We have developed algorithms to account for the three-dimensional effects of sand bodies on pressure. Trinity flow balance technique works with pressure data derived from seismic velocities, which reflect mostly background shale pressure, and Genesis 1D basin models that help provide pressure history and sedimentation rate effects. Permeability variations based on seismic or 1D models are used to calculate the sand pressure so that net flow into and out of the sand is balanced. The algorithm can take into account the permeability variation caused by shale de-watering at the base of the sand and under compaction at the top. This greatly increases the accuracy of pre-drill prediction. It is extremely fast and can be used in a probabilistic approach. Further development of this technology will be sponsored in part by our joint industrial consortium for the 2004-2006 period.

This example shows how an amplitude map can be used to define an outline for the sand body. The structure surface and the sand outline are used to define the 3D shape of the sand.The polygon is defined by Trinity's interactive auto-tracing capability.

References:

• Kilsdonk, W. 2004, 3D Seismic Pore Pressure Analysis in Deep Water Fold and Thrust Belts: A Map and Volume Based Flow Balance Approach, April 18-21, AAPG Annual Meeting, Dallas Texas
• Katahara, K. 2003, Analysis of Overpressure on the Gulf of Mexico Shelf, Offshore Technology Conference, Houston, Texas, U.S.A., 5-8 May 2003. OCT 15293.
• Lupa, J.A., Flemings, P.B., (in review), Overpressure and Flow Focusing in the Bullwinkle Field (Green Canyon 65, Gulf of Mexico), Journal of Marine and Petroleum Geology.
• Flemings P.B., Stump, B.B., Finkbeiner, T., Zoback, M., 2002, Flow Focusing in Overpressured Sandstones: Theory, Observations, and Applications, American Journal of Science, v. 302, p. 827-855.
• Traugott, M.O., 1997, Pore/Fracture pressure prediction in deep water, Deepwater Supplement to World Oil, August 1997.