Research and Application of Structured Flooding Fracturing Technology in the Qingcheng Shale Oil Reservoir

Qingcheng shale oil reservoirs have strong lateral and vertical heterogeneity, a low brittleness index, and a small reservoir pressure coefficient, necessitating large-scale volume fracturing. However, the complex topography of the Loess Plateau, characterized by arid conditions and water scarcity, poses the challenge of insufficient water supply for large-scale volume fracturing. In response to these issues, a numerical simulation method was used to optimize the fracturing energy enhancement mode. The internal wells were divided into energy enhancement wells and non-energy enhancement wells to improve the liquid utilization rate and achieve the goals of both energy enhancement and water usage reduction. Through differentiated fracturing process parameters for energy enhancement and non-energy enhancement wells and the optimization of fracturing sequences, a structured flooding fracturing technology was innovatively developed. This structured flooding fracturing technology not only increased the formation energy within the well group and maximized the degree of fracture control but also ameliorated the issue of insufficient water supply for fracturing. The technology showed good application results in Qingcheng shale oil. Compared with conventional volume fracturing, the new technology saved an average of 5 000 m³ of fracturing fluid and 1 200 m³ of proppant per well, with an initial oil production increase of 1.1 t/d. The results show that structured flooding fracturing technology can reduce costs and increase efficiency, and it has good value for field promotion and application.