Empirical and Conceptual Challenges in Hydraulic Fracturing with Special Reference to the Inflow

Abstract

In this paper, a systematic study was carried out to computationally explore the significance of different mechanisms involved in hydraulic fracturing treatments in practice, with special reference given to the hydrofracture inflow. For this reason, our well-established extended finite-element framework for modeling of hydraulic fracturing treatments in saturated porous media was employed. Accordingly, the u−p formulation was adopted to develop the coupled set of equations governing the hydromechanical response of the fractured porous media. The spatial discretization was carried out by means of the extended finite-element method (X-FEM) in order to incorporate the strong discontinuity in the displacement field due to the fracture body as well as the weak discontinuity in the pressure field due to the leak-off flow. Important mechanisms and parameters studied include proppant settlement, fracture energy, leak-off flow, fluid-lag zone, fracture surface roughness and tortuosity, pressure fluctuations, and flow regimes. By benchmarking the results against the reference solution obtained in the absence of the mechanism under consideration, a beneficial criterion for the significance of each mechanism was deduced.