Overpressure is a global phenomenon and is important for both hydrocarbon exploration and drilling safety. An understanding of pore pressure is therefore crucial to identify the regions of overpressure in any hydrocarbon reservoir. However, Pore pressure prediction can be challenging in HPHT environment. Many rock physics models that are suitable for type 1 overpressure are not suitable for HPHT environments. To mitigate such challenge, we utilize seismic-data-derived velocity models, integrate with rock physics models and offset wells, to derive a fit-for-purpose pore pressure model.

We created a workflow named Pore Pressure Assisted Earth-Model Building, in which overpressure mechanisms are used to guide seismic velocity model building for imaging. The effective stress model derived from pore pressure and overburden stress is used to interpolate well-based velocity data through co-kriging which can provide an initial velocity model for tomography. This workflow has recently been applied in several Multiclient projects from the Northern Gulf of Mexico with significant impacts on subsalt imaging and pore pressure prediction. 

In this presentation, we will also review 1) Rock physics model for velocity to effective stress transform; 2) Steps to convert seismic Vp to pore pressure; 3) pore pressure and overpressure QC; 4) Overpressure mechanisms.

Speaker Biography: Yangjun (Kevin) Liu, Schlumberger
Yangjun (Kevin) Liu received an M.S (2009) in geophysics and an M.S. (2007) in physical chemistry from University of Houston. He is currently a senior geophysicist at Schlumberger with more than 10 years of experience in the oil and gas industry. His current duties include technical support on key imaging projects and technical training on rock physics for integrated earth-model building.