There are significant reserves of shale oil in China, which has substantial potential. The efficient development of these resources is crucial for ensuring national energy security and accelerating strategic transformation in the industry. This study introduces an innovative extraction technique that combines horizontal wells with radial water jet drilling, aimed at optimizing the recovery of shale oil. The approach involves drilling radially distributed boreholes around the horizontal well to penetrate the adjacent contamination zone, which can increase the contact area with the reservoir and establishing highly conductive pathways to enhance production and injection performance. A coupled flow model considering formation damage was developed to enable accurate predictions of productivity from shale oil reservoirs developed via horizontal and radial jet drilling. The model, employing dual refined grids, accurately describes the pressure dynamics within shale oil reservoirs and analyzes the impact of radial well parameters such as length, diameter, initial angle, number of laterals, drilling locations, and cluster numbers on productivity. Comparative analyses between reservoirs developed under identical conditions by radial jet drilling versus hydraulic fracturing were conducted. Findings reveal that radial wells significantly mitigate near-well fluid flow resistance and expand the effective drainage area of the formation. Enhancements in radial well dimensions, including length, number of branches, clusters, and diameter, are shown to increase cumulative shale oil production. Although increasing the number of clusters in radial wells expands the drainage area and benefits oil production, the interference between wells intensifies with more clusters, leading to a diminishing trend in the increase of cumulative oil production. The initial angle of radial wells, influenced by anisotropic permeability and gravity, is crucial for targeting vertical formations. Longer radial wells demonstrate that opening positions have a minimal impact on output. Under equal cluster conditions, a radial well with four 30 m laterals slightly outperforms a hydraulically fractured well with 15 m fracture height; when combined with a 15 m hydraulic fracture, the output slightly exceeds that of a 25 m fracture height. This study reveals that the horizontal plus radial well model not only serves as an effective alternative or supplement to hydraulic fracturing techniques but also facilitates more efficient, cost-effective shale oil extraction. The technique proposed herein combines the horizontal well and radial jet drilling technology and has higher economic feasibility, which can serve as a supplementary technology for the hydraulic fracturing approach and provide reference for efficient development of shale oil resources.
戴佳成, 李根生, 孙耀耀, 李敬彬, 王天宇. 基于水平井的径向井开采页岩油产能模拟和参数分析. 石油科学通报, 2024, 04: 604-616 DAI Jiacheng, LI Gensheng, SUN Yaoyao, LI Jingbin, WANG Tianyu. Productivity simulation and parameter analysis of shale oil production in radial wells based on horizontal wells. Petroleum Science Bulletin, 2024, 04: 604-616.