Iman Morshedi - Imam Khomeini International University, Tehran, I.R. Iran
M. Ali Riahi
H.Reza Hemmati

Pore pressure is one of the important concepts in hydrocarbon exploration and drilling. Abnormal pore pressures are encountered worldwide, often resulting in drilling problems such as kicks, blowouts, borehole instability, stuck pipe, and lost circulation. Because of this, a quantitative predrill prediction of pore pressure is required for the safe and economic drilling of wells in overpressured formations. Also the pore pressure maps can be used to study hydrocarbon migration paths and cap rock quality.To obtain the pore pressure, tomography velocity data - that is obtained from Prestack velocity - is used. These data have to be extremely accurate. To build the velocity cube in reservoir region, first the 3-D gridding is obtained and then the velocity data are merged in it. Using the velocity data and stochastic methods, the unknown velocity in the cells is interpolated. Also, using sonic velocity logs and RHOB, a correlation is introduced which will be used to model the density cube. Now that the density cube exists, the overburden pressure can be modeled. Also using RFT logs and Bowers equation, effective stress cube is modeled. finally using the fundamental Terzaghi relation the pore pressure cube is modeled. In each modeling process, the quality of model is estimated using the known well data. The results show high correlation for this method.

Pore Pressure, tomography, seismic, velocity modeling