Impact of injection pressure during cold water reinjection on the state of stress in geothermal reservoirs

Abstract

During cold water injection into geothermal reservoirs, pore pressure increases and the reservoir rock is brought closer to fracturing conditions. The fracturing may cause early cold water breakthrough into production wells. A 2-D reservoir simulator describing fully coupled fluid flow, thermal flow, and geomechanical behavior was used in this study. The objective of this work is to investigate the evolution of the stress state in liquid-dominated reservoirs and to establish how principal stress directions change during injection pressure increase. The paper describes simulated fracturing pressure changes due to cold-water injection. It also discusses how to predict orientation/re-orientation of hydraulic fracture propagating from an injector.