Research On On-off Flexible Seal System And Its Control Technique In Snubbing Service

On-off flexible seal system applied to oil field is very wide. The control technique of the system in snubbing service is the synthesis of on-off flexible seal system and automation control method by changing the sealing state frequently. The seal unit used for well head blowout preventer is representative on-off flexible seal system. This paper analyzed and summed up the flexible seal structure, seal working mechanism and application field, as follows:Introduced on the composition and working principle of the on-off flexible seal system in snubbing service.Mechanics property of on-off flexible seal system is analyzed,and the approximate relationship between pressure and deformation when the rubber operating is obtained. By modeling and analysis of the seal rubber core of the ram blowout preventer, ascertained the main structure parameters of the seal rubber core, summed up the working mechanism of the on-off flexible seal system.According to process features and control methods of the blowout preventer in snubbing service used for high pressure water injection wells, some auxiliary devices of on-off flexible seal system in snubbing service are developed. Principle and design method of tubing coupling detector and the supporting device used for strengthening and protecting the tube from leaning are illustrated. The auxiliary devices have been accomplished on designing and manufacturing.A new control method of on-off flexible seal system by adopting the electro-hydraulic proportional control technology is put forward. The mathematics model and simulation model of the control system based on MATLAB software are created, and the simulation analysis of the dynamic performance can meet design request.Sealing pressure control experiment is performed on the experimental snubbing unit system which can provide the test data to control technique in snubbing service.