ИСТИНА

The paper investigates the influence of the presence and location of hydraulic fractures on the dynamics and quality of oil displacement. Particular attention is paid to ascertaining whether the presence of a hydraulic fracture increases the oil recovery coefficient or only intensifies oil production. The paper considers numerical modeling of two-dimensional displacement of a fluid from a porous medium a less viscous fluid. Moreover, the phase boundary is unstable: due to random perturbations superimposed on the distribution of permeability and porosity in the computational domain, the initially flat boundary loses its shape, the growth of “viscous fingers” begins, which significantly affects the quality of the displacement. The main features of the mathematical models are as follows: two incompressible fluids in the pore space, thermal effects are not taken into account, seepage is modeled by Darcy's law (taking into account the relative permeabilities of the phases, excluding capillary effects at the phase boundary), the fracture is modeled by the region of increased permeability and porosity, in addition, permeability in the entire area has a small random “ripple”, which provokes the emergence of displacement instability. An important condition for performing high-quality hydraulic fracturing is to thoroughly clean the fracture from hydraulic fracturing This paper also discusses the process of cleaning a fracture from hydraulic fracturing fluid by oil. The following geometry of the position of the wells is considered: 4 injection wells in the corners and one production well in the center. In the center is a symmetrical fracture with proppant. The reservoir area around the crack is filled with fracturing fluid. Using numerical modeling on the basis of the constructed mathematical model, a relationship is established between the quality of hydraulic fracture cleaning and the geometrical parameters of the fracture and the region filled with hydraulic fracturing fluid.