Numerical Modelling of Multiple Stage Hydraulic Fracturing Using XFEM

Recently, new hydraulic fracturing designs in adjacent lateral wells have been introduced to increase the production of low-permeable shale reservoirs. The evolution of completion techniques has reached the point to perform numerous stimulation stages through multiple perforation clusters. The main goal is to create induced fractures more closely spaced than can be achieved with a single well. Generally, the completion of horizontal well hydraulic fracturing is performed using an injection scheme such as the Simultaneously Hydraulic Fracturing (SimHF), in which multiple fractures are potentially initiated and propagated together in one horizontal wellbore. A key operational parameter is the clusters spacing, which could determine the success of the operation. The stress perturbation owing to placement of multiple fractures can affect the fracture geometry such as length, aperture, height, and propagation direction. Therefore, multiple hydraulic fracturing treatments should not be designed in the same way as a single hydraulic fracturing stimulation. Numerical modelling of hydraulic fracturing can reduce uncertainties in the reservoir integrity. In this work, The Extended Finite Element Method (XFEM) was implemented in a hydro-mechanical coupled formulation to simulate hydraulic fracturing processes considering the propagation of several vertical planar fluid-driven fractures in a transient analysis. This paper focuses on the stress shadowing effects on the resulting fracture geometry considering the Simultaneously Hydraulic Fracturing scheme. The advantages and disadvantages of the stress shadowing effects, as a function of fracture spacing, on the geometry and propagation path have been studied in detail. As a result, several fracture geometries developed according to the completion scheme adopted. In addition, the Simultaneously Hydraulic Fracturing scheme of closely spaced clusters generates longer and outward deviated side fractures and straight shorter middle fractures.