ANALYZING FAULT REACTIVATION POTENTIAL OF CO2 STORAGE

Carbon storage and enhanced oil recovery (EOR) are two methods which make rocks to get exposed to CO2. Therefore, injection of CO2 may alter acoustic emission and geomechanics behavior of the rocks and therefore may reactivate faults in the basin. This research aims to study the behavior of the organic rich shale and reservoir rocks when flooded with CO2 in the Bakken Formation where the feasibility of EOR and storage is being studied currently. Analysis of the ground-surface deformation with response to the mechanical changes of the rock, estimation of potential fault reactivation, and induced seismicity when samples are exposed to CO2 for a certain period of time is being investigated. We also, quantified the physical and chemical effects of CO2 saturation on the geomechanical parameters of the host formation such as the Young’s modulus and Poisson’s ratio. In order to do so, core plugs retrieved from active wells producing from the Bakken Formation (Upper, Lower and Middle member) in North Dakota were used in this study. The uniaxial compressive strength test (UCS) and trial compressive strength test (TCS) was conducted on the core samples from each member before and after exposure to CO2 for about 2-30 days. Changes in mechanical characteristics are reported at each stage while SEM images enabled us to evaluate pore structures to define the pattern of changes before and after CO2 saturation. This geomechanical analysis will guide in determining the volume of CO2 needed for EOR and storage, and determine the capacity and integrity of the Bakken Formation in North Dakota.