Microseismic imaging using a source-independent full-waveform inversion method

Wang, Hanchen

doi:10.1190/segam2016-13946573.1

Cited by 14 publications

(8 citation statements)

References 11 publications

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“…However, an inaccurate velocity model of the subsurface usually leads to inaccurate passive seismic events determination. In order to solve this problem, Wang and Alkhalifah (2016) developed a source-independent full waveform inversion method to invert for the velocity model, as well as the passive seismic 2 Page 2 of 36 GEOPHYSICS 1 2 3 4 5 6 7 8 9 This paper presented here as accepted for publication in Geophysics prior to copyediting and composition.…”

Section: Introductionmentioning

confidence: 99%

“…In this article, we use the wave equation in an optimization problem to invert the source image and velocity model including the multi-scattered energy simultaneously in the frequency domain. Unlike the conventional time-domain wave equation used in passive seismic source image inversion (Wang and Alkhalifah, 2016), which separates the source term into the spatial and wavelet components, we incorporate the spatial and wavelet parts 3 Page 3 of 36 GEOPHYSICS 1 2 3 4 5 6 7 8 9 This paper presented here as accepted for publication in Geophysics prior to copyediting and composition. © 2019 Society of Exploration Geophysicists.…”

Section: Introductionmentioning

confidence: 99%

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Passive seismic event estimation using multiscattering waveform inversion

Song

Alkhalifah

2019

GEOPHYSICS

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Passive seismic monitoring has become an effective method to understand underground processes. Time-reversal-based methods are often used to locate passive seismic events directly. However, these kinds of methods are strongly dependent on the accuracy of the velocity model. Full-waveform inversion (FWI) has been used on passive seismic data to invert the velocity model and source image, simultaneously. However, waveform inversion of passive seismic data uses mainly the transmission energy, which results in poor illumination and low resolution. We developed a waveform inversion using multiscattered energy for passive seismic to extract more information from the data than conventional FWI. Using transmission wavepath information from single- and double-scattering, computed from a predicted scatterer field acting as secondary sources, our method provides better illumination of the velocity model than conventional FWI. Using a new objective function, we optimized the source image and velocity model, including multiscattered energy, simultaneously. Because we conducted our method in the frequency domain with a complex source function including spatial and wavelet information, we mitigate the uncertainties of the source wavelet and source origin time. Inversion results from the Marmousi model indicate that by taking advantage of multiscattered energy and starting from a reasonably acceptable frequency (a single source at 3 Hz and multiple sources at 5 Hz), our method yields better inverted velocity models and source images compared with conventional FWI.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Passive seismic event estimation using multiscattering waveform inversion

Song

Alkhalifah

2019

GEOPHYSICS

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“…They used FWI to invert for the source components. Wang and Alkhalifah (2016) developed a source-independent FWI method to invert for the velocity model, as well as the micro-seismic source image. By convolving reference traces with the observed and modeled data (Choi and Alkhalifah, 2011), the effect of the unknown source origin time can be mitigated.…”

Section: Introductionmentioning

confidence: 99%

Microseismic event estimation and velocity analysis based on a source-focusing function

Song

Alkhalifah

2019

GEOPHYSICS

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Attaining information corresponding to the microseismic source location helps in understanding the reservoir fracturing process. Time-reversal-based migration methods are widely used to obtain a source image directly. Such source-locating methods share a fundamental weakness: The accuracy of the source image depends highly on the accuracy of the velocity model. Full-waveform inversion (FWI) has been used in microseismic data to include an optimization of the source image and velocity model, simultaneously. However, such inversions are vulnerable to cycle-skipping problems, more so when the source location and source origin time are unknown. The computational cost of FWI is also high. To solve these problems, we have developed a source-focusing function as an additional objective to optimize the velocity model and source image. This objective function used to measure the source-image focusing property is defined by the estimated source-location coordinate and the source image. The source image is poorly focused if the velocity is inaccurate, and the objective function reaches a minimum when the velocity is accurate. We use the geometric-mean imaging condition to get a high-resolution source image at each iteration. Then, we use this source image to calculate the estimated source-location coordinate and the gradient of the objective functional with respect to the velocity. The optimized velocity can improve the source-image quality. In the end, the final output velocity and source image will allow us to fit the objective for all these attributes of the model and source image. Using synthetic data generated from the 2D Marmousi and the 3D overthrust models, we highlight the cycle-skipping immune and high-resolution features of our method. The application to field data also indicates that our method can improve the velocity model and source-image quality.

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“…We use l 2 norm to measure the difference between the modeled data and the observed data, for simplicity. More advanced Norms, such as the source independent objective function (Wang and Alkhalifah, 2016) can also be used. Unfortunately, the optimization problem (1) is highly nonlinear and suffers from cycle skipping.…”

Section: Theorymentioning

confidence: 99%

A New Wave Equation Based Source Location Method with Full-waveform Inversion

Wu¹,

Alkhalifah²

2017

Proceedings

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SummaryLocating the source of a passively recorded seismic event is still a challenging problem, especially when the velocity is unknown. Many imaging approaches to focus the image do not address the velocity issue and result in images plagued with illumination artifacts. We develop a waveform inversion approach with an additional penalty term in the objective function to reward the focusing of the source image. This penalty term is relaxed early to allow for data fitting, and avoid cycle skipping, using an extended source. At the later stages the focusing of the image dominates the inversion allowing for high resolution source and velocity inversion. We also compute the source location explicitly and numerical tests show that we obtain good estimates of the source locations with this approach.

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Microseismic imaging using a source-independent full-waveform inversion method

Cited by 14 publications

References 11 publications

Passive seismic event estimation using multiscattering waveform inversion

Passive seismic event estimation using multiscattering waveform inversion

Microseismic event estimation and velocity analysis based on a source-focusing function

A New Wave Equation Based Source Location Method with Full-waveform Inversion

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