On the risk of hydraulic fracturing in CO₂geological storage

Abstract

SUMMARYWe present a contribution on the risk of hydraulic fracturing in CO2 geological storage using an analytical model of hydraulic fracturing in weak formations. The work is based on a MohrCoulomb dislocation model that is extended to account for material with fracture toughness. The complete slip process that is distributed around the crack tip is replaced by superdislocations that are placed in the effective centers. The analytical model enables the identification of a dominant parameter which defines the regimes of brittle to ductile propagation and the limit at which a mode-1 fracture requires infinite energy to advance. We examined also how the corrosive effect of CO2 on rock strength may affect the hydraulic fracture propagation. We found that a hydraulically induced vertical fracture from CO2 injection is more likely to propagate horizontally than vertically, remaining contained in the storage zone. The horizontal fracture propagation will have a positive effect on the injectivity and storage capacity of the formation.The containment in the vertical direction will mitigate the risk of fracturing and migration of CO2 to upper layers and back to the atmosphere. Though the corrosive effect of CO2 is expected to decrease the rock toughness and the resistance to fracturing, the overall decrease of rock strength promotes the ductile behavior with the energy to dissipate in plastic deformation and hence mitigates the mode-1 fracture propagation.

Flow Regime Analysis of the Pressure Build-Up during CO2 Injection in Saturated Porous Rock Formations

“…Steps (4) and 5are repeated for a prescribed number of times to correct for non-orthogonality of the control volumes in the numerical solution [8,31].…”

“…It is worth mentioning that related technologies for CCS are still under development and much focus is devoted from the oil and gas industry, because it presents similarities with enhanced oil recovery (EOR) and enhanced gas recovery (EGR). Currently, any CCS projects are economically viable primarily when they are combined with other oil and gas technologies like enhanced oil recovery (EOR) [1][2][3][4][5][6][7].…”

Mohr–Coulomb plasticity for sands incorporating density effects without parameter calibration

“…The Mohr–Coulomb plasticity model is also widely used in research work, since it allows one to capture the pressure‐dependent strength of a geomaterial with a fraction of costs for sophisticated constitutive models. This exceptional efficiency makes the model a common choice for computationally intensive simulations in geomechanics, such as those involve complex domains, soil‐structure interactions, contacts, large deformations, and/or coupled multiphysics …”

Numerical analysis of mixed-mode rupture propagation of faults in reservoir-caprock system in CO2 storage

“…Nevertheless, their methodology is limited to mode II and cannot calculate the magnitude of the SIF. On the other hand, Papanastasiou et al (2016) presented an analytical model of hydraulic fracturing in weak formations to investigate the risk of hydraulic fracturing in CO 2 storage. The analytical model of Papanastasiou et al (2016), which is limited to mode I, is based on a Mohr-Coulomb dislocation model that is extended to account for materials with fracture toughness.…”

“…On the other hand, Papanastasiou et al (2016) presented an analytical model of hydraulic fracturing in weak formations to investigate the risk of hydraulic fracturing in CO 2 storage. The analytical model of Papanastasiou et al (2016), which is limited to mode I, is based on a Mohr-Coulomb dislocation model that is extended to account for materials with fracture toughness. They found that a hydraulically induced fracture from CO 2 injection is more likely to propagate horizontally than vertically, remaining contained in the storage formation.…”