Characteristics of permeability variation in water well fracturing-flooding reconstruction and its numerical simulation representation

Hydraulic fracturing flooding technology can effectively increase reservoir pressure and improve water injection capacity by injecting a large amount of fluid into the formation in a short time, which is especially suitable for low permeability, ultra-low permeability and tight sandstone reservoirs. In this paper, the study of water well fracturing flooding is carried out in the low permeability block of Jiangsu Oilfield. The relationship between permeability and effective stress is established by core fracturing flooding experiment, and the constitutive equation describing the change of reservoir physical properties after fracturing flooding is constructed. The method is applied to simulate the physical response of the reservoir near the wellbore during the fracturing flooding process. It is clear that there are two stages of permeability change before and after fracture, which meet the exponential relationship respectively. The constitutive equation is introduced into numerical simulation, and combined with the fracture propagation module, the dynamic characterization of reservoir physical property changes in the fracturing flooding transformation area is realized. The simulation results show that the proposed method can reasonably reflect the change of injection pressure in the process of fracturing flooding, improve the distribution of permeability field, and effectively evaluate the effect of fracturing flooding on the improvement of water injection capacity, average pressure near the wellbore and oil well production. The research provides theoretical basis and technical support for the optimization and effect evaluation of water well fracturing flooding parameters in low permeability reservoirs.