Production Dynamic Characteristic of Fractured Wells in Multilayer Reservoirs Considering the Effect of Non-Uniform Flux Distribution

Abstract

Hydraulic fracturing stimulation, which improves matrix permeability and reduces production costs, has been extensively used in the exploitation of multilayer reservoirs. However, little research on the production dynamic characteristics of vertically fractured wells in stratified reservoirs has been done in the literature. The influence of flux variation along the fracture on the pressure transient behavior has been ignored in these previous works. Therefore, this paper introduces a novel semi-analytical model for fractured wells in multilayer reservoirs, in which the finite difference method is used to characterize fluid flow in the fracture and the Green’s function method is used to characterize fluid flow in the matrix. With the aid of the model, the production dynamic characteristics of fractured wells in multilayer reservoirs can be readily investigated. In addition, based on the assumption of nonuniform flux distribution along the fracture, we successfully recognize four flow regimes occurring in the pressure drop and pressure derivative curves. Following that, the influences of several parameters on the pressure dynamics and layered flux contribution are studied. The calculation results indicate that a larger storability ratio, as well as a larger permeability ratio, can increase the values of the pressure drop and the pressure derivative; the greater the fracture height, the greater the fluid flow into each layer of the fracture. During the production of this model, increasing the fracture conductivity can reduce the pressure drop and pressure derivative, which means lower flow resistance in the fracture.