Abstract: Thermal Conductivity in Hydrocarbon-Saturated Rocks and its Possible Effects on Temperature Anomalies Near the Red Fault in South Eugene Island Block 330

Ming Luo, James Wood, Lawrence Cathles

Non-wetting pore fluids affect the thermal conductivity of sediments significantly more strongly than do wetting phases. As a consequence, gas saturation can reduce the thermal conductivity of sediments relative to brine-saturated values by a factor of 7, and oil saturation can reduce thermal conductivity by a factor of 2. Such large reductions in thermal conductivity could produce significant thermal anomalies near hydrocarbon-saturated faults. The effects of oil and gas saturation and lithologic variation are described using a fabric theory. The fabric theory provides a slightly more accurate description of sediment thermal conductivity as a function of lithology and porosity than alternative geometric mean descriptions. This is largely because the fabric theory approach is more fle ible. The flexibility also means that the effects of oil and gas saturation can be easily incorporated. A fabric theory thermal conductivity model has been developed that includes the effects of oil and gas saturation. It has been incorporated into 2-D Akcess.Basin^TM calculations. The Akcess.Basin calculations identify the conditions under which thermal conductivity variations due to oil and gas saturation could produce significant thermal anomalies near the Red fault in South Eugene Island Block 330. The presence of salt is also considered. Any estimate of fluid flow up the Red fault based on observed temperature anomalies must subtract the portions of the anomalies that are caused by variations in thermal conductivity of the kinds considered here.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994