Simulation and Analysis of High-rate Continuous Wave Mud Pulse Decoding Experimental Pipeline
In response to the growing demand for drilling deep and ultra-deep wells in China,continuous wave mud pulse technology is evolving in the direction of long distance and high speed.COSL has constructed a mud circulation experimental system with a depth of 6 000 meters above ground.However,using a 50.8 mm hose upstream of the test instrument results in significant pipeline pressure loss and severe reflection interference due to diameter reduction.Consequently,the long-distance high-rate decoding experimental research is restricted.A simplified tool,namely a pipeline numerical model,has been established based on the experimental system to address this issue.This model has been employed to study the influence of the 50.8 mm hose on continuous wave signals and to verify the findings through decoding experiments.The results indicate that there is an enlargement of the 50.8 mm hose and circulating pipeline upstream of the test instrument,which results in waveform distortion due to the superposition of reflected waves and generated waves.The generated wave distortion becomes more pronounced with an increase in frequency.The inner diameter of the 50.8 mm hose is relatively small,the friction pressure drop along the pipeline is considerable,and the attenuation degree of pressure wave transmission is greater than that of an equal-length underground straight pipe.Following the replacement of the 50.8 mm hose with a 101.6 mm hose,the phenomenon of reducing reflection is eliminated,the friction pressure drop is reduced along the way,the low-frequency pressure wave shape is improved,the amplitude after transmission is increased by more than 75%,and the decoding bit error rate is effectively reduced.Finally,the experimental transmission rate of pipeline decoding at a height of 6 000 meters above ground was increased from 6bps to 8bps,which corroborates the findings of the numerical simulation.superposition of reflected waves and generated waves.The generated wave distortion becomes more pronounced with an increase in frequency.The inner diameter of the 50.8 mm hose is relatively small,the friction pressure drop along the pipeline is considerable,and the attenuation degree of pressure wave transmission is greater than that of an equal-length underground straight pipe.Following the replacement of the 50.8 mm hose with a 101.6 mm hose,the phenomenon of reducing reflection is eliminated,the friction pressure drop is reduced along the way,the low-frequency pressure wave shape is improved,the amplitude after transmission is increased by more than 75%,and the decoding bit error rate is effectively reduced.Finally,the experimental transmission rate of pipeline decoding at a height of 6 000 meters above ground was increased from 6 bps to 8 bps,which corroborates the findings of the numerical simulation.
deep wellcontinuous wave mud pulsetransmission rate2FSKpressure wave distortionnumerical simulation
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