Stephen P. Cumella¹

(1) Barrett Resources, Denver, CO

ABSTRACT: Development of Mesaverde Nonmarine Reservoirs in Grand Valley, Parachute, and Rulison Fields, Piceance Basin, Colorado

Grand Valley, Parachute, and Rulison fields are located in the southern Piceance Basin in Garfield County, Colorado. Production in these fields, which is from the Williams Fork Formation of the Mesaverde Group, is currently over 130 MMCFPD. These fields are part of a basin-centered gas trap that has formed in the deep part of the basin adjacent to an area of active gas generation. The Williams Fork produces gas from approximately 2,000 feet of gas saturated nonmarine strata in these fields. Detailed reservoir description of the nonmarine sandstones of the Williams Fork is made possible by the 20-acre well density that exists in parts of all three fields. The presence of multiple, laterally discontinuous gas-saturated sandstone bodies in this field necessitates drilling on 20-acre spacing in order to recover the existing gas-in-place in these fields. The Williams Fork overlies the marine Rollins sandstone, which was deposited during the final regression of the Cretaceous seaway. The lower part of the Williams Fork is comprised of the Cameo Coal Member. Deposition of laterally continuous coals in the Cameo is related to transgressive-regressive cycles of the Rollins shoreline to the east. Detailed correlations of coals were used to subdivide the Cameo into genetic stratigraphic units. Fluvial, distributary channel, and estuarine sandstone reservoirs can be differentiated using net sandstone mapping and log curve shape analysis of these units. Detailed understanding of the distribution of these sandstone reservoirs is useful in designing completion procedures.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado