Graduation Year

2009

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Civil and Environmental Engineering

Major Professor

Jeffrey A. Cunningham, Ph.D.

Co-Major Professor

Alexander Domijan, Jr, Ph.D.

Committee Member

Mark Ross, Ph.D.

Committee Member

Mark Stewart, Ph.D.

Committee Member

Maya Trotz, Ph.D.

Keywords

Greenhouse gas, Horizontal wells, Carbon Capture and Storage (CCS), Global climate change, Deep saline aquifer

Abstract

Many geoscientists endorse Carbon Capture and Storage (CCS) as a potential strategy

for mitigating emissions of greenhouse gases. Deep saline aquifers have been reported to

have larger CO

2 storage capacity than other formation types because of their availability

worldwide and less competitive usage. This work proposes an analytical model for screening

potential CO

2 storage sites and investigates injection strategies that can be employed to

enhance CO

2 storage.

The analytical model provides of estimates CO 2

storage efficiency, formation pressure

profiles, and CO 2

–brine interface location. The results from the analytical model were

compared to those from a sophisticated and reliable numerical model (TOUGH 2

). The

models showed excellent agreement when input conditions applied in both were similar.

Results from sensitivity studies indicate that the agreement between the analytical model

and TOUGH2 strongly depends on irreducible brine saturation, gravity and on the relationship

between relative permeability and brine saturation.

A series of numerical experiments have been conducted to study the pros and cons of

different injection strategies for CO 2 storage in confined saline aquifers. Vertical, horizontal,

and joint vertical and horizontal injection wells were considered. Simulations results

show that horizontal wells could be utilized to improve CO 2 storage capacity and efficiency

in confined aquifers under pressure-limited conditions with relative permeability

ratios greater than or equal to 0:01. In addition, joint wells are more efficient than single

vertical wells and less efficient than single horizontal wells for CO 2 storage in anisotropic

aquifers.

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