Dynamic proppant-carrying performance of VES-CO2 foam fracturing fluid in the pipeline and the fracture

Abstract

A viscoelastic surfactant (VES) fluid blends with CO 2 to form the foam fracturing fluid. To obtain the dynamic proppant-carrying behaviors of the VES-CO 2 foam fluid, an experimental system with a horizontal transparent tube and a visual fracture is built. In the horizontal pipeline, it is displayed that the critical settling flow velocity of the ceramsite proppant in the flowing VES-CO 2 foam fluid increases with the temperature. Further, the critical settling flow velocity initially decreases and then increases with both the increases of the foam quality and the proppant ratio, and its transition points are at the foam quality of 0.75–0.80 and at the proppant ratio of 0.25, respectively. In addition, considering the influencing parameters in the experiments, we obtain a correlation equation of the critical settling flow velocity. In the experiments of the fracture observation section, the height of the equilibrium sand bank and the angle of repose are mainly investigated. Both of these two parameters decrease as the foam quality, as well as the injection flow velocity, is increased. Especially, it is found that the angle of repose is below 20° at larger injection flow velocity. • The dynamic proppant-carrying behaviors of the degradable VES-CO 2 foam fracturing fluid are studied. • A correlation equation of the critical settling flow velocity of the proppant-carrying foam fluid is obtained. • The angle of repose in the fracture is generally below 20° at larger flow velocity. • This work provides a reference for the related prediction in the fracturing project.