井身结构安全评价技术研究与应用

Application of Safety Assessment Method for Wellbore Structure

合理评价井身结构安全性有助于保障井下安全,提高钻井工程综合效益。特别是在勘探开发初期,所能获取的地层压力数据较少,压力信息具有不确定性,评价井身结构安全性势在必行。假设地层压力数据服从三角分布,构造模糊隶属函数,并采用层次分析法确定各层位漏、涌、塌、卡事故权重,计算出井身结构风险概率,并对其进行安全级别评定,形成了一种安全评价技术方法。该方法可为现场预防井下事故提供决策依据,也可为分析井下事故、确定事故层位提供参考。

Reasonable assessment of wellbore structural safety was helpful to ensure down-hole safety and drilling efficiency.Especially at the early stage of oilfield exploration and development,data of formation pressure were rarely obtained,therefore pressure information was unstable,it was necessary to assess the wellbore structural safety.It was assumed that the formation pressure was distributed in triangle form,fuzzy subordinate function was created and hierarchical analytical method was used to determine the weight of leakage,well kick,borehole collapse and sticking.The wellbore risk probability was calculated and its safety level was assessed.A new method of assessment is proposed and provides a reference for prevention downhole accident.