Claims
- 1. A method for recovering liquid and gaseous products from an in situ oil shale retort in a subterranean formation containing oil shale, such an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale and having upper, lower, and side boundaries, comprising the steps of:
- excavating formation from within the retort boundaries for forming a lower void extending generally horizontally across a lower level of the retort site, leaving a first zone of unfragmented formation within the retort boundaries above the lower void;
- excavating formation from a production level spaced below the lower void for forming at least one production level drift, leaving a second zone of unfragmented formation between the lower void and the production level drift;
- forming a plurality of product withdrawal passages through said second zone of unfragmented formation between the lower void and the production level drift for providing fluid communication between the fragmented mass in the retort and the production level drift, each of said product withdrawal passages containing a permeable mass of particles;
- explosively expanding such first zone of unfragmented formation toward at least the lower void for forming a fragmented permeable mass of formation particles containing oil shale within the retort;
- withdrawing the mass of particles from the product withdrawal passages;
- establishing a retorting zone in an upper portion of the fragmented mass in the retort and advancing the retorting zone through the fragmented mass in the retort for producing liquid and gaseous products of retorting;
- passing such liquid and gaseous products of retorting from the fragmented mass in the retort through each of such a plurality of empty product withdrawal passages to the production level drift; and
- withdrawing such products of retorting from the production level drift.
- 2. The method according to claim 1 wherein the product withdrawal passages are spaced apart across the horizontal cross section of the lower void for withdrawing products of retorting from separate locations spaced apart across the horizontal cross section of the fragmented mass in the retort.
- 3. The method according to claim 1 comprising forming such a product withdrawal passage with a larger horizontal cross-sectional area adjacent the lower void and a smaller horizontal cross-sectional area adjacent the production level drift.
- 4. The method according to claim 1 comprising filling at least a portion of the production level drift with a mass of particles prior to explosive expansion of the first zone of unfragmented formation for supporting the mass of particles in each product withdrawal passage during such explosive expansion, withdrawing the mass of particles from the production level drift after such explosive expansion.
- 5. The method according to claim 1 comprising forming the product withdrawal passages with a total cross-sectional area for gas flow that is greater than about 1% of the horizontal cross-sectional area of the fragmented mass in the retort.
- 6. The method according to claim 1 comprising forming the production level drift with a horizontal cross-sectional area less than the horizontal cross-sectional area of the fragmented mass in the retort.
- 7. The method according to claim 1 comprising forming a plurality of production level drifts each communicating with at least one product withdrawal passage.
- 8. The method according to claim 1 including backfilling each of a plurality of such product withdrawal passages with a mass of particles up to the vicinity of the lower level void prior to explosive expansion of the first zone of unfragmented formation.
- 9. The method according to claim 1 comprising forming the production level drift with a plurality of branch drifts each communicating with at least one product withdrawal passage, and at least one principal drift communicating with such branch drifts for withdrawing products of retorting from the branch drifts.
- 10. The method according to claim 9 comprising forming the principal drift with a cross-section for gas flow that is greater than the cross section for gas flow through such a branch drift.
- 11. The method according to claim 1 including placing means for inhibiting flow of particles into such a product withdrawal passage at the top of such a product withdrawal passage.
- 12. A method for recovering liquid and gaseous products from an in situ oil shale retort, such an in situ oil shale retort in a subterranean formation, such as in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale and having upper, lower and side boundaries, comprising the steps of:
- excavating formation from within the retort boundaries for forming a lower void extending generally horizontally across a lower level of the retort site, leaving a first zone of unfragmented formation within the retort boundaries above the lower void;
- excavating formation from a production level spaced below the lower void for forming at least one production level drift, leaving a second zone of unfragmented formation between the lower void and the production level drift;
- forming a plurality of product withdrawal passages through said second zone of unfragmented formation between the lower void and the production level drift for providing fluid communication between the fragmented mass in the retort and the production level drift, each of said product withdrawal passages containing a permeable mass of particles;
- explosively expanding such first zone of unfragmented formation toward at least the lower void for forming a fragmented permeable mass of formation particles containing oil shale within the retort, wherein the mass of particles in each of the product withdrawal passages has a void fraction which is greater than the void fraction of the fragmented mass of particles in the retort;
- establishing a retorting zone in an upper portion of the fragmented mass in the retort and advancing the retorting zone through the fragmented mass in the retort for producing liquid and gaseous products of retorting;
- passing such liquid and gaseous products of retorting from the fragmented mass in the retort through each of such a plurality of product withdrawal passages to the production level drift; and
- withdrawing such products of retorting from the production level drift.
- 13. The method according to claim 12 comprising excavating a plurality of such product withdrawal passages extending diagonally upwardly between the product withdrawal drift and locations mutually spaced apart across the horizontal cross section of the lower void.
- 14. The method according to claim 12 comprising forming the product withdrawal passages so they extend to a plurality of locations mutually spaced apart across the horizontal cross section of the production level drift; and including conveying the gaseous products of retorting from the product withdrawal passages through the production level drift from each of a plurality of such locations past gaseous products entering the production level drift from the other of such locations in the production level drift.
- 15. The method according to claim 12 including placing at least one gas collection conduit in the production level drift for withdrawing off gas from at least one such product withdrawal passage independently of gas flow in the production level drift from another such product withdrawal passage.
- 16. A method for forming an in situ oilshale retort in a subterranean formation containing oil shale, such an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale within upper, lower and side boundaries of unfragmented formation comprising the steps of:
- excavating formation from within the retort boundaries for forming at least one retort level void extending horizontally across a lower level of the retort adjacent to the bottom boundary, leaving at least one remaining portion of unfragmented formation within the boundaries of the retort and having a horizontally extending free face overlying such a void;
- excavating at least one production level drift in formation below the retort level void, leaving a lower zone of unfragmented formation between the bottom boundary of the retort and the production level drift;
- excavating a plurality of product withdrawal passages extending through said lower zone of unfragmented formation from the retort level void to such production level drift for providing fluid communication from the retort to the production level drift, said product withdrawal passages being mutually spaced apart across the horizontal cross section of the retort being formed;
- placing a permeable mass of particles in each of such product withdrawal passages;
- explosively expanding such remaining portion of unfragmented formation toward at least the retort level void for forming a fragmented permeable mass of formation particles containing oil shale within the upper, lower, and side boundaries of the retort site; and
- removing the masses of particles from such product withdrawal passages after said explosive expansion step.
- 17. The method according to claim 16 comprising the step of placing a grizzly at the top of each product withdrawal passage prior to the explosive expansion step.
- 18. The method according to claim 16 in which the horizontal cross-sectional area of the production level drift is less than the horizontal cross-sectional area of the fragmented mass in the retort.
- 19. The method according to claim 16 comprising forming a plurality of such product withdrawal passages so that they communicate with a single production level drift.
- 20. A method for forming an in situ oil shale retort in a subterranean formation containing oil shale, such an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale within upper, lower and side boundaries of unfragmented formation comprising the steps of:
- excavating formation from within the retort boundaries for forming at least one retort level void extending horizontally across a lower level of the retort adjacent to the bottom boundary, leaving at least one remaining portion of unfragmented formation within the boundaries of the retort and having a horizontally extending free face overlying such a void;
- excavating at least one production level drift in formation below the retort level void, leaving a lower zone of unfragmented formation between the bottom boundary of the retort and the production level drift;
- excavating a plurality of product withdrawal passages extending through said lower zone of unfragmented formation from the retort level void to such production level drift for providing fluid communication from the retort to the production level drift, said product withdrawal passages being mutually spaced apart across the horizontal cross section of the retort being formed;
- placing a permeable mass of particles in each of such product withdrawal passages;
- explosively expanding such remaining portion of unfragmented formation toward at least the retort level void for forming a fragmented permeable mass of formation particles containing oil shale within the upper, lower, and side boundaries of the retort site;
- placing a grizzly at the top of each product withdrawal passage prior to the explosive expansion step; and
- removing the masses of particles from such product withdrawal passages after said explosive expansion step.
- 21. A method for forming an in situ oil shale retort in a subterranean formation containing oil shale, such an in situ oil shale retort having a top boundary, a bottom boundary, and generally vertically extending side boundaries of unfragmented formation and containing a fragmented permeable mass of formation particles containing oil shale, the method comprising the steps of:
- excavating a lower void extending across the lower boundary of the retort, leaving a remaining zone of unfragmented formation within the side boundaries above the lower void;
- excavating a production level drift below the lower boundary of the retort, leaving a lower zone of unfragmented formation between the lower void and the production level drift;
- excavating a plurality of product withdrawal passages through the lower zone of unfragmented formation between the bottom boundary of the retort and such a production level drift;
- filling each of said product withdrawal passages with a permeable mass of particles;
- explosively expanding such a remaining zone of unfragmented formation toward at least the lower void for forming such a fragmented permeable mass of formation particles containing oil shale within the retort;
- withdrawing the permeable mass of particles from such product withdrawal passage after the explosive expansion step;
- establishing a retorting zone in an upper portion of the fragmented mass in the retort and advancing the retorting zone through the fragmented mass in the retort for producing liquid and gaseous products of retorting;
- passing such liquid and gaseous products of retorting from the fragmented mass in the retort through each of such a plurality of empty product withdrawal passages to the production level drift; and
- withdrawing such products of retorting from the production level drift.
- 22. The method according to claim 21 wherein the product withdrawal passages are mutually spaced apart across the horizontal cross section of the lower void for withdrawing products of retorting from locations spaced across the lower portion of the fragmented mass in the retort.
- 23. The method according to claim 21 comprising passing liquid and gaseous products of retorting from the fragmented mass in the retort through each of a plurality of such product withdrawal passages to the production level drift.
- 24. The method according to claim 21 comprising forming such a product withdrawal passage with a larger horizontal cross-sectional area adjacent the lower void and a smaller horizontal cross-sectional area adjacent the production level drift.
Parent Case Info
This application is a continuation-in-part of U.S. patent application Ser. No. 204,641, entitled FLUID OUTLET AT THE BOTTOM OF AN IN SITU OIL SHALE RETORT, filed Nov. 6, 1980 and now abandoned.
Government Interests
The Government of the United States of America has rights in this invention pursuant to Cooperative Agreement DE-FC20-78LC10036 awarded by the U.S. Department of Energy.
US Referenced Citations (12)
Continuation in Parts (1)
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Number |
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204641 |
Nov 1980 |
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