2D Forward Research And Response Analysis For The Marine CSEM Method

Marine controlled source electromagnetic (Marine controlled-sourceelectromagnetic survey, MCSEM) are widely used in the prediction and evaluation ofreservoir value prior to the drilling of offshore oil and gas reservoirs. Marine CSEMtechnology owns many obvious advantages, include highly integrated data acquisitionequipments, controllable excitation frequency, controllable exploration depthaccording to the needs of target body, and abilities which can avoid climate changeimpacts and weak random natural source signal, laying the field source directly to topof the seabed target, detection of thin hydrocarbon layer of seabed several kilometersdeep. Comprehensive interpretation of CSEM and seismic, well logging, geology datacan effectively improve the interpretation accuracy of sheet resistivity oil and gas todistinguish between the underground oil or gas and other fluids, increase the precisionand accuracy of the exploration, improve drilling success rate.This article is based on the basic principles of the existing marine CSEMelectromagnetic method which mainly complete the following work:(1) In the frequency domain Maxwell equations for the theoretical foundation,in-depth understanding of the principle of marine controlled source electromagneticmethod, analysis of marine CSEM in domestic and international situation anddevelopment trend, with an emphasis on marine electromagnetic method of frequencydomain.(2) Master the basic theory of the electromagnetic field which is based on thefactor of marine layered medium electric dipole electromagnetic field propagationequation, the source of electric dipole emission of electromagnetic waves through astratified medium expression.(3) Describe the2.5-dimensional electromagnetic field numerical calculation ofthe theoretical methods, finite difference method to rewrite the2.5-dimensional (three-dimensional source, the two-dimensional geoelectric body) forward program,program input and output control and process analysis. By several calculations fortypical marine geoelectric models, it has been verified that is of feasibility andeffectiveness for the marine controlled source electromagnetic method in practicalapplications.(4) By understanding the characterization of propagation of horizontal electricaldipole in marine environment, marine magnetotelluric exploration of single-layersheet and double sheet model, the forward modeling, application MVO curve methodfor marine controlled source electromagnetic response characteristics of the study,discuss response to changes of parameters (distance between transmitter and receiver,the modes of transmission, depth, frequency).The thesis completes two-dimensional forward theoretical calculations of themarine controlled source electromagnetic method and finishes the analysis ofresponse to characteristics of the dipole source in the frequency domain, helps to carryout the better application in actual production for the marine CSEM method, laids atheoretical foundation for carrying out data processing and inversion. in the future.