In order to increase production rate, reduce treatment period, and solve some special problems, multi-well completion has been proposed, especially in mountain areas with limited well pads. Simultaneous fracturing and zipper fracturing are two new fracturing patterns in multi-well completion, which can increase fracture network complexity and stimulated reservoir volume (SRV) because of the interference of wells or fractures. However, unlike multi-frac treatments of a single well, interference between multi-wells also increases difficulties on hydraulic fracturing design.
In the previous papers, we have shown that natural fractures impacted the direction of hydraulic fracture propagation and mechanical properties of reservoir formations, which increases the complexity of fracture network complexity. As known, hydraulic fracture propagation is a complicated process influenced by frac spacing, hydraulic fracture length, mechanical properties of natural fractures, and in-situ stress. Especially, in-situ stress and natural fractures play more complex roles in multi-well completions.
In this paper, we presented one numerical model to better understand the process of hydraulic fracture propagation in multi-well completions, which includes influences of in-situ stress changes and interactions between hydraulic fracture and natural fractures. The numerical results show that in addition to hydraulic fracture propagating, natural fracture opening also changes in-situ stress, which makes hydraulic fracture network more complex. The model has been validated in a zipper fracturing case, and the optimization of well spacing, frac spacing and treatment volume has been proposed to enhance stimulated reservoir volume (SRV) and increase shale gas production.
The simulation results of this paper provide some guidelines for hydraulic fracturing design in multi-well completions, which contains optimum well spacing, frac spacing, and treatment volume. The results of this paper may also help deal with limited well pad area and increase gas production, and ultimately it should lead to improved well economics.