The Study of Permeability Change of Fractal Under Fracturing Basing on Damage Theory

In order to research the evolution of permeability and damage of fractal rock under hydraulic fracturing, a new damage variable that describing relative reduction of pore amounts as radius is bigger than r any fracturing stage is defined. Assuming the process of evolution of micro-fracturing is in accord with standard model of Logistic bifurcation theory, according to energy conservation principle, the models of rock damage and infiltration of evolution under hydraulic fracturing were established based on damage theory. then the evolution model of rock is also done. One well of Ji Lin oil field is chosen, the changes of porosity and permeability were calculated, the results coincided with engineering practice.