The role of stress interference in hydraulic fracturing of horizontal wells

One of the newly introduced fracturing designs is Texas Two-step, which still requires to be studied in depth, in particular, the impacts of stress shadowing and parameters involved for a more effective fracturing job. In this work, a poro-elasto-plastic computational model for 2-D hydraulic fracture propagation simulation is presented. The Cohesive Crack Model (CCM) is employed for modeling fracture propagation and represents inelastic behavior ahead of fracture tip. On the other hand, the rock formation in the entire simulation domain is modelled by the elasto-plastic constitutive equations of the Drucker-Prager model. The solution accounts for fracture initiation and propagation, coupling between elastic deformation and fluid flow within the hydraulic fractures, stress interactions between induced fractures (stress shadowing effect). This study also takes into account the presence of a local pressure drop in a perforation by considering a specific type of pore pressure element, called Perforation Entry Element (PEE), in the model. The crucial contribution of the present work is to investigate the influences of stress shadowing and In-situ Stress Ratio (ISR) on the propagation path of the fractures in both Texas two-step and Sim-HF designs. It has been concluded that design of the actual Fracture Spacing (FS) of the first two fractures in Texas two-step is of highly importance so as to ensure adequate degree of interference without the concern of generating so much induced stress such that the middle fracture propagation is restricted.