Experimental investigation and correlations for proppant distribution in narrow fractures of deep shale gas reservoirs

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Hydraulic fracturing is a crucial stimulation for the development of deep shale gas reservoirs. A key challenge to the effectiveness of hydraulic fracturing is to place small proppants in complex narrow fractures reasonably. The experiments with varied particle and fluid parameters are carried out in a narrow planar channel to understand particle transport and distribution. The four dimensionless parameters, including the Reynold number, Shields number, density ratio, and particle volume fraction, are introduced to describe the particle transport in narrow fractures. The results indicate that the narrow channel probably induces fluid fingers and small particle aggregation in a highly viscous fluid, leading to particle settlement near the entrance. The low viscous fluid is beneficial to disperse particles further into the fracture, especially in the high-speed fluid velocity. The linear and natural logarithmic laws have relationships with dimensionless parameters accurately. The multiple linear regression method developed two correlation models with four dimensionless parameters to predict the bed equilibrium height and covered area of small particles in narrow fractures. The study provides fundamental insight into understanding small size proppant distribution in deep reservoirs.