Parameter crosstalk and modeling errors in viscoacoustic seismic full-waveform inversion

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. R641-R653 ◽  
Author(s):  
Scott Keating ◽  
Kristopher A. Innanen
Keyword(s):  
Waveform Inversion ◽  
Sufficient Information ◽  
Full Waveform Inversion ◽  
Full Spectrum ◽  
Attenuation Model ◽  
Frequency Bands ◽  
Intrinsic Attenuation ◽  
Full Waveform ◽  
Modeling Errors ◽  
Seismic Acquisition

Simultaneous use of data within relatively broad frequency bands is essential to discriminating between velocity and [Formula: see text] errors in the construction of viscoacoustic full-waveform inversion (QFWI) updates. Individual frequencies or narrow bands in isolation cannot provide sufficient information to resolve parameter crosstalk issues in a surface seismic acquisition geometry. At the same time, too broad a frequency band introduces significant problems in the presence of modeling errors. The risk of modeling errors arising in QFWI is high because of the range of very different geologic contributors to attenuation and dispersion and the variety of available mathematical descriptions. We perform numerical tests that suggest that by relaxing the typical requirement that the frequency dependence of the assumed intrinsic attenuation model be self-consistent across the full spectrum, significant improvement in the fidelity of the inversion results can be obtained in cases where the attenuation model assumed in the inversion differs substantially from the true subsurface behavior. We find that the size of the frequency bands used in this inversion approach is a useful hyperparameter controlling trade-off between crosstalk reduction and flexibility in coping with uncertain physics.

scholarly journals Semiglobal viscoacoustic full-waveform inversion

Geophysics ◽  
2019 ◽  
Vol 84 (2) ◽  
pp. R271-R293 ◽  
Author(s):  
Nuno V. da Silva ◽  
Gang Yao ◽  
Michael Warner
Keyword(s):  
Physical Properties ◽  
Wave Velocity ◽  
Seismic Data ◽  
Waveform Inversion ◽  
P Wave ◽  
Full Waveform Inversion ◽  
Data Set ◽  
Intrinsic Attenuation ◽  
Full Waveform ◽  
P Wave Velocity

Full-waveform inversion deals with estimating physical properties of the earth’s subsurface by matching simulated to recorded seismic data. Intrinsic attenuation in the medium leads to the dispersion of propagating waves and the absorption of energy — media with this type of rheology are not perfectly elastic. Accounting for that effect is necessary to simulate wave propagation in realistic geologic media, leading to the need to estimate intrinsic attenuation from the seismic data. That increases the complexity of the constitutive laws leading to additional issues related to the ill-posed nature of the inverse problem. In particular, the joint estimation of several physical properties increases the null space of the parameter space, leading to a larger domain of ambiguity and increasing the number of different models that can equally well explain the data. We have evaluated a method for the joint inversion of velocity and intrinsic attenuation using semiglobal inversion; this combines quantum particle-swarm optimization for the estimation of the intrinsic attenuation with nested gradient-descent iterations for the estimation of the P-wave velocity. This approach takes advantage of the fact that some physical properties, and in particular the intrinsic attenuation, can be represented using a reduced basis, substantially decreasing the dimension of the search space. We determine the feasibility of the method and its robustness to ambiguity with 2D synthetic examples. The 3D inversion of a field data set for a geologic medium with transversely isotropic anisotropy in velocity indicates the feasibility of the method for inverting large-scale real seismic data and improving the data fitting. The principal benefits of the semiglobal multiparameter inversion are the recovery of the intrinsic attenuation from the data and the recovery of the true undispersed infinite-frequency P-wave velocity, while mitigating ambiguity between the estimated parameters.

scholarly journals Bayesian Full-waveform Inversion with Realistic Priors

Geophysics ◽  
2021 ◽  
pp. 1-20
Author(s):  
Xin Zhang ◽  
Andrew Curtis
Keyword(s):  
Prior Information ◽  
Velocity Structure ◽  
Waveform Inversion ◽  
Full Waveform Inversion ◽  
Reflection Seismic ◽  
Variational Bayesian Inference ◽  
Full Waveform ◽  
Highly Nonlinear ◽  
Seismic Acquisition ◽  
Using Data

Seismic full-waveform inversion (FWI) uses full seismic records to estimate the subsurface velocity structure. This requires a highly nonlinear and nonunique inverse problem to be solved, so Bayesian methods have been used to quantify uncertainties in the solution. Variational Bayesian inference uses optimization to provide solutions efficiently. However, previously the method has only been applied to a transmission FWI problem, and with strong prior information imposed on the velocity such as is never available in practice. We show that the method works well in a seismic reflection setting, and with realistically weak prior information, representing the type of problem that occurs in reality. We conclude that the method can produce high-resolution images and reliable uncertainties using data from standard reflection seismic acquisition geometry, realistic nonlinearity, and practically achievable prior information.

Introduction to this special section: Seismic acquisition

2022 ◽  
Vol 41 (1) ◽  
pp. 8-8
Author(s):  
Keith Millis ◽  
Guillaume Richard ◽  
Chengbo Li
Keyword(s):  
Special Section ◽  
Waveform Inversion ◽  
Environmental Concerns ◽  
Full Potential ◽  
Full Waveform Inversion ◽  
Low Frequencies ◽  
Seismic Surveys ◽  
Operational Risks ◽  
Full Waveform ◽  
Seismic Acquisition

In the life cycle of a seismic product, the lion's share of the budget and personnel hours is spent on acquisition. In most modern seismic surveys, acquisition involves hundreds of specialized personnel working for months or years. Seismic acquisition also must overcome potential liabilities and health, safety, and environmental concerns that rival facility, pipeline, construction, and other operational risks. As only properly acquired data can contribute effectively to processing and interpretation strategies, a great deal of importance is placed on acquisition quality. Arguably, many of the advances the seismic industry has experienced find their origin arising from advances in acquisition techniques. Full-waveform inversion (FWI), for example, can reach its full potential only when seismic acquisition has provided both low frequencies and long offsets.

Seismic Soundoff

2020 ◽  
Vol 39 (4) ◽  
pp. 296-296
Author(s):  
Andrew Geary
Keyword(s):  
Survey Design ◽  
New Technology ◽  
Waveform Inversion ◽  
Full Waveform Inversion ◽  
Seismic Surveys ◽  
Full Waveform ◽  
Short Course ◽  
Seismic Acquisition

The following is an excerpt from SEG's podcast, Seismic Soundoff. In this episode, host Andrew Geary previews Dave Monk's upcoming Distinguished Instructor Short Course and book titled, “Survey design and seismic acquisition for land, marine, and in-between in light of new technology and techniques.” In this engaging conversation, Dave and Andrew discuss how full-waveform inversion impacts survey design, the research breakthroughs needed for the next evolution of seismic surveys, and one group that may not realize that this course is for them. Listen to the full episode at https://seg.org/podcast/post/8946 .

Source-independent time-domain vector-acoustic full-waveform inversion

Geophysics ◽  
2019 ◽  
Vol 84 (4) ◽  
pp. R489-R505 ◽  
Author(s):  
Yu Zhong ◽  
Yangting Liu
Keyword(s):  
Particle Velocity ◽  
Time Domain ◽  
Seismic Data ◽  
Waveform Inversion ◽  
Velocity Model ◽  
Full Waveform Inversion ◽  
Full Waveform ◽  
Adjoint State ◽  
Dual Sensor ◽  
Seismic Acquisition

Dual-sensor seismic acquisition systems that record the pressure and particle velocity allow the recording of the full-vector-acoustic (VA) wavefields. Most previous studies have focused on data-domain processing methods based on VA seismic data; whereas, few studies focused on using full-VA seismic data in full-waveform inversion (FWI). Conventional acoustic FWI only takes advantage of the pressure recordings to estimate the medium’s velocity model. Some artifact events will appear in the adjoint-state wavefields based on the conventional acoustic FWI method. These artifact events further reduce the accuracy of acoustic FWI. To simultaneously use pressure and vertical particle velocity recordings, we introduced a new time-domain VA FWI method. The VA FWI method can take advantage of directivity information contained in the VA seismic data. Thus, the adjoint-state wavefields based on VA FWI are more accurate than those from the conventional acoustic FWI method. In addition, we applied a convolution-based objective function to eliminate the effects of the source wavelet and implement a time-domain multiscale strategy in VA FWI. Synthetic examples are presented to demonstrate that VA FWI can improve the accuracy of acoustic FWI in the presence and absence of a free surface in the acoustic case. In addition, VA FWI does not significantly increase the computation and memory costs, but it has better convergence when compared with conventional acoustic FWI.

scholarly journals Addressing viscous effects in acoustic full-waveform inversion

Geophysics ◽  
2018 ◽  
Vol 83 (6) ◽  
pp. R611-R628 ◽  
Author(s):  
Òscar Calderón Agudo ◽  
Nuno Vieira da Silva ◽  
Michael Warner ◽  
Tatiana Kalinicheva ◽  
Joanna Morgan
Keyword(s):  
Wave Velocity ◽  
Waveform Inversion ◽  
Velocity Model ◽  
P Wave ◽  
Full Waveform Inversion ◽  
Viscous Effects ◽  
Approximate Estimate ◽  
Intrinsic Attenuation ◽  
Full Waveform ◽  
P Wave Velocity

In conventional full-waveform inversion (FWI), viscous effects are typically neglected, and this is likely to adversely affect the recovery of P-wave velocity. We have developed a strategy to mitigate viscous effects based on the use of matching filters with the aim of improving the performance of acoustic FWI. The approach requires an approximate estimate of the intrinsic attenuation model, and it is one to three times more expensive than conventional acoustic FWI. First, we perform 2D synthetic tests to study the impact of viscoacoustic effects on the recorded wavefield and analyze how that affects the recovered velocity models after acoustic FWI. Then, we apply the current method on the generated data and determine that it mitigates viscous effects successfully even in the presence of noise. We find that having an approximate estimate for intrinsic attenuation, even when these effects are strong, leads to improvements in resolution and a more accurate recovery of the P-wave velocity. Then, we implement and develop our method on a 2D field data set using Gabor transforms to obtain an approximate intrinsic attenuation model and inversion frequencies of up to 24 Hz. The analysis of the results indicates that there is an improvement in terms of resolution and continuity of the layers on the recovered P-wave velocity model, leading to an improved flattening of gathers and a closer match of the inverted velocity model with the migrated seismic data.

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