Stratigraphic Architecture, Reservoir Quality, and Sandstone-Body Connectivity of the Mesaverde Group, Central Mamm Creek Field, Piceance Basin, Colorado

Alicia Hewlett
University of Colorado at Boulder, Department of Geological Sciences Boulder, Colorado
[email protected]

The reservoir architecture, reservoir quality, and associated sandstone-body connectivity of the lower to middle Williams Fork Formation (Mesaverde Group; Upper Cretaceous) at Mamm Creek Field vary stratigraphically with changes in depositional setting. Lower to middle Williams Fork Formation fluvial and marine sandstones were deposited within lower coastal-plain to shallow-marine and alluvial-plain depositional settings.

The stratigraphy and reservoir characteristics of the lower to middle Williams Fork Formation is assessed using data (well logs, cores, borehole images) from 93 wells on 10-acre spacing for two sections (2 mi², 5.2 km²) and the surround area. Formation tops have been interpreted and correlated for key stratigraphic units throughout the area to establish the stratigraphic framework. Within this framework, lithology logs and logs that show the variability in sandstone-body type (i.e., architectural elements: channel bodies, crevasse splays) have been interpreted to document their stratigraphic variability.

Architectural-element logs, paleocurrent data from borehole images, and existing outcrop dimensional data are inputs to generate three-dimensional architectural-element models of the Williams Fork Formation using object-based and multi-point geostatistical methods. These models provide estimates of the “field-scale” spatial variability of the fluvial and marine deposits. Within these deposits, petrophysical (porosity and permeability) models are generated to investigate intra-body or intermediate-scale heterogeneity and are used to estimate pore volumes, show potential fluid-flow pathways, and evaluate static reservoir connectivity. Because there is uncertainty in the spatial variability and size of the deposits (reservoirs), several model scenarios are investigated.

AAPG Search and Discovery Article #90094 © 2009 AAPG Foundation Grants in Aid