Research On Theory And Its Application Of Controllable Flexible Sealing

On-off flexible seal system is being used for fluid medium which is impurity, low lubricating and low viscosity. It can save energy and protect the environment by sealing the high pressure fluid in the well.The summary on the development history and current research situation is implemented. The characteristics of the controllable flexible sealing are put forward based on analysis, summary and generalization of the sealing areas. The hydrodynamics principle, mechanics principle and flexible sealing principle are introduced to study the flexible sealing, which provides some theory methods for researching the sealing flow and pressure field.The estimating method of mechanics performance of the flexible seal system is investigated by means of fitting and predicting the rubber material experimental data. The Ogden model and the Mooney-Rivlin model can not be used in computation simulation on the flexible seal system. The Arruda-Boyce model and the Yeoh model can be respectively considered as the computation simulation result upper limit and lower limit. The Marlow model can show reasonable computation simulation results, and the modified Arruda-Boyce model can fit the experimental data of uniaxial tension under different temperature condition and give better prediction about mechanics performance.According to process features and control methods of the controllable flexible sealing in ram BOP in snubbing service, a new flexible sealing composed of polymer and elasticity rubber is being used. The polymer contacts with the pipe and bears the pressure and implements the assistant sealing in order to decrease the abrasion and prolong the lifespan of the sealing rubber. The force acting on the sealing rubber is analyzed based on the sealing operating principle. The mechanics model of sealing contact pressure is deduced. The foundation of design and control the controllable flexible sealing in the ram BOP in snubbing service is established.The mathematics model of the hydraulic control system of the controllable flexible sealing is created, and its simulation analysis is performed by means of MATLAB software. The result shows that the dynamic performance of the controllable flexible sealing can meet design request under the general condition.The On-off flexible sealing experiment system has been developed, which can perform the operating process and control program simulation according to the real working condition in snubbing service in oil field. Base on the experimental system, the basis test and engineering experiment can be implemented, such as the sealing performance test, the sealing control test, the sealing driving pressure test, the sealing deformation test, the sealing tribology test, and so on. It provides a benefit test condition for developing the novel controllable flexible sealing and necessary assistant device. 11 water injection wells field test under high pressure in snubbing service have proved that the on-off flexible sealing developed in paper can be used under 21MPa sealing condition with good performance. The security and lifespan of the flexible sealing in snubbing service have been greatly improved, and it will have a good popularized prospects.