Numerical Analysis of Three-Dimensional Fracture Propagation and Proppant Transport in Heterogeneous In-Situ Stress Reservoirs

ABSTRACT: A fully coupled fracturing model of wellbore-perforation-fracture is proposed, considering key physical behaviors, such as the dynamic proppant-laden slurry distribution at each cluster, perforation erosion, nonplanar 3D fracture propagation, and proppant transport within fractures. The accuracy of the non-planar 3D fracture model is validated using the laboratory results from true triaxial hydraulic fracturing experiments. Numerical simulation results show that due to the solid-fluid density difference, proppant transport in the wellbore is affected by the particle slip effect, resulting in different proppant turning efficiencies among perforation clusters. For the given simulation parameters, the proppant concentration distribution in the wellbore presents a toe bias. In heterogeneous in-situ stress reservoirs, multiple fractures propagate in non-uniform and non-planar geometries. The uniformity of multi-fracture propagation is significantly influenced by the heterogeneous inter-cluster stress distribution, as the middle cluster fractures situated in high-stress regions struggle to initiate effectively. In-situ stress deviation promotes non-planar propagation and the intersection of hydraulic fractures. A larger deviation angle of the in-situ stress causes fractures to deviate and merge earlier, thereby limiting the propagation area of most fractures. Reducing the proppant particle size or increasing injection concentration can enhance the propped fracture area, which is particularly beneficial for fractures in reservoirs with smaller in-situ stress deviation angles. 1. INTRODUCTION Multi-stage and multi-cluster fracturing technology for horizontal wells is currently the most effective method for stimulating unconventional oil and gas reservoirs (Miskimins, 2020). By conducting multi-cluster perforation and hydraulic fracturing within the designated stages, multiple fractures can be created simultaneously to maximize the stimulated reservoir volume (Ciezobka, 2021; Yang et al., 2023; Zou et al., 2022). Although multiple hydraulic fractures initiate and propagate simultaneously, their geometries and sizes are challenging to control with precision. Fracturing monitoring results in the field indicate that there is competitive propagation among multiple fractures, and the fracture morphologies are influenced by various factors, including rock mechanical properties, in-situ stress distribution, natural fractures, and pumping parameters (Ugueto et al., 2021).