盐岩层钻大斜度井的井壁稳定性研究

Study on wellbore stability during high-angle well drilling in salt rock

针对盐岩井段易发生蠕变缩径,引起卡钻、固井后又易发生挤毁套管等事故的现象,应用有限元方法,建立了描述盐岩层中斜井井眼蠕变缩径的空间力学模型,从岩石力学角度分析了塔里木油田羊塔克地区盐岩层钻大斜度井的井壁稳定性,论述了一定地应力状态下井斜角和方位角对井眼缩径的影响规律。该研究成果为盐层段定向井井眼轨迹设计、合理确定泥浆密度和盐岩层钻井施工提供了理论参考,已成功应用于塔里木地区钻遇盐岩层时钻井工程的设计和施工。

During drilling of high-angle well in salt rock, the creep of salt rock often happens, which gives rise to the shrinkage of well -bore diameter and results in drill pipe sticking and casing failure. A three-dimensional mechanical model for describing creep and shrinkage of wellbore diameter was developed with the finite element analysis. The wellbore instability of high-angle well drilled in the salt rock of Yangtake district in Tarim Oilfield was studied. The correlations of creep rule with the drift angle and drift azimuth were discussed. The study result provided the theoretical reference for design of directional well path, determination of mud density and drilling high-angle wells in salt rock. The model was used to drilling engineering design and drilling operation in Tarim Oilfield.