The Application of 2D and 3D Seismic Data in the Exploration for Cherokee ChannelsÑTombstone Gap Field, Ness County, Kansas

William A. Miller.  Miller Consulting Services, Littleton, Colorado 80122  [email protected]

The discovery and development of Tombstone Gap field in Ness County, Kansas, is a classic example of the evolution of a prospect from the original subsurface lead to the shooting of 2D seismic data followed by 3D seismic data. It also provides a comparison of the effectiveness of 2D versus 3D seismic data in imaging Cherokee sandstones deposited in channels incised into the underlying Mississippian carbonates and in determining geologic structure.

The original prospect well was drilled solely on the basis of subsurface data and did encounter almost 80 gross feet of the target Cherokee sandstones. The reservoir was wet, however, and the initial well was completed dry and abandoned. Approximately 6.0 miles of 2D seismic data were then acquired to further delineate the prospect and subsequently led to the drilling of the successful discovery well. A 4.0-square-mile 3D seismic survey was acquired after the discovery and guided the development drilling of the field. In order to further define the extents of the field, an additional 2.0-square-mile 3D seismic survey was later acquired and merged in data processing into the original 3D survey. The presentation will show how the interpretation of the geometry of the Cherokee channel system evolved as additional seismic data were acquired.