| Abstract |
Hydraulic fracturing is a promising method for enhancing the permeability of geothermal and high-temperature petroleum reservoirs hosted in volcanic rocks. However, the inherent porosity of these rocks, coupled with the reduced viscosity of water at elevated temperatures, often leads to substantial fluid loss into the matrix, thereby limiting fracture opening and propagation. Field operations in volcanic gas reservoirs in Japan have reported significant challenges in proppant transport and placement, likely due to these effects. To address these limitations, we propose a novel reactive, high-viscosity, water-based fracturing fluid composed of glutamic acid diacetate (GLDA)—a biodegradable, biobased chelating agent—and scleroglucan—a thermally stable polysaccharide thickener. GLDA facilitates rock weakening by extracting metal ions from rock-forming minerals and suppressing secondary precipitation, while scleroglucan maintains high viscosity across a broad range of temperatures, pH levels, and salinities. Laboratory-scale hydraulic fracturing experiments conducted on volcanic rocks demonstrate that this GLDA–scleroglucan fluid generates significantly wider fractures compared to water under equivalent injection pressures. These findings indicate strong potential for the GLDA–scleroglucan system to improve fracture efficiency and enhance reservoir permeability in high-temperature volcanic formations. |