The Effect of Temperature on the Overpressure Distribution and Formation in the Central Paleo‐Uplift of the Sichuan Basin

Abstract

AbstractTemperature and pore pressure are two important physical fields in sedimentary basins. Temperature controls the distribution characteristics and formation of overpressures. Firstly, the relationship between the measured temperature and pore pressure was analyzed. Secondly, temperature‐pressure relationship for sealed formation water was modeled in laboratory. The maximum paleo‐temperatures for different regions in the Paleo‐Uplift were reconstructed by using vitrinite reflectance, and then the effect of temperature on the overpressure distribution characteristics was analyzed. Finally, the impacts of temperature on the overpressure generation through oil cracking and disequilibrium compaction were discussed. Based on the study results, a positive correlation between the temperature and pressure in the Central Paleo‐Uplift was discovered. When the pressure is greater than 15 MPa, it would change 1.076 MPa as temperature change 1 °C in an absolutely sealed condition. The difference in temperature reduction is the primary cause for various intensity of pressure within the Central Paleo‐Uplift. Besides that, lateral transfer and leakage of pressure must occur. Overpressure in the Lower Paleozoic, generated by oil cracking, formed during from 180 to 110 Ma and redistributed in 90 Ma. Temperature effect on disequilibrium compaction overpressure is negligible.