A new method for pore pressure prediction using logging and seismic data

Eaton's equation and Yan's equation are widely used in pore pressure prediction. In these equations, velocity from the normal compaction trend line (V_normal) must be calculated. But it is hard to accurately obtain when the shallow velocity logging data is incomplete or fluctuates strongly. In this case, the predicted result is unreliable due to the error caused by V_normal. To solve the problem, this paper proposes a new method for pore pressure prediction. The new method combines the Eaton's method and Yan's method to calculate the pore pressure through iterative computations. V_normal is not needed as a necessary input in the new method. Thus the new method essentially eliminates the error caused by the unreliable V_normal which calculated from poor-quality shallow velocity logging data. Through the calibration of the measured pressure, the prediction result from the new method is proved to be more accurate than Eaton's equation and Yan's equation. Then the new equation is used to study the influence of density and P-wave velocity on pressure which contributes to analyze the characteristics of gas reservoir. What's more, the new method has been successfully applied to seismic data and turned out to be reliable since the predicted result from seismic data match well with that from logging data.