Joint Inversion Method of Ocean Controlled Source Electromagnetic and Magnetotelluric Based on Product Function

Abstract

The invention provides a combined inversion method of ocean controllable source electromagnetic and magnetotelluric based on a product function, comprising: reading and converting ocean controllable source electromagnetic field and ocean magnetotelluric data; setting joint inversion execution parameters; establishing joint inversion Initial model; constructing joint inversion objective function; nonlinear transformation of inversion parameters; obtaining Jacobian and Hessian matrices of inversion data for formation anisotropic resistivity and formation thickness; calculating model parameter update based on inversion parameters search inversion update amount step size; calculate the inversion iteration fit difference; judge whether the inversion requirements are met; output the final inversion model. The method simultaneously inverts the anisotropic resistivity and thickness of the submarine formation, and the inversion efficiency is higher; at the same time, it combines the high resolution of the oceanic controllable source electromagnetic data for shallow formations, and the ability of magnetotelluric data to detect deep structures. The inversion effect is better than the traditional single electromagnetic data inversion; the proposed joint inversion method has wider applicability.

Description

technical field [0001] The invention relates to the technical field of marine geophysics of multi-parameter joint inversion, in particular to a joint inversion method of marine controllable source electromagnetic and magnetotelluric. Background technique [0002] The frequency domain ocean controlled source electromagnetic (CSEM) method emits high-power electromagnetic waves with a specific frequency, which can effectively distinguish the resistivity difference between surrounding rocks and oil and gas within a certain depth range, and has the ability to detect high-resistance thin layers. The natural electromagnetic field used by the marine magnetotelluric (MT) method has the characteristics of horizontally polarized plane waves, which makes the marine MT data sensitive to low-resistance formations. However, the MT method is not suitable for detecting oil and gas layers with shallow buried depth and thin layers. Mainly used to detect deep structures. In summary, CSEM and M...

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Problems solved by technology

However, the above methods only invert the resistivity information of the seabed medium, and the inversion model obtained by using the OCCAM method cannot reconstruct the high-resistivity oil and gas layers on the seafloor, and the inversion effect is not good; in addition, the inversion parameters of this method do not include Including the thickness of the seabed stratum, when setting the inversion model, set the seabed stratum to be divided into multiple thin layers for inversion, the inversion speed is slow and the efficiency is low

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