井下温度对钻柱扭转振动固有频率影响的讨论  

Discussion for the influence on downhole temperature on torsion vibration natural frequencies of drill strings

作　　者：李军强[1] 

机构地区：[1]西安石油大学机械工程学院,陕西西安710065

出　　处：《石油矿场机械》2006年第6期1-4,共4页Oil Field Equipment

基　　金：国家自然科学基金重点项目(50234030);国家863"十五"重大项目(2003AA602013)资助

摘　　要：钻柱共振是引起深井钻具失效的主要原因,钻柱工作在井下的高温环境中,温度的升高必然使钻柱的固有频率发生变化。分析了井下温度对钻柱扭转振动固有频率的影响,推导出了井下任意温度时钻柱扭转振动固有频率的计算公式。通过实际算例,讨论了井下温度对钻柱扭转振动固有频率的影响。分析结果表明:钻柱扭转振动固有频率随着温度的升高而降低,不管钻柱多长,二阶固有频率的降低幅度都大于一阶固有频率的降低幅度,但二者差别不大。当井下温度不超过200℃时,钻柱扭转振动固有频率的变化幅度不会超过常温下计算值的3.7%。当温度升高时,钻柱扭转振动固有频率的降低幅度与钻柱长度关系很小,可以忽略钻柱长度的影响。任意温度时钻柱扭转振动固有频率与温度成近似线性关系,可以根据常温下的计算值和温度变化值通过一个简单的一次函数来计算,避免了求解超越方程的困难。Drilling string resonance is the main cause of the drilling tools failure. The drilling string is in higher temperature conditions, the natural frequencies of drill string should be changed when downhole temperature rises. Downhole temperature influence on torsion vibration natural frequency of drill string in deep wells is investigated. The calculation formula of torsion vibration natural frequencies of drill string is educed; it can be applied to any downhole temperature conditions. The effects of the downhole temperature of deep wells on natural frequencies are illustrated by numerical examples. It is shown that the frequencies decrease gradually with the rise of downhole temperature. For any length of drilling string, the temperature influence on the second frequency larger than on the first frequency, but the difference is small. When downhole temperature is below 200℃ the decrease of the natural frequencies is smaller than 3.7 %. When the temperature rises, the influence of the length of drilling string on the decrease of natural frequencies is so small that it can be ignored. The natural frequencies of drill string vary linearly and approximately with the downhole temperature; the natural frequencies can be calculated by a simple linear function through downhole temperature and normal natural frequency＇ value.

关 键 词：温度 钻柱 扭转振动 固有频率 

分 类 号：TE921.201[石油与天然气工程—石油机械设备]