Towing cable earthquake data and little OBS data combined waveform inversion method

Abstract

The invention relates to a towing cable earthquake data and little OBS data combined waveform inversion method, and belongs to the field of full-waveform inversion speed modeling of ocean seismic prospecting. The method mainly comprises the following steps that 1) observed towing cable and OBS earthquake record data is obtained, and preprocessed; 2) seismic wavelets are extracted by a higher-orderstatistical method; 3) forward and backward wave fields corresponding to a towing cable earthquake record as well as those corresponding to an OBS earthquake record are calculated; 4) a gradient field of an objective function is calculated on the basis of an adjoint state method; 5) a conjugate gradient field and a correction of a speed model are calculated; 6) the speed model is updated in an iteration way; and 7) whether an iteration ending condition is met is determined, if NO, the step 3) is returned to, and otherwise, a result is output. The problem that waveform inversion only via the towing cable earthquake record lacks low-frequency earthquake information and is in accurate in an inversion result can be solved.

Description

technical field [0001] The invention relates to a waveform inversion method combining streamer seismic data and a small amount of OBS data, belonging to the field of full waveform inversion velocity modeling of seismic exploration. Background technique [0002] There are many methods of velocity modeling, such as travel time tomography, slope tomography, Fresnel body tomography, migration velocity analysis, full waveform inversion, etc. Among these methods, full waveform inversion is one of the research hotspots in recent years, and it is also one of the methods most likely to obtain high-resolution and high-fidelity velocity modeling. [0003] However, full waveform inversion relies heavily on the accuracy of the initial velocity model and the low-frequency seismic information in the observed seismic records. For areas with complex geological structures, it is usually difficult to establish a sufficiently accurate initial velocity model for full waveform inversion using ex...

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Problems solved by technology

[0006] Aiming at the above defects in the prior art, the present invention proposes a waveform inversion method combining streamer seismic data and a small amount of OBS data, using a small amount of OBS observations to obtain the actual seismic low-frequency components, and solving the problem of using only streamer data for full During waveform inversion, the inversion result is unreliable due to the lack of low-frequency components

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