超深井套管屈曲后钻具通过性计算模型研究

Calculation Model of Drilling Tool Passing Through Buckled Casing in Ultradeep Wells

针对超深油藏井下载荷工况愈发恶劣的现状,对钻具在三维屈曲套管中的通过性进行了研究。通过对比钻具、套管、井筒尺寸的几何关系,考虑了套管屈曲相关参数,确定了钻具在套管正弦及螺旋2种屈曲形式下的不变形通过最大长度,建立了套管屈曲后钻具通过性计算模型,并利用该模型进行了实例计算。应有限元确定了实例中套管屈曲形式,计算了不同屈曲时的通过性。计算结果表明,钻杆及钻铤在屈曲套管中可自由通过,钻具的通过性主要受钻头尺寸的影响。通过全尺寸实物试验对钻头在屈曲套管中的通过性进行了验证。结果显示,建立的计算方法也可用于其他井下工具的通过性计算,如油管在屈曲套管中、井下工具在屈曲油管中的通过性等,对油田现场作业具有重要指导意义。

The downhole loading conditions in ultra-deep reservoir are increasingly severe,so the capacity of drilling tool passing through three-dimensionally buckled casing was studied.By comparing the geometric relation-ships among drilling tool,casing and wellbore size,and considering the relevant parameters of buckled casing,the maximum length by which drilling tool passes through sinusoidally and spirally buckled casing was determined.A calculation model of drilling tool passing through buckled casing was built and used for example calculation.The casing buckling form in the case was determined using the finite element method,and then the passing capacity in different buckling forms was calculated.The results indicate that the drill pipe and drill collar can freely pass through the buckled casing,and the passing capacity of the drilling tool is mainly affected by the bit size.Finally,the pass-ing capacity of the bit in the buckled casing was verified through full-scale entity test.The calculation model estab-lished can also be used for determining the passing capacity of other downhole tools,such as tubing in buckled cas-ing,and downhole tool in buckled tubing,and it is of great guiding significance for on-site operation of oilfields.