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The design and evaluation of hydraulic fracture modeling is critical for efficient production from tight gas and shale plays. The efficiency of fracturing jobs depends on the interaction between hydraulic (induced) and naturally occurring discrete fractures. We describe a coupled reservoir-fracture flow model which accounts for varying reservoir geometries and complexities including non-planar fractures, faults and barriers. In addition our model is coupled with linear elasticity using iterative coupling to solve a multi-phase Biot system. The approach presented here is in contrast with existing averaging approaches such as dual and discrete-dual porosity models where the effects of fractures are averaged out. We model the fractures and reservoirs explicitly, which allows us to capture the flow details and impact of fractures more accurately. Moreover, accurate modeling of solid deformations necessitates a better estimation of fluid pressure inside fracture, which our flow model provides. We utilize different flow models for the fractures and the reservoir closely capturing physics when needed. A quantitative comparison is made in order to identify situations where a multiphysics flow description is critical to accurate prediction compared to an averaging based approach. We present several numerical tests, including a field scale case study, to illustrate the above features and their impact on recovery predictions.

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A B S T R A C TRecently, mode converted shear waves (C-waves) have been shown to enable overpressure prediction in media where primary wave acquisition is inhibited by gas and fluid effects -C-wave moveout is analysed and a long standing relationship between differential stress and primary-wave (P-wave) velocity is modified and employed. Though pore-pressure prediction based on C-waves is supported by empirical evidence from laboratory and field experiments, a theoretical justification has yet to be developed. In this research note, we provide a supporting algebra for the original relationship between pore pressure and C-wave velocity.