Numerical Simulation of Proppant Transportation in the Nonplanar Fracture

ABSTRACT: The fractures produced by hydraulic fracturing twist and extend in three-dimensional space, often forming complex nonplanar shapes, which makes the transportation law of proppant more complicated. To study the transportation law of proppant in the nonplanar fractures, the morphology of fracture propagation was obtained by phase field method, and a fluid-solid coupling model of proppant transportation in the three-dimensional nonplanar fractures was established. The solution was based on computational fluid dynamics (CFD) and discrete element method (DEM), and the effects of injection rate, sand ratio, proppant density and proppant size on the transportation law were studied. The results show that the nonplanar fractures make the transportation law of proppant more complicated. Increasing the injection rate can avoid sand plugging in the near-well area and increase the sand distribution distance. Low sand ratio can effectively improve the proppant transportation effect. With the decrease of proppant density and size, the sand distribution height decreases. This study clarifies the transportation law of proppant in the nonplanar fractures, which helps to guide the design of proppant pumping parameters during fracturing construction. 1. INTRODUCTION As oil and gas production gradually moves towards unconventional resources, hydraulic fracturing technology has become an important measure for enhanced oil recovery (Liew et al., 2020). During the hydraulic fracturing process, if the fracture initiation is not in the direction of maximum horizontal principal stress, the fracture may turn from the perforation direction to the direction of maximum horizontal principal stress after expansion, forming a complex nonplanar fracture (Tan et al., 2017). In order to improve the effect of reservoir transformation, proppant needs to be injected into the formation to fill the propped fracture and form a diversion channel for oil and gas production (Liang et al., 2016). If the proppant cannot be effectively laid in the nonplanar fracture, it will have an important impact on the effect of hydraulic fracturing.