Multi-Physics Pore-Scale Modeling of Particle Plugging due to Fluid Invasion during Hydraulic Fracturing

摘要

The productivity from hydraulically fractured wells is contingent to different mechanisms of formation damage by the fracturing fluid, such as fluid leakoff, proppant embedment, and fines generation from proppant crushing. Particle plugging during fluid invasion in hydraulic fracturing is considered to have a significant detrimental effect on production. In this work, we developed a multi-physics pore-scale plugging simulator integrated with a fracture simulator to investigate the impact of particle plugging and quantify the formation damage of the invaded region near hydraulic fractures. Our multi-physics simulator bridges pore-scale phenomena with those occurring at the reservoir scale. The pore-scale particle-plugging simulator uses 3-D pore-network models based on pore-body and pore-throat characteristics derived from petrophysical measurements. Based on filtration theory we compute transport and retention of particles, and permeability changes due to fracturing-fluid invasion. These parameters are interfaced with a fracture simulator that provides pressure, leak-off rate, proppant size and concentration to the pore-network model. These parameters are representative of typical multi-stage hydraulic-fracturing operations. The fracture simulator also provides fracture-geometry and fracture-conductivity. Our methodology enables a novel and practical way to understand the particle-plugging process in the matrix- fracture interface during hydraulic-fracturing operations. The coupled model considers heterogeneity at pore scale to account for the role of pore structure on particle transport, concurrently studying its behavior on the fracture. We used petrophysical measurements and well log data obtained from Wolfcamp shales in this study. From the sensitivity analysis performed for different hydraulic-fracturing operational constraints and fluid properties like proppant size and concentration, we are able to determine the effect of these variables on matrix-fracture permeability impairment at the pore-scale. The multi-scale integration allowed us to quantify the influence of filtration on the fracturing operations.