Abstract:

In the measurement while drilling system，the transport method of consecutive pulse is phase modulation.Considering viscosity and frequency feature of transmission system,the model in time domain is not suitable for the phase modulation.In this paper,starting with the analysis of transient flow,combining with the theory of transmission line,the concept of complex frequency is introduced,the calculating model of frequency domain for the pulse velocity in drilling fluid built and the impendence and transmission operator of drilling fluid obtained.With the hypothesis of linear friction,the calculating method for the frequency domain model is obtained.

Key words: complex frequency, phase modulation, frequency domain, theory of transmission line, linear friction, drilling fluids