Research On The Opening And Closing Short Section Seal Of The Downhole Blowout Preventer

Since the last century, With the increasing number of drilling, exploration field in the process of gradually expanding, the drilling safety problem more and more be taken seriously, blowout out of control accident to happen occasionally, becoming the primary factor of drilling safety threat. Down-hole blowout preventer arises at the historic moment, Stop ring air flow to the mouth of the well fluid, so as to prevent the blowout. Bypass is part of the Down-hole BOP, In the normal drilling process it is closed,which to prevent the drilling fluid flow to the annulus inside the drill string, So the by-pass sealing performance directly affects the normal drilling fluid circulation. Existing by-pass structure is complex, and more for one-time use, open after unable to close, then remove from underground to replace parts can only be used once again, and not easy to operate. Therefore, to solve above problems, This article puts forward can be repeated use and convenient control of downhole blowout preventer by-pass open-close sub structure. The structure can be achieved by the opening of valve core, repeatedly open and close the bypass. The characteristics of his structure is simple operation and reliable in use.In this paper, the Down-hole BOP by-pass open-close nipple sealing principle of sealing, the sealing process, and sealing conditions, in-depth analysis and research, from the seal material, structure, size and form-position errors, affecting the Down-hole blowout preventer by-pass open-close nipple sealing factors are discussed, the main factors of affecting its seal, and by changing these factors on the nipple seal optimization analysis, and then improve the sealing performance and reliability of Down-hole BOP to bypass open-close nipple sealing structure design and working process of by-pass short section provides theory basis for the choice of opening and closing.According to the alignment error on sealing performance influence the results, and reduce the alignment error change seal structure optimization of ideas, and gives three kinds of optimization, finite element analysis and compared with ordinary structure of sealing performance, finally chooses a layer of rubber vulcanization on the valve core composite structure of the valve core. This structure can improve the alignment error and tilt and offset alignment error exists when sealing performance. To improve the sealing performance of Down-hole blowout preventer and reduce the influence of alignment error on sealing performance to provide a theoretical basis.Down-hole BOP by-pass open-close preventer bypass opening and closing the analysis of the sealing performance, short in the following ways can effectively increase the sealing performance:1、Choose the appropriate matching cone Angle, the sealing surface roughness length, sealing surface, material;2、Rational optimization of valve core and valve seat structured;3、Using composite valve core etc.