Examining Fault Characteristics to Evaluate The Feasibility of CO₂ Storage in Area ‘R’, Talang Akar Formation, Asri Basin.

Abstract

The increase in carbon emissions resulting from the use of fossil fuels has driven the development of various solutions for climate change mitigation, one of which is Carbon Capture and Storage (CCS) technology. In Indonesia, the Asri Basin is recognized as a region with high potential for geological CO₂ storage, particularly within the Talang Akar Formation. This study aims to assess the feasibility of the "R" Area as a site for CO₂ injection and storage, with a focus on analyzing fault characteristics that may either serve as migration pathways or act as fluid barriers. The methods employed include 3D seismic data interpretation, petrophysical analysis, subsurface structural and rock property modeling, and Fault Seal Analysis (FSA) based on Shale Gouge Ratio (SGR) calculations and lithological juxtaposition evaluation. The study identified two main faults, Fault 1 (F1) and Fault 2 (F2) with, oriented north–south, and dipping westward and southwest–northeast and dipping towards the northwest, respectively. SGR values for both faults generally exceed 20%, a commonly accepted threshold for fault sealing capacity, indicating the potential role of these faults as barriers to CO₂ migration. Additionally, the distribution of shale volume (VShale) and the juxtaposition analysis results reveal that sealing lithologies such as shale and coal are in frequent contact with reservoir rocks, particularly within the TAF–Zelda interval. The 3D geological model also highlights facies heterogeneity and anisotropy in petrophysical parameters, both of which influence fault sealing performance. The integration of these multidisciplinary methods suggests that the "R" Area possesses favorable geological characteristics for long–term and secure CO₂ injection and storage. The sealing nature of the faults, combined with the geological properties of the Talang Akar Formation, reinforces the position of the "R" Area as a strong candidate for CCS implementation in Indonesia.