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Risk analysis of injection-induced seismicity associated with geological CO2 storage through enhanced oil recovery
  • Yashvardhan Verma,
  • Vikram Vishal,
  • PG Ranjith
Yashvardhan Verma
Indian Institute of Technology Bombay

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Vikram Vishal
Indian Institute of Technology Bombay
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PG Ranjith
Monash University
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Abstract

CO2 enhanced oil recovery (EOR) is being increasingly deployed for the exploitation of depleted conventional oil and gas fields, due to the twofold benefit of improved recovery efficiency and reduction in carbon dioxide emissions. Geomechanics starts playing an increasingly important role with the injection of CO2 in the subsurface and the subsequent pore pressure buildup. However, the release of pressure through oil production enables a higher amount of CO2 to be introduced into the ground without causing undesirable effects. Understanding the stress perturbation due to fluid injection and withdrawal aids in comprehending the fault activation mechanism and the risks of induced seismicity. The current study evaluates the geomechanical influence of CO2 injection for enhanced oil recovery in a depleted oil field, and assesses the risk of injection and production induced seismicity as a constraint in geologic containment of CO2. The Ankleshwar field in Cambay basin in India is chosen for the study. The field is a potential CO2 EOR site due to its excellent permeability and recovery efficiency. Coupled multiphase fluid flow modeling and geomechanical analysis were carried out to study the hydro-mechanical characteristics of CO2 injection and fluid production. The rise in pore pressure near the injection site induces stress changes even far away from the site of injection due to poroelastic coupling in rocks. The risk of induced seismicity was then analyzed through simulation of fault slip potential in the field. FSP analysis suggests orientation of faults along with proximity to injection site are key parameters influencing fault stability in the Ankleshwar field.