Pore pressure prediction of paleozoic shale reservoir in Southern China and its application

Reservoir pressure is an important factor that affects the deployment of shale gas horizontal wells and reservoir fracturing. The lateral change of pressure in southern China Paleozoic shale reservoir is large, so the ability to predict the pore pressure of target formation is critical for gas exploration. It is proved that the prediction methods for conventional reservoir do not apply to the southern China Paleozoic shale reservoir. Considering Fillippone method and Eaton method in the problems existing in the application of real data, and applying the pressures relationship and the velocities relationship under the normal compaction in Fillippone and Eaton's formulas, a new prediction method is put forward, called the “Fillippone+Eaton” method, and a new prediction workflow is established. This workflow calculates the normal compaction velocity trend based on the maximum and minimum compaction velocities from the Fillippone formula, integrating with well logging velocity calibration using VSP data, and three-dimensional velocity model inversion using the low-frequency trend built by velocity spectrum and seismic reflectors. The presented workflow is applied in different shale gas exploration zones with the high match degrees between the predicted results and the drilling data.