Multi-sanding fracturing technology used for CBM wells

After active water fracturing technology is applied to high-rank coal reservoirs in the Qinshui Basin, the average coalbed methane (CBM) production rate of each vertical well is only about 1 000 m³/d.It is indicated from theoretical analysis and fracturing monitoring statistics that conventional active water fracturing technology is disadvantageous with easy interlayer communication and poor carrying capacity and short support distance of active water, which restrict the stimulation effect of coal beds and the improvement of single-well production rate.In this paper, the idea of multi-sanding fracturing technology for coal beds was proposed to improve the stimulation efficiency of CBM well fracturing.Fractures and sand banks were taken as the research objects to establish the mathematical model of multi-sanding active water fracturing according to the material balance theory.Meanwhile, the technological parameters were optimized, including fracturing flow rate, fluid volume and proppant grain diameter.And finally, it was tested on site.It is shown that after three-sanding fracturing is adopted, the coalbed fracturing channeling degree is decreased significantly and post-fracturing average CBM production rate of each well is up to 2 223 m³/d.It is verified that three-sanding numerical mathematical model is feasible to guide the field construction.