3-D And The Minnelusa "C" - Northern Powder River Basin

By

Charles D. Wolf and Owen L. Stone

Stone & Wolf, LLC, Sheridan, WY

The SA Draw field was discovered from leads developed from 2-D seismic lines in conjunction with an ongoing 3-D survey to delineate a Muddy channel discovery. An apparent Minnelusa "C" amplitude was observed and appeared to connect on two of six 2-D seismic lines in the Muddy channel area. The 3-D survey was expanded from approximately two to fourteen square miles to accommodate evaluating this anomaly. Only one well (a dry hole) penetrated the Minnelusa in this project area, which was located in the far southeast corner of the survey. This well had a thin "C" sand that was tite and a thick "D" sand.

The 3-D shows two major "D" dunes present trending N45°E±. The southern dune was tested by the above-mentioned dry hole. The northern "D" dune has superimposed a "C" dune trending N30°E± with an abrupt or steep termination on the northwest side. The discovery well for the SA Creek field (S&W MAO State 1-36) was drilled in April of 1998 at the northeast terminus of the "C" dune initially producing ±300 BOPD. The field is currently under waterflood with three producers and an injection well making approximately 1400 BOPD.

It is interesting to note that the amplitudes that were connected together on the original 2-D interpretation are actually two separate dunes as evidenced by a 40-acre offset well that was drilled and tested as completely separate "C" dunes. The reliability of 3-D interpretation in this area is exceptional as each well came in as projected.

AAPG Search and Discovery Article #90004©2002 AAPG Rocky Mountain Section, Laramie, Wyoming