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Multi-trace nonstationary sparse inversion with structural constraints

100%

Cheng L. , Wang S. , Li S. , Ji Y.

Acta Geophysica

2020

tom Vol. 68, no. 3

675--685

The recorded seismic signals are attenuated and spatially correlated due to their propagation through an elastic earth and the sedimentary rule of strata. This attenuation phenomenon is quantifed by means of the earth quality factor (Q) or the attenuation factor (1∕Q). Nowadays, the related Q-compensation and multi-trace inversion for the seismic data are two challenging problems when used for enhancing the temporal resolution and preserving the spatial continuity. Separately estimating Q and refectivity are difcult and produce the uncertainty or ill-condition problems. To overcome these limitations, we have developed a multi-trace nonstationary sparse inversion with structural constraint. Using prior dipping-angle information and refectivity sparsity property, the proposed method simultaneously estimates equivalent-Q and refectivity with structural constraint. Constructed by the source wavelet and diferent scanned equivalent-Q, a series of time-varying (nonstationary) wavelet matrices are provided for the forward-modeling schemes and the corresponding inversions. When the Q-model is infnitely close to the true attenuation mechanism, the corresponding inverted refectivity is comparatively sparse and quantifed as maximum sparsity or minimum sparse representation. A sparse representation function, such as l0.1-norm, is used for sparsity measurement of the inverted refectivity corresponding to each scanned Q. Through optimizing these sparse representation values, a suitable equivalent-Q, as well as the corresponding inverted refectivity with structural preservation and Q-attenuation, is determined. The synthetic and feld examples both confrmed a substantial improvement on seismic records, especially for Q-estimation, structure preservation and Q-compensation.

Multichannel sparse spike deconvolution based on dynamic time warping

88%

Zhao X. , Wang S. , Yuan S. , Cheng L. , Cai Y.

Acta Geophysica

2021

tom Vol. 69, no. 3

783--793

Seismic sparse spike deconvolution is commonly used to invert for subsurface refectivity series and is usually implemented as an inversion scheme. Conventional sparse spike deconvolution method does not utilize the relationships among adjacent traces resulting in instability and poor lateral continuity of the inverted result. We propose a multichannel sparse spike deconvolution method with a sparsity-promoting constraint and an extra lateral constraint exploiting the spatial relationships among adjacent seismic traces. Firstly, the dynamic time warping (DTW) is performed between any two adjoining seismic traces to obtain the warping path (a series of estimated time shifts of one seismic trace relative to the other). Based on the assumption that if the inverted refectivity series is convolved with the same wavelet used for inversion, the newly constructed adjoining seismic traces shall also be conformable to the relationships exploited among the original seismic traces by DTW. A diference operator is constructed with the estimated time shifts to guarantee the diference operation is performed between corresponding time samples on adjoining seismic traces and the inversion is regularized with this diference operator as the lateral constraint. Synthetic and real data case studies confrm that inverted result obtained by the proposed method is superior to those obtained by single-channel sparse spike deconvolution method and another multichannel deconvolution method based on horizontal frst-order derivative constraint in both signal-to-noise ratio and lateral continuity.