Application of fault sealing evaluation technology based on 3D modeling in CCS/CCUS

CCS/CCUS technologies are essential for achieving zero and even negative carbon emissions, and fault sealing is a critical factor determining the effectiveness and safety of CO 2 storage. Predominantly relying on the shale gouge ratio (SGR) on both sides of a fault for evaluating fault sealing, traditional methods are highly dependent on well data and feature oversimplified evaluation parameters, which results in low evaluation accuracy in areas with limited CCS/CCUS exploration data and thus fails to meet practical requirements. The method can be optimized from the following aspects to solve the above-mentioned problems. ① High-precision 3D modeling integrated with well and seismic data is carried out to characterize the heterogeneity of fault zones. As a result, this can solve the problem that traditional methods are difficult to apply to areas with few or no wells, and establish a framework for 3D sealing evaluation, improving the vertical evaluation accuracy from the 10-meter scale to the meter scale. ② A method for fault permeability ( K f ) calculation is improved, and a model for fault transmissibility (TM) evaluation is introduced, thereby eliminating the influence of maximum burial depths and burial depths at the time of formation, and advancing the transformation from 2D fault planes to 3D fault bodies. Field application results show that compared with traditional methods, the proposed evaluation method improves the average accuracy by more than 20 %. It has supported the implementation of a 127.5 km 2 CCS storage geological body in Well SQ3 in the eastern Junggar Basin, with the key factors causing CO 2 gas channeling in the H pilot test area identified. Additionally, the early warning accuracy is over 90 %, which helps reduce the incidence of gas channeling and provides strong technical support for CCS/CCUS safety.