Seismic pore-pressure prediction using reflection tomography and 4-C seismic data

Abstract

Pore pressure is important for both exploration and drilling. During the exploration phase, a prediction of pore pressure can be used to develop fluid migration models, to study the effectiveness of seals, and to rank prospects. In drilling, a predrill pore pressure prediction allows the appropriate mud weight to be selected and allows the casing program to be optimized, thus enabling safe and economic drilling. A predrill estimate of pore pressure can be obtained from seismic velocities given a suitable velocity to pore pressure transform. This paper describes the use of seismic reflection tomography and 4-C seismic data for pore pressure prediction. Reflection tomography gives higher spatial resolution than conventional methods based on the Dix equation, while the additional information provided by 4-C data may help to reduce the ambiguity between variations in pore pressure and variations in lithology and fluid content.