Key Technologies for High-Efficiency One-Well Multi-Control Development of Fractured-Vuggy Reservoirs in Tahe Oilfield

The karst caves are the main oil storage space in the fractured-vuggy carbonate reservoirs in Tahe Oilfield. During multiple rounds of development, the reserve quality and scale of the karst caves keep declining, the benefit risk of the development method of single well producing single cave intensifies with each passing year. For this reason, high-efficiency development technologies of one-well multi-control that can simultaneously exploit multiple fracture-cave bodies were developed on the basis of geology-engineering integration. Specifically, the hierarchical characterization and description technology for fractures and caves was employed to hierarchically demarcate the boundaries between the internal bedrock and the effective fracture-cave bodies in the complex fracture-cave bodies. Due to the differences in the spatial distribution of the fractures and caves in fractured-vuggy reservoirs, a variety of “series” wellbore trajectories as close to the boundaries of the effective fractures and caves as possible were designed to advance geology-engineering integration. Furthermore, a completion technology featuring staged reconstruction and one-time production for fractured-vuggy reservoirs was developed so that one wellbore could connect and exploit production from multiple fracture-cave bodies to further improve the capacity and development benefit of single-well. Field tests of the one-well multi-control technologies were carried out in Tahe Oilfield. During the tests, fracture and cave characterization, trajectory design, and the completion technology were iteratively optimized, which supported the continuous improvement of the reserve production scale and productivity of the one-well multi-control evaluation wells. As a result, the reserve production scale of these wells reached more than 1.5 times that of the vertical wells, and the daily oil production capacity of the oil wells increased by over 10%. The proposed one-well multi-control technologies provide a new developing mode for the fractured-vuggy carbonate reservoirs in TaheOilfield.