Multiwell Fracturing Characteristic in Layered Heterogeneous Formation and the Optimization of Stimulated Reservoir Volume

Abstract

Hydraulic fracturing within multiwell pads is considered an effective technique for enhancing the recovery of oil/gas resources, but the fracture propagation behaviors have not been fully understood, typically considering the layered heterogeneous construction and intricate stress interference effects. This work establishes a multiwell fracturing model based on the threedimensional displacement and pore pressure coupled cohesive method to precisely characterize the propagation and morphology features of the hydraulic fracture. The flow behavior in the well follows the Bernoulli equation, and the fluid distribution at each perforation point is automatically regulated with the fluid pipe element. The fracturing model is validated with the analytical solution for the penny-shaped fracture. Various fracturing scenarios, including the spatial relations of wells and clusters and the geological conditions are thoroughly revealed. The results demonstrate that the layered formation significantly influences the stress interference between wells and clusters and thus alters the fracture propagation. It can be observed that the intercluster stress interference is weakened when confined within the layered formation, where the fractures grow uniformly along the lateral direction even with a small cluster spacing. When the wells are located at different layers, three typical propagation modes are summarized as lateral propagation, penetration, and aggregation, depending on the in situ stress, rock strength, and fracture energy of different layers in the formation. Meanwhile, optimization of the well pattern is discussed from the perspective of the fracture area to achieve the maximization of the stimulated reservoir volume (SRV). These insights are helpful for the design and implementation of multiwell fracturing technology in tight formation with layered heterogeneous construction.