Evaluation of CO2 sequestration potential in shale reservoirs using an improved embedded discrete fracture model

Document Type

Article

Publication Date

8-1-2026

Abstract

CO2 capture, utilization, and storage in depleted petroleum reservoirs is one of the rapidly growing areas of research in the petroleum industry. Of these reservoirs, shale gas reservoirs are particularly promising, considering the potential for trapping the injected CO2 by sorption, in addition to other trapping mechanisms expected in other subsurface reservoirs. However, accurate characterization of the pressure transient behaviors during CO2 injection is imperative for the estimation of reservoir properties and CO2 storage capacity. The accuracy of standard models for capturing transient flow dynamics remains limited in representing the early-time interactions between fractures and the surrounding matrix. To address these limitations, this study proposes an Analytically Projected Embedded Discrete Fracture Model (AEDFM), in which fractures are projected onto all six faces of three-dimensional host matrix elements. This approach systematically incorporates the influence of surrounding matrix blocks, enabling a more accurate simulation of the CO2 pressure transient behaviors of multi-stage fractured horizontal wells (MFHWs) in shale gas reservoirs. The accuracy of the proposed model is validated against reference solutions.Utilizing the proposed AEDFM, we developed a workflow for CO2 storage capacity evaluation based on pressure transient analysis. Furthermore, we analyzed the impact of fracture and reservoir parameters on pressure response and CO2 storage performance. Based on pressure test data from a shale gas well in the Longmaxi formation, reservoir rock properties, such as permeability, were obtained through curve matching. Using the matched property values, the CO2 storage capacity was evaluated at different injection rates. Overall, the proposed model offers an efficient and accurate framework for analyzing transient flow and assessing CO2 storage capacity in shale reservoirs.

Publication Source (Journal or Book title)

International Journal of Rock Mechanics and Mining Sciences

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