Abstract

Knowledge of formation pore pressure ahead of the drill bit is not only critical for safe and cost-effective drilling of wells but also essential in studying the hydrocarbon trap seal and analyzing the trap configurations. A predrill estimate of the formation pore pressure can be obtained from seismic velocities and employing a velocity-to-effective stress transform. However, limitations abound in the use of seismic velocities for accurate pore pressure prediction. These limitations are traceable to some main factors such as the correctness of the seismic velocities themselves and the accuracy of the local parameters of the pore pressure prediction method used. Knowledge of the sources of overpressure in the formation is also an essential factor. This paper discusses these factors and attempts to put them into context for accurate pore pressure prediction using seismically-derived velocities.

Key words: Pore pressure prediction, overpressure, geopressure, seismic velocities, tomographic inversion, seismic inversion.