Gas fracturing behavior and breakdown pressure prediction model for granite under different confining pressure and injection rate

Abstract Conventional hydraulic fracturing techniques are often found problematic for extracting geothermal energy in hot dry rock (HDR). As an alternative, employing the less viscous gas to replace water as fluid showed great potential more effective of HDR. In this work, failure behavior and mechanism granite during under different confining pressures injection rates comprehensively examined. It is shown that breakdown pressure increases with increase pressure, whereas higher rate can result evident decrease pressure. grows, acoustic emission (AE) event rapidly, much AE counts observed at high than low rates. Comparatively, decreases due probably transitioning from brittle ductile. interesting b -value varies dramatically becomes significant fluctuations, indicating ratio large fracture small changes drastically fracturing. addition, length induced fractures fracturing, width vertical evidently larger when rate. Last, a novel theoretical predictive model proposed estimating based on average tensile stress criteria, which featured by considering effect flow behaviors. The prediction agrees experimental results. present study provide valuable results analysis engineering applications stimulating HDR reservoirs.