PSDM yields accurate pore pressure prediction

摘要

In a case study from the Caspian Sea, accurate and detailed velocity analysis from a prestack depth migration was adapted to calculate accurate pressure prediction in an undrilled area. Surface seismic velocities from compressional (P) wave energy are influenced by the compaction of clastic sediments. Pore pressure affects the compaction; therefore, changes in formation velocity can be calibrated to changes in pore pressure, assuming there is no change in lithology. Velocities derived from surface seismic data can provide an indirect way to predict pressure in the subsurface before drilling. Two scenarios applied this concept. In Area 1, five wells with logs of varying quality were available to calibrate the velocity from 3-D prestack depth migration; however, pressure prediction profiles were needed closer to these wells. Area 2, approximately 36 miles (60 km) northwest of Area 1, has no available well data.