Abstract: To address the issues of high unsealing load and short sealing validity period in the multi-stage injection string unsealing of highly deviated deep well in Jidong Oilfield,an equilibrium dual unseating water injection packer is developed through 3D simulation and optimization design of key structures based on the analysis of the packer structure.The packer is equipped with an independent dual unseating mode to minimize unseating load.It utilizes the spring and the pressure difference between the interior and exterior of the water injection string for automatic closing of the backwash valve.A combination of rubber extrusion and metal wire seating methods is employed to enhance the seating reliability of the backwash valve.High-strength fluorine rubber material has been selected to improve the temperature and pressure resistance of the rubber cylinder,while a equilibrium piston is designed to protect the unseating pin,eliminating the risk of premature unseating due to high pressure difference.The technology has been successfully deployed in 11 wells,achieving a flawless construction success rate of 100% and surpassing a seating validity period of 30 months.The unseating load of the lifting has been reduced by 17.2%.With an extended seating cycle and decreased unseating load,this packer effectively meets the long-term seating requirements for high-pressure separate injection in highly deviated deep wells,presenting promising economic benefits and application prospects.

Key words: highly deviated deep well, water injection packer, unseating load, seating validity, precise water injection