Source Analysis and Countermeasure Research of Sand Production after Hydraulic Fracturing in Tight Sandstone Gas Reservoir

Abstract

Abstract Sand production is the most common problem after hydraulic fracturing treatment. This problem is particular prominent in sandstone reservoirs. For Jinqiu gas reservoir of Sichuan Basin in China, the average sand production after fracturing is 103 tons, and the sand production rate is 2.36% through statistics of 12 wells. The sand production will seriously damage the downhole equipment as well as ground facilities. In this study, based on the analysis of sand production source, it is clear that the sand production mainly is 70/140 mesh sand flowback after hydraulic fracturing treatment. In order to control this proppant flowback, average fibers length of about 3 mm, 6 mm, 9 mm, and 12 mm are selected for proppant flowback control experimental study. A series of laboratory evaluations are designed to quantify the effectiveness of fibers on proppant flowback control, so as to explore the mechanisms behind for optimizing their properties for a chosen reservoir. The key fiber properties include dispersion performance, microstructure, the influence on proppant transport in fracture, fracture conductivity, and critical flowrate. The dispersion of fibers with different lengths and concentrations in slickwater is good, and the fibers can form a net-like structure that reinforces the pack, and for 70/140 mesh sand and 40/70 mesh resin-coated sand, with the increase of fiber length and concentration, the sand transport distance and critical flowrate increase, but fracture conductivity decreases. The field test is carried out through the fiber type and dosage optimized by indoor experiment. A systematic indoor evaluation and field test shows that fiber plays a significant role in proppant flowback control. The findings of this study can help for a better understanding of the source analysis and countermeasure research of sand production after hydraulic fracturing in tight sandstone gas reservoir.