深井高温对钻柱横向振动固有频率影响研究

钻柱共振是引起深井钻具失效的主要原因。钻柱在深井段处在一个高温的环境下,温度的升高必然使钻柱的固有频率发生变化。为此,分析了井下高温对钻柱横向振动固有频率的影响,推导出井下任意温度时在轴向力作用下钻柱横向振动固有频率的计算公式。通过实际算例,分析了考虑轴向力因素时井下高温对钻柱横向振动固有频率的影响。计算结果表明随着温度的升高,钻柱横向振动的固有频率逐渐降低,其降低的幅度随着轴向压力的增大而增大;轴向压力较大时,温度对钻柱横向振动一阶固有频率的影响远大于对二阶固有频率的影响;轴向压力对钻柱一阶固有频率随温度变化的影响程度远大于轴向拉力的影响程度。

The influence of high temperature in deep holes on inherent frequency of drill string lateral vibration

Drill string resonance is the major cause of drill tool failure. Under the high temperature condition in deep wells, temperature rising will inevitably change the inherent frequency of drill strings. Therefore, the influence of downhole high temperature on inherent frequency of drill string lateral vibration is analyzed, the equations for calculating the inherent frequency under the axial force are derived under random temperature, and the influence of downhole temperature on the inherent frequency of lateral drill string vibration is analyzed in consideration of axial force. The result shows that the inherent frequency of lateral drill string vibration decreases gradually with the increase of temperature, the range of its decrease goes up with the increase of axial pressure. When the axial pressure is higher, the influence of its lateral vibration on the first-order inherent frequency is much higher than that on the second order; the range of influence of axial pressure on the first-order inherent frequency is much higher than that of axial tension.