球形防喷器胶芯失效分析

球形防喷器胶芯是井控设备中的易损件,弄清胶芯的失效形式和原因对于提高其使用寿命和可靠性具有重要意义。根据球形防喷器的工作原理,分析胶芯在几种典型工况下的受力与变形规律;结合现场使用情况,总结出胶芯的主要失效形式有:胶芯上表面开裂和层块状脱落;胶芯内壁大块脱胶;胶芯底部与活塞接触处橡胶开裂;胶芯不能密封住井底高压流体;封井后胶芯不能及时恢复等。综合分析上述各种失效形式后,认为提高球形防喷器胶芯的密封可靠性和性能,应主要从胶芯材料和结构方面入手,即应优化胶芯和支撑筋的结构形状和尺寸,降低胶芯中的峰值应力;应改进胶芯橡胶材料配方和硫化工艺,提高橡胶的抗拉性能、扯断永久伸长率、耐油性能、抗老化性能等。

Analysis of Failure for Rubber Core in Spherical Blowout Preventer

Rubber core in spherical blowout preventer(BOP)is consumable in the well control equipments.It is important to understand the failure modes and the reasons to improve their life and reliability.According to the working principle of spherical BOP,the laws of force and deformation of rubber core in several typical working conditions were analyzed.Based on the information of their application on-site,the main failure modes of the rubber core included that it had cracking and block off layer on the upper surface of the rubber core,large degumming on the inner surface of the rubber core,and rubber cracking at the position where the bottom of rubber core contacting with the piston;rubber core couldn’t seal the high pressure fluid from the well bottom,and rubber core couldn’t be promptly restored after plugging.According to the comprehensive analysis of various failure modes,the improvement of the seal reliability and performance of spherical BOP rubber core from structures and materials of rubber core was put forward,including optimizing the shape and size of the rubber core and supporting tendons to reduce the peak stress in the rubber core,and improving the formulation and vulcanization process of rubber material to raise the tensile properties,ripped permanent elongation,oil resistance and anti-aging properties of the rubber.