考虑随机性变量的钻井钻柱运转稳定性研究

Study on Operation Stability of Drilling Drill String through Considering Random Variables

在超深井钻进时,钻柱系统稳定性直接影响钻井安全、钻进速度和钻井成本。以钻柱扭转动力学理论为基础,结合最大熵原理建立了含随机性变量的钻柱扭转动力学模型,模型采用现场钻井数据验证可靠性并进行现场应用。在考虑平衡摩擦系数、岩石受限抗压强度、钻井液密度、阻尼比的不确定性影响条件下,分析了不同变异系数下钻柱的随机扭转稳定曲线,可对现场生产提出合理化建议。

While drilling the ultra-deep wells,the stability of the drill string system directly affects the drilling’s safety,speed and costs.Based on the theory of drill string torsion dynamics and combined with the principle of maximum entropy,a drill string torsion dynamic model with random variables was established and its reliability was verified with field drilling data and it’s applied in the field.In addition,through considering the uncertainties of drilling fluid density,equilibrium friction coefficient,damping ratio,and restricted compressive strength,the random torsional stability’s curves of the drill string under different coefficients of variation were analyzed,and reasonable suggestions for on-site production were proposed.