Experimental Investigation on the Conductivity of Quartz Sand Considering Economic Cost and Its Application in Deep Coal Seam

This study explores the economic feasibility and performance of using quartz sand as a substitute for conventional ceramic proppant in hydraulic fracturing for deep coal seams. Experimental investigations on proppant conductivity and crush ratio, combined with numerical simulations of single-well fracturing, were conducted to evaluate the impact of proppant type, particle size, volume ratio, and pumping mode. Results show that desert sand, due to its smaller particle size, higher crushing rate, and lower conductivity, is not suitable for replacing quartz sand in fracturing operations. Mixed-proppant systems, particularly the 40/70 mesh ceramic proppant and quartz sand combination, demonstrate superior conductivity, with intermittent pumping methods reducing crushing rates. Numerical simulations further suggest that a 6:4 ratio of ceramic proppant to quartz sand optimizes both fracture conductivity and economic efficiency, resulting in a moderate conductivity loss (18% to 35%) while achieving significant cost savings compared to pure ceramic proppant use. This study provides a comprehensive evaluation framework for selecting proppant mixtures in deep coal seam fracturing, offering a balanced approach to maintaining performance while reducing operational costs.