Research On Adaptive Finite Element2.5D Forward For The Marine CSEM Based On MPI

MT is widely used in oil exploration、geology and the earth’s deep interior and soon which has obtain significant results. There are many kinds of marineelectromagnetic methods. The most common methods are Marine MT and Marinecontrolled-source electromagnetic method. The first one records natural field and thesecond one records data from man-made source. However in marine environment,especially deep ocean area, the accuracy of MT is greatly reduced. This result isbecause sea water is a good conductor of electricity and can strongly absorbhigh-frequency natural field which makes MT cannot identify the shallow structure ofseafloor. Based on this situation EM is so long not applied in seafloor oil explorationfield. Until the last century90s, the instruments man-made transmitter and receiverwhich can stably work make it become possible for the use of Marine CSEM.Although foreign MCSEM is developing fast, domestic MCSEM still develops veryslowly. Each kinds of study assignment including instruments and sufficiently fastprogram are still far behind. Based on this situation, this paper complete the followwork which the author hopes to support the next step of study.(1)Investigate the foreign develop and study situation. Analyze the developdirection of Marine CSEM.(2)Brief introduction to foreign Marine CSEM instruments including transmitter、receiver and oil-exploration vessels. Brief introduction to the fundamentals of EMexploration theory and HED.(3)Brief introduction to the conception of2.5D, derivation of2.5D differentialequations, weighted residual quantity, finite element method, self-adaptive method,MPI and the process of2.5D program.(4)Tough the computing of2D verifies the2.5D program. Analyze the differencebetween1D and2D MVO. Analyze the influence of transmitter、reservoir、frequency、sea water and basement. This paper adopts MCSEM2.5D self-adaptive finite elementmethod to complete2D simulation. Discuss and analyze the influence of differentkinds of factor for MVO which provide the foundation of theory for the work andinversion in further.