Date of Graduation

2013

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Hema J Siriwardane

Committee Co-Chair

Raj K Gondle

Committee Member

Udaya B Halabe

Committee Member

John D Quaranta

Committee Member

Hema J Siriwardane

Abstract

Geologic formations, such as unmineable or depleted coal seams, are considered to be potential reservoirs for CO2 storage. Coal seams are naturally fractured reservoirs which consist of primary and secondary cleat networks. During production, coalbed methane (CBM) is desorbed from the coal surface and flows through the cleat network. When carbon dioxide (CO2) is injected into a coal seam, large amount of the injected CO2 is sorbed on the coal surface due to the greater affinity of CO2 towards coal than methane. This provides two advantages: potential CO 2 storage and enhanced coalbed methane recovery. Several pilot studies have been performed to evaluate enhanced coalbed methane production and assess the performance of coal reservoirs during CO2 injection. Limited studies have been conducted to investigate CO2 leakage in the overburden geologic layers. In certain cases, there is likely to be a secondary coal seam above the primary coal layer targeted for CO2 injection. If CO2 breaks through the seal layer into the overburden formations, the secondary (upper) coal seam could possibly act as a CO 2 barrier due to the high affinity of CO2 to the coal matrix.;The main objective of the current research work is to investigate whether a coal layer present above the target coal reservoir could act as a CO 2 barrier. The study also investigates coalbed methane recovery from the upper coal seam, when some of the injected CO2 in the lower coal seam leaks through a pre-existing permeable caprock zone. Coupled multiphase flow and deformation analyses were used to investigate the CO2 transport behavior and ground response during CO2 injection. Different injection scenarios were considered based on two different well configurations. Results of the current study are presented in this report. Modeling results obtained from this study show that secondary (upper) coal seam can act as a CO2 barrier in the presence of a CO2 leakage. However, the leaked CO2 may not enhance the coalbed methane recovery from the upper coal seam.

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