大斜度井中套管磨损机理研究

A Study on the Casing Wear Mechanism in Highly-deviated Well Drilling

针对套管在大斜度井中的磨损失效,首先开展了套管的磨损实验研究,根据Dawson和White提出的基于能量损失的线性磨损模型以及本文的实验数据,获得了钻杆接头与套管的磨损系数。建立了钻杆接头与套管磨损机理研究的有限元模型,通过任意拉格朗日-欧拉自适应网格划分,在数值模拟过程中可以对套管磨损的节点进行"实时调整",并对网格单元做光滑处理,不断更新钻柱接头与套管的接触关系,对钻进过程中套管磨损机理进行了研究。在磨损后套管结构形状研究的基础上,开展了套管剩余抗挤强度的数值模拟研究,得到了套管的最大磨损深度随时间的变化关系,建立了套管剩余抗挤强度与最大磨损深度的关系,进而可以预测套管在某一累积磨损时间内套管的最大磨损深度和套管的剩余强度,为磨损套管的安全性评价提供了理论依据。

Aimed at studying the wear failure in the drilling process of highly-deviated well, this paper firstly carried out casing wear experiment research. According to the liner casing wear model based on the energy loss suggested by Dawson R and White J, and the experiment, the joint-casing wear coefficient is obtained. The finite element model of casing wear mechanism research is constructed using ABAQUS software. This paper uses the re-development user subroutine and Arbitrary Lagrange- Euler mesh. In the process of numerical simulation, the location of the wear node can be adjusted timely, the mesh element is smoothed, and the contact relations between joint and casing is altered continuously, which all contribute to the study on casing wear mechanism. Based on the shape of worn casing, the numerical simulation research is carried out to determine the remaining collapse strength, as a result of which, the relationship between the maximum wear depth and wear time is obtained. On this basis, the exact relationship between the maximum wear depth and wear time is determined to predict the maximum wear depth and remaining strength of casing after a period of accumulating wear time, which also provides theoretical basis for the safety assessment of worn casing.