Experimental study on proppant diversion transportation and multi-size proppant distribution in complex fracture networks

Proppant transportation in fracture networks is significant for hydraulic fracture design and evaluation. Previous studies on proppant placement in complex fracture networks had shortcomings in terms of proppant diversion transportation, proppant distribution in a secondary fracture, and proppant distribution with different particle sizes. This experimental study was conducted on proppant diversion transportation and distribution in complex fracture networks based on the visualization proppant placement model. The findings revealed that the critical proppant diversion time rapidly decreased with the increase in the pumping rate. When the pumping rate was lower than 2.5 m(3)/h, no proppant diversion transportation was found in the second- and third-branch fractures. The smaller-sized proppant particles (100 mesh) were distributed mainly in the fracture located far away from the wellbore or the major fracture. More smaller-sized proppant particles were distributed in the deeper fracture when the difference between the proppant particle sizes was large. Increasing the pumping times increased the transport of proppant particles to deeper fractures. However, the increase in the amplitude was larger in 100-mesh proppant particles than in 30/50-mesh proppant particles. Smaller-sized proppant particles were more easily transported to branch fractures, thus increasing the proppant placement efficiency. The experimental findings can be used to optimize the parameters of the stimulated reservoir volume fracturing to improve the effectiveness of fracture networks.