US3362751A - Method and system for recovering shale oil and gas - Google Patents

Description

Jan. 9, 1.968 w, T|NL|N I 3,362,751

METHOD AND SYSTEM FOR RECOVERING SHALE OIL AND GAS Filed Feb. 28, 1966 Ihn l PART B Unitecl States atent 3,362,751 METHOD AND SYSTEM FOR RECOVERING SHALE GIL AND GAS William Tinlin, 21 Hickory St., Chicago Heights, Ill. 60411 Filed Feb. 28, 1966, Ser. No. 530,423 6 claims. (er. 299-4) This invention relates to a method ofrecovering shale oil 'and gas from shale oil formations through the application of heat under controlled conditions wherein both the hydrocarbon liquids and vapors are recovered. The invention depends in part upon the excavation of a certain configuration or system of tunnels and galleries having prescribed slopes or elevations in -relation yto each other in combination with heat lconveying means, valve means and condenser means whereby substantially 'all hydrocarbon liquids and vapors freed by the heat are recovered.

Attention has I'been direction for sometime ito the recovery of hydrocarbon loil from shale formations by various methods. One approach involves mining the shale, crushing the large aggregate and subjecting the comminute'd shale to retorting in furnaces of various designs and capacities. The necessity of handling the shale adds greatly to the cost. -In situ treatment of shale has been -practiced but has not attracted too much attention because of costs informing tunnels, inefficiency in the application of heat and the apparent necessity of using radditional expedients, such as lpressure, complex |tunnel and shaft systems and extreme direct heat or combustion of the shale strata itself tto obtain the desired Irecovery. The prior art processes have not become practical because of the high costs due to least in part to these yfactors. 1n addition little attention has been directed to recovery of the vapors that result from the in situ application of heat to a shale oil formation.

Now in accordance with this invention these diiculties are overcome by the provision of a method which is characterized lby the use of a simple tunnel and shaft system with tunnels and `galleries having certain slopes and elevations, along with the use of heat conveying and recovery means and provision for the continuous how recovery yof substantially `all of the oil and vapors as such or in the form of additional heat for the process. The process of this invention is also characterized in one `aspect iby `control of the air passing into the :tunnels wherein heat -is being applied to the shale in such a manner as to allo-w complete heat utilization through the application of heat lunder controlled conditions within a system of convecting tunnels and shafts.

Ilt becomes a primary object of this invention to provide a method of recovering oil from shale oil formations in situ.

Another object of this invention is -to provide a system of simple valve-controlled tunnels, shafts and galleries within 1a shale formation to provide for heat circulation and recovery along with condensers and oil sumps in a particular combination for emcient shale oil recovery.

Another object of this invention is ythe provision of an interrelated system of converging heating and return tunnels, vertical vapor shafts and interconnecting galleries with cooperating condenser and sumps, whereby heat applied Ito the shale 'formation passes upwardly and inwardly therethrough a manner t drive out oil and vapors into the heating Itunnel or tunnels toward at least one vapor shaft whereby IVthe oil descends -to a gallery and return tunnel for recovery, and vapors are allowed to ascend the cooler walls for partial condensation and return to the gallery and return tunnel and any uncondensed vapors are trapped in `a condenser at the `top orf the shaft for separate recovery or return thereto.

Another object of this invention is to provide a methice od of in situ oil and gas recovery from an exposed shale formation wh-ich includes `the steps of 1) 'forming at least a pair of lconverging spaced upper and lower tunnels in a vertical face of the exposed shale formation, (2) forming an interconnected gallery between 'the lower tunnels, (3) forming at least one vertical `shaft extending from an upper portion of the shale formation and communicating with the `tunnels and gallery, applying heat to the Iformation through the tunnels from an exrternal, high temperature, heat `source and recovering oil and condensate |by direct dlow from the lower tunnel.

The invention has as one feature the placement of at least one pair of tunnels one above the other such that the top tunnel is sloped downwardly into the formation and the bott-om tunnel is opposite, that is, slopes upwardly into the formation. `By connecting the ,upper and -lower 'tunnels with a vertical shaft, and applying heat to the -tunnel system an effective in situ shale oil recovery system is provided.

A yfeature of this invention is that ithe application of high temperature heat to the shale for-mation in the vicinity of the tunnels causes the lflow of oil and vapors therefrom, the former Ibeing directed by the downward slope of lthe upper tunnel to a vertical vapor shaft and thence ito `a lower gallery and through the oppositely sloped return tunnel to a sump for recovery or use, and the latter being `directed lto said vertical vapor shaft and by the stack effect Itherein to suitable condensing means for recovery.

Another feature of this invention is the provision of air control locks on the inlet ends of said heating and return tunnels whereby the ow of convection air through said system is controlled for maximum heat utilization and oil recovery.

These and other objects of this invention will become apparent or be described as the specification proceeds.

This invention may be illustrated by various embodiments including those illustrated by the drawings wherein:

FIG. 1 is a diagrammatic illustration of the vertical face of an exposed shale formation showing two forms (Parts A and B) of tunnel, recovery and heating systems; and

FIG. 2 is a cross-sectional view also in diagrammatic form taken along lines 2-2 (Part A) of FIG. 1.

FIGS. 1 and 2 show diagrammatically a shale formation 10 with cliff face 12 as it may appear after removal or stripping of surface material to expose same for treatment. Referring to FIG. 2, tunnels 14 and 16 are drilled` into the face of the shale formation to a depth of about 50 to 100 feet. Tunnel 14 is sloped downwardly into the formation. The amount of slope is not as important as the presence of sufl'icient slope to cause any liquid oil therein to flow freely inward under the influence of gravity. Similarly tunnel 16 is cut or drilled at a lower elevation into the face 12 at a slight upward slope, again for the purpose of free gravitational outward flow therein. Tunnels 14 and 16 are cut at different elevations into the face 12, that is tunnel 14 is about 30 to 50 feet above tunnel 16. A shaft 1S is drilled into the top of the shale formation 10 to intersect tunnel 14 and terminate at tunnel 16. In the simplest form this invention can be practiced with only two tunnels 14 and 16 in combination with a single shaft 18 as will hereinafter be explained. The tunnel and shaft system shown is made possible by modern continuous drilling equipment such as that shown in my Patent #3,005,627, or that disclosed in my copending applications Ser. Nos. 360,555, filed Apr. 1, 1964, now U.S. Patent No. 3,314,724, and 392,484, iiled Aug. 27, 1964, now U.S. Patent No. 3,314,725.

At the top of shaft 18 there is provided condenser 20 which may be of any suitable type designed and controlled to provide suicient cooling to condense the hydrocar- 3 bon vapors, except the noncondensible gases, issuing from shaft 18. Flue 22 is provided to collect and convey any uncondensibles for separate recovery or use.

Heat source 24 is located on valley floor 26, preferably a few feet below tunnel 16, i.e. 2 to 6 feet, and may cornprise any means for supplying heat to the shale oil formation. Heat source 24 may produce heat in the form of hot gases, or liquids and preferably in the form of superheated stream at a temperature of about 800 degrees F. to 1600 degrees F. With a three stage heater, for example, a temperature as high as 1800 degrees F. can be attained. The heat carrying medium from heat source 24 is conveyed through conduit 28 which extends through tunnel 14 and then, via leg 311 and return line 32 passing through tunnel 16, back to heat source 24.

The open end of tunnel 14 is provided with a valve means indicated at 34 which may comprise any means for opening and closing the entrance to tunnel 14 in a manner so that control of the air flow thereinto is attained. To illustrate a frame member 36 is provided Within Which a sliding door member 38 operates to attain the desired graduated opening and closing thereof. A similar valve means 4d is illustrated in relation to the open end of tunnel 16 by means of frame 42 and sliding door 44. Other equivalent valve means than a sliding door arrangement can be used.

ln order that liquid oil in tunnel 16 is collected there is provided a trough means 46 and sump 48 which later is shown as a sunken tank. Conduit 50 connects between sump 48 and heat source 24 for the purpose of providing a source of fuel for heater 24 Where same is an oil burning furnace.

Tunnels 14 and 16 may be provided with a suitable shoring, not shown, to prevent collapse as the removal of liquids `and gases proceeds within the shale formation surrounding tunnel 14. Galleries connecting the junctures of a series of the tunnels and shafts, one to the other are shown at 54 and 56 (see FIG. l).

In one aspect of this invention one pair of tunnels 14 and 16 can be used with one shaft 1S and one heat source 24. However, in a preferred embodiment one heat source is used with a plurality of tunnels as illustrated in FIG. l wherein corresponding parts to FIG. 2 bear the Same numerals.

In addition, FIG. l shows that the shafts 18 and 18 may be substantially vertical With tunnels 14 (and 14') and 16 (and 16') being similarly aligned (Part A) or may be (as shown in Part B) arranged so that shafts 18 and 18 converge downwardly or are not vertical and tunnels 14 and 14' and 16 and 16 are likewise arranged. In each instance, the tunnels intersect with the shafts at the point of intersection with the galleries 54 and 56.

In order to illustrate this invention the following examples are given:

EXAMPLE I T wo tunnels and one shaft After exposure of shale formation and cliff face 12 by removal of surface rock and other covering, tunnels 14 and 16 are drilled therein using a boring machine which cuts a hole about six feet in diameter. When necessary, suitable shoring means is installed in tunnel 14 las the bore progresses. Shaft 18 is then drilled from the top of the clil to connect the ends of tunnels 14 and 16. Tunnel 14 is cut so that it slopes into the shale formation at the rate of about 1 to 2 inches per foot. Tunnel 16 is cut so that it slopes in the opposite direction, that is, out of the shale formation, and at about the same slope as tunnel 14. With this size tunnel and shaft there is no difliculty in the installation of heat conduit 28 therein and connected back to heat source 24, which may be a three stage furnace capable of producing super heated steam at 800 degrees F. to 1600 degrees F. and as high as 1800 degrees F. Condenser is installed and valve members 34 and 40 are attached over an open ends of tunnels 14 and 16. Trough 46, and sump 4S are installed to provide gravity A flow of oil from tunnel 15. Line 'S0 is connected to sump 4S for auxiliary fuel.

Heat in the form of super-heated steam at about 1200 F. is sent through conduit 28 and valves 34 and 40 are closed. As the heat permeates the shale formation, oil begins to dow therefrom and gravitate into tunnel 14. The backward slope thereof causes this collected oil to ow into shaft 1S, downward into tunnel 16 and out tunnel 16 to sump 48. To hasten the initial heating, valve 34 is closed and valve 40 is opened. As the heating continues, vapors of lower boiling hydrocarbons and uncondensible gas C1 and C3 are collected in shaft 18 and rise to condenser 20 for recovery. Any uncondensible gases are conveyed to a suitable separate recovery system (not shown) by means of olf-gas flue 22. Gradual removal of vapors from the system is controlled so that there is substantially no dow of air into tunnel 16 via valve 40. As removal of oil from the formation lil continues, valve 40 is gradually closed and valve 34 gradually opened to allow more air to enter tunnel 14. This carries heat from conduit 28 and the surrounding partially denuded shale further into the formation and increases over-all recovery. The temperature in the shale will reach about 1000o F. Control of air intake from this point on to maximize the transfer of heat to the shale formation is accomplished by the operation of condenser 20 and ue 22 and manipulation of the values 34 and 40. Finally, the shale around and above tunnel 14 is denuded of oil and begins to crumble and cavitate. Valve 34 can be fully closed to drive the heat from the cavities and crumbled shale into the formation still further. The pocket of denuded shale so created may also be removed to recover the conduit 28 and to expose a new cliff face and the process steps repeated.

EXAMPLE H Four tunnels, two sltczfts and one or more galleries The steps of Example I are repeated and each pair of tunnels is connected at its rearward end with a shaft and a substantially horizontal gallery` As heat is applied, this time in the form of a molten metal, the valves are operated in the same manner as in Example I to control by natural convection the flow of air through tunnels 14 and 14 so as to transfer the heat to the surrounding shale body. The temperature of the shale may rise to about 1800 degrees F. In using a molten metal as the heating medium care lmust be taken not to allow too great a rate of heat transfer on the one hand and freeze-up in the conduit on the other. Oil passes into tunnels 14 and 14', drains into gallery 56 and thence through tunnels 16 and 16 into sump 48.

EXAMPLE III A plurality of tunnels, shafts and galleries The steps of Example II are continued by drilling a plurality of tunnels 14 and 14 into the face of a shale cliff. Interconnecting vertical and slanting shafts are sunk to connect with the extended ends of the tunnels. The interconnecting galleries `are drilled. The conduits, condensers, valves, perforated pipe, heat sources and sumps are installed. Heat is applied to the shale formation for about two days over about 1500 linear feet of cliff face 50 feet high. lOil is continuously recovered in the sumps and condensate from the condensers. At the end of this time the conduits are removed and a fresh cliff face exposed by removal of denuded shale.

From the foregoing examples and description, it is apparent that the process of this invention has several unforeseen advantages. First, the provision of the control of the `air flow helps to retain the heat in the upper tunnel for a sullicient time to drive the heat into the formation by natural convection and aids in regulating the conveyance of oil and vapors from the top tunnels. Secondly, the withdrawal and recovery of vapors is also in the direction of natural convection through the system which further aids and augments heat utilization and oil recovery. Recovery of the vapors immediately as they form prevents further breakdown or cracking and reduces losses due to decomposition. The over-all system mitigates losses and waste of heat and oil and vapors. The rate that oil is taken from any shale hed will be determined by the heat used, by the number of tunnels and shafts and the control of the air allowed to enter the system.

Having thus `described this invention, it should be understood that details thereof may be altered or omitted Without departing from the spirit of the invention as dened by the following claims.

I claim:

1. The method of recovering shale oil and gas from an exposed shale formation which comprises (a) forming at least one pair of vertically spaced tunnels into the face of said formation, the uppermost of said tunnels being inwardly sloped and the lowermost of said tunnels being outwardly sloped,

(b) forming an interconnecting shaft between the top of said formation and said tunnels,

(c) passing a heating medium at a temperature sufi-icient to cause the separation of oils and gases into indirect contact with said shale formation surrounding said spaced tunnels, said heating medium being sent rst through said uppermost tunnel, through said vertical shaft and out through said lowermost tunnel, and

(d) recovering liquefied oil from said tunnels and recovering said gases from said shaft.

2. The method according to claim r1 wherein the air entering the said tunnels is regulated to control the stack eect of said shaft.

3. The method in accordance with claim 1 in which said heating medium is maintained at a temperature within the range from about l800 F. to -about 1600 F. in the said uppermost tunnel and the air flow entering said upper tunnel is regulated to control the stack effect of said shaft.

4. The method in accordance with claim 1 in which a plurality of said tunnels and shafts are formed in said shale formation, interconnecting galleries are formed between the ends of said tunnels and their points of intersection with said shafts, said heating medium is maintained at a temperature sufcient to produce a space temperature of at least about 800 F. within the upper of said tunnels, and said vapors are recovered by condensing the efuent from said shafts.

5. A system for recovering shale oil and gas from a shale oil formation comprising a pair of vertically spaced tunnels in said formation, a shaft interconnecting said tunnels adjacent their inner ends and opening to the top of said formation, a high temperature heat source, conduit means for transmitting heat from said heat source into the upper of said tunnels, said conduit means leading through said shaft to the lower tunnel and thence returning to said heat source, adjustable gate means at the entrance to each tunnel for regulating the volume of air entering thereinto, and means at the top of said shaft for trapping and condensing vapors and gas issuing therefrom.

6. A system for recovering shale oil and gas from a shale oil formation as defined by claim 5 wherein a series of spaced tunnels and shafts are created in said formation to provide a series of pairs of vertically spaced tunnels each pair having -an interconnected shaft, said conduit means leads into each of the upper tunnels, down the respective shaft and out through the respective lower tunnel to return to said heat source, and wherein a sump means is provided for collecting liqueed oil and vapors owing from the lower tunnels.

References Cited UNITED STATES PATENTS 1,269,747 6/191'8 Rogers 166-39` 1,418,097 5/ 1922 Schneiders 299-4 X 1,520,737 12/ 1924 Wright 166--40 X 1,660,818 2/1928 Ranney 299--2 1,919,636 7/1933 K-arrick 299-2 2,481,051 9/1949' Uren.

2,970,826 2/1961 'VVoodrufIr 166-11 X 2,974,937 3/1961 Kiel 166-39 X 3,228,468 1/1966 'Nichols 166-11 X 3,338,306 8/1967 Cook 166-40 STEPHEN I. NOVOSAD, Primary Examiner.

Claims (2)

1. THE METHOD OF RECOVERING SHALE OIL AND GAS FROM AN EXPOSED SHALE FORMATION WHICH COMPRISES (A) FORMING AT LEAST ONE PAIR OF VERTICALLY SPACED TUNNELS INTO THE FACE OF SAID FORMATION, THE UPPERMOST OF SAID TUNNELS BEING INWARDLY SLOPED AND THE LOWERMOST OF SAID TUNNELS BEING OUTWARDLY SLOPED, (B) FORMING AN INTERCONNECTING SHAFT BETWEEN THE TOP OF SAID FORMATION AND SAID TUNNELS, (C) PASSING A HEATING MEDIUM AT A TEMPERATURE SUFFICIENT TO CAUSE THE SEPARATION OF OILS AND GASES INTO INDIRECT CONTACT WITH SAID SHALE FORMATION SURROUNDING SAID SPACED TUNNELS, SAID HEATING MEDIUM BEING SENT FIRST THROUGH SAID UPPERMOST TUNNEL, THROUGH SAID VERTICAL SHAFT AND OUT THROUGH SAID LOWERMOST TUNNEL, AND (D) RECOVERING LIQUEFIED OIL FROM SAID TUNNELS AND RECOVERING SAID GASES FROM SAID SHAFT.

5. A SYSTEM FOR RECOVERING SHALE OIL AND GAS FROM A SHALE OIL FORMATION COMPRISING A PAIR OF VERTICALLY SPACED TUNNELS IN SAID FORMATION, A SHAFT INTERCONNECTING SAID TUNNELS ADJACENT THEIR INNER ENDS AND OPENING TO THE TOP OF SAID FORMATION, A HIGH TEMPERATURE HEAT SOURCE, CONDUIT MEANS FOR TRANSMITTING HEAT FROM SAID HEAT SOURCE INTO THE UPPER OF SAID TUNNELS, SAID CONDUIT MEANS LEADING THROUGH SAID SHAFT TO THE LOWER TUNNEL AND THENCE RETURNING TO SAID HEAT SOURCE, ADJUSTABLE GATE MEANS AT THE ENTRANCE TO EACH TUNNEL FOR REGULATING THE VOLUME OF AIR ENTERING THEREINTO, AND MEANS AT THE TOP OF SAID SHAFT FOR TRAPPING AND CONDENSING VAPORS AND GAS ISSUING THEREFROM.

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