Simulation of Fluid-Solid Miscible Flow in Hydraulic Fractures Considering Dynamic Fractures

Abstract Hydraulic fracturing technology is an important means to improve the production of oil and gas wells, but the design of fracturing construction parameters is highly empirical, and the existing proppant transport model does not consider the influence of dynamic fracture expansion during fracturing, which is prone to the phenomenon of difficult proppant addition and proppant plugging. In order to solve this problem, the proppant transport model considering dynamic fracture and the proppant transport model considering static fracture are numerically simulated under the condition of changing fracturing construction parameters. In this paper, a two-fluid model is adopted, which considers the proppant carrying fluid flow as a solid-liquid two-phase flow. The governing equation describing the proppant carrying fluid flow and proppant transport is established. The influence of dynamic fracture on proppant placement is considered according to the volume conservation. The finite difference method is used to simulate the discrete programming of the control equation. Under the condition that other parameters remain identical, a dynamic fracture model was employed to simulate proppant transport following the injection of different pad fluid volumes. The results demonstrate that within the simulation framework, sand plugging in fractures is prone to occur when the injected pad fluid volume is less than 30 m3, and the optimal pad fluid injection volume under these simulation conditions is determined to be 100 m3. A comparative analysis of proppant transport in fractures was conducted between the static and dynamic fracture models under the same conditio ns. Taking injection displacement as an example, the sand levee length simulated by the dynamic fracture model is 13% shorter than that of the static fracture model. Both the fracture length and proppant transport distance exhibit a linear relationship with the injection displacement. Similarly, this paper systematically compares and investigates the influence of variations in other relevant parameters such as fracturing fluid viscosity and proppant particle size on proppant transport under static and dynamic fracture conditions. The model established in this study is closer to the real proppant transport in fracturing operations. Through the comparison of dynamic and static fracture proppant transport, it is found that the results of static fracture simulation in the past are significantly different from those of real dynamic fracture placement. This simulation method can better understand the concentration placement pattern of proppant, and is helpful for better follow-up productivity and post-pressure analysis.