带压作业闸板防喷器胶芯失效机理研究

Study on failure mechanism of rubber core in ram blowout preventer during snubbing service

针对带压作业过程中闸板防喷器胶芯易失效的问题,以现场使用的带压作业闸板防喷器胶芯为研究对象,通过实验确定了橡胶基体的本构关系,利用ABAQUS软件对比研究了4种不同井筒压力对胶芯的疲劳失效与密封失效的影响。结果表明:分析结果与现场应用胶芯的失效位置相符,验证了分析的正确性;胶芯的疲劳失效位置集中在橡胶基体与闸板上下部的4个尖角接触区域,上部区域失效严重;井筒压力的大小影响橡胶基体密封面上的接触应力分布,但对耐磨块密封面上接触应力分布影响不显著。建议在橡胶基体与闸板上下部的4个尖角区域补强以增加胶芯寿命。

Aiming at the problem that the rubber core of ram blowout preventer is easy to be failure during snubbing service,taking the rubber core of ram blowout preventer in snubbing service used in field as research object,the constitutive relation of the rubber matrix was determined through experiment,then the influence of four different wellbore pressures on the fatigue failure and sealing failure of rubber core was comparably studied by ABAQUS software. The results showed that the analysis results were consistent with the failure locations of the rubber core applied in the field,which verified the correctness of the analysis. The fatigue failure locations of rubber core were concentrated on the four sharp corner contact areas between rubber matrix and top or bottom of ram,with a severe failure on the top area. The wellbore pressure affected the distribution of contact stress on the sealing surface of the rubber matrix,but it is not obvious for the wear block. It was suggested to increase the strength at four sharp corner areas between rubber matrix and top or bottom of ram,so as to increase the lifetime of the rubber core.