Chemical logging of geothermal wells
AssigneeThe United States of America as represented by the United States Department of Energy
InventorsCharles A. Allen, Richard E. McAtee
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Abstract
The presence of geothermal aquifers can be detected while drilling in geothermal formations by maintaining a chemical log of the ratio of the concentrations of calcium to carbonate and bicarbonate ions in the return drilling fluid. A continuous increase in the ratio of the concentrations of calcium to carbonate and bicarbonate ions is indicative of the existence of a warm or hot geothermal aquifer at some increased depth.
Claims2
A method of detecting the presence of a geothermal aquifer while drilling a well in a geothermal formation, before the formation water is penetrated, comprising:
- analyzing the return drilling fluid recovered from predetermined depths during the drilling operation to determine the concentration of calcium and bicarbonate ions;
- maintaining a log of the ratio of the concentration of calcium ion to bicarbonate ion relative to the drill depth of the hole at which the concentrations were present;
- and
- monitoring the log to observe any changes in the ratio of the concentrations of the calcium to bicarbonate ion, whereby a continuously increasing ratio of the concentrations of calcium to bicarbonate ion is indicative of the presence of a geothermal aquifer at some greater depth.
Dependencies are inferred from the claim text.