Design and Control Technology of Horizontal Well Cluster Trajectory for Shale Oil in Dagang Oilfield

The main development method of shale oil in Dagang Oilfield is cluster horizontal well groups. During the drilling process, there are many difficulties, including multiple constraints on optimizing the trajectory of three-dimensional horizontal wells, complex wellbore trajectories, high friction and torque in long horizontal sections, backing pressure in horizontal sections, unstable signal of downhole instruments, and difficulty in trajectory control. Therefore, an integrated study was conducted on the trajectory design and trajectory control during drilling of the long horizontal section of shale oil in Dagang Oilfield. The offset ratio K (offset distance/effective target front distance) was defined, and combined with the size of the offset distance, the optimal criteria for dual augmented trajectory, seven segment three-dimensional trajectory, and dual two-dimensional trajectory applicable to the deep shale oil horizontal well group in Dagang were explored, developing a track control technique that is supported by a ‘one trip drilling’ string design, ‘three high and two large’ drilling parameters, and a friction reduction and drag reduction technology. This method has been promoted and applied in the development of shale oil in Dagang Oilfield, achieving a horizontal section length of 2091 m under water-based drilling fluid. Wherein, GY5-1-5H has broken the record for the shortest drilling cycle of a horizontal well in the long horizontal section of Dagang Shale Oil by 38.9 days. Research and application have shown that the optimization of wellb bore trajectory design and supporting control techniques provide technical support for the efficient development of shale oil in Dagang Oilfield.