Sensitivity analyses of acoustic impedance inversion with full-waveform inversion

Yao, Gang; Silva, Nuno V. da; Wu, Di

doi:10.1088/1742-2140/aaa980

Cited by 7 publications

(1 citation statement)

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“…b At subsequent iterations, reflected energy exists in both wavefields. Cross-correlation can now update the velocity model, but the magnitude of this tomographic effect varies as R 2 , whereas updates to the reflectivity vary as R. Usually, R is much smaller than 1 (Yao and Wu 2017) the significance of FWI inverting reflection-dominated data (Wang and Rao 2009;Lazaratos et al 2011;Plessix and Li 2013;Routh et al 2016;Yao et al 2018b). The contradiction and trapping in a local minimum are the second weakness of conventional FWI for inverting reflection data.…”

Section: The Weaknesses Of Conventional Fwi For Inverting Reflection mentioning

confidence: 99%

A review on reflection-waveform inversion

Yao

Wang

2020

Pet. Sci.

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Full-waveform inversion (FWI) utilizes optimization methods to recover an optimal Earth model to best fit the observed seismic record in a sense of a predefined norm. Since FWI combines mathematic inversion and full-wave equations, it has been recognized as one of the key methods for seismic data imaging and Earth model building in the fields of global/regional and exploration seismology. Unfortunately, conventional FWI fixes background velocity mainly relying on refraction and turning waves that are commonly rich in large offsets. By contrast, reflections in the short offsets mainly contribute to the reconstruction of the high-resolution interfaces. Restricted by acquisition geometries, refractions and turning waves in the record usually have limited penetration depth, which may not reach oil/gas reservoirs. Thus, reflections in the record are the only source that carries the information of these reservoirs. Consequently, it is meaningful to develop reflection-waveform inversion (RWI) that utilizes reflections to recover background velocity including the deep part of the model. This review paper includes: analyzing the weaknesses of FWI when inverting reflections; overviewing the principles of RWI, including separation of the tomography and migration components, the objective functions, constraints; summarizing the current status of the technique of RWI; outlooking the future of RWI.

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Section: The Weaknesses Of Conventional Fwi For Inverting Reflection mentioning

confidence: 99%

A review on reflection-waveform inversion

Yao

Wang

2020

Pet. Sci.

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3-D joint inversion of seismic waveform and airborne gravity gradiometry data

Jiang

2020

Geophysical Journal International

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Summary Seismic full waveform inversion is a robust velocity model building technique for hydrocarbon exploration. However, the density reconstruction within the framework of multiparameter full waveform inversion leads to more degrees of freedom in the parameterization, and the sensitivity of the inversion change significantly from velocity to density, thereby increasing the ill-posedness of the inverse problem. Gravity gradiometry data inversion is an effective method for resolving density distribution. Combining gravity gradiometry data in full waveform inversion could alleviate the nonlinearity of the inversion by contributing additional density information for the velocity model building. I develop a 3D joint seismic waveform and gravity gradiometry inversion method for estimating the velocity and density distribution in the subsurface. The method alternatingly minimizes the waveform and gravity gradiometry misfit. The cross-gradient constraint is applied to enhance the structural similarity between the density and velocity models. The effectiveness of the joint inversion algorithm is demonstrated by a 3D checkerboard model and 3D SEAM model. Synthetic examples demonstrate that the joint inversion can improve the image quality in geologically complex areas. A case study from the South China Sea shows that the joint inversion improves the velocity and density solutions compared to a standalone seismic full waveform inversion. The joint inversion results are consistent with the prestack depth migration section and the shape of the salt body is well resolved.

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Full-waveform inversion of ground-penetrating radar data in frequency-dependent media involving permittivity attenuation

Tan

Bohlen

Allroggen

2022

Geophysical Journal International

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Summary Full-waveform inversion (FWI) of ground-penetrating radar (GPR) data has received particular attention in the past decade because it can provide high-resolution subsurface models of dielectric permittivity and electrical conductivity. In most GPR FWIs, these two parameters are regarded as frequency independent, which may lead to false estimates if they strongly depend on frequency, such as in shallow weathered zones. In this study, we develop frequency-dependent GPR FWI to solve this problem. Using the τ-method introduced in the research of viscoelastic waves, we define the permittivity attenuation parameter to quantify the attenuation resulting from the complex permittivity and to modify time-domain Maxwell’s equations. The new equations are self-adjoint so that we can use the same forward engine to back-propagate the adjoint sources and easily derive model gradients in GPR FWI. Frequency dependence analysis shows that permittivity attenuation acts as a low-pass filter, distorting the waveform and decaying the amplitude of the electromagnetic waves. The 2-D synthetic examples illustrate that permittivity attenuation has low sensitivity to the surface multi-offset GPR data but is necessary for a good reconstruction of permittivity and conductivity models in frequency-dependent GPR FWI. As a comparison, frequency-independent GPR FWI produces more model artefacts and hardly reconstructs conductivity models dominated by permittivity attenuation. The 2-D field example shows that both FWIs reveal a triangle permittivity anomaly which proves to be a refilled trench. However, frequency-dependent GPR FWI provides a better fit to the observed data and a more robust conductivity reconstruction in a high permittivity attenuation environment. Our GPR FWI results are consistent with previous GPR and shallow-seismic measurements. This research greatly expands the application of GPR FWI in more complicated media.

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Sensitivity analyses of acoustic impedance inversion with full-waveform inversion

Cited by 7 publications

References 50 publications

A review on reflection-waveform inversion

A review on reflection-waveform inversion

3-D joint inversion of seismic waveform and airborne gravity gradiometry data

Full-waveform inversion of ground-penetrating radar data in frequency-dependent media involving permittivity attenuation

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