SHEN Yunqi¹, LI Fengxia¹, ZHANG Yan², LIU Changyin¹, ZHANG Xuhui²

1. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China;

2. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

Abstract: The hydraulic fracturing technology has been widely applied to the development of shale gas and oil reservoirs. For higher productivity, the proppant and sand-carrying fluid are mixed into the fracture in terms of different mass ratios, which can form an effective proppant layout, thereby improving the fracture conductivity. The transportation distance and placement range of proppants in the complex fracture network are of vital importance to measuring the effect of hydraulic fracturing. Physical experiments are conducted to study the effects of the sand ratio, included angle between the main fracture and the branch fracture, and types of proppant on the proppant transportation and placement in complex fracture networks. In these ways, we reach the following conclusions: ① As the sand ratio increases from 3.0% to 4.2%, the ratio of proppant placement height to fracture height in the main fracture rises from 0.44 to 0.465, and the mass ratio of proppant in the branch fracture to that in the complex fracture network grows from 21% to 25%. ② As the included angle between the main fracture and the branch fracture decreases from 90° to 30°, the mass ratio of proppant in the branch fracture to that in the complex fracture network increases from 22% to 30%. ③ The mass ratio of proppant entering the complex fracture network to the total mass of the proppant used in the experiment shows a tendency to increase rapidly first and then slowly with the ratio of experimental time to total experimental time. When the ratio of experimental time to total experimental time is 0.6, the mass ratio of proppant entering the complex fracture network to the total mass of the proppant used in the experiment ranges from 65% to 80%. ④ The ceramsites and self-suspending proppants are not well placed at the entrance of the fracture. The proppant placement height has obvious abrupt changes at the intersection of the main fracture and the branch fracture and at the position where the fracture height changes.