A workflow has been developed for a shale play in North America for the strategic deployment of refracturing in an unconventional reservoir. Although it is clearly understood in the industry that refracturing in tight unconventional reservoirs can have a dramatic impact on the productivity and longevity of economic production, until now there has been no workflow that could be counted on to deliver consistent results. The impact of production and stress re-orientation plays a significant role in adding a fourth dimension of time to the existing three-dimensional problem of hydraulic fracture modeling in these reservoirs.
We examined the re-orientation of reservoir stress and the change in stress magnitude with production in a case from the Eagle Ford. The stress redistribution occurring due to poroelastic effects was simulated using a finite element geomechanical simulator and then tied back to predict the new hydraulic fracture growth. Fracture geometry as it relates to draining the unstimulated domain was found to play a significant role in fracturing success. The impact of adding new perforations in the wellbore and application of a suitable diversion technique were also considered in the study. Our numerical investigation of the potential increase in productivity with selection of the optimum refracturing treatment timing and technique led to development of a methodology that solves the complex four-dimensional problem.
By adopting the guidelines from the case study application of the end-to-end workflow, operators can avoid the futility of too early or too late fracturing and thereby maximize their return on investment.