An integrated understanding of geomechanical effects, fracture propagation and reservoir dynamics is critical in the efficient and cost-effective application of rejuvenation technologies for unconventional plays. While various reservoir models depicting the hydraulic fracturing process are available in the industry, many tend to be simplified or do not capture the numerous parameters that affect both the initial and restimulation processes. This study takes a further step towards building a more realistic picture of fracturing in unconventional plays. In particular, a workflow is presented to couple the geomechanical effects and reservoir simulation modeling in unconventional plays. The objective is to make use of the learnings from this modeling in the successful application of rejuvenation technology.

The integrated model is developed using existing horizontal unconventional wells in a US shale play. During the initial phase of hydraulic fracturing, variations in stress occur both during injection and production periods. These stresses affect the growth of the fracture and its consequent fracture geometry. While employing various rejuvenation technologies, the ability to re-stimulate the rock will depend on a combination of factors, two primary ones being stress variation and pore-pressure depletion. These effects are incorporated into the reservoir model. Consequently, the production history-matched reservoir model incorporates pressure-dependent permeability variation as well as capillary pressure to account for varying reservoir dynamics.

Results from this study highlight the importance of changing stress regimes on fracture geometry and its consequent impact on production. We present a methodology to integrate geomechanical effects into a reservoir simulation model. The study also indicates the importance of treatment fluid volumes pumped at various stages during the refracturing operation.

Additional benefit of restimulating a well will vary from one well to another. The benefit is realized in terms of cumulative fluid volumes and reservoir contacted. The modeling techniques presented may help in application of such restimulation operations based on its impact on recoverable reserves. In summary, this study shows that a comprehensive understanding of stress changes coupled with reservoir dynamics will help better plan the application of various rejuvenation technologies.

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