“Conventional” Unconventional Gas: Perspectives from Wamsutter, a Tight Gas Accumulation in the Eastern Greater Green River Basin

Laura A. Banfield¹, W. A. Hill¹, Robert Lieber², Tony McClain², Noel McInnis², Lee McRae², Kristian Meisling¹, and Jon Vaitl^3
1North America Gas - Reserves and Renewal, BP America, Houston, TX
²North America Gas - Wamsutter, BP America Production Co., Houston, TX
³Consultant, Wimberley, TX

An integrated project focused on viewing the Wamsutter field in a regional context and revisiting the building blocks of the petroleum system has improved BP’s understanding of the large tight gas accumulation in southwestern Wyoming. There is always a tension between balancing a busy operational program (or “feeding the rig monster”) and updating the regional geologic model to improve operational workflows. The integration of regional tectonics, local structure, and stratigraphy has provided a better understanding of the source rock potential, migration history, and trap formation for the field.

In addition, a rigorous, yet fundamental approach to petrophysics, involving new core data and a large normalized log database has helped us to extend the improved regional understanding to the reservoir level. While some studies are ongoing, several observations have been made regarding questions common to the public discussion of tight gas accumulations and their characterization. For instance, what is the trap? What role does pressure play in that trapping configuration? What is the timing of structural development and how does it affect the distribution of hydrocarbons? Does a sequence stratigraphic reservoir description result in a better development strategy? How do syndepositional tectonics affect the reservoir interval?

Wamsutter and other “unconventional” accumulations might be more conventional than previously realized.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas