Hydromechanical modelling to evaluate impact of fault structure on CO2 migration in stacked storage system. (February 2020)

• Record Type: Journal Article
• Authors: Zulqarnain, Muhammad; Zeidouni, Mehdi; Hughes, Richard G.
• Is Part Of: International journal of greenhouse gas control. Volume 93(2020)
• Publication Date: 2020-02
• Subjects: Fault heterogeneities -- Shale smear factor -- Local capillary trapping -- Fault leakage rates -- CO2 storage integrity; Greenhouse gases -- Environmental aspects -- Periodicals; Air -- Purification -- Technological innovations -- Periodicals; Gaz à effet de serre -- Périodiques; Gaz à effet de serre -- Réduction -- Périodiques; Air -- Purification -- Technological innovations; Greenhouse gases -- Environmental aspects; Periodicals; 363.73874605
• DOI: 10.1016/j.ijggc.2019.102886
• Languages: English
• ISSNs: 1750-5836

Abstract

Highlights: 3D fault heterogeneities are captured to understand implications for CO2 migration. Stacked sand system is investigated for inter- and intra-sand leakages. Across-fault leakage found more prevalent in comparison to vertical up-fault leakage. Up to four fold increase in leakage is observed due to interconnected fractures. Abstract: Faulting processes produce a complex fault damage zone (FDZ) having permeability variations over several orders of magnitude within a very short distance. In this study we use an example normal fault system from a depleted oil field in southern Louisiana with multiple stacked sand beds along the fault structure. Geostatistical techniques are used to introduce heterogeneities of several orders of magnitude over very short distances that honor the across- and along-fault architecture of the system. A total of 15 cases are simulated to account for the impact of a fragmented core, an intact core and a naturally fractured core on inter-sand leakage rates. The presented results show the complex nature of CO2 migration within the fault structure, where an interplay between overcoming the fault core's high capillary entry pressure and stress propagation in the vertical direction dictates the leakage direction and rates. It is observed that hydromechanical evolution of fracture flow properties may result in significant leakage from the storage zone. In one case with small caprock thickness, a loss of 18% of the total injected mass is observed. The results presented highlight some unique features of representative fault related leakage in stacked sand systems and thus will be beneficial for storage integrity analysis in these systems.