Research On Signal Processing Method Of Drilling Fluid Continuous Wave In Oil Drilling

In the Measurement While Drilling system，the data transfer rate of drilling fluidpositive pulse is very low，which affects the productive effency seriously；while thecontionuous pressure wave has ability of higher data transfer rate and strongeranti-jamming. This paper does the research work of contionuous pressure wave in thesimulation environment of MATLAB，and establishes the mathematical model ofcontionuous wave through analyzing the transmission characteristics and noisecontribution of observed data，and presents a de-noising scheme. The research work asfollows：Firstly，the mathematical model of acquired contionuous wave is established. Makea study of the background knowledge of Measurement While Drilling system，includingthe way and the characteristic of data transter，and the state of development ofcontinuous wave. According to the observed data and noise contribution, themathematical model of acquired contionuous wave is established.Secondly，the overall de-noising scheme is programmed. Based on the establishedmathematical model，the MPSK based on PPM is determined after compares to thetransmission performance of two typical Modulation Type. The acquired contionuouswave is emulated through setup simulation parameters. And different de-noising methodis used to dispose two types of noise：pump noise and white Gaussian noise. Afterremoving the noise，the useful information is extracted from reconstructed signal.Thirdly，in order to remove white Gaussian noise further，a united de-noisingscheme is designed based on stationary wavelet transform and Empirical ModeDecomposition，this scheme can behave the advantage of both stationary wavelettransform and Empirical Mode Decomposition. The mirror extension is chosed and themiddle part of the reconstructed data is reserved to inhibit the end effect during thedecomposition process. In the implementation process，the wavelet basis、the level ofdecomposition、threshold and threshold function are determined. The simulation testshowes the united scheme has a better denoising effect and higher reliability than thestationary wavelet transform.