Abstract:

By analyzing the limitations of the traditional pore pressure prediction methods,a new pore pressure prediction approach based on the effective stress theorem and the acoustic velocity model is proposed.It first calculates clay content,porosity,and acoustic velocity with relevant log data,and then calculates vertical effective stress by using Support Vector Machines for Regression and the overburden pressure with density log data,and finally calculate formation pore pressure by the effective pressure theorem.Practical application of the approach shows that it is feasible in prediction of abnormal formation pressure of sandstone and shale caused by undercompaction.Compared with traditional pore pressure prediction methods,the approach does not require establishing normal compaction trend line and has better adaptability and higher accuracy of predictions.

Key words: pore pressure, support vector machine for regression, sonic velocity, porosity, shale content, vertical effective stress