Safety Analysis And Evaluation Of Blowout Preventer For Releasing Blowout Preventer Tool In Pumping Well

Releasing blowout prevention tool for pumping well is one of the tools used for pumping well to prevent bottom hole overflow or blowout.As there is a risk of safety accidents such as well overflow or blowout caused by downhole pressure fluctuation when pumping wells are lifted and lowered,it is necessary to carry out blowout prevention treatment for pumping wells.In view of the problem that the pump can not be checked,the production channel can not be closed,and the production pipe string can be lowered to open the production channel,so as to achieve the goal function of automatic blowout prevention,this paper puts forward the blowout prevention treatment of the pumping well with the release blowout prevention tool,which adopts the blowout prevention idea of the combination of the release packer and the independently designed downhole blowout prevention valve.Oil well production and blowout prevention are realized by opening and closing the central channel inside the blowout prevention tool.This paper takes the releasing blowout prevention tool of pumping well as the research object,combined with the actual working conditions of pumping well in an oil production plant of Daqing Oilfield,understands the blowout prevention principle of blowout prevention tool,analyzes the stress of packer rubber barrel,slip and downhole blowout prevention valve switching spool that affect its blowout prevention performance,and determines the failure mechanism of rubber barrel,slip and spool.The failure judgment method of rubber cylinder,slip and valve core is obtained.Through the finite element analysis of the packer rubber cylinder sealing system and slip anchoring system,the size and distribution of the contact stress between the rubber cylinder and the casing under different setting pressure are obtained;Under the maximum setting pressure(18 MPa),the change of contact stress between rubber cylinder and casing with casing pressure and the change of slip anchoring force with setting pressure are obtained.The rubber cylinder compression experiment and slip anchoring performance experiment are carried out respectively.The maximum errors between the rubber cylinder and slip experimental results and the finite element analysis results are 15.43% and 8.57% respectively.Within the acceptable range in engineering,the reliability of the numerical simulation results is verified.The finite element analysis model of downhole blowout prevention valve spool is established.Through numerical analysis,the change of contact stress of sealing ring and sealing strip in contact with the spool with the change of casing pressure is obtained.As the downhole fluid passes through the valve switch,the internal flow channel and valve core of the valve have erosion effect.The erosion wear of downhole blowout prevention valve is studied,and the influence of erosion wear on the sealing performance of downhole blowout prevention valve is analyzed.According to the numerical analysis results of rubber barrel,slip under different setting pressure and valve spool under different casing pressure,formulate the failure judgment standard of rubber barrel,slip and valve spool,determine the blowout prevention pressure limit of the blowout preventer,establish the safety evaluation method of releasing blowout prevention tools in pumping wells,and draw the blowout prevention safety evaluation chart,which plays a positive role in preventing the occurrence of safety accidents such as bottom hole overflow and blowout.It also provides a reference for the establishment of blowout prevention safety analysis and safety evaluation methods of other downhole blowout prevention technologies.