Stratigraphic Trapping in the Rollins Sandstone of the Mesaverde Group, Mamm Creek Field, Piceance Basin, Northwest Colorado
Cumella, Stephen P.
Bill Barrett Corp, Denver, CO
Most gas production in the southern Piceance Basin is from the Williams Fork and Iles formations of the Mesaverde Group. In ascending order, the Iles Formation is comprised of three eastwardprograding marine parasequences sets, the Corcoran, Cozzette, and Rollins members. Across most of the southern Piceance Basin most operators avoid completing in the Rollins because it commonly produces water, due to its thick, laterally continuous nature and the fact that the northeast depositional strike of the Rollins shoreline is generally perpendicular to structural dip. However, in the Mamm Creek Field area, the Rollins produces gas from a series of marine shoreface parasequences that pinch out up dip across the northwest plunge end of the Divide Creek anticline where the northeast trend of the shoreline is sub-parallel to structural dip. Individual parasequences within the Rollins can be identified by flooding surfaces that are overlain by shale intervals that thicken seaward. These shales pinch out in a landward direction, but the tops of the parasequences can still be identified on well logs by cleaner sandstones overlain by higher gamma ray sandstones. The productive intervals of the Rollins parasequences are areas where the sandstone has relatively good porosity and permeability and a top seal is present (either an overlying shale or a burrowed, finer-grained sandstone with higher capillary pressure).
AAPG Search and Discovery Article #90071 © 2007 AAPG Rocky Mountain Meeting, Snowbird, Utah