调制式振动对大斜度井减摩阻影响规律

基于钻柱振动与井壁摩阻间的耦合作用研究,依据弹性杆理论,建立大斜度井激发钻柱产生轴向振动减小摩阻的数学模型,分析激振力强度、激振频率、摩阻系数和钻井液黏滞系数对钻柱振动减阻效果的影响。采用正交数值试验对各因素的影响程度进行分析。结果表明:提高激振力强度、频率或降低摩阻系数和钻井液黏滞系数均可提高振动减阻效果,其中激振频率存在最优值;各因素对钻柱振动减阻效果的影响由大到小依次为激振器强度、摩阻系数、激振器频率和钻井液黏滞系数。

Influence laws of modulated vibration on friction reduction in inclined-wells

By coupling vibration of drill string and friction of borehole, a mathematic model was established according to the elastic rod theory to investigate the friction reduction caused by axial vibration of drill string during jarring in highly inclined-wells. This model was used to analyze the influences of the intensity of vibration force, vibration frequency, friction coefficient and the drilling fluid viscosity on the friction reduction effect. Orthogonal experiment was used to analyze the magnitude of the effects from those factors. The results show that improving the excitation intensity and frequency or reducing the friction coefficient and drilling fluid viscosity coefficient can effectively help friction reduction, and there is an optimum value for excitation frequency. Regarding to friction reduction effect magnitude, excitation intensity ranks the highest, and then come friction coefficient, excitation frequency and fluid viscosity coefficient.