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Regional 3-D Pore Pressure Volumes: Understanding Regional Trends of Overpressure Related to Salt / Subsalt in the Northern Gulf of Mexico

Noeth, Sheila 1; Sayers, Colin M.1; den Boer, Lennert D.1; Hooyman, Patrick 1
1 Geomechanics, Schlumberger, Houston, TX.

An understanding of regional trends of overpressure, related to sedimentation rates and diagenesis as well as other factors is needed for safe, cost-effective drilling of difficult wells in deeper water or in High-Temperature High-Pressure areas. In this presentation the workflow used to build an integrated regional 3D geomechanical model, comprised of density, velocity, vertical stress, effective stress, pore pressure and temperature is described, and is based on combining publicly available well data with high quality tomographic velocities obtained from reprocessing multiclient seismic data. The inclusion of geomechanical data allows the dependence of seismic velocity on effective stress to be determined, and enables an improved estimate of sub-salt velocities resulting in improved sub-salt imaging and pore pressure estimation. The resulting volumes are used for regional pressure and seal analysis as well as for evaluating the sealing potential of faults, and are suitable for updating while drilling in a way that allows the uncertainty in the pore pressure estimation ahead of the bit to be continuously reduced using data acquired while drilling. The volumes also allow the hydraulic connectivity in a basin to be assessed. Last but not least, these models represent useful tools for basin hunting and prospect high grading.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009