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US 4,223,726 AGranted
Determining the locus of a processing zone in an oil shale retort by effluent water composition
AssigneeOccidental Oil Shale, Inc.
InventorChang Y. Cha
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AssigneeOccidental Oil Shale, Inc.
InventorChang Y. Cha
Estimating the term…
A processing zone advances through a fragmented permeable mass of particles containing oil shale in an in-situ oil shale retort in a subterranean formation containing oil shale. The retort has an effluent water passing therefrom. The effluent water carries a constituent which is formed, by advancement of the processing zone through the fragmented mass, from a precursor contained in the formation. In a first aspect of the invention, the locus of the processing zone is determined by assaying the formation at selected locations in the retort for content of the precursor before processing the selected locations, and effluent water from the retort is monitored for concentration of the selected constituent. For example, the nitrogen content of kerogen can be the precursor and effluent water from the retort can be monitored for the concentration of ammonia and/or ammonium sulfate produced by retorting of kerogen in the oil shale. In the second embodiment of the invention, recognition is made of the correlation between the Fischer Assay of the oil shale and the amount of water it contains. Core samples of the formation are analyzed prior to processing to determine the water content and the predicted water production rate due to the passage of a processing zone through that location in the formation. Actual water production rate can then be compared with the predicted rate and the locus of the processing zone determined.
A method for determining the locus of a processing zone as it advances through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort formed in a subterranean formation containing oil shale, the retort having boundaries of unfragmented formation, comprising the steps of assaying the subterranean formation at selected locations for the content of at least one precursor for at least one selected constituent resulting from advancement of the processing zone through the formation;
A method for determining the locus of a processing zone advancing through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale, the retort having boundaries of unfragmented formation and the retort having an effluent water passing therefrom containing a selected constituent, the selected constituent being formed from at least one precursor contained in the formation by advancement of the processing zone through the fragmented mass, the method comprising the steps of:
A method for determining the locus of a processing zone advancing through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale, the retort having boundaries of unfragmented formation, the formation containing connate water, the retort having an effluent water passing therefrom containing connate water released from the formation, the method comprising the steps of:
A method for determining the locus of a processing zone advancing through a fragmented permeable mass of particles containing oil shale in an in situ oil shale retort in a subterranean formation containing oil shale, the retort having boundaries of unfragmented formation, the oil shale containing nitrogen, the retort having an effluent water passing therefrom comprising the steps of determining the nitrogen content in the formation at selected locations in the retort before processing the selected locations;
Dependencies are inferred from the claim text.