Increasing Confidence of Seismic Derived Reservoir Parameters from a Large 3-D Merge
Skidmore, Charles; Porter, Phil; Porter, Arnie; Early, Ray
The Anadarko basin has long been explored for deep gas, with thousands of wells targeting zones from 12,000 to 25,000 feet. During this time numerous proprietary and spec 3-D surveys were shot to aid in identifying these reservoirs. Recently, zones that were "passed over" in favor of deeper targets, have yielded significant oil discoveries. These shallow horizontal oil plays are now rejuvenating the basin, and with their complex stratigraphy and identifiable seismic signatures, make ideal candidates for 3-D seismic analysis.
The prospective area is significantly larger than any single 3-D in the basin, but there are a number of 3-D's that overlap or lie juxtaposed. In order to properly preserve the seismic character a complete reprocessing and merge of 41 individual surveys totaling 3655 square miles were used to generate one large 2790 square mile 3-D survey. During the processing two important steps needed to be addressed in order to produce data of sufficient quality for attribute analysis. The first would be how to handle the refraction statics, and the second was how to handle the phase differences between surveys.
To properly address the refraction statics it was decided that one model would be used to cover the whole area. Over 480,000 shots, 1,641,517 receiver locations, 6,255,207 bins, would be used to generate a single solution that covers the 2790 square miles. This approach was the first step in merging the surveys, as it was instrumental in helping remove the various acquisition footprints and create continuous reflectors to work with.
The 41 surveys all had differing acquisition parameters and ranged in age from 2 to 15 years old. To properly create a seamless volume they would all need to be phase matched. Using newly developed tools and methods it was determined that almost half of the 41 surveys required major phase corrections. During the process one of the biggest surprises was the ability of the residual statics routines to try and correct the phase differences, often times masking the true phase of the data at the individual survey boundaries.
The survey's 2790 square miles has thousands of wells, in numerous plays, that can be used to correlate reservoir properties over large areas. Pre and Post stack attributes can be tied into wells with confidence, testing various combinations for maximum leverage in identifying optimal locations for future successful wells.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013