Research on the Mechanism and Process of Fracturing Reduction for High Fracture Pressure and Low Permeability Reservoirs

The ultra-deep reservoir has dense lithology and underdeveloped pores and fractures. Due to its high fracturing pressure, it is difficult to break open the formation during reservoir reconstruction, making acid fracturing construction difficult. In view of the high fracture pressure reservoir with tight lithology, this paper puts forward the corresponding technical countermeasures from two aspects: increasing the bottom hole treatment pressure and reducing the rock mechanical strength. Firstly, physical simulation experiment is used to study the effects of different acid types, concentrations, injection amounts and reaction time after pump shutdown on the mechanical properties of reservoir rock. On this basis, an acid leaching pretreatment method was proposed for reservoirs with different physical properties. Three density adjustable solid-free, temperature resistant, low corrosion, and low-cost well killing working fluids were selected, and their temperature resistance and corrosion rate were evaluated through indoor experiments. This research achievement provides new ideas and materials for solving the problems of difficult fracturing and high acid fracturing wellhead pressure in ultra-deep and high stress reservoirs.