Pore Pressure Estimation of One of the Gas Fields in Southwestern Iran Using Well Log and Seismic Data

Estimating and predicting pore pressure is essential to avoid drilling hazards in areas with high pore pressure. By predicting the pore pressure, this information can be used in  the wells planning, the optimum weight of drilling mud, finding the new exploration targets and etc. The main purpose of this study is to estimate the pore pressure using well logs and seismic data and  to compare their performance. In the well logging method, the pore pressure was estimated employing the relationships presented by Eaton in 1975 in three different ways that uses the resistivity, sonic and velocity logs. Then, in 1995, utilizing  Bowers equations, the overburden pressure was calculated from density log, and then the effective stress was estimated using the velocity relationship. Finally, the pore pressure was estimated using the Terzaghi relationship. In the next step, using three-dimensional seismic data and seismic inversion products the pore pressure was estimated in a three-dimensional cube employing Eton and Bowers methods. The estimated three-dimensional cubes were then assessed with the pressure data in the existing wells. The results of this study show that the Eaton velocity method with an error of 9.7% represent the good consistency with the measured data at the well location. It also provides the most appropriate spatial distribution of pressure at the reservoir and shallower depths. Therefore, Eaton velocity method is proposed on the similar regions for the pore pressure estimations.