Date of Award

Spring 1-1-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Geological Sciences

First Advisor

Matthew J. Pranter

Second Advisor

Edmund R. Gustason III

Third Advisor

Rex D. Cole

Abstract

The Mesaverde Group (Late Cretaceous) at Red Wash Field within the Uinta Basin produces oil and natural gas from low-permeability, fluvial sandstone reservoirs that were deposited in a predominantly freshwater, low-energy setting with minor brackish-water influence. Four main architectural elements present in core and nearby outcrops include fluvial bars, crevasse splays, floodplain deposits, and coal. Depositional trends reflect an overall decrease in energy toward the northwest, where subsurface deposits are located on the periphery of the main channel belt, while contemporaneous outcrop deposits record more extensive brackish-water influence.

Static reservoir connectivity (total and constrained), assessed using 3-D reservoir models of the fluvial deposits at Red Wash Field, varies as a function of well density, sandstone-body geometry, and net-to-gross ratio (sandstone-body abundance). Results suggest that sandstone geometry produces a minor (6%) increase in total connectivity; however, the abundance of crevasse splays is a major contributor to total connectivity and should be considered as an important factor in reservoir development. Stratigraphic zones with < 40% net-to-gross ratio exhibit greater total connectivity (up to 81.8%) with higher well density. Above 40% net-to-gross ratio, only a minor increase (10-15%) in connectivity resulted. For porous sandstones (porosity > 6%), connectivity is, on average, 26% lower than total sandstone connectivity and is more sensitive to well density and net-to-gross ratio.

Share

COinS