled recombination of effluents pumped out of the deposit by one or several production wells from the PW deposit.
  • effluents include generally a liquid phase consisting of water and oil, and a phase carbonated.
  • the effluents therefore pass through a water-oil-gas separator S1.
  • the gas phase possibly supplemented by external contributions, crosses a separator S2 intended to separate the recoverable gases moreover for other applications, acid gases that we want to recycle.
  • Water from separator S1 is then recombined with the acid gases recovered in a controlled mixing device M, so as to form the saturated mixture or supersaturated under the conditions prevailing at the bottom of the well.
  • the pressure required to inject the fluid into the porous mass is less than the CO 2 liquefaction pressure, a liquid phase and a gaseous phase will be present in the injection well.
  • the user must ensure that the dispersion of the gas is maximum and that the gas plugs circulating in the injection well are entrained by the liquid column at the bottom of the well, in other words that the liquid speed is greater than the ascent rate of the gas plugs in order to avoid segregation in the injection well.
  • the pressure required to inject the fluid into the porous mass is greater than the liquefaction pressure of CO 2 .
  • the liquefied gas will be intimately mixed with the water and an emulsion formed of fine droplets of liquefied gas in the water will then be injected.
  • a small proportion of surfactant is added to the aqueous phase, promoting the dispersion of the gas bubbles.
  • additives promoting its dissolution such as monoethanol amine, diethanol amine, ammonia, sodium carbonate, potassium carbonate, sodium or potassium hydroxide, potassium phosphates, diamino-isopropanol, methyl diethanol amine, tri-ethanol amine and other weak bases.
  • concentration of these additives in water can vary from 10 to 30% by weight.
  • the injection wells can be vertical or horizontal wells.
  • the aqueous phase can be injected at the base of the tank to be drained by means of one or more horizontal wells and the liquid hydrocarbon phase can be drawn off from the roof of the tank by means of one or more horizontal wells.
  • the injection and production wells will be vertical, and the sweeping of the hydrocarbons in place will be parallel to the limits of the tank.
  • Wells of more complex geometry can be used without departing from the scope of the present invention.
  • the recovery principle according to the invention makes it possible to provide the deposit additional energy.
  • the benefits of simultaneous injection water and acid gases are plentiful.
  • Carbonated water solubilizes the soluble carbonates present in the rock, calcite and dolomite, by forming soluble bicarbonates according to the reactions: Ca CO 3 + H 2 CO 3 ⁇ Ca (HCO 3 ) 2 Mg CO 3 + H 2 CO 3 ⁇ Mg (HCO 3 ) 2
  • This partial dissolution of carbonates causes an increase the permeability of the porous medium, whether it is sandstone, in which the dissolution will attack the cements and calcium deposits frequently present around the quartz grains, or a limestone formation in which the porous connection will be improved.
  • the gain in permeability resulting from the dissolution of carbonates may be notable, as is well known to specialists.
  • Carbonated water is also known to prevent swelling of clays frequently present in petroleum reservoirs. This effect is particularly sensitive for clays whose basic ion is sodium.
  • the dissolution of calcium also has an influence on the stabilization of clays at sodium ions by replacing sodium with calcium which gives more stable clays resistant to flow without disintegrating and clogging the porous medium.
  • the viscosity of water increases when the CO 2 dissolves in it.
  • the volume of this carbonated water increases from 2 to 7% depending on the concentration of dissolved gas and its density decreases slightly.
  • the overall effect of decreasing the density contrast between water and oil reduces the risk of segregation by gravity.
  • the water / oil mobility ratio is improved by the decrease in the oil / water viscosity ratio.
  • Carbon dioxide is much less soluble in water than in deposit oils. This solubility is a function of the pressure, the oil temperature and characteristics. Under certain conditions, the carbon dioxide may be partially or completely miscible with hydrocarbons. When injected into the deposit as water carbonate, carbon dioxide will preferentially pass from water to oil.
  • the dissolution of carbon dioxide in the oil also causes a decrease in its viscosity. This decrease will be greater when the amount of CO 2 increases.
  • An oil having initially a high viscosity will be more sensitive to the phenomenon. For example, an oil with a density of 12.2 API (0.99 g / cm 3 ) and having a viscosity of 900 mPa.s at ambient pressure and a temperature of 65 ° C will see its viscosity decrease to 40 mPa.s under pressure of 150 bars of CO 2 . Under identical conditions, the viscosity of an oil with a density of 20 API (0.93 g / cm 3 ) will drop from 6 to 0.5 mPa.s.
  • the swelling of the oil like the drop in its viscosity, promotes increased recovery of hydrocarbons initially in place in the deposit. They also speed up the recovery process hydrocarbons.
  • the carbonated water is at least saturated with CO 2 when it is injected into the tank.
  • the pressure of the injected fluid will drop due to the pressure losses linked to the flow.
  • gas will be released.
  • the nucleation of carbon dioxide bubbles will preferably occur in contact with the rock and specifically in areas with a high concentration of rock / liquid interfaces. These zones correspond to massifs of low permeability; the enlargement and migration of the gas bubbles will expel the oil which is trapped in the small diameter pores of the rock. This phenomenon significantly increases the rate of hydrocarbons mobilized during production.
  • the recovery process as described above finds a advantageous application when bringing into production a deposit a double porosity system such as cracked deposits.
  • a simple representation of these deposits is a set of rock blocks from decimetric or metric sizes with pores of small diameters and saturated in oil, linked together by a network of cracks providing a passage to the flow of fluids of a few tens of micrometers on average.
  • the water When these tanks are injected with water as part improved recovery of petroleum effluents, the water will preferably invade the cracks. The water will then tend to soak blocks of low permeability by driving out the oil trapped in the pores towards the network of cracks. If the tank is wettable with water, imbibition will will do under the effect of capillary forces and gravity. If the tank is wettable with oil, only gravity will favor the phenomenon of imbibition.
  • the exploitation of the deposit can include injection and depletion.
  • injection period production will be stopped or decreased while the injection of carbonated water will be maintained, in order to make build up the pressure in the tank above the water bubble pressure and thereby increase the concentration of available carbon dioxide.
  • This injection period will be followed by a production and partial depletion of the deposit.
  • the hydrocarbons produced have increasing concentrations of acid gases. As we saw above, these gases are advantageously separated from the gas that can be reused elsewhere and reinjected into the deposit. If the gas processing and refining units are close to producing wells, gas and oil will be separated by successive detents in separator tanks S1, S2 (Fig. 3) located near the production area.

Abstract

A permanent control at the wellhead controls the flow rates of the aqueous phase and the gas forming the balancing fluid so gas is saturated or supersaturated at the bottom of the injection shaft The petroleum fluid is recovered by continuous injection into the deposit through an injector (IW) of a balancing fluid mad water with a gas added to it which is at least partially miscible with an aqueous phase and in the petroleum fluid. The balancin fluid is formed by mixing the aqueous phase with the gas at the bottom or the top of the injection shaft. A means of control pla in the shaft is used to increase the rate of dissolution of the gas in the aqueous phase and/or a packing is placed in the injec shaft to ensure the thorough mixing of the gas and the aqueous phase and/or a multi-phase pump is used to mix the gas and the aqueous phase. Data from detectors at the bottom of the shaft are used to control the flow so the gas is saturated. The gas cont an acid gas such as carbon dioxide or hydrogen sulfide. At least one treatment device is used to extract the effluents from the deposit, including at least part of the balancing fluid. At least part of the gaseous effluent from a thermal or chemical unit i used to form at least part of the gas, and the water from the deposit is used as all or part of the aqueous phase. A tensioactiv additive is added to the aqueous phase to improve the gas dispersion and/or an additive is added to the aqueous phase to improve gas solubility. Carbonized water is injected into shafts which are substantially sloped, horizontal or with complex geometry. Th petroleum fluid is recovered using a devious or complex shaft. Each shaft is local to the top of the deposit.

Description

La présente invention concerne un procédé de récupération assistée d'hydrocarbures par injection combinée d'eau et de gaz dans un gisement.The present invention relates to an enhanced recovery method of hydrocarbons by the combined injection of water and gas into a deposit.

Le procédé selon l'invention trouve des applications notamment pour améliorer le déplacement des fluides pétroliers vers les puits producteurs et de ce fait accroítre le taux de récupération des fluides valorisables, huile et gaz, initialement en place dans le massif rocheux.The method according to the invention finds applications in particular for improve the movement of petroleum fluids to producing wells and this increases the recovery rate of recoverable fluids, oil and gas, initially in place in the rock mass.

ART ANTERIEURPRIOR ART

Il existe de nombreux procédés de type dits primaire secondaire ou tertiaire pour récupérer des hydrocarbures dans des gisements.There are many so-called primary secondary or tertiary to recover hydrocarbons from deposits.

La récupération est dite primaire quand les fluides pétroliers sont produits sous la seule action de l'énergie présente in situ. Cette énergie peut résulter de la détente des fluides sous pression dans le gisement : détente de l'huile saturée ou non en gaz, expansion d'un chapeau de gaz au-dessus du gisement d'huile, ou d'un plan d'eau actif. Au cours de cette phase, si la pression dans le gisement descend au-dessous du point de bulle de l'huile, la phase gazeuse issue de l'huile contribuera à augmenter le taux de récupération. La récupération par drainage naturel dépasse rarement 20% des fluides initialement en place pour des huiles légères et est souvent inférieure à cette valeur pour les gisements d'huiles lourdes.Recovery is said to be primary when petroleum fluids are produced under the sole action of the energy present in situ. This energy can result from the expansion of pressurized fluids in the deposit: expansion of oil saturated or not in gas, expansion of a gas cap above the oil deposit, or an active body of water. During this phase, if the pressure in the deposit drops below the oil bubble point, the gas phase from the oil will help increase the recovery rate. Recovery by natural drainage rarely exceeds 20% of fluids initially in place for light oils and is often less than this value for heavy oil deposits.

Des méthodes de récupération secondaires sont utilisées pour éviter une baisse de pression trop importante dans le gisement. Le principe de ces méthodes consiste à apporter au gisement une énergie extérieure. Pour ce faire, des fluides sont injectés dans le gisement par un ou plusieurs puits injecteurs afin de déplacer les fluides pétroliers valorisables (ci-après désignés par " huile ") vers des puits de production. L'eau est fréquemment utilisée comme fluide de déplacement. Toutefois son efficacité est limitée. Une grande partie de l'huile reste en place du fait que notamment sa viscosité est supérieure à celle de l'eau. En outre, l'huile reste piégée dans les rétrécissements de pores de la formation en raison de la forte différence de tension interfaciale entre elle et l'eau. Enfin, le massif rocheux est fréquemment hétérogène. Dans ce contexte, l'eau injectée empruntera les chemins de plus grandes perméabilités pour atteindre les puits producteurs, en laissant de larges massifs d'huile non balayés. Ces phénomènes induisent une perte importante de récupération.Secondary recovery methods are used to avoid excessive pressure drop in the deposit. The principle of these methods is to bring external energy to the deposit. To do this, fluids are injected into the deposit by one or more injector wells in order to move the recoverable petroleum fluids (hereinafter designated by "oil") to production wells. Water is frequently used as displacement fluid. However, its effectiveness is limited. Much oil remains in place because in particular its viscosity is greater than that of water. In addition, the oil remains trapped in the pore narrowing of training due to the large difference in interfacial tension between it and water. Finally, the rock mass is frequently heterogeneous. In this context, the injected water will take the paths of greatest permeability to reach the producing wells, leaving large masses of oil not swept away. These phenomena induce a significant loss of recovery.

Un gaz sous pression peut également être injecté dans un gisement à des fins de récupération secondaire, le gaz a la propriété bien connue de déplacer des quantités non négligeables de pétrole. Toutefois, si la formation est hétérogène, le gaz étant beaucoup moins visqueux que l'huile et l'eau en place, il traversera le massif rocheux en n'empruntant que quelques chenaux les plus perméables et arrivera rapidement aux puits producteurs sans avoir l'effet de déplacement attendu.Pressurized gas can also be injected into a deposit at for secondary recovery, the gas has the well-known property of displacing significant amounts of oil. However, if the training is heterogeneous, the gas being much less viscous than the oil and water in place, it will cross the rocky massif using only a few of the most permeable and will arrive quickly at producing wells without having the effect of expected displacement.

Il est également connu de combiner des injections d'eau et de gaz suivant une méthode dite de WAG pour " Water Alternate Gas ". Selon cette méthode, l'eau et le gaz sont injectés successivement tant que les fluides pétroliers sont produits dans des conditions économiques. Le rôle des bouchons d'eau est de réduire la mobilité du gaz et accroítre la zone balayée. De nombreuses améliorations de cette technique sont proposées : l'ajout de tensioactifs à l'eau afin de décroítre la tension interfaciale eau - huile, l'ajout d'agent moussant dans l'eau : la mousse formée en présence du gaz réduira de façon significative la mobilité de ce dernier. Une telle méthode est par exemple décrite dans le brevet US N° 3,893,511. Par le brevet FR 2,735,524 du demandeur, on connaít également un procédé amélioré consistant à additionner à au moins un des bouchons d'eau injectés en alternance un agent diminuant la tension interfaciale entre l'eau et le gaz. Sous l'effet de cet agent, de l'alcool par exemple, l'huile ne peut s'étaler sur le film d'eau recouvrant le massif rocheux. L'huile reste sous forme de gouttelettes qui freinent le déplacement du gaz. Par le brevet FR 2 764 632 du demandeur, on connaít également un procédé comportant l'injection alternée de bouchons de gaz et de bouchons d'eau dans lequel au moins un des bouchons d'eau est additionné de gaz sous pression à la fois soluble dans l'eau et dans l'huile. L'étape de production comporte le relâchement de la pression régnant dans le gisement, de manière à générer des bulles de gaz qui vont chasser les hydrocarbures des pores du massif rocheux.It is also known to combine water and gas injections according to a method called WAG for "Water Alternate Gas". According to this method, water and gas are injected successively as long as the fluids tankers are produced under economic conditions. The role of water plugs is to reduce gas mobility and increase the swept area. Many improvements of this technique are proposed: the addition of water surfactants in order to decrease the water-oil interfacial tension, adding foaming agent in water: the foam formed in the presence of the gas will reduce significantly the mobility of the latter. One such method is by example described in US Patent No. 3,893,511. By patent FR 2,735,524 of the applicant, there is also known an improved method consisting in add an agent to at least one of the water plugs injected alternately reducing the interfacial tension between water and gas. Under the influence of this agent, alcohol for example, the oil cannot spread on the film of water covering the rocky massif. The oil remains in the form of droplets which brake the displacement of gas. By patent FR 2 764 632 of the applicant, we know also a process comprising the alternating injection of gas caps and water plugs in which at least one of the water plugs is added with pressurized gas both soluble in water and oil. The stage of production involves the release of the pressure prevailing in the deposit, so as to generate gas bubbles which will expel the hydrocarbons from pores of the rock mass.

Ces techniques de récupération secondaire conduisent à des taux de récupération de 25 à 50% de l'huile initialement en place.These secondary recovery techniques lead to rates of recovery of 25 to 50% of the oil initially in place.

La récupération tertiaire a pour objectif d'améliorer ce taux de récupération, quand la saturation résiduelle en huile est atteinte. On regroupe sous cette appellation l'injection dans le réservoir de gaz miscible, de micro émulsion, ou de vapeur ou encore la combustion in situ. Tertiary recovery aims to improve this rate of recovery, when the residual oil saturation is reached. We regroup under this name the injection into the miscible gas tank, of micro emulsion, or steam or in situ combustion.

La définition de ces techniques de récupération primaire, secondaire et tertiaire comme leur application chronologique lors de la mise en production d'un réservoir, datent de quelques années. On assiste actuellement à la mise en place de techniques de maintien de pression dès le début d'exploitation des réservoirs et d'injection de fluides antérieurement qualifiés de tertiaires avant un déclin prononcé de la pression initiale du réservoir.The definition of these primary, secondary and tertiary as their chronological application during the start of production of a reservoir, date back a few years. We are currently witnessing the implementation place of pressure maintenance techniques from the start of operation of tanks and injection of fluids previously qualified as tertiary before a pronounced decline in initial reservoir pressure.

Plus de 30 % des champs d'hydrocarbures mis en production contiennent des composés acides tels que CO2 et H2S. L'exploitation de ces champs nécessite la mise en place de procédés de traitement permettant de séparer les gaz valorisables des gaz acides. Le dioxyde de carbone issu de ces installations, est fréquemment rejeté à l'atmosphère, augmentant les perturbations climatiques et l'effet de serre. La gestion de l'hydrogène sulfuré est problématique de par la grande toxicité de ce gaz. Il sera généralement transformé en soufre solide par une chaíne Claus. Ce procédé demande un investissement élevé qui n'est pas rentabilisé à une époque où la production mondiale de soufre solide excède les besoins. La réinjection de ces gaz acides dans le gisement après solubilisation complète ou partielle dans une phase aqueuse, qui peut être tout ou partie de l'eau de production, de l'eau douce ou une saumure issue d'une nappe phréatique, de l'eau de mer ou autre, présente un double intérêt : se débarrasser des gaz acides à faible coût sans rejet atmosphérique polluant et accroítre la productivité du réservoir.More than 30% of the hydrocarbon fields put into production contain acid compounds such as CO 2 and H 2 S. The exploitation of these fields requires the implementation of treatment processes making it possible to separate the recoverable gases from the acid gases. Carbon dioxide from these facilities is frequently released to the atmosphere, increasing climatic disturbances and the greenhouse effect. The management of hydrogen sulfide is problematic due to the high toxicity of this gas. It will generally be transformed into solid sulfur by a Claus chain. This process requires a high investment which is not profitable at a time when the world production of solid sulfur exceeds the needs. The reinjection of these acid gases into the deposit after complete or partial solubilization in an aqueous phase, which may be all or part of the production water, fresh water or brine from a groundwater, seawater or other, has a double advantage: get rid of low-cost acid gases without polluting atmospheric discharge and increase the productivity of the tank.

DEFINITION DE L'INVENTIONDEFINITION OF THE INVENTION

Le procédé de récupération assistée d'un fluide pétrolier produit par un gisement selon l'invention vise, par une injection combinée d'une phase aqueuse et de gaz venant d'une source extérieure ou, dans la mesure du possible, au moins en partie de gaz acides provenant des effluents issus du gisement lui-même, à augmenter le taux de récupération des hydrocarbures.The process of enhanced recovery of a petroleum fluid produced by a deposit according to the invention aims, by a combined injection of a phase water and gas from an external source or, to the extent of possible, at least in part from acid gases from effluents from deposit itself, to increase the rate of recovery of hydrocarbons.

Le procédé comporte l'injection continue par un puits d'injection d'un fluide de balayage constitué d'une phase aqueuse additionnée de gaz au moins partiellement miscible dans l'eau et dans le fluide pétrolier, avec un contrôle permanent en tête du puits d'injection, du rapport des débits de cette phase aqueuse et de gaz formant le fluide de balayage pour que, en fond du puits d'injection, le gaz y soit en état de saturation ou de sursaturationThe method includes continuous injection through an injection well a sweeping fluid consisting of an aqueous phase with gas added to it less partially miscible in water and in petroleum fluid, with a permanent control at the top of the injection well, of the flow rate report for this aqueous and gas phase forming the sweeping fluid so that, at the bottom of the injection well, the gas is there in a saturation or supersaturation state

Le fluide de balayage peut être formé soit en fond de puits avec acheminement séparé des constituants jusqu'à la zone d'injection, soit en tête de puitsThe sweeping fluid can be formed either at the bottom of the well with separate routing of the constituents to the injection zone, i.e. at the top well

On peut utiliser un moyen disposé dans le puits d'injection pour créer une perte de charge tel qu'une vanne ou une restriction de conduit et ainsi augmenter le taux de dissolution du gaz dans l'eau. Un garnissage placé dans le puits d'injection afin de mélanger intimement le gaz et la phase aqueuse du fluide de balayage, augmente également la perte de charge et le taux de dissolution.We can use a means arranged in the injection well to create a pressure drop such as a valve or a pipe restriction and so increase the rate of dissolution of gas in water. A packing placed in the injection well in order to thoroughly mix the gas and the aqueous phase of the sweeping fluid, also increases the pressure drop and the rate of dissolution.

Suivant un mode de mise en oeuvre, on utilise une pompe polyphasique de type rotodynamique par exemple pour comprimer le gaz, pressuriser la phase aqueuse et former un mélange intime entre cette phase aqueuse et de gaz sous pression avant de l'injecter dans le puits d'injection.According to an embodiment, a pump is used multiphase rotodynamic type for example to compress the gas, pressurize the aqueous phase and form an intimate mixture between this phase water and gas under pressure before injecting it into the injection well.

Pour bien s'assurer que le gaz est au moins en condition de saturation (et de préférence en sursaturation en fond de puits), on utilise de préférence des données produites de capteurs d'état en fond de puits (capteurs de pression, capteurs de température, etc., installés à demeure) pour contrôler que le gaz du fluide de balayage est au moins en état de complète saturationTo make sure that the gas is at least in saturation condition (and preferably in supersaturation at the bottom of the well), preferably used data produced from downhole condition sensors ( pressure, temperature sensors, etc. permanently installed) to check that the gas of the sweeping fluid is at least in a state of complete saturation

Le gaz dans le fluide de balayage contient au moins un gaz acide tel que du dioxyde de carbone et / ou de l'hydrogène sulfuré et éventuellement, dans des proportions variables, d'autre gaz : du méthane, de l'azote, etc. Ces gaz peuvent être prélevés dans les effluents issus d'un gisement, opération réalisée par une unité de traitement adaptée à les séparer d'autres gaz valorisables par ailleurs ou bien provenir d'unités chimiques ou d'unités thermiques brûlant de la lignite, du charbon, du fioul, du gaz naturel etc.The gas in the sweeping fluid contains at least one acid gas such as than carbon dioxide and / or hydrogen sulfide and optionally, in varying proportions, other gas: methane, nitrogen, etc. These gases can be taken from the effluents from a deposit, operation carried out by a processing unit adapted to separate them from other gases otherwise recoverable or come from chemical units or units thermal burning lignite, coal, fuel oil, natural gas etc.

La phase aqueuse utilisée pour former le fluide de balayage peut être par exemple de l'eau issue d'un gisement souterrain (une nappe phréatique par exemple ou une saumure produite durant l'exploitation d'un gisement) ou tout autre eau facilement disponible (eau de mer).The aqueous phase used to form the sweeping fluid can be for example water from an underground deposit (a water table by example or brine produced during the exploitation of a deposit) or any other readily available water (seawater).

Suivant un autre mode de mise en oeuvre, on ajoute à la phase aqueuse un additif tensioactif pour y favoriser la dispersion du gaz et/ou un ou plusieurs additifs pour augmenter la solubilité du gaz dans le fluide de balayage.According to another mode of implementation, the aqueous phase is added a surfactant additive to promote the dispersion of the gas therein and / or one or several additives to increase the solubility of the gas in the scanning.

Suivant un autre mode de mise en oeuvre, le fluide de balayage est injecté par exemple dans un ou plusieurs puits de fort déport, horizontaux ou de géométrie complexe localisé par exemple à la base du gisement .et le fluide pétrolier est produit par exemple par un ou plusieurs puits déviés ou de géométrie complexe pouvant être localisé au toit du gisement.According to another embodiment, the sweeping fluid is injected, for example, into one or more wells, horizontal or of complex geometry located for example at the base of the deposit .and the fluid tanker is produced for example by one or more deviated wells or complex geometry that can be located on the roof of the deposit.

Le procédé peut être mis en oeuvre dès le début de l'exploitation du gisement. La phase aqueuse injectée préférentiellement en périphérie de la zone productrice, balaie le milieu poreux contenant les hydrocarbures à récupérer. Dans les premiers temps de cette circulation, le dioxyde de carbone, beaucoup plus soluble dans l'huile que dans l'eau injectée, passe du fluide de balayage au fluide pétrolier provoquant son gonflement et diminuant sa viscosité. Ces deux phénomènes favorisent un accroissement de la récupération des hydrocarbures en place. Lorsque le fluide approche des puits de production, sa pression chute, sous l'effet conjugué des pertes de charges liées à l'écoulement et de la déplétion naturelle du gisement. Si la pression est inférieure à la pression de bulle de l'eau contenant le gaz solubilisé, des bulles de gaz vont se former par nucléation dans les pores du massif rocheux, en chassant l'huile qui s'y trouve vers les zones les plus perméables où elle sera balayée. Ce dernier phénomène non seulement accroít le taux de récupération global de l'huile en place mais diminue le temps nécessaire pour atteindre un taux de récupération donné.The process can be implemented from the start of the operation of the deposit. The aqueous phase preferably injected at the periphery of the producing area, sweeps the porous medium containing the hydrocarbons to recover. In the early days of this circulation, carbon dioxide, much more soluble in oil than in injected water, passes fluid sweeping with petroleum fluid causing it to swell and reducing its viscosity. These two phenomena promote an increase in recovery of hydrocarbons in place. When the fluid approaches the wells pressure drops, under the combined effect of pressure drops related to the flow and natural depletion of the deposit. If the pressure is below the bubble pressure of the water containing the dissolved gas, bubbles gas will form by nucleation in the pores of the rock mass, in chasing the oil there to the most permeable areas where it will be swept. The latter phenomenon not only increases the recovery rate overall oil in place but decreases the time required to reach a given recovery rate.

L'invention concerne également un système de récupération assistée d'un fluide pétrolier extrait d'un gisement, par injection continue dans le gisement d'un fluide de balayage constitué d'une phase aqueuse additionnée de gaz au moins partiellement miscible dans la phase aqueuse et dans le fluide pétrolier, qui comporte un ensemble de conditionnement du fluide de balayage et une unité de contrôle permanent de l'ensemble de conditionnement adapté à contrôler le rapport des débits de cette phase aqueuse et de gaz formant le fluide de balayage parvenu en fond de puits, pour que le gaz y soit en état de saturation ou de sursaturation. De préférence, le système comporte des capteurs d'état disposés dans la zone d'injection pour mesurer des paramètres thermodynamiques et reliés à l'unité de contrôle. The invention also relates to an assisted recovery system. of a petroleum fluid extracted from a deposit, by continuous injection into the deposit of a sweeping fluid consisting of an added aqueous phase gas at least partially miscible in the aqueous phase and in the fluid tanker, which includes a set for conditioning the sweeping fluid and a permanent control unit for the packaging unit adapted to control the ratio of the flow rates of this aqueous phase and of the gases forming the sweeping fluid reached the bottom of the well, so that the gas is in a state of saturation or supersaturation. Preferably, the system includes status sensors arranged in the injection area to measure parameters thermodynamic and connected to the control unit.

D'autres caractéristiques et avantages du procédé selon l'invention, apparaítront à la lecture de la description ci-après d'exemples non limitatifs de mise en oeuvre, en se référant aux dessins annexés où :

  • la Fig.1 montre un premier mode de mise en oeuvre du procédé où le fluide de balayage est formé en fond de puits dans la zone d'injection ;
  • la Fig.2 montre un deuxième mode de mise en oeuvre du procédé où le fluide de balayage est formé en surface ; et
  • la Fig.3 montre un mode de mise en oeuvre où le gaz dans le fluide de balayage, est constitué de fractions acides de gaz issus du sous-sol ou produits par des unités de traitement chimiques ou d'unités thermiques brûlant des matériaux divers.
Other characteristics and advantages of the method according to the invention will appear on reading the following description of nonlimiting examples of implementation, with reference to the accompanying drawings in which:
  • Fig.1 shows a first embodiment of the method where the sweeping fluid is formed at the bottom of the well in the injection zone;
  • Fig.2 shows a second embodiment of the method where the sweeping fluid is formed on the surface; and
  • Fig.3 shows an embodiment where the gas in the sweeping fluid, consists of acid fractions of gas from the subsoil or produced by chemical treatment units or thermal units burning various materials.

Description détaillée :Detailed description :

Le procédé de récupération faisant l'objet de la présente invention comprend quatre étapes :The recovery process which is the subject of the present invention includes four steps:

1. La préparation du fluide de balayage.1. The preparation of the sweeping fluid.

Bien que ceci ne soit pas limitatif, on utilise de préférence des gaz facilement disponibles non valorisés par ailleurs tels que le dioxyde de carbone CO2 ou le sulfure d'hydrogène, SH2.Although this is not limiting, it is preferable to use readily available gases which are not otherwise valued, such as carbon dioxide CO 2 or hydrogen sulfide, SH 2 .

Le dioxyde de carbone mélangé à la phase aqueuse (ci-après désignée par eau) réagit suivant la réaction équilibrée : CO2 + H2O ↔ H2CO3    donnant de l'acide carbonique. La solubilité du dioxyde de carbone dans l'eau dépend de la salinité de l'eau, de la température et de la pression. Le taux de dissolution du CO2 augmente avec la pression et diminue avec la température. Dans le domaine de pression et température rencontré pour les applications d'injection, typiquement une pression variant de 75 à 300 bars (7,5 à 30 Mpa) et une température variant de 50 à 100°C, l'effet de la pression est prépondérant. En d'autres termes, le taux de dissolution du dioxyde de carbone au fond d'un puits d'injection est supérieur au taux de dissolution en surface et ce malgré l'augmentation de température due au gradient géothermal.The carbon dioxide mixed with the aqueous phase (hereinafter referred to as water) reacts according to the balanced reaction: CO 2 + H 2 O ↔ H 2 CO 3 giving carbonic acid. The solubility of carbon dioxide in water depends on the salinity of the water, the temperature and the pressure. The CO 2 dissolution rate increases with pressure and decreases with temperature. In the pressure and temperature range encountered for injection applications, typically a pressure varying from 75 to 300 bar (7.5 to 30 Mpa) and a temperature varying from 50 to 100 ° C, the effect of pressure is preponderant. In other words, the rate of dissolution of carbon dioxide at the bottom of an injection well is higher than the rate of dissolution on the surface, despite the increase in temperature due to the geothermal gradient.

A des pressions inférieures à 100 bars, le CO2 se dissout moins dans l'eau salée que dans l'eau pure. A une pression supérieure, la salinité affecte beaucoup moins la solubilité du gaz. Dans l'eau pure, sous une pression de 150 bars (15Mpa) et pour une température de 70 °C, la solubilité du CO2 sera d'environ 4.5% poids (45 kg de CO2 sont dissous dans 1m3 d'eau). La dissolution du gaz acide dans l'eau entraíne une augmentation de sa viscosité, ce qui améliore le rapport de mobilité eau / huile. Le taux de dissolution de l'hydrogène sulfuré dans l'eau est supérieur, approximativement d'un facteur 2, à celui du dioxyde de carbone, quelles que soient la température, la pression et la composition de la phase aqueuse. À titre d'exemple, sous une pression de 150 bars et pour une température de 70°C, la solubilité de l'H2S sera d'environ 8.3% poids (83 kg de H2S sont dissous dans 1 m3 d'eau). Les gaz acides issus de la production pétrolière contiennent majoritairement du dioxyde de carbone, c'est la solubilité de ce gaz qui sera limitative quand le mélange sera dissous dans un fluide aqueux.At pressures below 100 bars, CO 2 dissolves less in salt water than in pure water. At higher pressure, salinity affects the solubility of the gas much less. In pure water, under a pressure of 150 bars (15Mpa) and for a temperature of 70 ° C, the solubility of CO 2 will be approximately 4.5% by weight (45 kg of CO 2 are dissolved in 1m 3 of water ). The dissolution of the acid gas in water causes an increase in its viscosity, which improves the water / oil mobility ratio. The dissolution rate of hydrogen sulfide in water is higher, approximately by a factor of 2, than that of carbon dioxide, whatever the temperature, the pressure and the composition of the aqueous phase. For example, under a pressure of 150 bars and for a temperature of 70 ° C, the solubility of H 2 S will be approximately 8.3% by weight (83 kg of H 2 S are dissolved in 1 m 3 d 'water). Acid gases from petroleum production mainly contain carbon dioxide, it is the solubility of this gas which will be limiting when the mixture is dissolved in an aqueous fluid.

2. Injection du fluide de balayage2. Injection of the sweeping fluid

Un point important qui rend le procédé selon l'invention particulièrement efficace dans le balayage d'un gisement, c'est que le fluide de balayage est injecté de telle sorte qu'en fond de puits, dans la zone d'injection, la solution d'eau injectée soit au moins saturée et de préférence sursaturée en gaz.An important point which makes the process according to the invention particularly effective in sweeping a deposit is that the sweep is injected so that at the bottom of the well, in the injection zone, the injected water solution is at least saturated and preferably supersaturated in gas.

Les volumes de gaz acides et d'eau susceptibles d'être réinjectés dans le gisement peuvent être disponibles dans un ratio très supérieur au rapport de solubilité du gaz acide dans l'eau. Ce ratio peut évoluer au cours de l'exploitation ou au gré des contraintes de production. L'augmentation de la pression en fond de puits d'injection est partiellement compensée par une augmentation de la température liée au gradient géothermal. Toutefois, l'effet de la pression est généralement plus important, d'autant plus que le fluide injecté n'atteint pas en écoulement les conditions d'équilibre thermique.The volumes of acid gases and water likely to be reinjected into the deposit may be available in a ratio much higher than the ratio of solubility of acid gas in water. This ratio may change during exploitation or according to production constraints. The increase in pressure at the bottom of the injection well is partially compensated by a increase in temperature linked to the geothermal gradient. However, the effect pressure is generally higher, especially as the fluid injected does not reach flow conditions of thermal equilibrium.

Pour que cette condition de saturation ou de sursaturation en fond de puits soit respectée en permanence, on va donc utiliser un système d'injection qui peut être disposé tout entier en surface ou bien comporter aussi des éléments en fond de puits.For this condition of saturation or supersaturation at the bottom of well is respected at all times, so we will use an injection system which can be placed entirely on the surface or also include elements at the bottom of the well.

Suivant le mode de mise en oeuvre schématisé à la Fig.1, le fluide de balayage est produit par un ensemble de conditionnement PA et ses constituants, amenés séparément dans la zone d'injection en fond de puits. Le gaz est comprimé par un compresseur 1 et injecté par un tube d'injection 2 jusqu'au fond du puits d'injection IW, alors que l'eau issue d'une pompe 3, est injectée dans l'espace annulaire 4 entre le cuvelage et le tube d'injection 1. Le mélange entre les deux phases s'effectue sous la garniture d'étanchéité 5 au droit de la zone d'injection. Les pressions d'injection du compresseur 1 et de la pompe 3 sont déterminées par un dispositif de contrôle 6. According to the mode of implementation shown diagrammatically in FIG. 1, the fluid scanning is produced by a PA packaging unit and its constituents, brought separately to the injection area at the bottom of the well. The gas is compressed by a compressor 1 and injected by an injection tube 2 to the bottom of the IW injection well, while the water from a pump 3 is injected into the annular space 4 between the casing and the injection tube 1. The mixing between the two phases is carried out under the seal 5 at right of the injection area. The injection pressures of compressor 1 and the pump 3 are determined by a control device 6.

Suivant un mode de réalisation préféré, l'injection de gaz requérant une forte pression en tête de puits, on préfère réaliser le mélange en surface avant de l'injecter. Cette injection simultanée permet d'accroítre le poids de la colonne liquide dans le puits d'injection, et de réduire sensiblement la pression de gaz nécessaire. Pour obtenir la condition requise de saturation et de préférence de sursaturation en fond de puits, il faut que le mélange réalisé en tête de puits soit fortement sursaturé en gaz acides et particulièrement homogène, le gaz étant dispersé dans la phase liquide.According to a preferred embodiment, the injection of gas requiring a high pressure at the wellhead, we prefer to mix the surface before to inject it. This simultaneous injection increases the weight of the liquid column in the injection well, and significantly reduce the pressure gas required. To obtain the required saturation and preferably supersaturation at the bottom of the well, the mixture produced in wellhead is strongly supersaturated with acid gases and particularly homogeneous, the gas being dispersed in the liquid phase.

On peut utiliser à cet effet (Fig.2) un dispositif de compression et pompage conventionnel connu des spécialistes, pour l'injection du fluide de balayage en condition de saturation ou sursaturation en fond de puits. Dans ce cas, les gaz acides sont comprimés dans un compresseur 1 par étapes successives et refroidis entre deux sections de compression. En parallèle, l'eau est pressurisée par une pompe 3 à une pression égale à celle appliquée par le compresseur 1. Le gaz et le liquide sont ensuite introduits dans un mélangeur statique ou dynamique 7 ayant une efficacité suffisante pour permettre la dispersion totale du gaz dans le liquide. En aval du mélangeur 7, le mélange peut être comprimé par une pompe supplémentaire 8 pour permettre, soit la dissolution d'une quantité supplémentaire de gaz, soit l'injection du fluide de balayage dans le puits IW. Les gaz acides, chauffés au cours de la compression, peuvent par exemple être refroidis, au moyen d'échangeurs de chaleur (non représentés) avant leur introduction dans le mélangeur 7 de façon à favoriser leur dissolution.A compression device can be used for this purpose (Fig. 2) and conventional pumping known to specialists, for injecting the scanning under saturation or supersaturation at the bottom of the well. In this case, the acid gases are compressed in a compressor 1 in stages successive and cooled between two compression sections. At the same time, the water is pressurized by a pump 3 at a pressure equal to that applied by the compressor 1. The gas and the liquid are then introduced into a mixer static or dynamic 7 having sufficient efficiency to allow the total dispersion of the gas in the liquid. Downstream of the mixer 7, the mixture can be compressed by an additional pump 8 to allow either dissolution of an additional quantity of gas, i.e. the injection of the scanning in the IW well. Acid gases, heated during the compression, can for example be cooled, by means of heat exchangers heat (not shown) before their introduction into the mixer 7 so to favor their dissolution.

Une pompe polyphasique de type rotodynamique peut avantageusement remplacer une chaíne conventionnelle de réinjection et remplir les trois fonctions : comprimer le gaz, pressuriser la phase liquide et mélanger intimement les deux phases. Une pompe polyphasique rotodynamique convenant pour ce type d'application, est décrite dans les brevets FR 2 665 224 (US 5 375 976) du demandeur ou FR 2 771 024 du demandeur. De par sa conception, ce type de pompe peuvent injecter dans un puits un mélange diphasique composé d'eau carbonatée saturée et d'un excès de dioxyde de carbone gazeux sans problème de cavitation.A multiphase pump of the rotodynamic type can advantageously replace a conventional reinjection chain and fill the three functions: compress the gas, pressurize the liquid phase and mix intimately the two phases. A rotodynamic multiphase pump suitable for this type of application, is described in patents FR 2,665,224 (US 5,375,976) of the applicant or FR 2,771,024 of the applicant. By its design, this type of pump can inject a mixture into a well diphasic composed of saturated carbonated water and an excess of carbon gas without cavitation problem.

Il est également possible d'introduire une perte de charge supplémentaire dans la conduite d'injection sous forme d'une vanne de laminage ou d'une restriction du conduit d'injection. Suivant un mode particulier de mise en oeuvre, on place également un garnissage dans le puits d'injection IW pour d'améliorer le mélange des constituants tout en induisant une perte de charge supplémentaire.De préférence, on utilise dans l'un et l'autre cas des capteurs d'état (non représentés) descendus jusqu'en fond de puits, dans la zone d'injection, pour mesurer différents paramètres thermodynamiques : pressions, températures etc., et reliés au dispositif de contrôle 6. Un système de transmission adapté à transmettre en surface des signaux issus de capteurs permanents installés à demeure dans des puits pour surveiller un gisement, et notamment de capteurs d'état permettant de connaítre par exemple les températures et pressions régnant en fond de puits, est décrit notamment dans le brevet US 5,363,094 du demandeur. Le dispositif de contrôle 6 ajuste les débits et leur ratio dans ce cas en fonction des conditions régnant in situ.It is also possible to introduce a pressure drop additional in the injection line in the form of a shut-off valve lamination or restriction of the injection pipe. According to a mode particular implementation, a lining is also placed in the well IW injection to improve the mixture of constituents while inducing an additional pressure drop, preferably in one and the other case of the state sensors (not shown) lowered to the bottom of well, in the injection area, to measure different parameters thermodynamics: pressures, temperatures etc., and linked to the control 6. A transmission system adapted to transmit surface signals from permanent sensors permanently installed in wells to monitor a deposit, and in particular state sensors allowing know for example the temperatures and pressures prevailing at the bottom of the well, is described in particular in US patent 5,363,094 of the applicant. The device control 6 adjusts the flow rates and their ratio in this case according to the conditions prevailing in situ.

Suivant le mode de mise en oeuvre schématisé à la Fig.3, le système est adapté à former un mélange saturé ou sursaturé au moins en partie à par recombinaison contrôlée d'effluents pompés hors du gisement par un ou plusieurs puits de production du gisement PW. Ces effluents comprennent généralement une phase liquide constituée d'eau et d'huile, et une phase gazeuse. Les effluents passent donc dans un séparateur eau-huile-gaz S1. La phase gazeuse, éventuellement complétée par des apports extérieurs, traverse un séparateur S2 destiné à séparer les gaz récupérables par ailleurs pour d'autres applications, des gaz acides que l'on veut recycler. L'eau issue du séparateur S1, est ensuite recombinée avec les gaz acides récupérés dans un dispositif M de mélange contrôlé, de manière à former le mélange saturé ou sursaturé dans les conditions régnant en fond de puits.According to the mode of implementation shown diagrammatically in FIG. 3, the system is adapted to form a saturated or supersaturated mixture at least in part through controlled recombination of effluents pumped out of the deposit by one or several production wells from the PW deposit. These effluents include generally a liquid phase consisting of water and oil, and a phase carbonated. The effluents therefore pass through a water-oil-gas separator S1. The gas phase, possibly supplemented by external contributions, crosses a separator S2 intended to separate the recoverable gases moreover for other applications, acid gases that we want to recycle. Water from separator S1, is then recombined with the acid gases recovered in a controlled mixing device M, so as to form the saturated mixture or supersaturated under the conditions prevailing at the bottom of the well.

Si la pression nécessaire pour injecter le fluide dans le massif poreux est inférieure à la pression de liquéfaction du CO2, une phase liquide et une phase gazeuse seront présentes dans le puits d'injection. L'utilisateur doit veiller à ce que la dispersion du gaz soit maximale et que les bouchons de gaz circulant dans le puits d'injection soient entraínés par la colonne liquide en fond de puits, en d'autres termes que la vitesse liquide soit supérieure à la vitesse de remontée des bouchons gazeux afin d'éviter la ségrégation dans le puits d'injection.If the pressure required to inject the fluid into the porous mass is less than the CO 2 liquefaction pressure, a liquid phase and a gaseous phase will be present in the injection well. The user must ensure that the dispersion of the gas is maximum and that the gas plugs circulating in the injection well are entrained by the liquid column at the bottom of the well, in other words that the liquid speed is greater than the ascent rate of the gas plugs in order to avoid segregation in the injection well.

Il est également possible que la pression nécessaire pour injecter le fluide dans le massif poreux, soit supérieure à la pression de liquéfaction du CO2. Le gaz liquéfié sera intimement mélangé à l'eau et une émulsion formée de fines gouttelettes de gaz liquéfié dans l'eau sera alors injectée.It is also possible that the pressure required to inject the fluid into the porous mass is greater than the liquefaction pressure of CO 2 . The liquefied gas will be intimately mixed with the water and an emulsion formed of fine droplets of liquefied gas in the water will then be injected.

De préférence, on ajoute à la phase aqueuse une faible proportion d'agent tensioactif favorisant la dispersion des bulles de gaz. Pour réduire l'excès de gaz par rapport aux conditions de saturation prévalant en surface, il est intéressant d'augmenter la solubilité du dioxyde de carbone dans l'eau en ajoutant dans cette dernière des additifs favorisant sa dissolution tels que du monoéthanol amine, de la diéthanol amine, de l'ammoniac, du carbonate de sodium, du carbonate de potassium, de l'hydroxyde de sodium ou de potassium, des phosphates de potassium, de la diamino-isopropanol, du méthyl diéthanol amine, du tri-éthanol amine et autres bases faibles. La concentration de ces additifs dans l'eau peut varier de 10 à 30 % en poids. On vérifie qu'un agent de solubilité tel que le mono-éthanol amine ajouté à de l'eau dans la proportion de 15% en poids, augmente par exemple d'un facteur 7 la solubilité du CO2 dans l'eau. Les puits d'injection peuvent être des puits verticaux ou horizontaux. En règle générale, si le réservoir est peu épais, il peut être avantageux de mettre en oeuvre l'injection d'eau carbonatée dans des puits de fort déport ou dans des puits horizontaux. La phase aqueuse peut être injectée à la base du réservoir à drainer au moyen d'un ou de plusieurs puits horizontaux et la phase hydrocarbure liquide peut être soutirée au toit du réservoir au moyen d'un ou plusieurs puits horizontaux. Pour des réservoirs de forte épaisseur les puits d'injection et de production seront verticaux, et le balayage des hydrocarbures en place sera parallèle aux limites du réservoir. Des puits de géométrie plus complexe peuvent être utilisés sans sortir du cadre de la présente invention.Preferably, a small proportion of surfactant is added to the aqueous phase, promoting the dispersion of the gas bubbles. To reduce the excess gas compared to the saturation conditions prevailing on the surface, it is advantageous to increase the solubility of carbon dioxide in water by adding additives promoting its dissolution such as monoethanol amine, diethanol amine, ammonia, sodium carbonate, potassium carbonate, sodium or potassium hydroxide, potassium phosphates, diamino-isopropanol, methyl diethanol amine, tri-ethanol amine and other weak bases. The concentration of these additives in water can vary from 10 to 30% by weight. It is verified that a solubility agent such as mono-ethanol amine added to water in the proportion of 15% by weight, increases for example by a factor of 7 the solubility of CO 2 in water. The injection wells can be vertical or horizontal wells. As a general rule, if the tank is not very thick, it may be advantageous to carry out the injection of carbonated water in wells with large offset or in horizontal wells. The aqueous phase can be injected at the base of the tank to be drained by means of one or more horizontal wells and the liquid hydrocarbon phase can be drawn off from the roof of the tank by means of one or more horizontal wells. For thick tanks the injection and production wells will be vertical, and the sweeping of the hydrocarbons in place will be parallel to the limits of the tank. Wells of more complex geometry can be used without departing from the scope of the present invention.

3. Balayage du réservoir3. Tank sweep

Le principe de récupération selon l'invention permet de fournir au gisement une énergie supplémentaire. Les bénéfices de l'injection simultanée d'eau et de gaz acides sont nombreux.The recovery principle according to the invention makes it possible to provide the deposit additional energy. The benefits of simultaneous injection water and acid gases are plentiful.

L'eau carbonatée solubilise les carbonates solubles présents dans la roche, calcite et dolomite, en formant des bicarbonates solubles selon les réactions : Ca CO3 + H2CO3 ↔ Ca (HCO3)2 Mg CO3 + H2CO3 ↔ Mg (HCO3)2 Carbonated water solubilizes the soluble carbonates present in the rock, calcite and dolomite, by forming soluble bicarbonates according to the reactions: Ca CO 3 + H 2 CO 3 ↔ Ca (HCO 3 ) 2 Mg CO 3 + H 2 CO 3 ↔ Mg (HCO 3 ) 2

Cette dissolution partielle des carbonates provoque une augmentation de la perméabilité du milieu poreux, qu'il s'agisse d'un grès, dans lequel la dissolution va attaquer les ciments et dépôts calciques fréquemment présents autour des grains de quartz, ou d'une formation calcaire dans laquelle la connexion poreuse sera améliorée. Le gain de perméabilité résultant de la dissolution des carbonates peut être notable, comme il est bien connu des spécialistes.This partial dissolution of carbonates causes an increase the permeability of the porous medium, whether it is sandstone, in which the dissolution will attack the cements and calcium deposits frequently present around the quartz grains, or a limestone formation in which the porous connection will be improved. The gain in permeability resulting from the dissolution of carbonates may be notable, as is well known to specialists.

Il est également connu que l'eau carbonatée prévient le gonflement des argiles fréquemment présentes dans les réservoirs pétroliers. Cet effet est particulièrement sensible pour les argiles dont l'ion de base est le sodium. La dissolution du calcium a aussi une influence sur la stabilisation des argiles à ions sodium par le remplacement du sodium par le calcium qui donne des argiles plus stables résistant à l'écoulement sans se déliter et colmater le milieu poreux.Carbonated water is also known to prevent swelling of clays frequently present in petroleum reservoirs. This effect is particularly sensitive for clays whose basic ion is sodium. The dissolution of calcium also has an influence on the stabilization of clays at sodium ions by replacing sodium with calcium which gives more stable clays resistant to flow without disintegrating and clogging the porous medium.

La viscosité de l'eau augmente lorsque le CO2 s'y dissout. Le volume de cette eau carbonatée augmente de 2 à 7% selon la concentration de gaz dissous et sa masse volumique diminue légèrement. L'effet global de la diminution du contraste de masse volumique entre l'eau et l'huile réduit les risques de ségrégation par gravité. En même temps, le rapport de mobilité eau / huile est amélioré par la diminution du rapport des viscosités huile / eau. Ces faits contribuent à améliorer sensiblement l'efficacité du balaye de l'huile par l'eau.The viscosity of water increases when the CO 2 dissolves in it. The volume of this carbonated water increases from 2 to 7% depending on the concentration of dissolved gas and its density decreases slightly. The overall effect of decreasing the density contrast between water and oil reduces the risk of segregation by gravity. At the same time, the water / oil mobility ratio is improved by the decrease in the oil / water viscosity ratio. These facts help to significantly improve the efficiency of oil sweeps through water.

Le dioxyde de carbone est beaucoup moins soluble dans l'eau que dans les huiles de gisement. Cette solubilité est fonction de la pression, la température et les caractéristiques de l'huile. Sous certaines conditions, le dioxyde de carbone peut être partiellement ou totalement miscible avec les hydrocarbures. Lorsqu'il est injecté dans le gisement sous forme d'eau carbonatée, le dioxyde de carbone va passer préférentiellement de l'eau à l'huile.Carbon dioxide is much less soluble in water than in deposit oils. This solubility is a function of the pressure, the oil temperature and characteristics. Under certain conditions, the carbon dioxide may be partially or completely miscible with hydrocarbons. When injected into the deposit as water carbonate, carbon dioxide will preferentially pass from water to oil.

La dissolution du dioxyde de carbone dans l'huile provoque un accroissement important de son volume. Pour un même taux de dissolution du dioxyde de carbone, ce phénomène sera plus sensible pour les huiles légères que pour les huiles lourdes.The dissolution of carbon dioxide in the oil causes a significant increase in its volume. For the same dissolution rate of the carbon dioxide, this phenomenon will be more sensitive for light oils than for heavy oils.

La dissolution du dioxyde de carbone dans l'huile provoque également une diminution de sa viscosité. Cette diminution sera plus importante quand la quantité de CO2 augmentera. Une huile ayant initialement une forte viscosité sera plus sensible au phénomène. A titre d'exemple, une huile de densité 12.2 API (0.99 g/cm3) et ayant une viscosité de 900 mPa.s à pression ambiante et une température de 65°C verra sa viscosité diminuer à 40 mPa.s sous une pression de 150 bars de CO2. Dans des conditions identiques une viscosité d'une huile de densité 20 API (0.93 g/cm3), chutera de 6 à 0.5 mPa.s.The dissolution of carbon dioxide in the oil also causes a decrease in its viscosity. This decrease will be greater when the amount of CO 2 increases. An oil having initially a high viscosity will be more sensitive to the phenomenon. For example, an oil with a density of 12.2 API (0.99 g / cm 3 ) and having a viscosity of 900 mPa.s at ambient pressure and a temperature of 65 ° C will see its viscosity decrease to 40 mPa.s under pressure of 150 bars of CO 2 . Under identical conditions, the viscosity of an oil with a density of 20 API (0.93 g / cm 3 ) will drop from 6 to 0.5 mPa.s.

Le gonflement de l'huile comme la baisse de sa viscosité, favorise un accroissement de la récupération des hydrocarbures initialement en place dans le gisement. Ils permettent également d'accélérer le processus de récupération des hydrocarbures.The swelling of the oil, like the drop in its viscosity, promotes increased recovery of hydrocarbons initially in place in the deposit. They also speed up the recovery process hydrocarbons.

L'eau carbonatée est au moins saturée en CO2 lors de son injection dans le réservoir. Dans le milieu poreux, la pression du fluide injecté va chuter à cause des pertes de charge liées à l'écoulement. Quand la pression sera inférieure à la pression de bulle de l'eau contenant le gaz solubilisé, du gaz sera libéré. La nucléation des bulles de dioxyde de carbone va se produire de préférence au contact de la roche et spécifiquement dans les zones présentant une forte concentration d'interfaces roche / liquides. Ces zones correspondent aux massifs de faible perméabilité ; le grossissement et la migration des bulles de gaz vont chasser l'huile se trouvant piégée dans les pores de faible diamètre de la roche. Ce phénomène augmente sensiblement le taux des hydrocarbures mobilisés lors de la production.The carbonated water is at least saturated with CO 2 when it is injected into the tank. In the porous medium, the pressure of the injected fluid will drop due to the pressure losses linked to the flow. When the pressure is lower than the bubble pressure of the water containing the solubilized gas, gas will be released. The nucleation of carbon dioxide bubbles will preferably occur in contact with the rock and specifically in areas with a high concentration of rock / liquid interfaces. These zones correspond to massifs of low permeability; the enlargement and migration of the gas bubbles will expel the oil which is trapped in the small diameter pores of the rock. This phenomenon significantly increases the rate of hydrocarbons mobilized during production.

Le procédé de récupération tel qu'il est décrit ci-dessus, trouve une application avantageuse lors de la mise en production de gisement présentant un double système de porosité tel que les gisements fissurés. Une représentation simple de ces gisements est un ensemble de blocs de roche de taille décimétriques ou métriques présentant des pores de faibles diamètres et saturés en huile, reliés entre eux par un réseau de fissures offrant un passage à l'écoulement des fluides de quelques dizaines de micromètres en moyenne.The recovery process as described above finds a advantageous application when bringing into production a deposit a double porosity system such as cracked deposits. A simple representation of these deposits is a set of rock blocks from decimetric or metric sizes with pores of small diameters and saturated in oil, linked together by a network of cracks providing a passage to the flow of fluids of a few tens of micrometers on average.

On peut typiquement distinguer deux types de réservoirs fissurés : les réservoirs dont la roche est mouillable à l'eau, et les réservoirs de mouillabilité intermédiaire ou mouillable à l'huile (par exemple certains massifs rocheux carbonatés).We can typically distinguish two types of cracked tanks: tanks whose rock is wettable with water, and wettability tanks intermediate or wettable with oil (for example certain rock masses carbonates).

Lorsque ces réservoirs sont soumis à une injection d'eau dans le cadre de la récupération améliorée des effluents pétroliers, l'eau va préférentiellement envahir les fissures. L'eau aura ensuite tendance à imbiber les blocs de faible perméabilité en en chassant l'huile piégée dans les pores vers le réseau de fissures. Si le réservoir est mouillable à l'eau, l'imbibition se fera sous l'effet des forces capillaires et de la gravité. Si le réservoir est mouillable à l'huile, seule la gravité favorisera le phénomène d'imbibition. When these tanks are injected with water as part improved recovery of petroleum effluents, the water will preferably invade the cracks. The water will then tend to soak blocks of low permeability by driving out the oil trapped in the pores towards the network of cracks. If the tank is wettable with water, imbibition will will do under the effect of capillary forces and gravity. If the tank is wettable with oil, only gravity will favor the phenomenon of imbibition.

Quand de l'eau carbonatée est injectée dans le milieu fissuré, dans le cas d'un réservoir mouillable à l'eau, le déplacement de l'huile par imbibition dans des blocs de faible porosité est suivi par l'expansion du gaz carbonique quand la pression sera inférieure à la pression de bulle de l'eau carbonatée. Le développement de bulles de gaz piégées dans les massifs de faible perméabilité induit une récupération d'huile considérablement accrue.When carbonated water is injected into the cracked medium, into the case of a tank wettable with water, the displacement of the oil by imbibition in low porosity blocks is followed by the expansion of carbon dioxide when the pressure will be lower than the bubble pressure of carbonated water. The development of gas bubbles trapped in low massifs permeability induces considerably increased oil recovery.

Dans le cas d'un réservoir de faible mouillabilité intermédiaire à l'eau ou mouillable à l'huile, le phénomène d'imbibition par l'eau sera moins efficace, les forces capillaires n'étant pas favorables au déplacement de l'huile par l'eau. Le dioxyde de carbone libéré lors de la déplétion remplace très avantageusement l'eau et envahit les blocs matriciels.In the case of a low intermediate wettability tank with water or wettable with oil, the water soaking phenomenon will be less effective, the capillary forces not being favorable to the displacement of the oil by water. The carbon dioxide released during the depletion very replaces advantageously water and invades the matrix blocks.

L'exploitation du gisement peut comprendre des cycles d'injection et de déplétion. Pendant la période d'injection, la production sera arrêtée ou diminuée alors que l'injection d'eau carbonatée sera maintenue, afin de faire remonter la pression dans le réservoir au-delà de la pression de bulle de l'eau et de ce fait augmenter la concentration de dioxyde de carbone disponible. Cette période d'injection sera suivie d'une période de production et de déplétion partielle du gisement.The exploitation of the deposit can include injection and depletion. During the injection period, production will be stopped or decreased while the injection of carbonated water will be maintained, in order to make build up the pressure in the tank above the water bubble pressure and thereby increase the concentration of available carbon dioxide. This injection period will be followed by a production and partial depletion of the deposit.

4. Production 4. Production

Au cours du temps les hydrocarbures produits présentent des concentrations croissantes de gaz acides. Comme on l'a vu plus haut, ces gaz sont avantageusement séparés du gaz valorisable par ailleurs et réinjectés dans le gisement. Si les unités de traitement de gaz et de raffinage sont proches des puits producteurs, le gaz et l'huile seront séparés par détentes successives dans des ballons séparateurs S1, S2 (Fig.3) localisés près de la zone de production. Over time, the hydrocarbons produced have increasing concentrations of acid gases. As we saw above, these gases are advantageously separated from the gas that can be reused elsewhere and reinjected into the deposit. If the gas processing and refining units are close to producing wells, gas and oil will be separated by successive detents in separator tanks S1, S2 (Fig. 3) located near the production area.

Si l'unité de raffinage d'un brut lourd est éloignée de la zone de production, il est possible de transporter sous pression le brut chargé de son gaz. Le CO2 qui diminue sensiblement la viscosité de l'huile lourde remplace avantageusement un agent fluxant.If the refining unit of a heavy crude oil is far from the production area, it is possible to transport under pressure the crude oil loaded with its gas. CO 2, which significantly reduces the viscosity of heavy oil, advantageously replaces a fluxing agent.

Des essais comparatifs ont été menés en laboratoire sur des carottes de roche imprégnés d'huile choisies et adaptées pour représenter un réservoir fissuré. Elles ont été placées dans une cellule de confinement associés à un système de circulation de fluides sous pression, du même type par exemple que celles décrites par les brevets FR 2 708 742 (US 5,679,885) ou FR 2.731.073 (US 5,679,885) du demandeur et soumises à différents tests de balayage par une phase gazeuse dans les conditions de saturation ou de sursaturation en gaz énoncées plus haut. Ces essais ont permis de démontrer toute l'efficacité du procédé selon la présente invention.Comparative tests have been carried out in the laboratory on carrots of oil-impregnated rock selected and adapted to represent a reservoir rift. They were placed in a containment cell associated with a pressurized fluid circulation system, of the same type for example as those described by patents FR 2,708,742 (US 5,679,885) or FR 2,731,073 (US 5,679,885) of the applicant and subjected to various scanning tests by a gas phase under the conditions of gas saturation or supersaturation set out above. These tests have demonstrated the effectiveness of the method according to the present invention.

A température égale, on a vérifié qu'une concentration croissante de CO2 dans l'eau carbonatée, induisait une forte augmentation de la récupération de l'huile en place. Cette augmentation est très sensible quand le fluide de balayage est sursaturé en gaz.At equal temperature, it has been verified that an increasing concentration of CO 2 in carbonated water induces a strong increase in the recovery of the oil in place. This increase is very noticeable when the sweeping fluid is supersaturated with gas.

Claims (19)

Procédé de récupération assistée d'un fluide pétrolier produit par un gisement, comportant l'injection continue dans le gisement, par un puits d'injection (IW), d'un fluide de balayage constitué d'eau additionnée de gaz au moins partiellement miscible dans une phase aqueuse et dans le fluide pétrolier, caractérisé en ce qu'il comporte un contrôle permanent en tête du puits d'injection, du rapport des débits de la phase aqueuse et de gaz formant le fluide de balayage pour que le gaz y soit en état de saturation ou de sursaturation au fond du puits d'injection.Process for the enhanced recovery of a petroleum fluid produced by a deposit, comprising continuous injection into the deposit, by a well injection (IW), a sweeping fluid consisting of water with gas added to it less partially miscible in an aqueous phase and in the fluid tanker, characterized in that it includes permanent control at the top of the injection wells, the ratio of the flow rates of the aqueous phase and of gas forming the sweeping fluid so that the gas is there in a saturation or oversaturation at the bottom of the injection well. Procédé selon la revendication 1, caractérisé en ce que l'on forme le fluide de balayage par mélange en fond de puits du gaz avec la phase aqueuse.Method according to claim 1, characterized in that the scanning fluid by mixing the bottom of the gas with the aqueous phase. Procédé selon la revendication 1, caractérisé en ce que l'on forme le fluide de balayage par mélange en tête de puits du gaz avec la phase aqueuse.Method according to claim 1, characterized in that the scanning fluid by mixing the gas well with the aqueous phase at the wellhead. Procédé selon l'une des revendications 2 ou 3, caractérisé en ce que l'on utilise un moyen de contrôle disposé dans le puits pour augmenter le taux de dissolution du gaz dans la phase aqueuse.Method according to one of claims 2 or 3, characterized in that using a control means arranged in the well to increase the rate of dissolution of the gas in the aqueous phase. Procédé selon l'une des revendications 1 à 4, caractérisé en ce qu'il comporte l'utilisation d'un garnissage placé dans le puits d'injection afin de mélanger intimement le gaz et la phase aqueuse du fluide de balayage.Method according to one of claims 1 to 4, characterized in that it involves the use of a lining placed in the injection well in order to thoroughly mix the gas and the aqueous phase of the sweeping fluid. Procédé selon l'une des revendications 1 à 5, caractérisé en ce qu'il comporte l'utilisation d'une pompe polyphasique pour former un mélange intime entre la phase aqueuse et de gaz et l'injecter dans le puits d'injection. Method according to one of claims 1 to 5, characterized in that it involves the use of a multiphase pump to form a mixture intimate between the aqueous and gas phase and inject it into the injection well. Procédé selon l'une des revendications 1 à 6, caractérisé en ce qu'il comporte l'utilisation des données de capteurs d'état en fond de puits pour contrôler que le gaz du fluide de balayage est au moins en état de saturationMethod according to one of claims 1 to 6, characterized in that it involves the use of downhole state sensor data to check that the gas of the sweeping fluid is at least in a state of saturation Procédé selon l'une des revendications précédentes, caractérisé en ce que le gaz dans le fluide de balayage contient au moins un gaz acide tel que du dioxyde de carbone et / ou de l'hydrogène sulfuré.Method according to one of the preceding claims, characterized in that the gas in the sweeping fluid contains at least one acid gas such as carbon dioxide and / or hydrogen sulfide. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'il comporte l'utilisation d'un dispositif de traitement adapté à extraire des effluents issus d'un gisement, au moins une partie du gaz dans le fluide de balayage.Method according to one of the preceding claims, characterized in that it involves the use of a processing device adapted to extract effluents from a deposit, at least part of the gas in the scanning. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'il comporte l'utilisation d'effluents gazeux issus d'unités chimiques ou thermiques pour former au moins une partie du gaz dans le fluide de balayage.Method according to one of the preceding claims, characterized in what it involves the use of gaseous effluents from chemical units or thermal to form at least part of the gas in the sweeping fluid. Procédé selon l'une des revendications précédentes, caractérisé en ce que l'on utilise de l'eau issue d'un gisement souterrain pour injectée peut être tout ou partie une phase aqueuse associée à la production d'hydrocarbures.Method according to one of the preceding claims, characterized in what we use water from an underground deposit for injection can be all or part of an aqueous phase associated with the production of hydrocarbons. Procédé selon l'une des revendications précédentes, caractérisé en ce qu'on ajoute un additif tensioactif à la phase aqueuse pour y favoriser la dispersion du gaz.Method according to one of the preceding claims, characterized in what we add a surfactant additive to the aqueous phase to promote the gas dispersion. Procédé selon l'une des revendications précédentes, caractérisé en ce que l'on ajoute à la phase aqueuse au moins un additif pour augmenter la solubilité du gaz dans le fluide de balayage. Method according to one of the preceding claims, characterized in adding at least one additive to the aqueous phase to increase the solubility of gas in the sweeping fluid. Procédé selon l'une des revendications précédentes, caractérisé en ce que l'injection d'eau carbonatée est réalisée dans des puits de fort déport, horizontaux ou de géométrie complexe.Method according to one of the preceding claims, characterized in that the injection of carbonated water is carried out in wells with large offset, horizontal or complex geometry. Procédé selon la revendication 14, caractérisé en ce que l'injection du fluide de balayage est réalisée dans au moins un puits de fort déport, horizontal ou de géométrie complexe localisé à la base du gisement.Method according to claim 14, characterized in that the injection sweeping fluid is produced in at least one well with a large offset, horizontal or of complex geometry located at the base of the deposit. Procédé selon l'une des revendications 1 à 14, caractérisé en ce que la récupération du fluide pétrolier est réalisée dans au moins un puits dévié ou de géométrie complexe.Method according to one of claims 1 to 14, characterized in that recovery of the petroleum fluid is carried out in at least one deviated well or of complex geometry. Procédé selon la revendication 16, caractérisé en ce que chaque puits dévié ou de géométrie complexe est localisé au toit du gisement.Method according to claim 16, characterized in that each deviated well or complex geometry is located at the roof of the deposit. Système de récupération assistée d'un fluide pétrolier extrait d'un gisement, par injection continue dans le gisement d'un fluide de balayage constitué d'une phase aqueuse additionnée de gaz au moins partiellement miscible dans cette phase aqueuse et dans le fluide pétrolier, comportant un ensemble de conditionnement (PA) du fluide de balayage et une unité (6) de contrôle permanent de l'ensemble de conditionnement adapté à contrôler le rapport des débits de la phase aqueuse et de gaz formant le fluide de balayage parvenu en fond de puits, pour que le gaz y soit en état de saturation ou de sursaturation.System for the enhanced recovery of a petroleum fluid extracted from a deposit, by continuous injection into the deposit of a sweeping fluid consisting of an aqueous phase with gas added at least partially miscible in this aqueous phase and in the petroleum fluid, comprising a packaging assembly (PA) for the sweeping fluid and a unit (6) for permanent control of the packaging unit adapted to control the ratio of the flow rates of the aqueous phase and of the gas forming the sweeping fluid reached the bottom of the well, so that the gas is there in a state of saturation or supersaturation. Système de récupération assistée selon la revendication 18, caractérisé en ce qu'il comporte des capteurs d'état (SS) disposés dans la zone d'injection pour mesurer des paramètres thermodynamiques et reliés à l'unité de contrôle (6).Assisted recovery system according to claim 18, characterized in that it includes state sensors (SS) arranged in the area injection to measure thermodynamic and unit related parameters control (6).
EP00400945A 1999-04-23 2000-04-06 Method of enhanced hydrocarbon production by injection of a liquid and gaseous phase at least partially miscible with water Expired - Lifetime EP1046780B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9905584A FR2792678B1 (en) 1999-04-23 1999-04-23 ASSISTED RECOVERY OF HYDROCARBONS BY COMBINED INJECTION OF AN AQUEOUS PHASE AND AT LEAST PARTIALLY MISCIBLE GAS
FR9905584 1999-04-23

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CA2305946A1 (en) 2000-10-23
FR2792678A1 (en) 2000-10-27
NO20002029D0 (en) 2000-04-18
EP1046780B1 (en) 2006-02-08
US6325147B1 (en) 2001-12-04
NO20002029L (en) 2000-10-24
FR2792678B1 (en) 2001-06-15
DK1046780T3 (en) 2006-04-10

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