Estudo numérico dos efeitos das fraturas em reservatórios de petróleo

Abstract

The presence of fractures has a strong effect on the behavior of naturally fractured reservoirs, since they present abrupt changes in the porosity and permeability properties of the medium, acting as walls or preferred paths for the fluids flow. Due to these characteristics the simulation of this type of reservoir represents a great challenge. The fractures are arranged randomly in the porous medium, having specific distributions of length and inclination. In this work the effects of these distributions were investigated in the simulation of naturally fractured reservoirs. The hierarchical fracture model was used to simulate the flow in 2D porous media, through the MRST software in the MATLAB environment. Based on the literature, the power law distribution was used to characterize the fracture length and the Fisher distribution for its orientation. Based on their respective probability distributions, 1000 different configurations were generated and simulated for fracture length and orientation. These simulations measured the variations of parameters such as recovery factor, breakthrough time, production rate and cumulative production of oil and water, water cut, water-oil ratio, saturation in the producing well, injector well pressure and mean pressure in the matrix. The results show that the variations in fracture length have a much more significant effect on the behavior of the reservoir than the variations in orientation. It was also observed that the mean fracture length has an effect very similar to that caused by maximum length fractures in each simulation. The most sensitive variants of these variations were saturation in the producer well, recovery factor and oil and water production rate.