关键词: 钻井液, 连续脉冲信号, 传输频率, 频率相关摩阻, 拉普拉斯变换, 频域分析, 计算模型

Abstract:

The major energy loss of consecutive pulse signal of drilling fluid always comes from the friction of drilling fluid with the shell of pipe during underground transmission.In the consideration of the non-Newtonian characteristics of drilling fluid and the concept of complex frequency,a frequency-dependent friction model for consecutive pulse signal of drilling fluid transmission was set up using the Laplace transforms.The frequency domain of the pulse transition signal of drilling fluid in borehole was also discussed.The influencing factors and the disciplines of transient friction loss were analyzed with the practical data from similar projects.The analysis results showed that the attenuation of the pulse signal was smaller and the transmitting distance was longer in the low-frequency stage.Conversely,the signal transmitting was more stable in the high-frequency stage.The transient friction loss was only affected by the frequency of signal and the characteristics of drilling fluid.The influence of transient friction loss on the attenuation was more remarkable in the low-frequency stage.Thus,the lower viscosity of drilling fluid could result in the less transient friction loss.

Key words: drilling fluid, consecutive pulse signal, transient frequency, frequency-dependent friction, Laplace transform, frequency-domain analysis, calculation model