Rock Physics Template and its Significance in Velocity Model Building and Pore Pressure Prediction

Abstract

Abstract

Pore pressure has been routinely estimated using velocity information derived from seismic data. For a given velocity and a knowledge of overburden, pore pressure can be calculated through a rock model that relates velocity to effective stress, and then effective stress to pore pressure. Pore pressure is the difference between overburden pressure and effective stress. Conversely, velocity can be calculated given the knowledge of pore pressure.

A rock physics template (RPT) is the velocity response corresponding to the variation in pore pressure. It refers to a group of velocity trends versus burial depth that correspond to constant pore pressure gradients that vary from hydrostatic to near overburden pressure for a given location, usually at, but not restricted to, the wells. RPT is built based on an understanding of the general mineralogy, overburden, and a rock model that relates velocity to effective.

RPT can be generated at any desirable location or every common depth point of a seismic volume. With calibration from well measurements, it can be used to constrain the velocity model in seismic tomography, given the knowledge of the likely pressure and/or pressure bounds. Conversely, pore pressure can be derived from RPT, given knowledge of the velocity profile.

RPT has been extensively used in many large-scale seismic imaging and beyond imaging projects in the deep-water Gulf of Mexico and basins worldwide. It helps enhance both the velocity model used in seismic imaging and pressure prediction essential for exploratory drilling. Herein, we introduce the basic steps to build a RPT and show its applications in enhancing velocity model building and pore pressure prediction in the Gulf of Mexico.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016