The Technology for Releasing Packers by means of Formation Pressure in Well S22

AHR packer retrieval by normal overpull can be difficult when they have been set in highly deviated or horizontal sections,or when improper operations have caused workover problem.The axial force of tubing in horizontal well was analyzed based on structure and mechanism analysis of the AHR packer,and the over pull force that transmitted to the packer was simulated.Within the rated tensile strength of tubing if the overpull was not sufficient to overcome the preset releasing force of the packer,coil tubing could be utilized to evacuate the tubing by pumping nitrogen through positive circulation,and release formation pressure to push the packer upwards,at the same time, tubing could be pulled for shearing off the pins and releasing the packer.Taking Well S22 in Y field as an example,when the pulling force reached a tensile strength of 921 kN,the force transmitted to the packer was only 236 kN,then 1 650 m was tubing was evacuated and 205 kN upwards force was released,the total force applied to the pins of the packer was 441 kN,the packer was successfully released.The study demonstrated that the evacuation of partial fluid to release the formation pressure can compensate for the insufficient releasing force on the packer,and the approach can provide reference of theory and practice for releasing packers in highly deviated or horizontal wells.