Target-oriented predrill pore-pressure prediction for deepwater subsalt and other basins

 

Traditional methods for pore-pressure prediction, which are based on some variants of the effective-stress method, do not work well in deepwater subsalt and other complex geological settings. The reason is lack of availability of well-log data starting from the water bottom to the target zone of interest. These data are needed to calibrate various transform parameters– velocity to effective stress, velocity to density to overburden stress, and compaction trend.

 

In the Target-oriented pore-pressure (TPP) method as described in Banik et al. (2014), the focus is on the zone of interest, and so the only well-log data needed for calibration are limited to the zone of interest. This should reduce the uncertainties in the prediction. Recent advances in data acquisition and processing technologies, including imaging techniques, have significantly enhanced the ability to identify subsalt structures in deepwater Gulf of Mexico (GOM) and other offshore basins around the world. These advances have also improved the amplitude fidelity of subsalt data to such a degree that accurate, seismic inversion below salt is possible.

 

The subject of target-oriented predrill pore-pressure prediction for deepwater subsalt and other basins will be the focus of the presentation to be made by Dr. Nirajan Banik, Scientific Advisor at WesternGeco Schlumberger at the 7th Annual Sub-Saharan Africa Oil and Gas Conference scheduled for May 1 -2, 2014 at the Marriott Westchase, Houston.

 

Dr. Niranjan C. Banik is a Scientific Advisor with the Integrated Solutions Group of Schlumberger-WesternGeco in Houston, Texas. He has been in the oil industry for 28 years, working as an application geophysicist. He has previously worked for Gulf Oil, Arco Oil and Gas, T. D. Williamson, Inc., Texaco, and Unocal. During the last several years, Dr. Banik has been concentrating on integration of multiple geophysics disciplines for hydrocarbon exploration and exploitation in complex environment and in unconventional reservoirs. He has authored many papers on anisotropy, stratigraphic filtering, AVO and inversion, and pore-pressure Prediction. He received his Ph.D. in physics from Purdue University, West Lafayette, Indiana.

 

In his explanation on the methods used by his group in their research, Dr Banik said, “In the TPP method, we use seismically derived acoustic impedance and transform it directly into pore pressure. The method was successfully applied in a GOM deepwater basin, where full-azimuth, dual coil data were acquired and processed recently. We discuss the method and its application in GOM in details. The method is equally valid in similar other basins, including the subsalt basins in West Africa. Other basins, such as sub-basalt, unconventional reservoirs, are also applicable for this target-oriented pore-pressure prediction method.”