井控半封闸板体失效机理与密封性能研究

Failure Mechanism and Sealing Performance of Well Control Semi Sealing Ram Body

为了提高井控半封闸板防喷器(blowout preventer,BOP)安全性能,对现役的半封闸板防喷器进行了失效分析及密封性能评价,完成了闸板体的表征测试以及材料拉伸和冲击试验,通过溢流关井时半封闸板受力分析,基于闸板体材料应力应变测试数据,建立了全尺寸半封闸板防喷器模型,在井下高压流体和油缸压力复合载荷下对闸板体和密封胶芯的力学性能进行了仿真研究。结果表明:当油缸压力超过9.4 MPa,闸板本体的凹槽根部刚好进入屈服变形,最大等效应力发生在闸板本体的凹槽根部,导致闸板体过早断裂失效。胶芯与闸板上端接触区域的应力集中最为明显,可见由于复合载荷的作用,胶芯上部受到挤压作用,产生严重变形,进而失去密封能力。最后提出了减小闸板应力集中的措施。研究成果为溢流情况下半封闸板防喷器的安全操作提供指导依据。

In order to improve the safety performance of well control semi sealed ram blowout preventer(BOP),failure analysis and sealing performance evaluation were carried out for the semi sealed ram BOP in service,and the characterization test of ram body and material tensile and impact tests were completed.Based on the stress analysis of semi sealed ram during overflow shut in,and the stress and strain test data of ram body material,a full size semi sealed ram BOP model was established.The mechanical properties of ram and sealing rubber core were simulated under the combined load of downhole high-pressure fluid and cylinder pressure.The results show that when the cylinder pressure exceeds 9.4 MPa,the groove root of the ram body just enters the yield deformation,and the maximum equivalent stress occurs at the groove root of the ram body,leading to premature fracture failure of the ram body.The stress concentration in the contact area between the rubber core and the upper end of the ram is the most obvious.It is concluded that the upper part of the rubber core is squeezed due to the combined load,thus losing the sealing ability.Finally,measures to reduce ram stress concentration were proposed.The research results provide guidance for safe operation of semi sealed ram BOP under overflow.