Development and Experimentation of a Coiled Tubing Bottom Packer with No Back Pressure Control

The coiled tubing drag fracturing tool and its associated process technology are constrained by the mechanical drilling pressure and internal hydraulic pressure of the coiled tubing. Currently, it is only applicable to operating conditions where the shutdown pressure in the formation does not surpass 25 MPa. However, the highest shutdown pressure in some area has reached 40 MPa, which exceeds the capacity of existing coiled tubing bottom packers. To broaden the application scope of this technology, the development of a coiled tubing bottom packer with no back pressure Control is being carried out. The packer utilizes the pressure difference between the upper and lower annulus to activate the anti top anchoring unit, overcoming the upper top force of the lower formation without the need for high back pressure control through wellhead casing throttling, achieving coiled tubing bottom packer drag fracturing construction under a maximum pump stop pressure of 40 MPa. In indoor tests, when the lower pressure of the packer is 50 MPa, the anti toppling effect of the bottom packer without back pressure is significant, which can effectively overcome the hydraulic toppling force in the lower annulus. Six on-site tests were successfully conducted. Without controlling the throttling or low back pressure control, the no back pressure packer assisted in completing the coiled tubing bottom packer drag fracturing construction under high pump stop pressure, and the application effect was good.The successful development of this packer has solved the construction problem under high pump stop pressure of 40MPa and expanded the application scope of the coiled tubing bottom packer drag fracturing technology.