Velocity-based pore pressure prediction in a basin with late-stage erosion: Delaware Basin, US

Pore pressure is a critical parameter for the exploration and development of hydrocarbons, and it is difficult to predict in unconventional basins that have been unloaded by erosion. We predict pore pressure from mudrock velocities in the Delaware Basin, which is an unconventional basin with significant late-stage erosion. We use an elastoplastic model to describe mudrock decompaction due to unloading, resulting in a velocity-effective stress relationship that differs from a mudrock's normal compaction trend. We establish this velocity-effective stress relationship using well log and measured pore pressure data in a well with a known erosional value. We next use this relationship to estimate the amount of erosion at each new prediction well, and then predict vertical effective stress with depth. We calculate pore pressure as the lithostatic stress less the vertical effective stress. We demonstrate the predictive capability of our approach in four wells spanning the eastern portion of the basin where the amount of erosion differs, and show that our approach better matches the measured pore pressures