Wangfu Low-Permeability Volcanic Gas Reservoir Microstructure and Damage Mechanism

The microstructure of the Wangfu volcanic reservoir and the predicted permeability reduction of this reservoir are investigated. It is found that water block (strata permeability reduction due to the penetration of water into the pore space) and fracturing fluid residue are the main causes of reduced deposit gas permeability. A subsuite of this reservoir, Quan-1, is sensitive to water whereas the Huoshiling and Shahezi formations are sensitive to acids. Therefore, an acidic fracturing fluid should be used in the first instance, and fluid with a low concentration of guar gum and minimal acid content – in the second. However, fracturing fluids with anionic surfactants should be used to solve the water-block problem in all three deposits, thereby increasing process efficiency.