南海流花超大位移井套管磨损预测方法

Method of casing wear prediction for Liuhua mega-extended-reach wells in South China Sea.

在超大位移井的钻进过程中,造斜段的技术套管会发生严重的磨损问题。建立了超大位移井技术套管磨损后剩余壁厚的定量预测方法。根据能量原理,即套管内表面的磨损体积与旋转钻柱在相同位置所作的功成正比,建立了技术套管磨损体积与井眼轨迹、钻具组合、机械钻速、转速、钻进井段长度及套管磨损系数之间的函数关系。在假设磨损截面为新月形的条件下,根据磨损截面的几何关系,建立了套管磨损深度与体积之间的关系。应用一口超大位移井的实测数据对建立的模型进行验证,结果表明该模型可以用于超大位移井技术套管磨损深度的预测。根据研究结果,简要说明了套管防磨技术的主要方法。

Intermediate casings are under severe wear in the drilling duration of mega-extended-reach wells.A quantitative model was established for the prediction of the residual wall thickness of intermediate casing.According to the energy principle,the wear volume on the inner wall of casing is proportion to the work that is done at the same position by the rotation of drill string.The function of the wear volume of intermediate casing was established,it is related to well path,drill string,penetration rate,rotational speed,the section length drilled,and wear coefficient.Under the assumption that the shape of wear was in crescent shape,the relationship between casing wear depth and volume was established.The dada obtain from a really drilled mega-extended-reach well were used to verify the model established above,the results show that this model can be used to predict the wear depth in the wall of intermediate casing.The difficulty in the application of this model exists in that the wear coefficient was hard to obtain accurately.According to the results obtained above,the guide lines for avoiding casing wear problem are outlined.