Pore pressure and stress coupling in closely-spaced hydraulic fracturing designs on adjacent horizontal wellbores

Significant advancement in developing mechanical systems in oil and gas industry has paved the way for introducing more sophisticated completion design. Recently, new fracturing designs in neighboring lateral wells have been introduced to enhance the production of trapped hydrocarbons, in particular in low-permeable shale reservoirs. The new designs aim at mitigating side-effects of stress shadowing whereas enhance the far-field fracture complexity. The present paper concentrates on the numerical simulation of the various fracturing design on adjacent lateral wells including Simultaneously Hydraulic Fracturing (Sim-HF), Sequentially Hydraulic Fracturing (Seq-HF), Modified Zipper-Frac (MZF), and Modified MZF (M2ZF). In this study, the Cohesive segments method in combination with Phantom Node Method, termed CPNM, is established to simulate the initiation and propagation of multiple fractures along arbitrary, solution-dependent paths. The proposed CPNM is capable of simulating curving hydraulic fracture propagation for studying the stress shadow effects resulted from pre-existing/simultaneous induced fractures. As opposed to original MZF, the stress shadow effects in the M2ZF are managed through non-uniform fracture spacing. The advantages and disadvantages of the stress shadowing effects, as a function of fracture spacing, on the fracture propagation path, pore pressure of the formation, the horizontal-stress contrast, and the in-plane shear stress have been studied in detail. It has been inferred that the operation time between consecutive stages in MZF design plays a crucial role in the closure of the un-propped fractures and, as a result, in the production performance of the wellbores.