CA1265436A - Oil recovery process using a delayed polymer gel - Google Patents
Oil recovery process using a delayed polymer gelInfo
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- CA1265436A CA1265436A CA000525944A CA525944A CA1265436A CA 1265436 A CA1265436 A CA 1265436A CA 000525944 A CA000525944 A CA 000525944A CA 525944 A CA525944 A CA 525944A CA 1265436 A CA1265436 A CA 1265436A
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- Prior art keywords
- solution
- gelation
- high permeability
- region
- polymer
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
- C09K8/506—Compositions based on water or polar solvents containing organic compounds
- C09K8/508—Compositions based on water or polar solvents containing organic compounds macromolecular compounds
- C09K8/512—Compositions based on water or polar solvents containing organic compounds macromolecular compounds containing cross-linking agents
Abstract
OIL RECOVERY PROCESS USING A DELAYED POLYMER GEL
Abstract A process for reducing the permeability of a high permeability region in a subterranean hydrocarbon-bearing formation by preparing an aqueous gelation solution at the surface comprised of a water-soluble polymer, a metal carboxylate crosslinking agent and a carboxylic acid delaying agent. The delaying agent substantially delays gelation of the solution until it is injected and in place in the desired treatment region.
Abstract A process for reducing the permeability of a high permeability region in a subterranean hydrocarbon-bearing formation by preparing an aqueous gelation solution at the surface comprised of a water-soluble polymer, a metal carboxylate crosslinking agent and a carboxylic acid delaying agent. The delaying agent substantially delays gelation of the solution until it is injected and in place in the desired treatment region.
Description
3~
Description OIL RECOYERY PROCESS USING A DELAYED POLYME~ GEL
Background of the_Invention Technical Field:
OS The inYention relates to an oil recovery process and more particu-larly a process for reducing the permeability in a relatively high per-meability reg~on of a subterranean hydrocarbon-bearing formation.
Oescription of Related Art:
Poor vertical conformance results fram the vertical juxtaposltion of relatively high permeability geologic regions to relatively low per-meability reg10ns within a subterranean `formation. Poor areal confor-mance results from the presence of high permeability streaks and high permeability anomalies within the formation ma~rix9 such as vertical fractures and net~orks of the same, which have very high permeability relatl~e to the formation matrix. Fluids generally exhibit poor flow profiles and sweep efficiencies in subterranean formations having poor vertical or areal conformance. Poor conformance is par~icularly a problem where vertical heterogeneity and/or fracture networks or other structural anomalies are in fluid communication with a subterranean wellbore across which fluids are injected or produced, A number of attempts to remedy conformance problems exist. U.S.
Patents 3,762~476; 3,981,363; 4~018,286; and 4l039,029 to Gall or Gall ~2$5'~
Description OIL RECOYERY PROCESS USING A DELAYED POLYME~ GEL
Background of the_Invention Technical Field:
OS The inYention relates to an oil recovery process and more particu-larly a process for reducing the permeability in a relatively high per-meability reg~on of a subterranean hydrocarbon-bearing formation.
Oescription of Related Art:
Poor vertical conformance results fram the vertical juxtaposltion of relatively high permeability geologic regions to relatively low per-meability reg10ns within a subterranean `formation. Poor areal confor-mance results from the presence of high permeability streaks and high permeability anomalies within the formation ma~rix9 such as vertical fractures and net~orks of the same, which have very high permeability relatl~e to the formation matrix. Fluids generally exhibit poor flow profiles and sweep efficiencies in subterranean formations having poor vertical or areal conformance. Poor conformance is par~icularly a problem where vertical heterogeneity and/or fracture networks or other structural anomalies are in fluid communication with a subterranean wellbore across which fluids are injected or produced, A number of attempts to remedy conformance problems exist. U.S.
Patents 3,762~476; 3,981,363; 4~018,286; and 4l039,029 to Gall or Gall ~2$5'~
-2- Docket 850026-A
et al describe various processes where~n gel compositions are formed in high permeability regions of subterranean formations to reduce the per-meability therein. According to U.S. Paten~ 3,762,476, a polymer such as polyacrylamide is injected into a formation followed sequentially by o5 a crosslinking agent. The sequentially injected slugs are believed topermeate the ~rea~ment region of the formation and gel in situo It is generally held that effective polymer/crosslinking agen~
systems necessitate sequential injection of the gel components because gel systems mixed on the surface often set up before they can effec-tively penetrate the treatment region. However, in practice, treatments such as that disclosed in U.S. Patent 3,7679476 using sequentially injected gel systems have proven unsatisfactory because of the inability to achieve complete mixing and gelation in the formation. As a result9 gels only form at the interface of the unmixed gel componen~s and often lS in regions remote from the desired treatment reg~on. A need exists for a gelation process wherein the gelation solution substantially pene-trates the desired treatment region of a subterranean hydrocarbon-bearing formation before setting up.
Summary of the Invention ~0 The present invention provides a process for improving oil recovery from a subterranean hydrocarbon-bearing formation penetrated by a pro-duction and/or injection well. The process improves vertical and areal conformance in the formation and correspondingly improves flow profiles
et al describe various processes where~n gel compositions are formed in high permeability regions of subterranean formations to reduce the per-meability therein. According to U.S. Paten~ 3,762,476, a polymer such as polyacrylamide is injected into a formation followed sequentially by o5 a crosslinking agent. The sequentially injected slugs are believed topermeate the ~rea~ment region of the formation and gel in situo It is generally held that effective polymer/crosslinking agen~
systems necessitate sequential injection of the gel components because gel systems mixed on the surface often set up before they can effec-tively penetrate the treatment region. However, in practice, treatments such as that disclosed in U.S. Patent 3,7679476 using sequentially injected gel systems have proven unsatisfactory because of the inability to achieve complete mixing and gelation in the formation. As a result9 gels only form at the interface of the unmixed gel componen~s and often lS in regions remote from the desired treatment reg~on. A need exists for a gelation process wherein the gelation solution substantially pene-trates the desired treatment region of a subterranean hydrocarbon-bearing formation before setting up.
Summary of the Invention ~0 The present invention provides a process for improving oil recovery from a subterranean hydrocarbon-bearing formation penetrated by a pro-duction and/or injection well. The process improves vertical and areal conformance in the formation and correspondingly improves flow profiles
-3- Docket 850026-A
and sweep efficiencies of injected and/or produced fluids in the forma-tion. These objectives and others are achieved by an in situ polymer gelation process employing a gelation delaying agent~
The process comprises preparing an aqueous gelation solution above 05 ground containing a high molecular weight wa~er-soluble polymer, a metalcarboxylate crosslinking agent, and a carboxylic acid delay~ng agent.
The solution is injected into the desired trea~ment region via a well-bore in fluid con~unication therewith. The delaying agent advantage-ously inhibits complete gelation of the solution until the solution has 1~ propagated into ~he trea~ment region. Once in ~he treatment region the gelation solution sets up as a continuous single-phase gel composition comprised of the polymer and crosslinking agent which substantially re-duces permeabili~y therein.
After the gelation treatment, fluids may be injected into or pro-duced from the hydrocarbon-bearing regions of the formation in fluid communication with the wellbore. The gel is substantially incapable of flowing from the treatment reglon and is substantially permanent and resistant to in situ degradation.
The process provides distinct advantages over gelation processes ~a known in the art. The practitioner of the present invention can fully prepare the gelation solution at the surface under controlled condi-tions, yet delay substantially complete gelation of the solution until it is in place in the desired subterranean treatment region. The resul-tant gel has sufficient strength and stabil~ty to meet the demands of ~5 the treatment region.
3~i
and sweep efficiencies of injected and/or produced fluids in the forma-tion. These objectives and others are achieved by an in situ polymer gelation process employing a gelation delaying agent~
The process comprises preparing an aqueous gelation solution above 05 ground containing a high molecular weight wa~er-soluble polymer, a metalcarboxylate crosslinking agent, and a carboxylic acid delay~ng agent.
The solution is injected into the desired trea~ment region via a well-bore in fluid con~unication therewith. The delaying agent advantage-ously inhibits complete gelation of the solution until the solution has 1~ propagated into ~he trea~ment region. Once in ~he treatment region the gelation solution sets up as a continuous single-phase gel composition comprised of the polymer and crosslinking agent which substantially re-duces permeabili~y therein.
After the gelation treatment, fluids may be injected into or pro-duced from the hydrocarbon-bearing regions of the formation in fluid communication with the wellbore. The gel is substantially incapable of flowing from the treatment reglon and is substantially permanent and resistant to in situ degradation.
The process provides distinct advantages over gelation processes ~a known in the art. The practitioner of the present invention can fully prepare the gelation solution at the surface under controlled condi-tions, yet delay substantially complete gelation of the solution until it is in place in the desired subterranean treatment region. The resul-tant gel has sufficient strength and stabil~ty to meet the demands of ~5 the treatment region.
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-4- Docket 850026-A
Description of Preferred Embodiments According to the present invention, the aqueous gelation solution is prepared by admixing a crosslinkable polymer, a metal carboxylate crosslinking agent and a gelation delaying agent in an aqueous solvent ~5at the surface. The polymer may be substantially any high molecular weight crosslinkable b~opolymer or synthetic polymer. Useful synthetic polymers include acryla~ide polymers9 i.e., polymers containing one or more acrylamide groups, such as polyacrylamide or partially hydrolyzed polyacrylamide. The average molecular weight of the polymer used herein 10is in the range of about 10,000 to about 50,000,000, preferably about 100,000 to about 20,0009000, and most preferably about 200,000 to about 12,000,000. The polymer concentration in the gelation solu~ion may be about 1,000 pp~ up to the solubility limit of the polymer in the solvent or the rheological cons~raints of the solution.
15The metal carboxylate crosslinking agent is derived from a carbox-ylate compound or mixture thereof. In solution, ~he crosslinking agent comprises electronegative carboxylate species which may include one or more of the following water-soluble species: formate, acetate, propio-nate, lactate, lower substituted derivatives thereof, and mixtures ~0thereof. In addition to electronegative carboxylate species, the sQlu-tion is further comprised of electropositive metallic species, such as Ca2+, Mg2+, Ba~+, Al3+, Fe3+, Ti4~9 Zn2+, Sn4+, Cr3~, etc. The weight ratio of polymer ~o crosslinking agent ~s advantage-ously about 1:1 to about 500:1.
3~
Description of Preferred Embodiments According to the present invention, the aqueous gelation solution is prepared by admixing a crosslinkable polymer, a metal carboxylate crosslinking agent and a gelation delaying agent in an aqueous solvent ~5at the surface. The polymer may be substantially any high molecular weight crosslinkable b~opolymer or synthetic polymer. Useful synthetic polymers include acryla~ide polymers9 i.e., polymers containing one or more acrylamide groups, such as polyacrylamide or partially hydrolyzed polyacrylamide. The average molecular weight of the polymer used herein 10is in the range of about 10,000 to about 50,000,000, preferably about 100,000 to about 20,0009000, and most preferably about 200,000 to about 12,000,000. The polymer concentration in the gelation solu~ion may be about 1,000 pp~ up to the solubility limit of the polymer in the solvent or the rheological cons~raints of the solution.
15The metal carboxylate crosslinking agent is derived from a carbox-ylate compound or mixture thereof. In solution, ~he crosslinking agent comprises electronegative carboxylate species which may include one or more of the following water-soluble species: formate, acetate, propio-nate, lactate, lower substituted derivatives thereof, and mixtures ~0thereof. In addition to electronegative carboxylate species, the sQlu-tion is further comprised of electropositive metallic species, such as Ca2+, Mg2+, Ba~+, Al3+, Fe3+, Ti4~9 Zn2+, Sn4+, Cr3~, etc. The weight ratio of polymer ~o crosslinking agent ~s advantage-ously about 1:1 to about 500:1.
3~
-5- Docket 850026-A
The delaying agent is a carboxyllc acid, and preferably a low mole-cular weigh~ mono-basic carboxyl~c acid, such as formic, acetic, pro-pionic, lactic acid, or mixtures ~hereofO The delaying agent is advan-tageously added tn either the polymer or crosslinking agent before they 0~ are admixed. Pref~rably the delaying agent is admixed with the cross-linking agent, followed by the add~tion of the polymer to form a bulk gelation solution at the surface suitable for injection. Alternatively, though less preferred, the polymer, crosslinking agen~, and delaying agent can all be simultaneously mixed at or near the wellhead by in-line mixing means durlng ~njection.
The aqueous solvent of the gelation solu~ion may be fresh water or a brine having a total dissolved solids concentration up ~o the solubil-ity limit of the solids in water. Inert fillers such as crushed or naturally fine rock material or glass beads can also be added to the l~ gelation solution to reinforce the gel network structure.
The present process enables the ~ractitioner to prede~ermine the gelation rate of a gel for a given application as a function of the delaying agent concentration. The gelation rate is defined as the degree of gel formation as a funct10n of time or, synonymously, the rate of crosslinking in the gelation solution. The degree of crosslinking may be quantified in terms of gel Y1scosity and/or elasticity, such as storaye and loss moduli. These terms are defined in Middleman, S., The Flow of High Polymers3 Interscience Publishers, N.Y., 1968, at pp.
68-70.
The delaying agent is a carboxyllc acid, and preferably a low mole-cular weigh~ mono-basic carboxyl~c acid, such as formic, acetic, pro-pionic, lactic acid, or mixtures ~hereofO The delaying agent is advan-tageously added tn either the polymer or crosslinking agent before they 0~ are admixed. Pref~rably the delaying agent is admixed with the cross-linking agent, followed by the add~tion of the polymer to form a bulk gelation solution at the surface suitable for injection. Alternatively, though less preferred, the polymer, crosslinking agen~, and delaying agent can all be simultaneously mixed at or near the wellhead by in-line mixing means durlng ~njection.
The aqueous solvent of the gelation solu~ion may be fresh water or a brine having a total dissolved solids concentration up ~o the solubil-ity limit of the solids in water. Inert fillers such as crushed or naturally fine rock material or glass beads can also be added to the l~ gelation solution to reinforce the gel network structure.
The present process enables the ~ractitioner to prede~ermine the gelation rate of a gel for a given application as a function of the delaying agent concentration. The gelation rate is defined as the degree of gel formation as a funct10n of time or, synonymously, the rate of crosslinking in the gelation solution. The degree of crosslinking may be quantified in terms of gel Y1scosity and/or elasticity, such as storaye and loss moduli. These terms are defined in Middleman, S., The Flow of High Polymers3 Interscience Publishers, N.Y., 1968, at pp.
68-70.
-6- Docket 850026-A
The delaying agent advantageously enables the practitioner to cre-ate a gelation solution having a nonlinear gelation rate. The initial rate is sufficiently slow to substantially delay gelation of the solu-tion un~il it has been prepared at the surface, injected into the well-05 bore, an~ displaced into the desired trea~ment region. Once in place in the desired treatment region, the gelation rate of the solution advan-tageously accelerates to achieve substantially complete gelation of ~he solution relatiYely rapidly.
The present process is particularly applicable to cases where it is extremely difflcult to prepare a polymer/metal carboxylate gelation solu~ion having a ~avorable gelation rate under formation conditions.
For example, high formation temperatures, i.e., substantially greater than 38C at the depth of the treatment reglon, can cause premature gelation of a polymer/metal carboxylate gelation solution in the well-l~ bore and subsequent undesired plugging of portions of the formation or ' wellbore face. By incorporating a predetermined amount~ a delaying agentin the gelation solution, gelation can be delayed to a sufficient degree which enables the solution to be placed in a high temperature ~reatment region while the gel is still mobile.
The concentration of the delaying agent admixed in the gelation solution is generally in the range of about 0.05 to about 10% by weight, preferably about 0.1 to about 5.0~ by weight and most preferably about 0.~ to about ?.0~ by weight depending on ~he concentration of the gel components, the reaction temperature and the desired gelation time.
The delaying agent advantageously enables the practitioner to cre-ate a gelation solution having a nonlinear gelation rate. The initial rate is sufficiently slow to substantially delay gelation of the solu-tion un~il it has been prepared at the surface, injected into the well-05 bore, an~ displaced into the desired trea~ment region. Once in place in the desired treatment region, the gelation rate of the solution advan-tageously accelerates to achieve substantially complete gelation of ~he solution relatiYely rapidly.
The present process is particularly applicable to cases where it is extremely difflcult to prepare a polymer/metal carboxylate gelation solu~ion having a ~avorable gelation rate under formation conditions.
For example, high formation temperatures, i.e., substantially greater than 38C at the depth of the treatment reglon, can cause premature gelation of a polymer/metal carboxylate gelation solution in the well-l~ bore and subsequent undesired plugging of portions of the formation or ' wellbore face. By incorporating a predetermined amount~ a delaying agentin the gelation solution, gelation can be delayed to a sufficient degree which enables the solution to be placed in a high temperature ~reatment region while the gel is still mobile.
The concentration of the delaying agent admixed in the gelation solution is generally in the range of about 0.05 to about 10% by weight, preferably about 0.1 to about 5.0~ by weight and most preferably about 0.~ to about ?.0~ by weight depending on ~he concentration of the gel components, the reaction temperature and the desired gelation time.
-7- Docket 850026-A
The concentration of the delaying agent in the gelation solution is adjusted within the given range such that the gelation reaction proceeds extremely slowly for a rela~ively long ~nitial time period, during which very little gelation occurs. At the end of the initial period, the ~5 rate of the gelation reaction substantially accelerates, causing sub-stantially complete gelation to occur very rapidly thereafter. Gelation can generally be substantially delayed up to about 24 hours or more from the time the gelation solution is formula~ed and injected using the present process. Even under extremely unfavorable in situ conditions, ~q~
gelation can be delayed at least 1 to 12 hours or more~ preferably at least 6 to 12 hours by careful formulation of the gel.
The present gelation mechanism enables the practitioner to design a gelation solution which can be injected into a formation at a desired injeotion rate with little resistance to injec~ivity caused by premature 1~ gelation. Yet, the process is designed ta gel the solution very rapidlyafter it is all in place in the desired treatment region. This mini-~ ~ C~c C ~,0 '?
mizes lost production from shut in of injection and/or ~r~ t wells.
The process is applicable to conformance treatment of formations under most conditions and is specific to treating regions within the formation which are in fluid communication with an injection or produc-tion well. The process is applicable to the treatment of anomalies such as streaks of relatively high permeability, fractures or fracture net-works in direct communication via the anomaly with an injection or pro-duction well and is further applicable to the treatment of selected high permeability zones of the matrix.
~2~
The concentration of the delaying agent in the gelation solution is adjusted within the given range such that the gelation reaction proceeds extremely slowly for a rela~ively long ~nitial time period, during which very little gelation occurs. At the end of the initial period, the ~5 rate of the gelation reaction substantially accelerates, causing sub-stantially complete gelation to occur very rapidly thereafter. Gelation can generally be substantially delayed up to about 24 hours or more from the time the gelation solution is formula~ed and injected using the present process. Even under extremely unfavorable in situ conditions, ~q~
gelation can be delayed at least 1 to 12 hours or more~ preferably at least 6 to 12 hours by careful formulation of the gel.
The present gelation mechanism enables the practitioner to design a gelation solution which can be injected into a formation at a desired injeotion rate with little resistance to injec~ivity caused by premature 1~ gelation. Yet, the process is designed ta gel the solution very rapidlyafter it is all in place in the desired treatment region. This mini-~ ~ C~c C ~,0 '?
mizes lost production from shut in of injection and/or ~r~ t wells.
The process is applicable to conformance treatment of formations under most conditions and is specific to treating regions within the formation which are in fluid communication with an injection or produc-tion well. The process is applicable to the treatment of anomalies such as streaks of relatively high permeability, fractures or fracture net-works in direct communication via the anomaly with an injection or pro-duction well and is further applicable to the treatment of selected high permeability zones of the matrix.
~2~
-8- Docket 850026-A
The following examples demonstrate the practice and utllity of the present invention but are not to be construed as limiting the scope thereof.
0$ A series of gelation solutions are prepared by first mixing glacial acetic acid with an aqueous 2% by weigh~ unhydrolyzed polyacrylamide solution having a molecular weiyht of 11,000,000. This mixture is com-bined with a 50~ by weight chromium acetate solution resulting in a gel-ation solution ha~lng a weight ratio of 20:1 polyacrylamide to chromium acetate. The solution is gelled at a temperature of 60C and a pressure o~ 3,500 kPa. The gela~lon rate is determined by measuring the storage modulus, G', of the solution with a rheometer. Increasing values of G' indicate an increasing degree of gel formation.
A series of runs are performed using gelation solutions having dif-fering concentrations of the delaying agent, acetic acid. The results tabulated in Tables 1-4 show the gelation rate as a function of the acetic acid concentration. The units are consistent throughout Tables 1-8.
i5~3~
The following examples demonstrate the practice and utllity of the present invention but are not to be construed as limiting the scope thereof.
0$ A series of gelation solutions are prepared by first mixing glacial acetic acid with an aqueous 2% by weigh~ unhydrolyzed polyacrylamide solution having a molecular weiyht of 11,000,000. This mixture is com-bined with a 50~ by weight chromium acetate solution resulting in a gel-ation solution ha~lng a weight ratio of 20:1 polyacrylamide to chromium acetate. The solution is gelled at a temperature of 60C and a pressure o~ 3,500 kPa. The gela~lon rate is determined by measuring the storage modulus, G', of the solution with a rheometer. Increasing values of G' indicate an increasing degree of gel formation.
A series of runs are performed using gelation solutions having dif-fering concentrations of the delaying agent, acetic acid. The results tabulated in Tables 1-4 show the gelation rate as a function of the acetic acid concentration. The units are consistent throughout Tables 1-8.
i5~3~
-9- Docket 850026-A
Tabl e 1 Aceti c Aci d Concentrati on Gel ati on (wt~ of Total Solution Time G' 05Gel ati on Sol uti on ) ~H ( M~ n . )( dynes/ cm2) 0 8.3 30 1500 12~ 2900 210 32û0 Table 2 Gel ati on Aceti c Aci d Sol uti on Concentrati on pH Ti me G ' 0.1 5.0 30 250 ~2~5d~36
Tabl e 1 Aceti c Aci d Concentrati on Gel ati on (wt~ of Total Solution Time G' 05Gel ati on Sol uti on ) ~H ( M~ n . )( dynes/ cm2) 0 8.3 30 1500 12~ 2900 210 32û0 Table 2 Gel ati on Aceti c Aci d Sol uti on Concentrati on pH Ti me G ' 0.1 5.0 30 250 ~2~5d~36
-10- Docket 850026-A
Table 3 Gelation Acetic Aoid Solution Concentration _E~ Time G' 0~ 0.5 4.2 30 100 ~00 8~0 lS 780 1000 8~0 1300 ~200 1300 Table 4 Gelation 20 Acetic Acid Solution Concentration pH Time G' 1.0 3.9 30 100 go 240 ~5 ` 120 250 ~200 1800 5~
Table 3 Gelation Acetic Aoid Solution Concentration _E~ Time G' 0~ 0.5 4.2 30 100 ~00 8~0 lS 780 1000 8~0 1300 ~200 1300 Table 4 Gelation 20 Acetic Acid Solution Concentration pH Time G' 1.0 3.9 30 100 go 240 ~5 ` 120 250 ~200 1800 5~
-11- Docket 850026-A
A series o~ runs are performed using gelation solutions having dif-fering concentrations of acetic acid. The solutions are prepared by ~xing ~lacial acetic acid with~a 50X chromium acetate solution. The ~S resulting m~xture is added to a ?~ polyacrylamide solution having the same properties as Example l. The resulting gelation solution has a weight ratio of 10:1 polyacrylamide to chromium acetate. The solution ~s gelled at a temperature of 60C and a pressure of 3,500 kPa. Tables 5-8 show the gelation rate as a function of the acetic acid concentra-l~ tion.
Table 5 Acetic Acid Concentration Time G' 0.25 60 300 60~ 1850 ~ 960 2100 ~2$5i~3~
A series o~ runs are performed using gelation solutions having dif-fering concentrations of acetic acid. The solutions are prepared by ~xing ~lacial acetic acid with~a 50X chromium acetate solution. The ~S resulting m~xture is added to a ?~ polyacrylamide solution having the same properties as Example l. The resulting gelation solution has a weight ratio of 10:1 polyacrylamide to chromium acetate. The solution ~s gelled at a temperature of 60C and a pressure of 3,500 kPa. Tables 5-8 show the gelation rate as a function of the acetic acid concentra-l~ tion.
Table 5 Acetic Acid Concentration Time G' 0.25 60 300 60~ 1850 ~ 960 2100 ~2$5i~3~
-12- Docket 850026-A
Table 6 Acetic Acid Concentration Time G' ~.5 60 ~
l~ 720 1200 Table 7 Acetic Acid Concentra~ion Time G' 0.75 60 240 o _able 8 ~5 Acetic Acid Cancentration Time G' _ 1.0 60 0 .1200 600 2 ~iS~
Table 6 Acetic Acid Concentration Time G' ~.5 60 ~
l~ 720 1200 Table 7 Acetic Acid Concentra~ion Time G' 0.75 60 240 o _able 8 ~5 Acetic Acid Cancentration Time G' _ 1.0 60 0 .1200 600 2 ~iS~
-13- Docket 850026-A
The Examples indicate that the presence of acetic acid in the gela-tion solution substantially delays the onset of gelation as a funct~on of increasing acetic acid concentration. When the process is performed in accordance with the conditions of Table 8, no significant gelation 0~ occurs during the first eight hours after formulation of ~he gelation solution. This allows the practitioner sufficient time to inject the solution in~o a desired treatment region.
While foregoing preferred embodiments of the invention have been described and shown~ it is understood tha~ all alternatives and modifi-cations, such as those suggested and others, may be made thereto and follow in the scope of the invention.
The Examples indicate that the presence of acetic acid in the gela-tion solution substantially delays the onset of gelation as a funct~on of increasing acetic acid concentration. When the process is performed in accordance with the conditions of Table 8, no significant gelation 0~ occurs during the first eight hours after formulation of ~he gelation solution. This allows the practitioner sufficient time to inject the solution in~o a desired treatment region.
While foregoing preferred embodiments of the invention have been described and shown~ it is understood tha~ all alternatives and modifi-cations, such as those suggested and others, may be made thereto and follow in the scope of the invention.
Claims (18)
I claim:
1. A process for substantially reducing the permeability of a high permeability region in a hydrocarbon-bearing formation below an earthen surface penetrated by a wellbore in fluid communication with said re-gion, the process comprising:
preparing an aqueous gelation solution at the surface compris-ing a crosslinkable polymer, a metal carboxylate crosslinking agent, and a carboxylic acid;
injecting said gelation solution into said formation via said wellbore;
displacing said gelation solution into said high permeability region; and substantially gelling said solution in said region to substan-tially reduce the permeability of said region.
preparing an aqueous gelation solution at the surface compris-ing a crosslinkable polymer, a metal carboxylate crosslinking agent, and a carboxylic acid;
injecting said gelation solution into said formation via said wellbore;
displacing said gelation solution into said high permeability region; and substantially gelling said solution in said region to substan-tially reduce the permeability of said region.
2. The process of Claim 1 wherein said crosslinkable polymer is an acrylamide polymer.
3. The process of Claim 1 wherein said metal carboxylate cross-linking agent is comprised of an electronegative carboxylate species selected from the group consisting of formate, acetate, propionate, lactate, lower substituted derivatives thereof, and mixtures thereof.
4. The process of Claim 3 wherein said metal carboxylate cross-linking agent is further comprised of an electropositive metallic -15- Docket 850026-A
species selected from the group consisting of Ca2+, Mg2+, Ba2+, Al3+, Fe3+, Ti4+, Zn2+, Sn4+, Cr3+, and mixtures thereof.
species selected from the group consisting of Ca2+, Mg2+, Ba2+, Al3+, Fe3+, Ti4+, Zn2+, Sn4+, Cr3+, and mixtures thereof.
5. The process of Claim 1 wherein said carboxylic acid is selected from the group consisting of formic, acetic, propionic, lactic acid, and mixtures thereof.
6. The process of Claim 1 wherein said gelation solution is pre-pared by mixing said metal carboxylate crosslinking agent and carboxylic acid in solution and thereafter adding said crosslinkable polymer there-to.
7. The process of Claim 1 wherein said gelling of said solution is substantially delayed until said solution is displaced into said high permeability region.
8. The process of Claim 7 wherein said gelling is substantially delayed for at least about 1 hour from the time said solution is pre-pared.
9. The process of Claim 1 wherein the temperature of said high permeability region is greater than about 38°C.
10. The process of Claim 1 wherein said carboxylic acid is added to said solution in a concentration of about 0.05 to about 10 percent by weight based on the weight of said polymer.
11. The process of Claim 10 wherein the pH of said gelation solu-tion is about 2 to about 5.
12. The process of Claim 1 wherein said high permeability region is a fracture in said formation.
-16- Docket 850026-A
-16- Docket 850026-A
13. The process of Claim 1 wherein said high permeability region is an anomaly in said formation.
14. A process for substantially reducing the permeability of a high permeability region in a hydrocarbon bearing formation below an earthen surface penetrated by a wellbore in fluid communication with said re-gion, the process comprising:
preparing an aqueous gelation solution at the surface compris-ing a crosslinkable polymer, a metal carboxylate crosslinking agent and a carboxylic acid in sufficient concentration to substantially delay the crosslinking of said polymer by said crosslinking agent such that said solution remains sufficiently fluid to be displaced into said high permeability region;
injecting said gelation solution into said formation via said wellbore;
displacing said gelation solution into said high permeability region; and substantially gelling said solution in said high permeability region to substantially reduce the permeability of said region.
preparing an aqueous gelation solution at the surface compris-ing a crosslinkable polymer, a metal carboxylate crosslinking agent and a carboxylic acid in sufficient concentration to substantially delay the crosslinking of said polymer by said crosslinking agent such that said solution remains sufficiently fluid to be displaced into said high permeability region;
injecting said gelation solution into said formation via said wellbore;
displacing said gelation solution into said high permeability region; and substantially gelling said solution in said high permeability region to substantially reduce the permeability of said region.
15. The process of Claim 14 wherein said crosslinkable polymer is an acrylamide polymer.
16. The process of Claim 14 wherein said metal carboxylate cross-linking agent is comprised of an electronegative carboxylate species selected from the group consisting of formate, acetate, propionate, lactate, lower substituted derivatives thereof, and mixtures thereof.
-17- Docket 850026-A
-17- Docket 850026-A
17. The process of Claim 16 wherein said metal carboxylate cross-linking agent is further comprised of an electropositive metallic species selected from the group consisting of Ca2+, Mg2+, Ba2+, Al3+, Fe3+, Ti4+, Zn2+, Sn4+, Cr3+, and mixtures thereof.
18. The process of Claim 14 wherein said carboxylic acid is selected from the group consisting of formic, acetic, propionic, lactic acid, and mixtures thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US840,122 | 1986-03-14 | ||
| US06/840,122 US4706754A (en) | 1986-03-14 | 1986-03-14 | Oil recovery process using a delayed polymer gel |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1265436A true CA1265436A (en) | 1990-02-06 |
Family
ID=25281508
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000525944A Expired CA1265436A (en) | 1986-03-14 | 1986-12-22 | Oil recovery process using a delayed polymer gel |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4706754A (en) |
| CN (1) | CN1005730B (en) |
| BR (1) | BR8700140A (en) |
| CA (1) | CA1265436A (en) |
| GB (1) | GB2187773B (en) |
| NL (1) | NL188959C (en) |
| NO (1) | NO177019C (en) |
| SA (1) | SA91120197B1 (en) |
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| US5219476A (en) * | 1989-03-31 | 1993-06-15 | Eniricerche S.P.A. | Gellable aqueous composition and its use in enhanced petroleum recovery |
| IT1229217B (en) * | 1989-03-31 | 1991-07-26 | Eniricerche S P A Agip S P A | GELIFIABLE WATER COMPOSITION AND ITS USE IN OIL ASSISTED RECOVERY PROCEDURES. |
| US4957166A (en) * | 1989-07-14 | 1990-09-18 | Marath Oil Company | Lost circulation treatment for oil field drilling operations |
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| US5322123A (en) * | 1990-10-28 | 1994-06-21 | Institut Francais Du Petrole | Use of gel-based compositions for reducing the production of water in oil- or gas-producing wells |
| FR2668490B1 (en) * | 1990-10-29 | 1994-04-29 | Elf Aquitaine | SCLEROGLUCANE GEL APPLIES TO THE OIL INDUSTRY. |
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| US5156214A (en) * | 1990-12-17 | 1992-10-20 | Mobil Oil Corporation | Method for imparting selectivity to polymeric gel systems |
| US5277830A (en) * | 1990-12-17 | 1994-01-11 | Mobil Oil Corporation | pH tolerant heteropolysaccharide gels for use in profile control |
| US5213446A (en) * | 1991-01-31 | 1993-05-25 | Union Oil Company Of California | Drilling mud disposal technique |
| US5103909A (en) * | 1991-02-19 | 1992-04-14 | Shell Oil Company | Profile control in enhanced oil recovery |
| IT1245383B (en) * | 1991-03-28 | 1994-09-20 | Eniricerche Spa | GELIFIABLE WATER COMPOSITION WITH DELAYED GELIFICATION TIME |
| DK0544377T3 (en) * | 1991-11-26 | 1996-08-19 | Agip Spa | Aqueous gellable compositions containing an antisense agent |
| US5478802A (en) * | 1992-12-29 | 1995-12-26 | Phillips Petroleum Company | Gelling compositions useful for oil field applications |
| US5415229A (en) * | 1994-01-03 | 1995-05-16 | Marathon Oil Company | Hydrocarbon recovery process utilizing a gel prepared from a polymer and a preformed crosslinking agent |
| US5421411A (en) * | 1994-01-03 | 1995-06-06 | Marathon Oil Company | Process for reducing permeability in a subterranean hydrocarbon-bearing formation utilizing a gelation solution having a controlled gelation rate |
| US5431226A (en) * | 1994-01-03 | 1995-07-11 | Marathan Oil Company | Process for reducing permeability in a high-temperature subterranean hydrocarbon-bearing formation utilizing a decarboxylated crosslinking agent |
| US5423380A (en) * | 1994-02-22 | 1995-06-13 | Phillips Petroleum Company | Process for treating oil-bearing formation |
| US5476145A (en) * | 1994-05-10 | 1995-12-19 | Marathon Oil Company | Selective placement of a permeability-reducing material in a subterranean interval to inhibit vertical flow through the interval |
| US5547025A (en) * | 1995-04-14 | 1996-08-20 | Phillips Petroleum Company | Process for treating oil-bearing formation |
| US5816323A (en) * | 1996-09-24 | 1998-10-06 | Marathon Oil Company | Permeability reduction in a hydrocarbon-bearing formation using a stabilized polymer gel |
| US5849674A (en) * | 1996-10-15 | 1998-12-15 | Phillips Petroleum Company | Compositions and processes for oil field applications |
| US6432331B1 (en) | 1997-04-01 | 2002-08-13 | Marathon Oil Company | Tank bottom restoration process |
| US5842519A (en) * | 1997-05-21 | 1998-12-01 | Marathon Oil Company | Process for reducing hydrocarbon leakage from a subterranean storage cavern |
| US5947644A (en) * | 1998-04-03 | 1999-09-07 | Marathon Oil Company | Construction of a fluid impermeable subterranean barrier wall |
| US6189615B1 (en) | 1998-12-15 | 2001-02-20 | Marathon Oil Company | Application of a stabilized polymer gel to an alkaline treatment region for improved hydrocarbon recovery |
| US6025304A (en) * | 1998-12-15 | 2000-02-15 | Marathon Oil Company | Permeability or fluid mobility reduction treatment for a hydrocarbon-bearing formation using a dual molecular weight polymer gel |
| US6133204A (en) * | 1999-02-09 | 2000-10-17 | Atlantic Richfield Company | Use of oil-based gel-breaker/inhibitor compounds with polymer gels in well treatments |
| US6630429B1 (en) | 1999-12-29 | 2003-10-07 | Keet Stene Cremeans | Lost circulation material and method of use |
| EP1725616A2 (en) * | 2004-02-27 | 2006-11-29 | University Of Pittsburgh | Networked polymeric gels and use of such polymeric gels in hydrocarbon recovery |
| CN1313560C (en) * | 2004-09-22 | 2007-05-02 | 中国石油天然气股份有限公司 | Process for preparing high water absorption resin by underground polymerization |
| CN1313561C (en) * | 2004-09-22 | 2007-05-02 | 中国石油天然气股份有限公司 | Process for preparing inorganic filler type water absorption resin by underground polymerization |
| US8360151B2 (en) * | 2009-11-20 | 2013-01-29 | Schlumberger Technology Corporation | Methods for mitigation of annular pressure buildup in subterranean wells |
| US9850425B2 (en) | 2010-08-11 | 2017-12-26 | Conocophillips Company | Delayed gelling agents |
| CN102453473B (en) * | 2010-10-22 | 2014-01-15 | 中国石油化工股份有限公司 | Organogel blocking agent for water blocking and profile control, and preparation method and application thereof |
| RU2471062C1 (en) * | 2011-06-29 | 2012-12-27 | Открытое акционерное общество "Газпром" | Isolation method of brine water influx in well |
| RU2471061C1 (en) * | 2011-06-29 | 2012-12-27 | Открытое акционерное общество "Газпром" | Isolation method of brine water influx in well |
| CA3148845A1 (en) | 2013-01-18 | 2014-07-24 | Conocophillips Company | Nanogels for delayed gelation |
| AU2015350513B2 (en) * | 2014-11-19 | 2019-08-15 | Conocophillips Company | Delayed gelation of polymers |
| CN106916578A (en) * | 2015-12-24 | 2017-07-04 | 中国石油天然气股份有限公司 | A kind of high temperature resistant Weak Gels type profile control agent and preparation method thereof |
| CN106634905A (en) * | 2016-09-12 | 2017-05-10 | 西北大学 | Low-temperature salt-tolerant cross-linked polymer weak gel modifying and flooding agent preparation method |
| WO2020146884A1 (en) | 2019-01-11 | 2020-07-16 | Saudi Arabian Oil Company | Methods and compositions for mitigating water production |
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| US3306870A (en) * | 1964-06-01 | 1967-02-28 | Dow Chemical Co | Fluid gelable composition of acrylamide polymers and aqueous solutions of inorganic hydroxides and salts |
| US3762476A (en) * | 1972-01-03 | 1973-10-02 | Phillips Petroleum Co | Subterranean formation permeability correction |
| US3926258A (en) * | 1972-12-27 | 1975-12-16 | Phillips Petroleum Co | Method for reducing formation permeability with gelled polymer solution having delayed gel time |
| US4018286A (en) * | 1975-11-06 | 1977-04-19 | Phillips Petroleum Company | Controlled well plugging with dilute polymer solutions |
| US4039029A (en) * | 1975-11-06 | 1977-08-02 | Phillips Petroleum Company | Retreatment of wells to reduce water production |
| US3981363A (en) * | 1975-11-06 | 1976-09-21 | Phillips Petroleum Company | Partially crosslinked polymer used in correcting subterranean formation permeability |
| US4147211A (en) * | 1976-07-15 | 1979-04-03 | Union Oil Company Of California | Enhanced oil recovery process utilizing a plurality of wells |
| US4343363A (en) * | 1981-01-02 | 1982-08-10 | Marathon Oil Company | Process for cleaning a subterranean injection surface and for selectively reducing the permeability of a subterranean formation |
| US4460751A (en) * | 1983-08-23 | 1984-07-17 | Halliburton Company | Crosslinking composition and method of preparation |
| US4524829A (en) * | 1983-08-23 | 1985-06-25 | Halliburton Company | Method of altering the permeability of a subterranean formation |
| AU565273B2 (en) * | 1983-08-23 | 1987-09-10 | Halliburton Company | Polymer cross linking composition |
| US4606772A (en) * | 1984-05-04 | 1986-08-19 | Halliburton Company | Composition for and method of altering the permeability of a subterranean formation |
| US4552217A (en) * | 1984-07-09 | 1985-11-12 | Phillips Petroleum Company | Microbiocidal anionic sequesterants with polyvalent metal cations for permeability correction process |
| US4644073A (en) * | 1985-03-11 | 1987-02-17 | Phillips Petroleum Company | Permeability contrast correction employing a sulfate-free propionate-sequestered chromium (III) solution |
-
1986
- 1986-03-14 US US06/840,122 patent/US4706754A/en not_active Expired - Lifetime
- 1986-12-22 CA CA000525944A patent/CA1265436A/en not_active Expired
-
1987
- 1987-01-15 BR BR8700140A patent/BR8700140A/en unknown
- 1987-01-21 GB GB8701280A patent/GB2187773B/en not_active Expired
- 1987-02-23 NL NLAANVRAGE8700446,A patent/NL188959C/en not_active IP Right Cessation
- 1987-03-10 CN CN87101793.8A patent/CN1005730B/en not_active Expired
- 1987-03-13 NO NO871057A patent/NO177019C/en unknown
-
1991
- 1991-10-15 SA SA91120197A patent/SA91120197B1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NL188959B (en) | 1992-06-16 |
| NO871057L (en) | 1987-09-15 |
| US4706754A (en) | 1987-11-17 |
| SA91120197B1 (en) | 2003-02-22 |
| NO177019C (en) | 1995-07-05 |
| NL188959C (en) | 1992-11-16 |
| NO871057D0 (en) | 1987-03-13 |
| NO177019B (en) | 1995-03-27 |
| BR8700140A (en) | 1987-12-22 |
| CN87101793A (en) | 1987-09-23 |
| CN1005730B (en) | 1989-11-08 |
| GB2187773A (en) | 1987-09-16 |
| GB2187773B (en) | 1989-11-22 |
| GB8701280D0 (en) | 1987-02-25 |
| NL8700446A (en) | 1987-10-01 |
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