Journal Article

Experimental study on settling, transport, and packing mechanisms of proppants with different shapes in a physical model

Li, Jun, Wu, Mingyi, Tang, Kewen, Zhou, Changyin, He, Siyuan

2026

Overview

Hydraulic fracturing, as a critical technology for reservoir stimulation, has functioned as a central stimulation technique in the large-scale development of shale gas and coalbed methane. During hydraulic fracturing operations, the movement and distribution of proppants within fractures serve as the key determinant of both fracture conductivity created by fracturing and long-term sustained production performance. Meanwhile, the settling and packing mechanisms of proppants greatly affects proppant transportation efficiency and distribution within fractures, which in turn determines the level of oil and gas production. However, current research on settling and packing mechanisms of proppants has primarily focused on spherical proppants, while some aspects of the non-spherical shaped proppants with different shapes and structures have not yet been fully considered. In this study, 3D printing technology was utilized to fabricate various non-spherical proppants, including cube, rhombohedron, tetrahedron, cuboid, and cylinder shapes. Compared to spherical proppants, these non-spherical counterparts were examined in terms of their settling, transport, and packing mechanisms using visualized proppant settling and transport setup. The result show that proppants with irregular shapes, such as rhombohedrons and tetrahedrons, experienced greater turbulent effects in the fluid, while proppants with regular shapes, such as cuboids, cubes, cylinders, and spheres, generated much less turbulence. For instance, under a low viscosity of 1 mPa·s, the settling velocity of spherical proppants was measured at 0.086 m/s, significantly higher than the 0.046 m/s for rhombohedron and 0.052 m/s for tetrahedron proppants. More importantly, the angle variation during the settlement process was much larger for the irregular-shaped proppants than for the regular ones. Moreover, the results also indicate that under low-viscosity conditions (< 3 mPa·s), non-spherical shape has a more significant effect on settling velocity. However, this effect becomes less apparent when the viscosity increases to the range of 6–9 mPa·s. Porosity measurements further revealed that rhombohedron and tetrahedron proppants achieved higher porosities (approximately 40–45%) compared to spheres and cubes (~ 35%), suggesting potential for enhanced fracture permeability. Finally, six new mathematical models were developed to predict the terminal settling velocity of different types of non-spherical shape proppants. The study of non-spherical proppants might provide a new idea for proppants application with new structures in the future.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 3-D printers / 639/166 / 639/4077 / 639/766 / Behavior / Experimental methods / Fracture permeability / Gas production / Humanities and Social Sciences / Hydraulic fracturing / Mathematical models / multidisciplinary / Non-spherical shape proppant / Oil and gas production / Packing / Permeability / Porosity / Research methodology / Science / Science (multidisciplinary) / Settling velocity / Shale / Terminal settling velocity of the non-spherical shape proppant / Transport and packing mechanisms / Velocity / Viscosity