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Searches for new and innovative ways to explore for hydrocarbons have included consideration of various thermal techniques possessing the possibility of making significant contributions to exploration technology. The recognition of hydrocarbon maturation as basically a thermal process has made the relatively accurate determination of sedimentary-basin temperature history important. Whereas many thousands of bottom-hole temperature measurements have been made in hydrocarbon exploration holes in sedimentary basin, the necessarily marginal quality of these data has limited the application of heat flow, geothermal-gradient, and temperature techniques to hydrocarbon exploration and to the investigation of thermal properties of sedimentary basins.

There is no substitute for detailed and accurate temperature-depth logs made in holes that have reached thermal equilibrium. From these measurements, a large amount of thermal information can be determined, such as the effective in-situ thermal conductivity of the units encountered by the drill and evaluation of active migration phenomenon in the vicinity of the drill hole. Correlation of thermal conductivity with log properties can be used to extend throughout a sedimentary basin the detailed information from the few holes suitable for equilibrium temperature measurements. Actual logging experience and comparison of relative in-situ thermal-conductivity values with values in equivalent units measured in the laboratory demonstrate major discrepancies and emphasize the need for, and im ortance of, in-situ data.

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