Method of producing hydrocarbons from oil shale formations

Claim 1

The method of claim 1 including the step of maintaining said relatively cool fluid in contact with the cavern roof while circulating kerogen-pyrolyzing fluid through hydrocarbon-bearing material within the cavern.

Claim 10

A method of producing hydrocarbons from a subterranean hydrocarbon-bearing earth formation that is normally impermeable and contains a significant proportion of heat sensitive carbonate material, comprising the steps of: forming a generally horizontally-extensive cavern in the formation below the upper boundary region of said formation; opening fluid communication between a surface location and said cavern; circulating hot fluid from said surface location through said fluid communication and into contact with the roof of said cavern at a temperature sufficient to fracture at least portions of the roof of said cavern by releasing carbon dioxide from said carbonate material, and back to a surface location; and increasing the volume of fluid within the cavern and changing the flow paths of fluid within the cavern to maintain hot fluid in contact with the roof of the cavern for a time sufficient to enlarge the cavern by an upward migration of the roof of the cavern.

Claim 15

A method of producing oil from a subterranean oil shale formation containing heat-sensitive carbonate material comprising the steps of: measuring the geological properties of subterranean formations to identify the depth of at least an upper boundary region of a vertically extensive oil-bearing formation that is normally impermeable and contains a significant proportion of heat-sensitive carbonate material; forming a generally horizontally-extensive cavern in the formation below said upper boundary region; opening fluid communication between a surface location and said cavern; circulating hot fluid from said surface location through said fluid communication and into contact with the roof of said cavern at a temperature sufficient to release carbon dioxide from said carbonate material and back to said surface location; increasing the volume of said fluid within said cavern to maintain said circulating hot fluid in contact with the roof of the cavern for a time sufficient to enlarge the cavern by an upward migration of the roof of the cavern; displacing relatively cool fluid into contact with the roof of the cavern before the roof has migrated above said upper boundary region, with said relatively cool fluid having a temperature at which the rate of said upward migration of the roof of the cavern is insignificant; circulAting a kerogen-pyrolyzing fluid through the cavern; and recovering oil therefrom.

Claim 19

A method of producing oil from a subterranean oil shale formation containing heat-sensitive carbonate material comprising the steps of: penetrating at least one well bore into said formation; injecting an aqueous leaching fluid into said carbonate material containing oil shale to leach a portion of the carbonate material and form a cavern; fracturing and rubbling the partially leached cavern; circulating a hot fluid onto the roof of said fractured rubblized cavern at a temperature sufficient to release CO2 from the carbonate material; displacing cool fluid into contact with the roof of the cavern; circulating a kerogen-pyrolyzing fluid through the cavern; and recovering oil therefrom.

Claim 21

A method of producing hydrocarbons from a subterranean hydrocarbon bearing earth formation containing heat-sensitive carbonate materials comprising the steps of: a. penetrating the formation containing the heat-sensitive carbonates with at least one well; b. forming a cavern in formation (a) and establishing communication via the well between the cavern and the surface. c. contacting the roof of the cavern with a hot fluid at a temperature sufficient to decompose the heat-sensitive carbonates to carbon dioxide and water for a time interval sufficient to effect rubbling of the oil shale and enlargement of the cavern; d. terminating contacting the cavern roof with a hot fluid as in (c) and contacting the cavern roof with a cool fluid to terminate carbonate decomposition and rubbling; e. injecting a kerogen-pyrolyzing fluid through the cavern; and f. recovering hydrocarbons therefrom.