Date of Graduation

5-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Engineering (PhD)

Degree Level

Graduate

Department

Chemical Engineering

Advisor/Mentor

Gregory Thoma

Committee Member

Jackson Cothren

Second Committee Member

Ralph Davis

Third Committee Member

Jerry Havens

Fourth Committee Member

Richard Ulrich

Keywords

Applied sciences, Fractured reservoirs, Gas flow Hydraulic fractures, Shale formations, Shale gas

Abstract

Economic production from low permeability shale gas formations has been made possible by the introduction of horizontal drilling and hydraulic fracturing. To ensure that gas production from these formations is optimized and carried out in an environmentally friendly approach, knowledge about the patterns of gas flow in the shale reservoir formation is required. This work presents the development of a shale gas reservoir model for the characterization of flow behavior in hydraulically fractured shale formations. The study also seeks to develop more computationally efficient approaches towards the modeling of complex fracture geometries. The model evaluates the migration patterns of gas in the formations, and investigates the range of physical conditions that favor the direction of gas flux towards the wellbore and decreases the

probability of gas escape into the overlying formation.

Two conceptual models that bypass the need for explicit fracture domains are utilized for

this study, the semi-explicit conceptual model and the fractured continuum model. Fracture complexity is accounted for by modeling induced secondary hydraulic fractures. A novel approach to modeling the secondary fractures, which utilizes asymmetrical fractal representations is also implemented, and the governing equations for flow in the system are solved numerically using COMSOL Multiphysics 4.4b, a finite-element analysis software package. A parametric study is conducted on the reservoir and fracture properties and an assessment of their impacts on the production and formation leak off rates examined.

The study results are presented and analyzed using a combination of transient pressure

surface maps, production rate data curves and transient velocity distribution maps. Optimization of gas production rates from the studied formation is shown to be achievable by the use of long lateral fractures placed orthogonal to the wellbore. There is a need for an accounting of the distinct fracture systems present in a fractured formation for the accurate prediction of production values and flow patterns arising in the formation. This work extends the understanding associated with shale gas reservoir modeling and demonstrates the applicability of the fractured continuum model

approach for the simulation of complex fractured shale formations.

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