Effective stress on deep sedimentary formations under non-isothermal conditions

Development of High Pressure, High Temperature (HPHT) petroleum reservoirs demands the understanding of temperature effects on reservoir properties as well as models including temperature effects. Using an extension to Biot’s effective stress equation, we derived estimates of the nonisothermal effective stress in the deep North Sea Basin. We found that compared to the conventional isothermal effective stress the non-isothermal effective stress is smaller and results indicate that at great depth a neutral effective stress exists so that the post-Triassic formations are floating on the highly overpressured older layers.