基于钻柱屈曲的大位移井套管磨损预测模型

Prediction model of casing wear for extended reach wells considering buckling of drill string

大位移井由于井深长,狗腿度严重,摩阻扭矩大等原因,在钻柱下入过程中,钻柱可能会产生屈曲,这会导致钻柱轴线与井筒轴线不再平行,钻柱进尺长度会显著增加,加剧套管的磨损。在套管磨损预测模型中,引入由于钻柱屈曲而产生的钻柱进尺长度变化量,建立适合于大位移井的套管磨损预测模型。结合采用“井工厂作业”模式下的南海流花某大位移井W1的井径测试数据,对邻井W2进行套管磨损预测。结果表明:忽略钻柱的屈曲效应时,测深2144 m处的套管磨损深度预测值会被低估16.9%;仅考虑由钻柱屈曲所引起的附加载荷和套管截面几何变化,不考虑钻柱进尺长度变化量时,测深2144 m处的套管磨损深度被低估10%;针对大位移井的套管磨损预测,如果忽略由于钻柱屈曲所带来的钻柱进尺长度变化量,会使套管磨损深度预测值被低估。

The tubular string is vulnerable for buckling during downhole string loading operation due to many factors,such as long well depth,large dog-leg severity and high drag and torque.Buckling of the drill string can significantly increase its slide and footage,which aggravates casing wear.In this paper,the change of drill string footage due to bucking was coupled into a conventional casing wear prediction model,in which a new case wear model was established appropriating for extended reach wells.Referring to the caliper test data from well W1 in South China Sea,the casing wear prediction of the adjacent well W2 was conducted.The results indicate that,when the buckling of drill string is not considered,the predicted value of the casing wear at depth of 2144 m can be underestimated by 16.9%.When the change of drill string footage caused by buckling is ignored,the predicted value of the casing wear at the same depth can be underestimated by 10%.The new casing wear prediction model presented in this paper can accurately predict the casing wear in extended reach wells.