In situ recovery of oil from oil shale

Claim 1

A method for in situ recovery of oil from oil shale containing kerogen, comprising: thermally decomposing the kerogen underground to produce oil vapors, combustible gases, and solid carbon residue at a temperature below about 1100° F., conducting the oil vapors and combustible gases to aboveground and recovering them there, while leaving the solid carbon residue below ground, only after completing the recovering of the oil vapors and combustible gases at a given portion of a site, burning the solid carbon residue at that portion of the site underground at a controlled rate such that the temperature of the formation rises to about 1500° to 1900° F. but remains below the softening temperature of the spent shale and at controlled oxidation, so that carbon monoxide is produced, conducting the gases containing carbon monoxide aboveground and recovering the carbon monoxide there, injecting water into the hot formation at that portion of the site only after the burning step is completed at that portion of the site to produce steam at high temperature, and conducting the high temperature steam aboveground and recovering its heat values there.

Claim 2

A method for in situ recovery of oil from oil shale containing kerogen, comprising: thermally decomposing the kerogen underground to produce oil vapors, combustible gases, and solid carbon residue at a temperature below about 1100° F., conducting the oil vapors and combustible gases to aboveground and recovering them there, while leaving the solid carbon residue below ground, only after completing the recovering of the oil vapors and combustible gases at a given portion of a site, burning the solid carbon residue at that portion of the site underground at a controlled rate such that the temperature of the formation rises to about 1500° to 1900° F. but remains below the softening temperature of the spent shale and at controlled oxidation, so that carbon monoxide is produced, conducting the gases containing carbon monoxide aboveground and recovering the carbon monoxide there, injecting water into the hot formation at that portion of the site only after the burning step is completed at that portion of the site to produce steam at high temperature, and conducting the high temperature steam aboveground and recovering its heat values there.

Claim 10

A method for obtaining useful products from an oil shale formation, comprising the following steps: (1) drilling a series of wells into said formation from above ground, (2) opening and maintaining generally vertical passageways between wells in the shale formation, (3) retorting the shale in situ with controlled pyrolysis by (a) sending air down through some of said wells, as injection wells and injecting it into said passageways, (b) igniting the shale at the adjacent other said recovery wells, (c) burning the shale with the combustion front progressing generally horizontally from the recovery wells toward the injection wells, and (d) recovering vaporized petroleum products through said other wells as recovery wells, leaving in place unburned carbon residue and other non-volatile shale ingredients, (4) only after completion of steps 1-3 at some said wells, burning the carbon residue there in situ under controlled conditions while (a) sending air down through said injection wells at a controlled rate, (b) controlling the burning and air injection to produce a substantial amount of carbon monoxide, (c) recovering the carbon monoxide through said recovery wells, (d) preventing softening of the remaining formation, and (e) decomposing alkaline earth carbonates in said formation into alkaline earth oxides, and (5) soon after, but only after completing said burning step at said some wells, injecting water into said injection wells, thereby (a) producing steam at high temperatures, (b) recovering high-temperature steam through said recovery wells, and (c) reacting some of said steam with some of said alkaline earth oxides to produce some alkaline earth hydroxides.

Claim 11

A method for obtaining useful products from an oil shale formation, comprising the following steps: (1) drilling a series of wells into said formation from above ground, (2) opening and maintaining generally vertical passageways between wells in the shale formation, (3) retorting the shale in situ with controlled pyrolysis by (a) sending air down through some of said wells, as injection wells and injecting it into said passageways, (b) igniting the shale at the adjacent other said recovery wells, (c) burning the shale with the combustion front progressing generally horizontally from the recovery wells toward the injection wells, and (d) recovering vaporized petroleum products through said other wells as recovery wells, leaving in place unburned carbon residue and other non-volatile shale ingredients, (4) only after completion of steps 1-3 at some said wells, burning the carbon residue there in situ under controlled conditions while (a) sending air down through said injection wells at a controlled rate, (b) controlling the burning and air injection to produce a substantial amount of carbon monoxide, (c) recovering the carbon monoxide through said recovery wells, (d) preventing softening of the remaining formation, and (e) decomposing alkaline earth carbonates in said formation into alkaline earth oxides, and (5) soon after, but only after completing said burning step at said some wells, injecting water into said injection wells, thereby (a) producing steam at high temperatures, (b) recovering high-temperature steam through said recovery wells, and (c) reacting some of said steam with some of said alkaline earth oxides to produce some alkaline earth hydroxides.

Claim 16

A method for obtaining useful products from an oil shale formation, comprising the following steps: (1) drilling a series of wells into said formation from above ground in a hexagonal pattern with recovery wells at the vertices and drilling injection wells, one at the center of each hexagon, (2) opening passageways between wells in the shale formation, (3) retorting the shale in situ with controlled pyrolysis at approximately 600° F. to 1100° F., by (a) sending air down through said injection wells and injecting it into said passageways, (b) igniting the shale adjacent to said recovery wells, (c) burning the shale with the combustion front progressing from the recovery wells toward the injection wells, and (d) recovering vaporized petroleum products through said recovery wells, leaving in place carbon residue and other nonvolatile shape ingredients including alkaline earth carbonates, (4) only after completion of steps 1-3 at some said wells burning the carbon residue adjacent said wells in situ under controlled conditions, while (a) sending air down through those said injection wells at a controlled rate, (b) controlling the burning the air injection to produce a substantial amount of carbon monoxide, (c) recovering the carbon monoxide through those said recovery wells, (d) preventing softening of the remaining formation by holding the temperature of the formation between 1500° F. and 1900° F., and (e) decomposing the alkaline earth carbonates into alkaline earth oxides, (5) soon after, but only after, completing said burning step at those said wells, injecting water into said injection wells, thereby (a) producing steam at high temperatures (b) recovering high-temperature steam through those said recovery wells, and (c) reacting some of said steam with some of said alkaline earth oxides to produce some alkaline earth hydroxides, and (6) injecting waste gases containing carbon dioxide and sulfur oxides into those said injection wells, thereby (a) reacting said alkaline earth oxides and hydroxides to produce carbonates, sulfites, and sulfates, and, thereby, (b) strengthening said formation and (c) purifying said injected gases.

Claim 17

A method for obtaining useful products from an oil shale formation, comprising the following steps: (1) drilling a series of wells into said formation from above ground in a hexagonal pattern with recovery wells at the vertices and drilling injection wells, one at the center of each hexagon, (2) opening passageways between wells in the shale formation, (3) retorting the shale in situ with controlled pyrolysis at approximately 600° F. to 1100° F., by (a) sending air down through said injection wells and injecting it into said passageways, (b) igniting the shale adjacent to said recovery wells, (c) burning the shale with the combustion front progressing from the recovery wells toward the injection wells, and (d) recovering vaporized petroleum products through said recovery wells, leaving in place carbon residue and other nonvolatile shape ingredients including alkaline earth carbonates, (4) only after completion of steps 1-3 at some said wells burning the carbon residue adjacent said wells in situ under controlled conditions, while (a) sending air down through those said injection wells at a controlled rate, (b) controlling the burning the air injection to produce a substantial amount of carbon monoxide, (c) recovering the carbon monoxide through those said recovery wells, (d) preventing softening of the remaining formation by holding the temperature of the formation between 1500° F. and 1900° F., and (e) decomposing the alkaline earth carbonates into alkaline earth oxides, (5) soon after, but only after, completing said burning step at those said wells, injecting water into said injection wells, thereby (a) producing steam at high temperatures (b) recovering high-temperature steam through those said recovery wells, and (c) reacting some of said steam with some of said alkaline earth oxides to produce some alkaline earth hydroxides, and (6) injecting waste gases containing carbon dioxide and sulfur oxides into those said injection wells, thereby (a) reacting said alkaline earth oxides and hydroxides to produce carbonates, sulfites, and sulfates, and, thereby, (b) strengthening said formation and (c) purifying said injected gases.