(389g) Modeling of Pressure and Displacement Signatures for Detecting A Fracture in the Caprock During Geologic Sequestration

(For the Session Organized by Dr. Grant Bromhal and Dr. Dustin Crandall)

Modeling Of Pressure And Displacement Signatures For Detecting A Fracture In The Caprock During Geologic Sequestration

Hema Siriwardane ⁽¹⁾, Raj Gondle ⁽¹⁾ and Grant Bromhal ⁽²⁾

ABSTRACT

Finite difference and finite element methods were used to determine changes in fluid pressure and overburden deformations caused by the injection of carbon dioxide (CO₂) in a typical geologic formation such as a saline/brine aquifer. The objective was to evaluate the long-term storage potential by investigating the overburden geologic response and flow behavior due to the presence of fractures and faults in the caprock that could act as leakage pathways. The presence of geologic uncertainties such as fractures/faults in a caprock may lead to possible communication of injection fluid with overlying or underlying geologic media, which over a period of time can cause changes in fluid pressure and overburden deformations.

            In this study, single-phase and multi-phase fluid flow modeling was performed to simulate water and CO₂ injection into a geologic formation. Geomechanical effects were incorporated in the analysis. Coupled flow-deformation finite element analyses were used to model single phase fluid injection. Multi-phase fluid flow modeling based on the finite difference method was also performed.  Three different fracture locations were selected to investigate the influence of fracture, fracture location, and fracture permeability on the pressure and overburden response of the system. A comparison of numerical results based on single-phase and multi-phase fluid flow modeling is also presented in the paper. Results of the study show that the pressure and displacements signatures can be used to detect the presence of an existing fracture or the activation of a new fracture in the caprock layer.  Results from this study can be used in the development of smart monitoring technologies with limited field instrumentation coupled with numerical modeling work.

Keywords: carbon sequestration, numerical modeling, fracture/fault, single-phase, multi-phase

⁽¹⁾            NETL-RUA and Department of Civil and Environmental Engineering, West Virginia University, Morgantown, WV 26505-6103

⁽²⁾              National Energy Technology Laboratory (NETL), U.S. Department of Energy, P.O. Box 880, Morgantown, WV 26507-0880