The Investigation of Proppant Particle-Fluid Flow in the Vertical Fracture with a Contracted Aperture

Abstract

Summary Proppant placement plays a crucial role in maintaining the conductivity of fractures after a hydraulic fracturing treatment. The process involves the transport of particles by fluid flow in complex fractures. Many studies have focused on proppant transport and distribution in the fracture with a constant aperture, but relatively few studies have investigated the proppant-fluid flow in a vertical fracture with a contracted aperture. In this work, we examine experimentally proppant transport in a fracture with a contracted aperture. The objective is to evaluate the distribution of particle beds in the contracted fracture at different flow conditions. In this paper, particle-fluid flow in the contracted fracture is studied experimentally by a laboratory size slot. A planar slot with a constant width is used to benchmark the experimental results, and a published correlation validates the bed equilibrium heights in the planar slot. Six types of particles are chosen to simulate the effects of particle density and size. The proppant distribution is evaluated by the bed height when the bed reaches the equilibrium states. The effects of fluid velocity, fluid viscosity, particle density, particle size, and particle volume fraction on particle distribution are investigated. The results confirm that the proppant particle-fluid flow in the contracted slot is more complicated than that in the planar slot. The phenomena of particle vortices and resuspension were observed at the contraction of the cross-section. The shape on the top of the bed is like a descending stair in which the height gradually decreases in the length direction. The bed height in the contracted slot is lower and more irregular than that in the planar slot at the same flow conditions. Smaller sands injected at a high flow rate and fluid viscosity can form a lower bed. The trend would be reversed by using denser particles and high particle volume fraction. A reliable model expressed by four dimensionless numbers is developed by the linear regression method for predicting the bed equilibrium height. The model and experimental results provide directions to quantitatively evaluate the particle transport and distribution in a fracture with a contracted aperture.

Physical simulation study of proppant settling and migration within deep shale narrow fractures

“…Instead of being constant, the actual fracture width is at a maximum near the fracturing perforation, and then gradually decreases along the fracture length. [48,49] To study the effect of width change on proppant settlement and migration in long narrow fractures in deep shale, the present study designed two sets of fracture plates with different widths (i.e., 2-3-3 and 3-3-3 mm) for comparative experiments. A comparison of the results of Experiments 1 and 11 (Figure 17) showed that as the fracture width at the end of the flat plate decreased from 3 to 2 mm, the height and area of the sand bed at the outlet end decreased while the heights and areas of the sand bed at the inlet end and in the intermediate section did not change significantly, and the morphology of the sand bed was still overall uniform.…”

Simulation and solution of a proppant migration and sedimentation model for hydraulically fractured inhomogeneously wide fractures

“…Huang et al (2021) proposed a continuum model for simulating proppant transport and fluid flow in hydraulic fractures. Isaev et al (2023) proposed adaptive seeding/reseeding methods with exact integration of particles trajectories and local time step refinement in the vicinity of injection zones In these studies, equations describing the migration and sedimentation of proppant were derived based on the solid-liquid coupling relationship and sedimentation law during proppant flow (Hu et al, 2023;Li et al, 2023;Shi, 2016), and most of them were simulated with CFD-DEM (Gong et al, 2023;Liu et al, 2019;Lv et al, 2023;Shi, 2016;Tong and Mohanty, 2016;Xiang and Li, 2023;Zhang et al, 2022Zhang et al, , 2023aZhu et al, 2023) or CFD-XFEM software (Brannon et al, 2005;Qu et al, 2022Qu et al, , 2023Zhang et al, 2023b) such as fluent for two-dimensional and pseudo three-dimensional model. Through numerical simulations of parameters (Hang et al, 2023;Suri et al, 2019Suri et al, , 2020b based on different fracturing fluids and proppant morphologies, the velocity, concentration and pressure distribution of the proppant within the fracture were obtained, and proppant migration and sedimentation patterns were also derived for different fracture morphology parameters and proppant and fluid parameters.…”