Research on the flowback mechanism of fiber-controlled proppant based on fiber strength force

Abstract

Fiber sand control is widely used on site due to its advantages such as easy operation, significant effects, and low cost. However, the mechanism of fiber control proppant flowback is currently unclear, and the main controlling factors affecting the critical flow velocity are not yet clear. There is a lack of relevant theoretical support to optimize the design of fiber sand control. This article uses composite material theory to analogically calculate the tensile strength of fiber-reinforced sand and friction reinforcement theory to analogically calculate the shear strength of fiber-reinforced sand. The relationship between fiber strength force and tensile strength and shear strength is proposed, combined with the different stress conditions of proppant particles before and after fracture closure, and a fiber-controlled proppant flowback strength model is established based on the force arm balance. The critical velocity of proppant was calculated and compared through the stability experiment of fiber-reinforced proppant filling layer, and the accuracy of the model was verified and the influencing factors were analyzed. The results show that the influence of tensile strength and shear strength on fiber strength at the early stage of fracture closure is 0.2 and 0.8, respectively, and that after fracture closure is 0.1 and 0.9, respectively. The critical velocity calculated by the model is basically consistent with the experimental results. The critical velocity is most affected by the particle size and closure pressure of proppant, followed by the amount of fiber, and the influence of fiber length and diameter is relatively small.