Three-dimensional numerical simulation of multiphase filtration and fracture propagation at the pore scale

Over the past years in the development of oil and gas fields, there has been a trend towards an increase in the development of unconventional low-permeability reservoirs. In this regard, it is becoming increasingly important to study the problems associated with the use of hydraulic fracturing technology (HF) in rocks with a complex internal structure. To achieve the maximum oil and gas production rate and increase the drainage zone in the near-wellbore space, it is necessary to carry out hydraulic fracturing with the most extensive system of fractures.

In this work the authors investigate the propagation of a hydraulically driven fracture in a fully saturated, permeable, and porous medium at the pore scale. To achieve a goal, at the first stage, we set a system of determining ratios and a crack propagation criterion. At the next stage, a three-dimensional numerical poroelastic model of a rock sample is prepared based on a three-dimensional image of the pore space of rock samples. Then numerical poroelastic modeling of the processes of one- and two-phase filtration and rock destruction using the extended finite element method is performed. For a more accurate description of filtration processes, the authors have prepared a physico-mathematical model that takes into account the flow rate and leakage of fluid into the rock during fracture growth at the pore scale. The obtained numerical results are compared with the previously conducted results of laboratory studies.

As a result of the numerical simulation, the authors prepared a digital rock model (DRM) based on microCT data, performed numerical simulation of the filtration process in the DRM and numerical simulation of fracture propagation in a fully saturated, permeable, and porous medium at the pore scale. Then, the dependences of filtration, initiation and fracture propagation were investigated depending on various conditions of HF fluid injection.