Research On Noise Canceling Algorithm Of High Speed Mud Pulse Signal

Oil is called "the blood of industry",with the rapid development of modern industry,global oil demand has grown strongly.Logging is an integral part of oil exploration and production.Measurement While Drilling(MWD)technology can measure the collected downhole parameter information in real time while drilling,and transmit the obtained information to the ground through the transmission medium,then use the ground system to process and interpret the information,and finally achieve an improvement in drilling efficiency.In the MWD system,the use of mud pressure pulse signals in the drilling fluid column to transmit data is most widely used.However,the mud channel environment is very harsh,and the signal has a long-distance transmission attenuation effect.In addition,the working environment is very complicated.The drilling platform brings various kinds of mechanical noise,and some noise spectrum is distributed in the pulse signal band,eventually leading to the signal detected at the wellhead is very weak and there is a very serious noise interference,which causes great difficulty to the identification and processing of the signal.Therefore,how to separate the useful signal from the complex noise environment and suppress the noise interference becomes an urgent problem to be solved in the MWD system.In this paper,concerned about the issues of the complex channel bandwidth,variable noise structure and low data transmission rate of the mud wave MWD system,the analysis of the characteristics of mud channel,signal and noise in detail,and combines the well data to obtain the mud channel response.A simulation model of signal and noise is established.Furthermore,based on the simulation model,the methods of canceling noise are studied from the two aspects of adaptive denoising based on pumping interference model and null space pursuit(NSP).As a result,the effectiveness of the methods is given out by simulation experiments and real well data.The main research work and contributions of this thesis are listed as follows:1.In a brief statement,the generation and transmission process of mud continuous wave signal is briefly described.The characteristics of channel transmission,mud pulse signal and background noise are analyzed.The signal waveform and pumping interference model are established based on experimental data to generate different parameters.2.The adaptive denoising method based on the pump noise model is studied.The method is based on the output signal of the pump sensor.The pumping noise is periodic,and the time and frequency domain of pump noise are established model.The model parameters of the pump noise are adaptively estimated from the received signal,and the simulated analog signal and the real well signal are respectively considered in consideration of the time domain empirical waveform and the frequency domain suppression.For the Manchester coded mud pulse signal,the pump is based on the pump.The time domain adaptive denoising method of the interference model is better;for the FSK modulated mud pulse signal,the frequency domain adaptive denoising method based on the pumping interference model is better.3.The signal decomposition method based on null space pursuit(NSP)is studied.The theoretical model and solution steps of NSP algorithm are expounded in detail.The effectiveness of local orthogonal constraint on signal adaptive decomposition method is discussed,and the pulse continuous wave signal is applied.The characteristics of the algorithm are optimized.The simulation results verify the effectiveness of the NSP method for mud pulse continuous wave signal processing.