Effect of hydraulic fracturing on long-term storage of CO2 in stimulated saline aquifers

Abstract

Stimulation techniques, primarily as hydraulic fracturing, can contribute to improve practical storage capacity of low-permeable saline aquifers by increasing injectivity. Since the shape of the CO2 plume in the injection period can affect its subsequent migration, impact of hydraulic fracturing on post-injection plume migration should be investigated to assess CO2 long-term trapping in stimulated saline aquifers. Compositional reservoir simulation results, based on a case study of Rose Run sandstone aquifer in Ohio River Valley, show the important role of methods for increasing near wellbore injectivity on CO2 plume dynamics. Significant tradeoff between enhancing injectivity and long-term trapping of carbon dioxide in hydraulically fractured saline aquifers in normal faulting regime is proven by analysis of parameters controlling CO2 storage in saline aquifers such as gravity number. In addition, we discuss effects of the aquifer stress regime, fracture properties, and injection of water on immobilization of CO2 by residual and solubility trapping inside the stimulated saline aquifers. Finally, we show that non-Darcy flow effects inside the fracture could reduce injectivity of the stimulated saline aquifer by causing additional pressure drop inside the fracture.