摘要 |
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 shale oil passing therefrom. The shale oil contains a constituent which is carried from the formation by advancement of the processing zone through the fragmented mass. To determine the locus of the processing zone, the formation is first assayed at selected locations in the retort for content of the constituent before processing the selected locations, and, during processing, shale oil from the retort is monitored for concentration of the constituent. Preferred constituents are the heavy metals such as iron, vanadium, and arsenic.
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