Numerical simulation of proppant transportation and placement in several complex structure fractures of a shale reservoir using a CFD approach

Abstract

In the experimental simulation of proppant transportation in the complex fractures of shale reservoirs, the influence of many factors such as partial fracture parameters are often ignored, which cannot fully reflect the proppant transportation in the real situation. The Euler model and turbulence model were performed to numerically investigate proppant transportation and placement using the computational fluid dynamics (CFD) method, and was verified with experimental results. The formation process of proppant banks in branched, staggered, and different types of combined fractures was analyzed. The effects of the position, width, included angle of the secondary fracture, and fracture structure type on proppant transportation and placement were discussed. The simulations indicate that the proppant bank formation in the primary fracture is considered to occur in four stages and different from three stages in the secondary fractures. The proppant bank located at the node between the primary and the secondary fractures possesses good continuity, and the propagation of the proppant bank in the secondary fracture is closely related to the proppant bank state at the node in the primary fracture. The equilibrium time of the proppant bank in the secondary fracture and the primary fracture is related to the position of the secondary fracture. The total placement rate and settlement volume of proppant in the symmetrical oblique fracture is the highest for the same oblique angles, and the proppant bank morphology in the orthogonal fracture has good symmetry, improving the reliability of the fracturing design and the post-fracturing evaluation in shale reservoirs.