Analysis And Research On The Numeric Simulation Based On CSEM Emission Signal

In twenty-first Century, focus on oil exploration from land to seatransfer.3Dseismic exploration has been an important means of submarine formation for marinedrilling In many detection methods. But oil companies in the face of the huge risk ofoffshore oil and gas drilling, is not satisfied with only know the accuracy of submarin-e structure but also hope known fluid structures before drilling, in order to improvet-he success rate of drilling. based on the Marine controlled source electromagnetic so-unding method can be very good to complete the task, scense to the seabed rock med-ium is complex, and different media on the electromagnetic wave’s absorption, atten-uation and propagation characteristics are different, the high resistance body, relative-ly slow attenuation of electromagnetic wave, can be transmitted to a distance, and inthe low resistance body, the attenuation is very fast, at the same time,as everyoneknows electromagnetic wave decay into a proportionalrelationnship with the frequen-cy, the higher the frequency, the attenuation faster, the shorter transmission distance.Then for the bottom medium is complex,how the propagation characteristics of electr-omagnetic wave is?From this point this article mainly to achieve the following threeobjectives:（1） familiar with hardware of marine controlled-source electromagnetic(MCSEM) detection technology, determinating several importantparameters of it,and understanding its theoretical basis,and as basis asdeducting correlation formula.（2） Derivation of the electromagnetic field equation excited byderivation of electric dipole source,and the electromagneti wave’sattenation characteristics in the medium of submarine.（3） Find out the relation between emission frequency andsource-receiver offset and sounding,and Argument the feasibility ofair transmission mode by comparative analysis base on submarineemission mode.（4） Reasonable simulations of the relationship between the parameters ofMCSEM by the numerical simulation,and provide a theoretical basis for the selection of relevant parametersIn this paper, useed the electric dipole source as excitation source and establishthe corresponding model.Deduced the characteristics of electromagnetic wave exci-tationed by electric dipole source base on Maxwell equations and electromagneticfield theory.As to the attenuation of electromagnetic wave is decayingexponential,forincrease the electromagnetic in case of using artificeial sources to firing, can only usethe low frequency signal as excitation mode, generally between0.01Hz~50Hz, intheoryly the lower the frequency theattenuation is slowly, but withthe decrease of thefrequency,the near field of The electromagnetic field emosioned by electric dipole so-urce become bigger, and in the near field, the fluctuations are small,this case, theability to distinguish the target which lays in some shallow layer body will lose. Ther-efore, reasonable choice emission frequency is very important. Another parameter thathas an important effect on sounding is the transmitter receiver distance. If the transm-itter receiver distance too far, a lot of useful reflectionsignals may decay over beforeit propagate to the receiver. if too close will make direct wave transmissioning fromrock and seawater too strong to isolate useful reversal signal or can’t receives theelectromagnetic as to laying to S regional. therefore the selection of frequency and thetransmitter receiver distance is very important in the controlled source electromagn-etic marine sounding.In addition, The majior method of MCSEM sea bottom excitating,it is that usingKilometer’s cable on the end of a ship to drag the emission sources slow movingaboat50meters above the submarine. This mode can make energy of emissionedsignal translate into submarine as large as possible,but due to the transmit power isvery large in general range from100KW to200KW, so the requirements of cable isvery high, in addition, because the emission source is dragged in the seabad nearby,so there are requirements forsubmarine communication technology,therefore,thepossibility analys of emission by sea surface is nesessay.With the platform, because MATLAB has strong ability in mapping, but thereare some inadequate in object-oriented and visualization，on the contrary VC has st-rong ability in object-oriented and visualization but has some inadequate in mapping,according to this situation,this article use mixed programming with MATLAB and VCbase on COM component,by this technical support can obtain good effect both in thistwo aspects.