Physical simulation study on the transport of biomimetics dandelion proppant in similar coalbed methane fracture network

Accelerating the exploration and development of deep coalbed methane resources is a key direction for developing coalbed methane. However, with large-scale volume fracturing in deep coalbed methane development, the complexity of the fractures formed by deep coalbed methane fracturing gradually increases. However, the low-viscosity fracturing fluid carrying spherical proppants has limited transport and turning performance in complex deep coalbed methane fractures, resulting in the poor placement of proppant on the branch and deep fractures, seriously affecting the effect of deep coalbed methane large-scale volume fracturing. Thus, the author proposes a biomimetic dandelion proppant with efficient transport and steering capabilities in low-viscosity fracturing fluids. To further understand this proppant's transport and steering performance in deep coal seam fractures under different construction parameters, this study constructs a T-shaped visualized complex fracture proppant transport experimental system based on common T-shaped fractures in deep coal seams. The effects of construction parameters such as pump rate, perforation position, fracturing fluid viscosity, proppant particle size, and proppant concentration on biomimetic dandelion proppant transport and steering performance in T-shaped fractures were studied. It was found that with the increase of pump rate, the support area of biomimetic dandelion proppant in the primary fracture of T-shaped fractures would increase. The sand embankment channel rate was gradually increasing. At the same time, more proppants were turning into the branch fractures of the T-shaped fractures, indicating an increase in pump rate and an improvement in the transport and turning performance of the biomimetic dandelion proppants. Biomimetic dandelion proppants could maintain good transport efficiency in fracturing fluids of different viscosities and accumulate to form sand embankments with large channels. A single perforation in the middle could form better accumulation effects in both the branch and central fractures of the T-shaped fracture. As the sand ratio increases, the area of the proppant in the primary and branch fractures of the T-shaped gradually increases. However, as time passes, the increase of proppant area would slow down, and the channel rate of the sand embankment gradually decreases. Based on qualitative analysis of construction factors, it is recommended to use biomimetic dandelion proppant with medium to high displacement, low viscosity, middle perforation method, small particle size proppant, and 7%–11% sand ratio when applying it to deep coalbed methane. This study can promote the large-scale application of biomimetic dandelion proppants in deep coal seam fracturing and is also of great significance for the efficient development of deep coalbed methane in China.