Application of Bowers Model in Abnormal Pore Pressure Prediction in Deepwater Drilling

Abstract

Accurate prediction of formation pore pressure is of great significance to ensure drilling safety. Most of the traditional pore pressure analysis methods are based on the theory of unbalanced compaction of mudstone, and theoretically, only the abnormally high pressure formed during “loading” process can be predicted. The Bowers model is based on the effective stress principle, and can be used for most pore pressure prediction in different lithology and pressure mechanism. The Bowers model was used to analyse the abnormal formation pressure in deep-water area of the Q Basin, South China Sea. According to logging data and pressure test data of drilled wells, it was judged that the cause of abnormal pore pressure in the above area is both “loading” and “unloading” mechanism and the empirical coefficients of the Bowers model in this region were calculated. Using seismic interval velocity data, the pore pressure of an exploration well was predicted before drilling and the prediction error is less than 5% compared with the measured values after drilling. It is shown that the Bowers model has high accuracy for quantitative prediction of abnormal pore pressure in deep-water area of the Q basin.