多扶正器套管串在弯曲井段下套中的摩阻分析

在塞平－１井固井工艺设计中，为提高固井质量，大斜度进段和水平段采用了多扶正器套管串结构．多扶正器套管串在弯曲井眼的下套过程中，一方面由于井眼的空间弯曲，另一方面由于扶正器的存在增加了套管串的刚度，会使套管串在弯曲井段内所受的井壁支持力和摩阻升高，容易发生硬卡和自锁，增加了下会难度．本文针对这一问题，从力学理论出发，研究了多扶正器套管串在弯曲并段下套过程中的摩阻，给出了由于井眼弯曲造成的附加支持力和附加摩阻计算公式，并采用这些公式对塞平－１井１３９６ｍ～１４７６ｍ弯曲并段内扶正器套管串和摩阻进行了理论预测，该预测结果与后来的实测资料较一致．文中还从强度、刚度、固并质量、预防硬卡和自锁等方面综合考虑，对塞平－１井弯曲井段多扶正器套管串结构的适配性进行了理论分析，提出了套管、扶正器选型和合理搭配的建议，为套管器结构设计提供了理论依据．

Friction Analysis of Multi-Stabilizer Casing Strings During the Casing Process in Curved Well Segments

n the casing and cementing design of Saiping-1 horizontal well. multi-stabilizer casing string is to be used in large curved segments and horizontal segments to improve casing and cementing quality. But during the casing process in curved segments, the multi-stabilizer casing string will bear more supporting force and friction from the well wall because of the increased bending stiffness of the casing string caused by the borehole's curvature and the multi-stabilizer. To counter this problem, the friction of multi-stabilizer casing string in curved segment during the casing process was investigated theoreticelly. The formulas of the additional supporting force and friction caused by the well curvature have been obtained. By using these formulas,the friction of the multi-stabilizer casing of Saiping-1 horizontal well in the curved segment from 1396m to 1446m is theoratically predicted. The calculated results are in fairly good agreement with practically measured values. Moreover,the compatibility of multi-stabilizer casing string in curved segment of Saiping-1 horizontal well is analysed theoretically with comprehensive consideration of the strength,stiffness,casing and cementing quality,prevention against self-locking and sticking of drilling tool,etc. Based on this,some suggestions on rational selection and arrangement of casing tubes and stabilizer are made. The research work of this paper can provide scientific and theoretical basis for the design of casing string structure.