Experimental and numerical investigations of proppant pack effect on fracture conductivity of channel fracturing

Channel fracturing technology has been previously applied in the field; however, there are few studies on the shape and distribution pattern of the proppant pack and its effects on fracture conductivity. In this study, the shape and distribution of proppant packs in the channel fracturing process were studied by plate fracture experiments. Subsequently, proppant distribution geometry models were obtained based on a quantitative analysis of the experimental results. A conductivity calculation model was derived by the lattice Boltzmann method in order to investigate the proppant pack effect on fracture conductivity and optimize the distribution. Experimental results demonstrated that the shape and distribution of proppant packs were mainly controlled by the injection rate and pulse time, and four typical distribution types in the fracture were identified. Simulation results indicated that the flow resistance increased dramatically as the pillar-fracture ratio (PFR) increased. However, fracture conductivity was also strongly related to the fracture width under closure pressure, in that the average width of the fracture decreased or closed completely as the PFR decreased. Under the same PFR at 50%, fracture conductivity was dominated by the distribution type, and the streamlined proppant packs yielded the highest conductivity. Finally, corresponding laboratory parameters intended for generating the streamlined packs were converted to field application, thereby proposing recommended pumping rates for different fracture heights and fracture widths.