气体钻井钻柱失效因素分析与对策研究

文章通过对2005～2021年期间川庆气体钻井所发生的76次断钻具事故的统计分析，认为气体钻井中钻具失效的主要原因在于钻具疲劳、钻具振动、化学腐蚀以及高速冲蚀破坏等几个方面。其中，采用空气锤钻进时，在冲击力作用下钻具的瞬时中和点上移，疲劳点不一定集中于近钻头的Ø228.6mm钻铤；高频段的钻具振动对钻具产生的破坏影响较小，而低频段的钻具振动会引发低阶钻柱共振，进而引起钻具振动失效；在地层产水条件下实施气体钻井时，钻具易发生溶解氧腐蚀和二氧化碳弱酸性腐蚀，造成钻具的点蚀破坏；井底岩屑伴随高速气体呈间歇性的高速撞击钻柱形成冲蚀破坏，是造成钻具磨损失效的主因。基于上述原因分析，从优化钻具组合、完善雾化基液缓蚀工艺和气体注入参数等方面提出了具体的对策，为减少后期气体钻井过程中钻具失效机率做参考。

Drill String Failure Analysis and Countermeasure Research in Gas Drilling

Based on the statistical analysis of 76 drilling tool breaking accidents in Chuanqing gas drilling from 2005 to 2021, this paper concludes that the main causes of drilling tool failure in gas drilling are drilling tool fatigue, vibration, chemical corrosion and high speed erosion damage. When drilling with air hammer, the instantaneous neutralization point of the drilling string moves up under the impact force, and the fatigue point is not necessarily concentrated in the 228.6mm drill collar near the bit.The vibration of drill string in high frequency band has little influence on the damage of drill string, while the vibration of drill string in low frequency band causes low order resonance of drill string, and thenresultsinthe vibration failure of drill string. When gas drilling is carried out under the conditionwithformation water production, dissolved oxygen corrosion and weak acid corrosion of carbon dioxide are easy to occur in drilling tools, resulting in the pitting damage of drilling tools. Bottom hole cuttings with high velocity gasflowimpact the drill string intermittently. Erosion is the main cause of drilling tool wear failure. Based on the analysis of the above reasons, this paper puts forward specific countermeasures from such aspects as drilling assembly optimization, improving the corrosion inhibition technology of atomized base fluid and gas injection parameters, so as to provide reference for reducing the failure probability of drilling tools in the later gas drilling operations.