Target formation pore-pressure prediction using 3D seismic data via the Fillippone and Eaton approaches in southern Sichuan, China
Wang, Zi 1989-
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Abnormal pore pressure is a common occurrence in hydrocarbon basins due to hydrocarbon generation, migration, and accumulation. The study of changes in pore-pressure may reveal the enrichment characteristics and passageway of hydrocarbons, as well as lithological variation and characteristics. Abnormal pore pressure is directly related to the drilling safety and property security, and therefore important to oil and gas exploration. Such information will contribute toward a reasonable drilling fluid density design to ensure the stability of wellbore structure and the safety of drilling. In the southern Sichuan Basin, China, the potential shale gas formations usually have overpressure, so the ability to predict the pore pressure of the target formation is critical for shale gas exploration there and elsewhere. In this study, 36 square kilometers of 3D seismic data are used in testing several approaches of target formation pore-pressure prediction. In order to improve the velocity model, VSP data are used to correct acoustic velocity. Through the analysis and evaluation of pore-pressure prediction, a new approach of computing seismic velocity for normal compaction, called “Fillippone + Eaton” normal compaction velocity calculation, is introduced in this study based on the maximum and minimum compaction velocities calculated from the Fillippone formula. This new approach improves the inadequacy in the parameter setting of the two existing approaches. The feasibility of the new approach is verified through applying it using the 3D post-stack data in the study area, and the predicted pressure values match well with the measured pressure data.