| 摘要 |
Gas influx into a wellbore, which is commonly referred to as a "kick", is detected during active drilling of the borehole. In a preferred embodiment of the invention a determination of mud pump noise round trip transit time T by evaluating a function T=(n-(Phi)/2(pi))f where (Phi) is the phase between standpipe and annulus signals and f is the frequency of a drill fluid oscillation caused by a mud pump and n is an integer which is incremented or decremented until the rate of change of T with respect to frequency is zero. An alarm signal is generated when the rate of change of T with respect to time exceeds a predetermined threshold. In another embodiment of the invention a determination of the Doppler frequency shift of a mud pump signal expressed as a ratio signal, (Delta)f/f0 where (Delta)f is the change in frequency measured at the annulus from the frequency f0 of the mud pump signal measured at the standpipe. The ratio is compared with a threshold signal to determine whether or not gas influx has entered the annulus.
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