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Method for inverting reflection trace data from 3-D and 4-D seismic surveys and identifying subsurface fluid and pathways in and among hydrocarbon reservoirs based on impedance models

United States Patent

5,798,982
August 25, 1998
View the Complete Patent at the US Patent & Trademark Office
A method is disclosed for inverting 3-D seismic reflection data obtained from seismic surveys to derive impedance models for a subsurface region, and for inversion of multiple 3-D seismic surveys (i.e., 4-D seismic surveys) of the same subsurface volume, separated in time to allow for dynamic fluid migration, such that small scale structure and regions of fluid and dynamic fluid flow within the subsurface volume being studied can be identified. The method allows for the mapping and quantification of available hydrocarbons within a reservoir and is thus useful for hydrocarbon prospecting and reservoir management. An iterative seismic inversion scheme constrained by actual well log data which uses a time/depth dependent seismic source function is employed to derive impedance models from 3-D and 4-D seismic datasets. The impedance values can be region grown to better isolate the low impedance hydrocarbon bearing regions. Impedance data derived from multiple 3-D seismic surveys of the same volume can be compared to identify regions of dynamic evolution and bypassed pay. Effective Oil Saturation or net oil thickness can also be derived from the impedance data and used for quantitative assessment of prospective drilling targets and reservoir management.
He; Wei (New Milford, NJ), Anderson; Roger N. (New York, NY)
The Trustees of Columbia University in the City of New York (New York, NY)
08/ 641,069
April 29, 1996
The U.S. Government has certain rights to this invention and any patents covering this invention as provided for by the terms of Contract No. DE-FC22-93BC14961 awarded by the Department of Energy. A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever. A microfiche Appendix containing source code listing utilized in practicing the invention is included as part of the specification and is hereinafter referred to as Appendix I. Appendix I includes one microfiche labeled compute.sub.-- volume.sub.-- impedance with 54 frames.