The study of particle-fluid flow in narrow, curved slots to enhance comprehension of particle transport mechanisms in complex fractures

摘要

Effective particle placement in complex fractures plays a crucial role in unconventional reservoirs. Non-planar fracture geometry poses a challenge to assess particle placement. Compared to the straight slot, particle-fluid flow in a curved fracture has not been fully understood. In this paper, particle-fluid flow in curved fractures is studied experimentally by laboratory size slots. The experimental results are compared with the published data, and they are consistent. After validation, the effect of bending angle, fluid velocity, particle size, particle density, and particle volume fraction on particle distribution is investigated. The results show that particle-fluid flow mechanisms in the curved slot are more complicated than that of the straight slot. With the decrease of the bending angle, the height and coverage area of the bed decrease. The flow redirection around the bend induces particle vortices, which change the transport mechanism from fluidization to resuspension. Although the bending section has a hindering effect on particle transport, resuspension promotes particles to flow through the bending section further into the slot and avoid bridging at the bend. The fluid velocity and particle size are two crucial factors impacting particle placement, and an irregular bed with two depressions would be formed in the curved slots. A correlation is developed for predicting the normalized coverage area. This study provides fundamental insight into understanding particle-fluid flow in a curved fracture.