Analyzing oil shale retort off-gas for carbon dioxide to determine the combustion zone temperature

Claim 1

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation, the subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates in the subterranean formation; (b) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone, forming inorganic oxides and gaseous carbon dioxide; (c) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the processing zone, the carbon dioxide content of the withdrawn off-gas being a function of the temperature of the processing zone; (d) determining the carbon dioxide content of the withdrawn off-gas; and (e) correlating the carbon dioxide content of the withdrawn off-gas with the temperature of the processing zone.

Claim 2

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation, the subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates in the subterranean formation; (b) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone, forming inorganic oxides and gaseous carbon dioxide; (c) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the processing zone, the carbon dioxide content of the withdrawn off-gas being a function of the temperature of the processing zone; (d) determining the carbon dioxide content of the withdrawn off-gas; and (e) correlating the carbon dioxide content of the withdrawn off-gas with the temperature of the processing zone.

Claim 5

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation, the subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort containing a fragmented permeable mass of formation particles comprising keorgen and inorganic carbonates in the subterranean formation; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone, forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the processing zone, the carbon dioxide content of withdrawn off-gas being a function of the temperature of the processing zone; (e) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature of the processing zone at such selected elevations in the retort; (f) determining the locus of the processing zone; (g) determining the carbon dioxide content of the withdrawn off-gas; and (h) correlating the carbon dioxide content of the withdrawn off-gas with the temperature of the processing zone.

Claim 6

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation, the subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort containing a fragmented permeable mass of formation particles comprising keorgen and inorganic carbonates in the subterranean formation; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone, forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the processing zone, the carbon dioxide content of withdrawn off-gas being a function of the temperature of the processing zone; (e) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature of the processing zone at such selected elevations in the retort; (f) determining the locus of the processing zone; (g) determining the carbon dioxide content of the withdrawn off-gas; and (h) correlating the carbon dioxide content of the withdrawn off-gas with the temperature of the processing zone.

Claim 9

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) forming a combustion zone in the fragmented permeable mass; (c) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of the withdrawn off-gas being a function of the temperature of the combustion zone; (e) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature of the combustion zone; (f) determining the carbon dioxide content of the withdrawn off-gas; and (g) comparing the determined carbon dioxide content of the withdrawn off-gas with carbon dioxide content of off-gas predicted as a function of the temperature of the combustion zone.

Claim 10

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) forming a combustion zone in the fragmented permeable mass; (c) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of the withdrawn off-gas being a function of the temperature of the combustion zone; (e) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature of the combustion zone; (f) determining the carbon dioxide content of the withdrawn off-gas; and (g) comparing the determined carbon dioxide content of the withdrawn off-gas with carbon dioxide content of off-gas predicted as a function of the temperature of the combustion zone.

Claim 11

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) forming a combustion zone in the fragmented permeable mass; (d) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (e) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of withdrawn off-gas being a function of the temperature of the combustion zone; (f) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature of the combustion zone at such selected elevations in the retort; (g) determining the locus of the combustion zone; (h) determining the carbon dioxide content of the withdrawn off-gas; and (i) comparing the determined carbon dioxide content of the withdrawn off-gas with carbon dioxide content of off-gas predicted as a function of the temperature of the combustion zone.

Claim 12

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) forming a combustion zone in the fragmented permeable mass; (d) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (e) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of withdrawn off-gas being a function of the temperature of the combustion zone; (f) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature of the combustion zone at such selected elevations in the retort; (g) determining the locus of the combustion zone; (h) determining the carbon dioxide content of the withdrawn off-gas; and (i) comparing the determined carbon dioxide content of the withdrawn off-gas with carbon dioxide content of off-gas predicted as a function of the temperature of the combustion zone.

Claim 13

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) forming a combustion zone in the fragmented permeable mass; (c) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture being a function of the temperature of the combustion zone; (e) predicting the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture, as a function of the temperature of the combustion zone; (f) determining the carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture; and (g) comparing the determined carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture with a predicted carbon dioxide content in withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture as a function of the temperature of the combustion zone.

Claim 14

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) forming a combustion zone in the fragmented permeable mass; (c) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture being a function of the temperature of the combustion zone; (e) predicting the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture, as a function of the temperature of the combustion zone; (f) determining the carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture; and (g) comparing the determined carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture with a predicted carbon dioxide content in withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture as a function of the temperature of the combustion zone.

Claim 15

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) forming a combustion zone in the fragmented permeable mass; (d) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (e) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture being a function of the temperature of the combustion zone; (f) predicting the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture as a function of the temperature of the combustion zone at such selected elevations in the retort; (g) determining the locus of the combustion zone; (h) determining the carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture; and (i) comparing the determined carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture with a predicted carbon dioxide content in withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture as a function of the temperature of the combustion zone.

Claim 16

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) forming a combustion zone in the fragmented permeable mass; (d) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone forming inorganic oxides and gaseous carbon dioxide; (e) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture being a function of the temperature of the combustion zone; (f) predicting the carbon dioxide content of such withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture as a function of the temperature of the combustion zone at such selected elevations in the retort; (g) determining the locus of the combustion zone; (h) determining the carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture; and (i) comparing the determined carbon dioxide content of the withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture with a predicted carbon dioxide content in withdrawn off-gas per unit of oxygen in such oxygen-supplying gas in the retort inlet mixture as a function of the temperature of the combustion zone.

Claim 17

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) forming a combustion zone in the fragmented permeable mass; (c) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone, forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted being a function of the temperature of the combustion zone; (e) predicting the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone; (f) determining the amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted; and (g) comparing the determined amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted with a predicted amount of carbon dioxide in withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone.

Claim 18

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) forming a combustion zone in the fragmented permeable mass; (c) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone, forming inorganic oxides and gaseous carbon dioxide; (d) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted being a function of the temperature of the combustion zone; (e) predicting the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone; (f) determining the amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted; and (g) comparing the determined amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted with a predicted amount of carbon dioxide in withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone.

Claim 19

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) forming a combustion zone in the fragmented permeable mass; (d) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone, forming inorganic oxides and gaseous carbon dioxide; (e) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted being a function of the temperature of the combustion zone; (f) predicting the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone at such selected elevations in the retort; (g) determining the locus of the combustion zone; (h) determining the amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted; and (i) comparing the determined amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted with a predicted amount of carbon dioxide in withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone.

Claim 20

A method for determining the temperature of a combustion zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) sampling formation to determine the type and amount of inorganic carbonates present in the fragmented permeable mass of formation particles at selected elevations in the oil shale retort; (c) forming a combustion zone in the fragmented permeable mass; (d) introducing a retort inlet mixture comprising an oxygen-supplying gas for advancing the combustion zone through the retort for forming a retorting zone on the advancing side of the combustion zone for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the combustion zone, forming inorganic oxides and gaseous carbon dioxide; (e) withdrawing off-gas, including carbon dioxide from carbonate decomposition, from the retort on the advancing side of the retorting zone, the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted being a function of the temperature of the combustion zone; (f) predicting the amount of carbon dioxide in such withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone at such selected elevations in the retort; (g) determining the locus of the combustion zone; (h) determining the amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted; and (i) comparing the determined amount of carbon dioxide in the withdrawn off-gas per ton of oil shale retorted with a predicted amount of carbon dioxide in withdrawn off-gas per ton of oil shale retorted as a function of the temperature of the combustion zone.

Claim 21

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorgnic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone forming inorganic oxides and gaseous carbon dioxide; (c) determining the locus of the processing zone; (d) withdrawing off-gas including carbon dioxide from carbonate decomposition from the retort, the carbon dioxide content of withdrawn off-gas being a function of the temperature and locus of the processing zone; (e) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature and locus of the processing zone; (f) determining the carbon dioxide content of the withdrawn off-gas; and (g) correlating the carbon dioxide content of the withdrawn off-gas with a temperature of the processing zone having the determined locus.

Claim 22

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorgnic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone forming inorganic oxides and gaseous carbon dioxide; (c) determining the locus of the processing zone; (d) withdrawing off-gas including carbon dioxide from carbonate decomposition from the retort, the carbon dioxide content of withdrawn off-gas being a function of the temperature and locus of the processing zone; (e) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature and locus of the processing zone; (f) determining the carbon dioxide content of the withdrawn off-gas; and (g) correlating the carbon dioxide content of the withdrawn off-gas with a temperature of the processing zone having the determined locus.

Claim 24

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) determining the composition of the fragmented permeable mass of formation particles; (c) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone forming inorganic oxides and gaseous carbon dioxide; (d) determining the locus of the processing zone; (e) withdrawing off-gas including carbon dioxide from carbonate decomposition from the retort, the carbon dioxide content of withdrawn off-gas being a function of the temperature and locus of the processing zone; (f) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature and locus of the processing zone; (g) determining the carbon dioxide content in the withdrawn off-gas; and (h) correlating the carbon dioxide content of the withdrawn off-gas with the temperature of the processing zone having the determined locus.

Claim 25

A method for determining the temperature of a processing zone in a fragmented permeable mass of formation particles in an in situ oil shale retort in a subterranean formation comprising kerogen and inorganic carbonates, the method comprising the steps of: (a) forming an in situ oil shale retort in a subterranean formation, the in situ oil shale retort containing a fragmented permeable mass of formation particles comprising kerogen and inorganic carbonates; (b) determining the composition of the fragmented permeable mass of formation particles; (c) advancing a processing zone through the fragmented permeable mass of formation particles for producing liquid and gaseous products from the kerogen, at least a portion of such inorganic carbonates being decomposed in the processing zone forming inorganic oxides and gaseous carbon dioxide; (d) determining the locus of the processing zone; (e) withdrawing off-gas including carbon dioxide from carbonate decomposition from the retort, the carbon dioxide content of withdrawn off-gas being a function of the temperature and locus of the processing zone; (f) predicting the carbon dioxide content of such withdrawn off-gas as a function of the temperature and locus of the processing zone; (g) determining the carbon dioxide content in the withdrawn off-gas; and (h) correlating the carbon dioxide content of the withdrawn off-gas with the temperature of the processing zone having the determined locus.