Fully coupled XFEM formulation for hydraulic fracturing simulation based on a generalized fluid leak-off model

摘要

A novel fully coupled hydro-mechanical model is used to assess the effect of fluid loss on the efficiency of the fracturing treatment within saturated porous media. In the context of XFEM, the pore pressure is defined independently on either side of the hydro-fracture using the Heaviside enrichment function. Meanwhile, independent pressure degrees of freedom are employed to develop a generalized model for the hydro-fracture inflow. In this way, the pressure jump due to the formation of a bedding layer of settled proppants and/or additive chemicals in the vicinity of the hydro-fracture faces can be taken into account (technically referred to as the cake layer effect). On the other hand, the reduction in the hydraulic permeability of zones adjacent to those areas affected by the very high fracturing pressure, also known as filtrate effects, is taken into account through a series of experimental correlations. Finally, the ability of the developed framework to tackle the modelling of hydraulic fracturing, particularly in medium to low permeability formations, is illustrated by means of numerical simulations. (C) 2020 Elsevier B.V. All rights reserved.