Pumping pressure interference elimination method for drilling fluid continuous pressure wave signals

Abstract

The invention provides a pumping pressure interference elimination method for drilling fluid continuous pressure wave signals. Two pressure sensors are installed on a straight pipe and are away from a distance, one end of the straight pipe is connected with a drilling fluid pump, the other end of the straight pipe is connected with a wellhead, the underground drilling fluid pressure signals for reflecting underground information of measurement while drilling are conveyed to the ground from the wellhead through the straight pipe and received by the pressure sensors installed on the straight pipe, and measurement signals of the two pressure sensors are subtracted to obtain delay differential detection signals. Due to the fact that pump pressure interference transmission direction is opposite to underground drilling fluid pressure signal transmission direction, pressure interference generated by the drilling fluid pump is eliminated in the process, no pump pressure interference contents exist in the delay differential detection signals, and the underground drilling fluid pressure signals contained in the delay differential detection signals are recovered through a signal reconstruction method based on a time domain differential equation or Fourier transformation so as to eliminate pump pressure interference influence in the signals and improve signal to noise ratio of the signals.

Description

Technical field: [0001] The invention relates to a processing method of measurement-while-drilling / logging-while-drilling uploaded signals during oil and gas drilling, and in particular to a method for eliminating pump pressure interference of drilling fluid continuous pressure wave signals for downhole data transmission based on drilling fluid. Background technique: [0002] Downhole measurement while drilling / logging while drilling (MWD / LWD) is a modern drilling auxiliary technology that measures and transmits downhole information in real time during drilling. During the drilling process, the drilling fluid is pumped downhole from the surface through the drill string, sprayed out from the water hole of the drill bit for the lubrication and cooling of the drill bit, and returns upward to the wellhead through the annular space between the well wall and the drill string. MWD / LWD tools are installed Inside the drill collar at the top of the bit, see attached figure 1 . In MW...

AI Technical Summary

Problems solved by technology

The pressure interference generated by the drilling fluid pump is related to the pump stroke rate, including fundamental waves and higher harmonics. When the pistons of the drilling fluid pumps have sealing problems that cause unbalanced work or the pump is in an abnormal working state, some high-order harmonics The amplitude of harmonics will become very large. Although the drilling fluid pump pipeline is equipped with pressure buffers or dampers, the pressure pulsation generated by the drilling fluid pump can still reach or exceed the downhole drilling fluid pressure detected by the ground riser Signal strength, these high-order harmonics will enter the frequency band of the drilling fluid continuous pressure wave signal and cause great interference, which will seriously reduce the signal-to-noise ratio of the signal, thus affecting the extraction of downhole measurement signals while drilling

The current drilling fluid pressure signal detection mainly uses a pressure sensor installed at the ground riser to measure the drilling fluid pressure, and the signal processing methods used, such as matched filter method, adaptive compensation method, wavelet analysis method, etc. The pressure signal transmitted in the baseband mode; and for the drilling fluid continuous pressure wave signal with a relatively high transmission rate, because the signal has the characteristics of frequency band transmission, the pressure interference generated by the drilling fluid pump can easily enter the signal frequency band, and the above-mentioned downhole drilling fluid pressure signal None of the existing detection and processing methods can effectively eliminate the influence of drilling fluid pump pressure interference that has entered the signal frequency band

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