Effective proppant placement plays a crucial role in successful slickwater fracturing treatments and well stimulation. Non-planar fracture geometry in the field poses a challenge to predict proppant transport. With the common application of vertical planar fracture models in existing studies, proppant transport behaviors in the curved fractures have not been fully understood. This paper focuses on studying proppant transport in the field-scale curved fractures and investigating the effect of curving angles, proppant sizes and injection rates on proppant settlement and bridging in non-planar fractures with a narrow curvature.
In this paper, a 3D multi-phase particle-in-cell (MP-PIC) model was applied to simulate the proppant transport in curved fractures. We built a 180-m-long and 30-m-high fracture with a curving angle of 45°. In the base case, the proppants of 100 mesh size and an injection rate of 20 bpm are selected. After that, we conducted four cases with four curving angles of 0°, 30°, 60° and 75°. The impact of proppant size was tested with five different mesh sizes (35, 50, 100, 150 and 300). Also, the injection rate was changed to 15 bpm and 25 bpm in the other two cases. Our simulations show that the curved fracture geometry can significantly influence the proppant distribution. The number of proppants trapped in the first corner exceeds that in the second. With an increasing curving angle, the higher proppant bed with the constant mass will be obtained in the curving fracture section. The smaller proppants can bring out less settlement and cause larger propped area. The results show that more proppants will be transported to the third fracture section as the injection rate increases.
MP-PIC is an accurate and effective mathematical method to describe proppant transport in the field scale. The outcomes obtained from sensitivity analysis provide a perception of proppant behaviors in the field-scale fractures and critical insights for fracturing treatment optimization in unconventional reservoirs.