A thermal resistance method for computing surface heat flow and subsurface temperatures with application to the Uinta Basin of northeastern Utah

The thermal resistance method has been modified to test the utility of oil and gas well bottom-hole temperature data in determining heat flow and subsurface temperature patterns. Thermal resistance, defined as the quotient of a depth parameter '{Delta}{sub z}' and thermal conductivity 'k'', governs subsurface temperatures as follows: T{sub B} = T{sub 0} + q{sub 0} B {summation} z=0 ({Delta}z/k){sub i} where T{sub B} is the temperature at depth z = B, T{sub 0} is the surface temperature, q{sub 0} is surface heat flow and the thermal resistance ({Delta}z/k) is summed for all lithological units between the surface and depth B. In practice, bottom-hole temperatures are combined with a measured or estimated thermal conductivity profile to determine the surface heat flow q{sub 0}, which in turn is used for all consequent subsurface temperature computations. The method has been tested in the Tertiary Uinta Basin of northeastern Utah, a region of intermediate geologic complexity (structurally simple yet lithologically complex) where numerous oil and gas well data are available. Thermal conductivity values, determined for 852 samples from five representative wells varying in depth from 670 to 5180 meters, were used to assign average conductivities to geologic formations and to investigate the effect of facies changes on intra-formation conductivities. In situ conductivities were corrected for porosity and temperature effects. Formation thicknesses needed for the thermal resistance summation were obtained by utilizing approximately 2000 wells in the WEXPRO Petroleum Information file, the computations being expedited by describing all formation contacts as fourth order polynomial surfaces. Bottom-hole temperatures were used from 97 selected wells where multiple well logs permitted correcting temperatures for drilling effects