Study On The Analysis Of Marine Controlled-source Electromagnetic Signal Preprocessing Method

Marine controlled-source electromagnetic (MCSEM) directly display measuringtechnology of oil and gas exploration technology for identifying resistivity reservoirand the surrounding sediments. It not only complement the shortcomings of marineseismic surveys, improve the success rate of drilling and exploration, but effectiveexploration for seabed oil-gas and gas hydrate reservoirs. CSEM methods waslaunched which uses electric dipole low frequency electromagnetic signal into theground. Bass response via a multi-component electromagnetic receiver arrays tocollect, through careful handling can determine a few kilometers deep resistivitystructure beneath the surface. Due to differences in measuring environmental, marinecontrolled-source electromagnetic data processing and of magnetotelluric data on landare very different. Current domestic marine CSEM exploration technology the reallines of research is still at an early stage, there has been no comprehensive marineelectromagnetic data processing and interpretation techniques. Current domesticmarine CSEM exploration technology research is still at an early stage, there has beenno comprehensive marine electromagnetic data processing and interpretationtechniques.1、From theory of Maxwell’s equations,combined with boundary conditions toderived the Maxwell’s equations of harmonious fields and electromagnetic field of ahorizontal electric dipole in homogeneous half-space,and analysis of the propagationcharacteristics of electromagnetic waves in sea water;2、Analysis of the send and receive signals on marine CSEM,demonstrates thebest transmitted waveform is the square wave, the receiver receives signals from threemain communication paths: direct, air-wave and the reflection and refraction fromsub-surface;3、Analysis of the influence of frequency on marine CSEM signal, transmittingfrequency the higher the stronger the normalized anomalies, the same excursion case,electric field amplitude increases with frequency and smaller;4、Analysis of marine CSEM data preprocessing steps: raw data is initialized bytemporal filtering, unit conversion and adjustment time window analysis; usingelliptical polarization analysis and analysis of rotating axis for azimuth correction; Bypressing on the air waves and wavelet analysis to eliminate noise of marine CSEM;finally merge navigation position data; 5、Analysis of the impact of air wave, discuss the air waves problem in shallowwater, it gets the inline data and lateral data simultaneously, combined with two kindsof data to remove the air waves;propsed Model subtraction to remove air-waveresponse;6、Using the wavelet shrinkage threshold method for marine CSEM analog noisesignal processing;...