水平井套管下入载荷计算及扶正器减阻分析

Calculation of Casing Running Load in Horizontal Well and Analysis of Resistance Reduction of Centralizer

页岩油水平井由于深度深、水平段长,使得套管下入过程中摩阻过大,导致套管难以顺利下入,根据水平段的井斜角大小分为勺型井和大斜度井,不同井型套管下入摩阻不同,因此需要选择较为准确的摩阻预测模型。现场通过安放扶正器来减小套管下入摩阻,不同扶正器组合对勺型井、大斜度井的减阻效果又是不同的,因此需要对比出减摩效果最好的扶正器组合。采用纵横弯曲梁与软杆模型拟合了勺型井和大斜度井有无扶正器时套管下入大钩的载荷,并与实际值进行了对比;结合纵横弯曲梁模型分析了不同扶正器组合对套管下入的减阻效果。结果表明:考虑扶正器的纵横弯曲梁模型计算出的摩阻、钩载更符合实际,勺型井与大斜度井采用弹性/刚性扶正器组合时减阻效果最好,勺型井套管下入摩阻最大降低了79%,平均减阻70.3%,大斜度井套管下入摩阻最大降低了35.5%,平均减阻20.6%,由此可见勺型水平井比大斜度水平井更需要对扶正器组合进行优选。

Due to the deep depth and long horizontal section of the horizontal wells for shale oil,the friction resistance is too large during the running of the casing,which makes it difficult to run the casing smoothly.According to the size of the well inclination angle of the horizontal section,the horizontal wells are divided into spoon-shaped one and highly-deviated one,the friction resistance of different casing running for different well types is different,so it is necessary to choose a more accurate friction resistance prediction model.Centralizers are placed on site to reduce the casing running friction,different centralizer combinations have different resistance reduction effects on the spoon-shaped wells and highly-deviated wells,so it is necessary to determine the centralizer combinations with the best friction reduction effect through comparison.The vertical and horizontal bending beam and soft rod model were used to fit the load of hook running into the casing when the spoon-shaped wells and the highly-deviated wells had a centralizer or not,and the results were compared with the actual value.Combined with the vertical and horizontal bending beam model,the resistance reduction effect of different centralizer combinations on casing running was analyzed.The results show that the friction resistance and hook load calculated by considering the vertical and horizontal bending beam model of the centralizer are more realistic.The resistance reduction effect is the best when the elastic/rigid centralizer is used in the spoon-shaped wells and the highly-deviated wells.The friction resistance of casing running in the spoon-shaped wells reduced by 79% at the most and the average resistance reduced by 70.3%;and the friction resistance of casing running in the highly-deviated wells reduced by 35.5% at the most and the av-erage resistance reduced by 20.6%,which shows that the centralizer combinations optimization is more important for the spoon-shaped horizontal wells than that for the highly-deviated wells.