Numerical Investigation of Hydraulic Fracture Propagation and Proppant Transport in Multi-Well Fracturing Stimulation

Abstract

ABSTRACT Multi-well fracturing techniques are beneficial to enhance stimulated reservoir volume and completion efficiency in unconventional oil and gas development. However, severe inter-well stress interference aggravates the uncertainty of fracture propagation and proppant transport, which poses challenges to the efficient development of reservoirs and the optimization of completing parameters. In this study, a fully coupled multi-well fracturing model considering both 3D propagating fracture and proppant transport is established based on the displacement discontinuity method and Eulerian-Eulerian approach, and the integrated model accounts for hydraulic fractures interaction (i.e., stress-shadow effects), gravitational proppant settling, proppant bridging, and the transition of fracturing fluids from Poiseuille to Darcy flow. The numerical results indicate that fracture propagation geometry under the multi-well fracturing completion is jointly affected by a variety of stress interference mechanisms, such as asymmetric fracture propagations due to the intense inter-well stress interference and the heel bias resulting from inter-stage stress interference. Because proppant transport capacity is mainly controlled by fracture geometry and width, proppant accumulation and bridging are easy to occur at smaller fracture widths, resulting in a limited proppant placement range on the whole. Through several scenarios designed to investigate the influence of key parameters, it is found that increasing well spacing and cluster spacing can reduce the inter-fracture stress interference, and promote the fracture lateral propagation and proppant distribution uniformly in each fracture. Increasing proppant concentration and reducing proppant size are effective methods to improve the propped fracture area. The obtained conclusions can be helpful to provide a better insight into fracture propagation and proppant transport in multi-well fracturing stimulation. INTRODUCTION In response to the demand for unconventional oil and gas development, well pads with hydraulic fracturing technology are widely used due to high efficiency and cost saving. Compared to single-well fracturing, the stress interference mechanism in multi-well fracturing is more complex, increasing the uncertainty of fracture propagation and proppant distribution. It further causes fracture-hit and premature tip screen-out, which seriously affects the stimulated volume and completion efficiency of well pads. Therefore, the research of fracture propagation geometry and proppant distribution in multi-well fracturing can contribute to the formation of hydraulic fractures with appropriate size, orientation, and propped area, which is indispensable for the economic development of unconventional reservoirs.