US3001776A - Method of preparation for and performance of in situ retorting - Google Patents

Description

Sept. 26, 1961 H. K. VAN PooLLEN METHOD OF PREPARATION FOR AND PERFORMANCE OF IN SITU RETORTING 2 Sheets-Sheet 1 Filed April 10, 1959 le F 3 INVENTOR.

ATTORNEYS Sept. 26, 1961 H. K. VAN PooLLEN METHOD OF PREPARATION FOR AND PERFORMANCE OF 1N SITU RETORTING 2 Sheets-Sheet 2 Filed April lO, 1959 INVENTOR.

ATTORNEYS ment zone.

' its recirculation or reintroduction through utilize the processes United States Patent O 3,001,776 METHOD OF PREPARATION FOR FORMANCE OF IN SITU RETORTING Hendrik K. van Poolleu, Englewood, Colo., assignor to The Ohio Oil Company, Findlay, Ohio, a corporation of Ohio Filed Apr. 10, 1959, Ser. No. 805,396 12 Claims. (Cl. 2623) This invention relates to a method ground retorts in a in situ retorting operations utilizing such retorts.

In the oil shale deposits of western Colorado, the overburden may be on lthe order of 1,000 feet, under which shale may extend downwardly for another 1000 to 2000 feet. The available oil content of such a shale may be on the order of -75 gallons per ton of shale processed. Conventional mining and surface treatment methods may be utilized but they add a cost factor to the oil recovery expense because of the large quantities of material that are handled in mining, conveying to and in disposing of the solids residue of the surface retort. Additionally, large quantities of water are required in coking to bring the oil produced by a surface retort to pipeline quality, whereas there is littleV or no water input in in situ retorting.

Various in situ retorting methods have been devised, including both horizontal and vertical movement of a heat front. The vertical heat front movement involves several factors which make it attractive, but where the heat front movement involves travel through 1000 shale deposit and adequate permeability is dependent upon a progressive or continuous gravitational displacement of material from an upper point of its natural formation to a lower evacuated area, blockages may occur which will impede or terminate the heat front movement.

It is an object of myv invention to provide a simple, economical and efficient method of forming underground retorts for in situ combustion operations which provide controlled gravitational movement of shale or spent shale as a partof the underground retorting procedure.

Another object for forming underprogress in completing one or more of such retorts or groups of retorts while one or morer of the other retorts or groups of retorts are performing an in situ combustion operation.` p

A further object of economical and efficientl method of preparingl an underground deposit for in situ combustion operations includingv recirculation of a portion of the material under treatment to establish required permeability within the treat- The practice of the present invention combines certain conventional mining practices with drilling operations to provide novel formation and operating procedures ina series of in situ combustion operations. meability and porosity in the formation necessary to the movement of heat fronts along vertical courses may be provided by withdrawal of some untreated or partially treated material from a'lowerportion of the course and tion of the course for subsequent treatment. Suicient permeability has to be provided along a vertical course of substantial length, for example 1000 to 2000 feet, with good Ycontrol of temperature, rate of heat front movement and amount as aforesaid affects gravitation of loosened or spent shale throughout the heat front movement.

Certain features of the operations herein described the surface plant feet or more of oil of this invention is to provide a pattern yof associated underground retorts wherein work may my invention is to provide a simple,

Per-

an upper pordisclosed in the co-pending applica-l deposit, such as orl shale, and to the l f i y of extraction throughout the extent of the treatment course, and removal of such a portion `lection tunnel 18 to the outermost retort traction. Drill .for vstorage Aand subsequent introduction race tion of Victor D. Allred, Serial No. 778,868, filed December 8, 1958, for Vertical Flow Process for In Situ Retorting of Oil Shale, assigned to the assignee of the present application, and features disclosed but not claimed herein have been The practice of this invention will reference to the accompanying drawings illustrating typical procedures. In the drawings, in the several views of which like parts bear similar reference numerals,

FIG. l is a fragmentary vertical section taken approximately along the line 1-1, FIG. 2;

FIG. 2 is a top plan view of an area of deposit to be worked, viewed approximately at the top of the shale deposit, and depicting an arrangement of underground retorts according tothe present invention;

FIG; 3 is a vertical section through the entire structure of the workings in an arrangement of the type illustrated in FIG. 2 and at 90 to the position shown in FIG; l, illustrating progressive steps in the formation of the retort pattern; i

FIG. 4 is an enlarged fragmentary view of a drill hole or well of the type shown in FIG. 3, illustrating an arrangement for explosive shattering or fracturing of a portion of Y the shale deposit adjoining such hole m the formation of the retort pattern illustrated in FIGS. 2 and 3;

FIG. 5 is a plan view of `another type of retort pattern according to the present invention; an

FIG. 6 is a vertical section through the entire structure of a-working area in an arrangement of the type depicted in FIG. 5.

Referring first to the arrangement Vshown in FIGS. 1, 2 and 3, a main shaft 12 is sunk by any well-known method to penetrate from the surface 13 through overburden 14 and shale 15 to a a short distance below the shale deposit.` A plurality of cross drifts or tunnels 17 connect with a collection drift or tunnel 18, preferably in lining upwardly away from shaft 12 so as to provide a'gravity llow to the bottom 16 f the shaft. The cross drifts 17 also incline upwardly from the col- 19 of a given co1- lection arrangement, as shown in FIG. 1, providing an all system when desired.

pattern,` a vseries of stopes 21 are dug upwardly from cross drifts 17 to provide discharge passages for loosened shale or spent shale so as to permit removal of a portion of such shale to provideisuflicient permeability above the evacuated area to insure a controlled temperature and rate of heat front movement for obtaining substantially optimum exholes 22 are put down in as nearly a concentric arrangement as practical, thereby providing upper openings as well as lower openings which maybe inlets or outlets as required by a given operation.

As shown in FIG. 3, the stopes 'Z1 .are driven far the lower end of the retorts 19 and preferably in such operation some of the loosened shale' is withdrawn, and subsequently elevated to the" surface through shaft 12 or to another location above a retort throughone or more of the holes 22 or other inlet so as to be subjected to the retorting action in the associated retort 19.

The shale 15 adjoining a given hole 22 is fractured irnmediately above a stope 21 by any suitable method, such as the arrangement shown in FIG. 4. The upper end of stope 21 is closed b-y a plug 23 of any suitable type. A charge of explosive 24 is introduced into dril hole 22 above the plug 2i` and is capped .at its top with another plug 25 having a suitable detonating device (not shown) by which the charge 24 is exploded to shatter the shale as shown IG. 3. The same procedure is folat 2.6 in F lowed to shatter theshale in successive stages as shown same and to loosen the shale throughout the retort 19, on the surface is introduced recigrculating product for subsequent treatment in the retorts 19.

a pump (not shown) the surface.

mit passage of such vapors the surface without interfering with regular shaft operations. Otherwise, the shaft becomes the conduit for passing such vapors to the surface.

In addition to the operating in which air procedure just described, is injected downwardly through the holes oil recovery at the surface.

Another `practice involves starting combustion at the top, supplying air fromunderneath for counter-current at the surface.

of retorts, it will be Aclosed by a -needed for such subsequent use.

Inthe rst example, when the` group of retorts-19 have ucts from sump 16 to the surface.

operation may utilize the `and claimed in Serial No.

substantial amount of the evolved products have been reabsorbed in the pyrolyzed shale. In the first stage retorting, the py-rolyzed shale will fall to lthe bottom of the retor-t through whatevercavity is initially formed before intiating combustion, action continues as the FIGS. 5 and lllustrate another method of forming a group or series of retorts. jA shaft 12 such as previously described is sunk from the surface 13 through overburden 14 and the bed of shale 15 and terminates in a sump 16. Collection tunnels 17 and 18'are formed in the same arrangement as previously described and stopes 33 are driven to shape the lower ends of the several reperformed in senes F in the manner previou-sly described.

of retorts can be sealed from the shaft to yavoid any hazard at the shaft from high temperatures, explosive onnoxious mixtures, `or the like. In other operations, where the bottom Vcollection system is used, suitable piping and closed tanks or yother storage container-s may be provided, and the shaft sealedyas aforesaid to prevent heat loss through it and to avoid hazardous conditions at the shaft.

Also, in operations in which a portion of the contained shale is withdrawn through the bottom to provide the required permeability, it is not always necessary to lift it to the surface for return to a retort. Tunnels or drifts may be extended Ito a point above one or more of said retorts for such return, and when the overburden is relatively deep, a substantial lamount of hoisting and handling can be avoided in this way.

The foregoing description demonstrates how the practice of my invention according to the methods depicted in FIGS. 5 and 6 permits preparation of all the retorts 34 of the entire group for simultaneous in situ retorting or progressive retort formation with operation of one or more series within the group while retort preparation is being completed in other series of the group.

In all of such operations, combustion Will -be initiated at the top or bottom of each of the retorts in the manner previously described, with wells 22 providing the necessary oxygen supply when top injection is utilized and the production well 32, one or more wells 22, or the shaft 12 may function as the production well of such retorting. Usually, the necessary amount of moved before combustion is initiated to produce the desired permeability (which m-ay be on the order of onethird by volume or weight of the shale content of t-he retort), and this material will be recirculated and treated in the manner previously described. Any of these operations may utilize the reverse combustion action previously described, and all will control air flux for substantially optimum extraction. v

From the foregoing it Will be apparent that the practice of my invention permits a choice of procedures to suit the requirements of `a given installation, and provides simple, economical and eicient methods of forming and operating series or groups of underground retorts. While the operations described have reference to o'l shale deposits, it will be understood that `other underground oil-bearing deposits may be so treated, such as the Athabaska sands, for example, and similar formations.

I claim:

l. In the art of in situ retorting of oil shale, the steps of forming an underground retort by removal of a substantial portion of contained shale from the bottom of a substantially upright retorting zone so as to increase permeability within said zone by gravitational descent of the contained shale in said zone, inducing a heat front movement upwardly through said zone for recovery of evolved products, and returning the removed shale to the surface and into the top of said zone during progress of the gravitational descent and heat front movement therein.

2. In the art of in situ :retorting of oil shale, the steps of forming an underground retort by initial removal of a substantial portion of contained shale from the bottom of a series of upright retorting zones so as to increase permeability within said zones by gravitational descent of contained shale therein, injecting air directly into the upper end of each said zone, inducing a heat front movement through each such zone countercurrent to said injected flow for recovery of evolved products, collecting evolved products at the lower ends of said zones for delivery to the surface, and returning -removed shale into each zone with the injected air during progress of the gravitational descent and heat front movement therein.

3. In the art of in situ retorting of oil shale, the steps of forming an underground retort by removal of a substantial portion of contained shale from the bottom of a shale will be re- Y 6 series of upright retorting zones so as to increase permeability within said zones byY gravitational descent of contained shale therein after shale removal, injecting air directly through an inlet into each side zone, inducing a co-current heat front movement through each zone,

' collecting evolved products through an outlet at the end said system of said zone opposite the point of air introduction for delivery to the surface, and returning removed shale to the heat front in at least one vsaid zone during progress of the gravitational descent` and heat front` movement therein by introducing said removed shale into an upper portion of the retort in which said heat front is present.

4. In the art of in situ retorting of oil shale, the steps of forming an underground restortby initially removing a substantial portion of contained shale from the bottom of a series of upright retorting' zones so as to increase permeability withinsaid zones by gravitational descent of contained shale'therein after shale removal, injecting air directly through an inlet into each' said zone, inducing a countercurrent progressive' through each zone, collecting evolved products let at the end of the zone opposite the point of air introduction for delivery to the surface, and returning removed shale through an upper portion of said retort in a gravity iiow heat front maintained therein.

5. Inthe art of oil shale, the steps of forming an underground retort by initially removing a substantial portion of contained shale from the bottomof a series of upright retorting zones so as to increase permeability within said zones by gravitational descent of contained shale therein, injecting air directly into the lower end of each said zone, inducing a co-current heat front movement through each such zone, collecting evolved products at the upper ends of said zones for delivery to the surface, and returning removed shale countercurrent to the heat front in a -gravity flow in at least one said zone.

6. In the art of in situ retorting of oil shale, the steps of forming an underground retort by initially removing a substantial portion of contained shale from the bottom of a series of substantially upright retorting zones so as to increase permeability within said zones by gravitational descent of contained shale therein after shale removal, injecting air directly through an inlet into the upper end of each said zone, inducing a heat front movement through each such zone in cocurrent relation to said injected flow for recovery of evolved products, co1- lecting evolved products through an outlet at the bottom of said Yzones for delivery to the surface, and returning removed shale through an inlet in an upper portion of at least one retort for gravity flow to a heat front advancing progressively in at least one said zone.

7. In the art of in situ retorting of oil shale, the steps of forming a collection system at the bottom of a shale deposit, forming a series of retort zones extending upwardly through the extent of said deposit at intervals along said system, initially removing a substantial portion of the contained shale from the lower portion of each zone through said system for delivery to the surface, fracturing the shale above said evacuated portions for gravitational descent of contained shale therein and increased permeability in the zone, directing a ilow o air from the surface into the upper end of each said zone, initiating a heat front movement in the respective zones countercurrent to said air flow, and returning removed shale into any of said zones in conjunction with the air injection during progress of the heat front movement.

8. In the art of in situ retorting of oil shale, the steps of forming a collection system at the bottom of a shale deposit inclusive of a shaft extending to the surface, forming a series of retort zones extending upwardly through said deposit at intervals along said system remote from said shaft, initially removing a substantial portion of the shale in the bottom of each zone through for delivery to the surface, fracturing the 11. In the art of in situ retorting of oil shale, the steps Ving removed shale into an upper portion of at least one 0f fQlml'llg 11 Underground retort by removal 0f a Subthrough said co'iiectien 'Sys-tem for delivery `to Vthe surface. '1o Permeability within Said Zone byar-avtatinal descent of the Shaft 4thmugh ,a Substantial area, forming a group of '15 heat front With spent gases therefrom carrying evolved of said retorting zone after gravitational descent of pyrolyzed shale therein.

Y and Shaft to the surface 25 some of the lcontained shale in said zone, inducing a heat low the base of said deposit, forming a collection system beneath the shale extending forwardly and laterally from the shaft through a substantial area, forming a group of 30 Products to a pomt o u ri ht retort zones at intervals alon said s stem b iniremrfng preYiGusy .p g g y y of said retorting zon rolyzed shale therein.

said fracturing in one series in advance of another series, 35

for said completed senes from the remainder of the col- 1,913,395 Karri lection system, extending a production well from the sur- 1,919,636 Karri face to a low point 1n the sea-led collection system inject- 2,481,051 Uren ing air into the upper portion of the completed series of 40 2,780,449 Fishe f vdischarge from the retort zone, and removed shale to the upper portion e during gravitational descent of py- References Cited in the le of this patent UNITED STATES PATENTS ck June 13, 1933 ck July 25, 1933 Sept. 6, 1949 r et al Feb. 5, 1957

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