Evaluation of EGS Resources in the Eastern United States: Illinois, Michigan, Indiana, Western Ohio and Western Kentucky

Abstract

The large amounts of data from oil and gas wells include bottom-hole temperature and depth of measurement. But these temperatures need to be corrected because of drilling disturbances and these data alone are not sufficient for heat flow calculation. The temperature data after correction may be used to determine the well gradient. In order to calculate heat flow the thermal conductivity of the lithologic section encountered in the well is also necessary. The stratigraphic columns from the AAPG COSUNA data set were used to determine the lithology of each well along with the AAPG sediment thickness map. Thermal conductivities were assigned for each different rock type based on previously published values. The thermal section data were used to calculate mean conductivity for each well and by combining this value with the BHT data, heat flow was calculated. A comparison of the calculated heat flow to published values gives an accuracy of ±20 in percent for most borehole groups. After filtering, this method has added approximately 800 data points in the states of Illinois, Indiana, Michigan, and Ohio. The new heat flow map shows some interesting correlations to geophysical data (gravity and magnetics) that may identify the lithology of the basement. The results support the hypothesis that heat flow variations can be inferred based on some characteristics of the geophysics of a given area. The new heat flow map is more detailed and has shown that areas of the Midwest for focused future research and geothermal development can be defined.