A Seismic Inversion Method Based on Waveform Slight Change Matching

Abstract

The invention discloses a seismic inversion method based on waveform micro-variation matching. Firstly, the positions of sparse sequences having large reflection coefficients are roughly searched, square wave processed impedance predicting sequences matched with seismic amplitude, phase and frequency are established through speed trend and compaction trend constraints by combining with reservoir prediction and hydrocarbon detection results, then the positions of sparse sequences having small reflection coefficients (or impedance predicting sequences) are determined through repeated iteration according to waveform micro-variation information, information such as the physical micro structure of the earth and micro-geological seismic response is fully mined, finally more accurate geological meaning is endowed to the formation by combining with physical analysis results of rocks to achieve accurate analysis on seismic waveform characteristics. In the inversion process, due to the fact thatreflection coefficients have stronger sparsity, inversion result interfaces have blocked characteristics (similar to square wave characteristics) and strong anti-noise capacity, and the readability of a formation interface is effectively improved.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration, in particular to a seismic inversion method based on waveform micro-variation matching. Background technique [0002] The fundamental task of oil and gas seismic exploration is to study and extract the physical parameters of the underground medium, such as velocity and density, based on various observed information, and to evaluate the oil and gas bearing properties of the reservoir. Seismic inversion, as a key technology for oil and gas exploration reservoir prediction and fine reservoir description, has solved the current geological problems at various stages of technology development and achieved good oil and gas exploration results. With the progress of exploration and development of oil and gas fields, marine basins generally develop reservoirs with complex structures, such as channels, beach bars, etc., with small single-layer thickness, rapid lateral changes, and complex di...

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Problems solved by technology

Moreover, these inversion methods are all based on the theory of the convolution model, and it is easy to ignore the small changes in the waveform of the actual seismic data, and the seismic data eliminates such as surface seismic geological conditions, geometric diffusion and ground filtering effects, seismic wavelet distortion, instrument and In addition to the influence of acquisition parameters and other factors, the seismic waveform characteristics are the reflection of different underground lithological combinations and physical properties, that is, different underground geological combinations correspond to different seismic waveform characteristics, and similar underground geological combinations correspond to similar seismic response characteristics. Making full use of the advantages of full waveform (amplitude, frequency, phase) information for inversion is the key to improving inversion accuracy

[0007] Seismic waveform is a comprehensive reflection of dynamic characteristics such as amplitude, frequency, and phase of the reflected wave of an underground geological body. Conventional seismic inversion methods are often only a waveform feature analysis method for a single physical parameter, while ignoring the frequency, phase information and Information such as microstructure and microgeological seismic response is limited by the limited bandwidth of seismic data, and the resolution of conventional seismic inversion is limited, which leads to the inversion results showing gradual changes at the stratigraphic interface, and it is difficult to accurately describe the real position of the actual stratigraphic interface. The accuracy of depth and thickness prediction is low

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