井喷事故场景下闸板防喷器剪切能力评估与提升

Study on shearing capacity evaluation and promotion for blowout preventer ram in blowout scenario

基于钻杆力学模型和材料失效准则,建立深水闸板防喷器剪切分析模型,通过仿真计算与试验结果对比,验证模型的准确性及适用性。为探究井喷事故场景对钻杆剪切能力的影响,进一步分析钻杆不同内外压与轴向载荷作用下闸板剪切力的变化规律;考虑井喷事故场景下钻杆偏心情况,针对传统闸板剪切区域不完全覆盖的问题,优化闸板防喷器剪切刃结构,并开展钻杆偏心位置剪切评估。结果表明:钻杆轴向压缩载荷与内压载荷会急剧增加钻杆所需剪切力,为保证闸板防喷器剪切能力满足要求,需选择合适闸板防喷器类型,提高闸板剪切安全系数;提出的新型闸板防喷器不仅可以减少闸板防喷器的最大剪切力,还能有效解决钻杆偏心问题,显著地提高了闸板防喷器的剪切能力。

The analysis model was established to analyze the shearing force for the blowout preventer ram,based on the mechanical model on drilling bar and criterion of material failure.The simulation result has been compared with the experimental result,to verify the validity of the model.To explore the effect of blowout scenario on the shearing capacity,the variation laws on shearing forces of the drilling rod with different internal pressures,external pressures and axial loads were further investigated.By considering the off-center case of the drilling rod,and aiming to the problem that the conventional shearing zone of the ram cannot be fully covered,the structure on the shearing edge of the blowout preventer ram was optimized,and the shearing evaluation of the drilling rod at different eccentric positions was carried out.The results show that,the axial compressive load and internal pressure will significantly increase the required shearing force of the drilling rod.Therefore,to meet the demand of shearing capacity for the blowout preventer ram,it is necessary to choose the proper type of the blowout preventer ram,in ordr to increase its safety factor of shearing.The new designed shear ram can not only decrease the maximum shearing force,but also solve the problem that the drilling rod is at the off-center positions,which significantly promotes the shearing capacity of the blowout preventer ram.