ABSTRACT: Macro geologic controls on Coalbed Methane resource development, Raton Basin, S.E. Colorado, USA

Carlton, Dennis, and Chris Cornelius , Evergreen Resources, Inc, Denver, CO

The Raton Basin of SE Colorado, one of five major late Cretaceous/early Tertiary coal bearing basins along the eastern margin of the Rocky mountain foreland, is presently undergoing large scale development of its significant in-situ coalbed methane resource (est. 12-18 TCF). Medium to low-volatile bituminous coals, characterized by numerous (10-30) thin (1-8 ft) and often laterally discontinuous (< 3000 ft) seam geometry's in a thick fluvio-deltaic/alluvial basin fill sequence, have until recently proved elusive with regards to commercial development. However, new models of coal occurrence and enhanced completion practices are proving pivotal to on-going successful development strategies, making the basin one of the most active coalbed methane exploration regions in the world.

A comprehensive discussion will be presented on the "macro" geologic processes, which collectively control coal-seam distribution, reservoir geometry and ultimately impact reservoir quality. New depositional, tectonic, and hydrogeologic models based upon field and geophysical stratigraphic studies are allowing a greater understanding of the basin's regional/synsedimentary tectonic history and the complex juxtaposition of peat-forming environments with areas of active fluvial sedimentation. Collectively, these interactive processes are forming a predictive framework for coal occurrence and resource assessment, allowing strategic well sitting; details of which may be applicable to CBM exploration strategies elsewhere.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia