Numerical simulation of stress reorientation around wellbore in production and refracture stimulation.

• A poro-visco-VIB is developed to simulate the time-dependent porous rock. • Porosity- and stress-dependent permeability of the porous rock and fracture are considered. • Stress reorientation near wellbore in production is studied. • Hydraulic refracture by plugging treatment is studied. The refracture is a promising restimulation technique in the unconventional reservoir during production. It can be realized due to the stress reorientation. To study the mechanism of stress reorientation and refracturing behaviors, a new poro-visco-VIB (virtual internal bond) method is developed in this paper. In the framework of Boit's theory, the visco-VIB is used to describe the skeleton instead of the conventional continuum constitutive model. Through this poro-visco-VIB, both the time- and stress-dependent behaviors of the porous rock can be well simulated. The simulation results of stress reorientation show that the smaller in-situ stress difference can result in a larger stress reorientation scope. To include the fractures into the numerical model, the element partition method (EPM) is adopted. By this VIB/EPM method, the refracture by plugging is studied. The results indicate the plugging position significantly impacts the reorientation distance of refracture. The reorientation distance by plugging fracture end is much larger than by plugging fracture mouth. Thus, it is critically important to control the plugging position in refracture treatment. These findings provide valuable references for the refracture design. It also provides an efficient approach to hydraulic fracture simulation with consideration of the porosity and the time-dependency effect. [ABSTRACT FROM AUTHOR]