Subsurface Core and Analogous Outcrop Characterization of the Muddy/Newcastle Formation for the Bell Creek Oil Field, Powder River County, Montana

Jason Braunberger, Terry Bailey, Jordan Bremer, Charles Gorecki, and Benjamin Huffman

The Plains CO2 Reduction Partnership led by the Energy & Environmental Research Center (EERC) conducted several field trips to a Cretaceous Muddy (Newcastle) Formation outcrop in Wyoming which is analogous to the nearby Bell Creek oil field reservoir. Uplift during Tertiary time exposed the Muddy rocks while simultaneously burying the interior Powder River Basin and Muddy reservoir at Bell Creek to a depth of approximately 4500 feet. Ongoing work to prepare for a carbon dioxide (CO2) enhanced oil recovery project includes characterizing 100+ subsurface cores, analyzing whole core and sidewall plugs recently collected from an observation well and exploring additional outcrops. Although numerous wells and core are available in the field to interpret vertical and horizontal variations in facies and internal structure, there are subtleties in the geologic framework that occur at a finer resolution than the well control. Outcrop examination provides a source of extensive geologic data. This assists in gaining an understanding of regional structure, facies, and heterogeneities that can be correlated back to core. The investigation has shown good sedimentological correlation between outcrop and subsurface core. Thus describing the outcrop has provided a valuable visualization tool when the nature of reservoir rocks in the oil field is observed. Data collected from the outcrop provide insight for variogram ranges and help minimize uncertainty for developing the 3-D geologic models.

AAPG Search and Discovery Article #90156©2012 AAPG Rocky Mountain Section Meeting, Grand Junction, Colorado, 9-12 September 2012