Design and Test of Hydraulic Bottom Seal Fracturing Tool for Coiled Tubing

Abstract As the main tool for reservoir reconstruction of Longdong shale reservoir in Changqing Oilfield, the coiled tubing bottom seal drag-segment fracturing tool is currently in the stage of scale promotion, providing tool support for the efficient development of Longdong shale oil. However, in the process of horizontal construction with large water vertical ratio and super long horizontal section, there are construction problems such as natural depth limitation of the tool and difficulty in setting the bottom packer, which seriously affect the construction efficiency and quality. In view of the above problems, this paper carried out the development of pumped coiled tubing hydraulic bottom seal drag-segment fracturing tool. With the technical ideas of pumping cup deepening and hydraulic setting bottom packer, the hydraulic setting type bottom packer, soluble cup pumping sub and supporting tools were designed and developed. By using the method of annular pumping and tubing accompanying injection, the tail cup pumping sub was used to generate throttle and larger cup outer diameter, forming a large hydraulic traction force to carry the tool string to break the depth limit. Without applying drilling pressure, the bottom packer was set by oil injection and displacement, and the setting state was lifted and lifted after the fracturing construction, providing a reliable tool scheme for solving the above engineering problems. The indoor evaluation results show that the traction effect of the bowl pumping short joint with small displacement of water is good, the bottom packer is smooth in the setting and unpacking action at 120°C, and the sealing is reliable under 70MPa pressure. The overall test of the tool string can realize the setting and unpacking action without the intervention of drill pressure. Six well tests were carried out in the field. The pumping depth was 430m under the condition of 740L/min water pumping displacement, and the oil injection displacement was increased to 550L/min. The hydraulic setting was fast and reliable, which effectively improved the construction capacity of the coiled tubing fracturing tool in the ultra-long horizontal well, greatly shortened the time consumption of interlayer conversion, and improved the speed and efficiency significantly.