Semester

Fall

Date of Graduation

2008

Document Type

Thesis

Degree Type

MS

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Thomas Wilson.

Abstract

Local properties of a fractured reservoir are characterized using borehole geophysical logs. These properties are extrapolated to reservoir scale for future use in flow simulation and history matching exercises. The development of a reservoir scale fracture model is undertaken using data for the Tensleep oil reservoir at Teapot Dome, Wyoming. The Tensleep reservoir intervals at Teapot Dome are formed in tight eolian sands that produce primarily from open fracture systems. On the local scale, FMI logs were used to define the dominant systematic fracture sets existing in the reservoir. FMI logs reveal the presence of open fracture systems that consist predominantly of two hinge-oblique sets and one hinge-parallel. The local structural hinge trends about N30W. Fractures with the NW hinge-oblique orientation are more numerous than the hinge-parallel and NE-hinge-oblique sets. Dominant hinge-oblique fractures have an average N71W strike that closely parallel the strike of drilling induced fractures (N74W). Spacing, length and aperture distributions are also estimated for the fracture sets comprising the fracture network. Local fracture characteristics are combined with 3D seismic analysis to produce a layered starting model of the reservoir scale fracture systems suitable for flow simulation.;A 3D model has been developed that incorporates both the matrix and fracture properties for the reservoir. The reservoir model consists of 54648 cells that are 100 x 100 feet in size and distributed in five geologic zones corresponding to major stratigraphic subdivisions of the reservoir including a water drive. Each zone includes a uniquely defined open fracture network. The matrix portion of the model is characterized by matrix porosity and permeability, relative permeability, oil-water contact depth, and initial reservoir pressure. The fracture portion of the model consists of eleven fracture sets distributed among Tensleep sandstones A and B, and an intervening Dolomite B. The fracture sets are based on FMI log observations and are distributed within the reservoir model using Petrel's ant tracking 3D seismic attribute. In future work, these analyses can be used to refine simulation models for accurately matching production histories in the field.;Preliminary flow simulation results for both a single porosity matrix model and single porosity fracture network model significantly underestimate historical oil and water production from the Tensleep reservoir. Future work will require refinement of both matrix and fracture network properties and additional development activities on the part of Schlumberger to successfully run a true dual permeability simulation.

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