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Collaborating Authors
Reservoir Description and Dynamics
Multi-scale full-waveform inversion constrained with patch-ordering smoothing
He, Huili (China University of Petroleum, Beijing) | Zhou, Hui (China University of Petroleum, Beijing) | Wang, Lingqian (China University of Petroleum, Beijing) | Fang, Jinwei (China University of Petroleum, Beijing) | Jiang, Shuqi (China University of Petroleum, Beijing)
In the process of patch-ordering Preconditioning and regularization is adopted to stabilize the smoothing, we decompose the inverted model into inverse problem in full waveform inversion. However, overlapping patches, construct a permutation matrix to order conventional isotropic smoothing blurs layer interfaces such these patches into a regular smooth sequence, and use a as faults and salt boundaries. In this paper, we propose a simple smoothing filter to obtain a stable reconstructed result patch-ordering smoothing operator for multi-scale full (Ram et al., 2013). Finally, we apply the proposed multiscale waveform inversion to improve the stability and lateral FWI constrained with patch-ordering smoothing to the continuity of the inversion result. Our algorithm is to apply 2D Overthrust model. The inversion result shows that the patch-ordering smoothing based on velocity magnitude interfaces are faithfully preserved and sharpened with our information obtained from each frequency-band velocity proposed method. Our algorithm is also able to delineate the inversion result.
- Research Report > New Finding (0.35)
- Research Report > Experimental Study (0.35)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic modeling (1.00)
ABSTRACT Reverse time migration with compensation (-RTM) is an effective approach to enhance the resolution of seismic images because it retrieves the amplitude loss and phase distortion induced by the viscosity of media. According to the crosscorrelation imaging condition, -RTM requires compensation for the amplitude loss in the propagation paths of source and receiver wavefields, which can be realized by solving an amplitude-boosted wave equation. However, the amplitude-boosted simulations suffer from numerical instability due to the amplification of high-frequency noise. We have developed a robust stabilization strategy for -RTM by incorporating a time-variant filter into the amplitude-boosted wavefield extrapolation step. We modify the Fourier spectrum of the operator that controls the amplitude compensation to be time variant, and we add to the spectrum a stabilization factor. Doing so, we integrate the time-variant filter into the viscoacoustic wave propagator implicitly, and we avoid any explicit filtering operation in -RTM. We verify the robustness of this stabilized -RTM with two synthetic data examples. We also apply this technique to a field data set to demonstrate the imaging improvements compared to an acoustic RTM and a more traditional -RTM method.
ABSTRACT The spatial derivatives in decoupled fractional Laplacian (DFL) viscoacoustic and viscoelastic wave equations are the mixed-domain Laplacian operators. Using the approximation of the mixed-domain operators, the spatial derivatives can be calculated by using the Fourier pseudospectral (PS) method with barely spatial numerical dispersions, whereas the time derivative is often computed with the finite-difference (FD) method in second-order accuracy (referred to as the FD-PS scheme). The time-stepping errors caused by the FD discretization inevitably introduce the accumulative temporal dispersion during the wavefield extrapolation, especially for a long-time simulation. To eliminate the time-stepping errors, here, we adopted the -space concept in the numerical discretization of the DFL viscoacoustic wave equation. Different from existing -space methods, our -space method for DFL viscoacoustic wave equation contains two correction terms, which were designed to compensate for the time-stepping errors in the dispersion-dominated operator and loss-dominated operator, respectively. Using theoretical analyses and numerical experiments, we determine that our -space approach is superior to the traditional FD-PS scheme mainly in three aspects. First, our approach can effectively compensate for the time-stepping errors. Second, the stability condition is more relaxed, which makes the selection of sampling intervals more flexible. Finally, the -space approach allows us to conduct high-accuracy wavefield extrapolation with larger time steps. These features make our scheme suitable for seismic modeling and imaging problems.
- Asia > China (0.47)
- North America > United States (0.29)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.46)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic modeling (1.00)
Compensating time-stepping error in fractional Laplacians viscoacoustic wavefield modeling
Wang, Ning (State Key Laboratory of Petroleum Resources and Prospecting, CNPC Key Lab of Geophysical Exploration, China University of Petroleum, Beijing) | Zhou, Hui (State Key Laboratory of Petroleum Resources and Prospecting, CNPC Key Lab of Geophysical Exploration, China University of Petroleum, Beijing) | Zhu, Tieyuan (Department of Geoscience and Institute of Natural Gas Research, Pennsylvania State University)
ABSTRACT The decoupled fractional Laplacian (DFL) viscous wave equations are commonly solved using the pseudospectral (PS) method, which usually introduces a high spatial accuracy but only second-order temporal accuracy. To eliminate the time-stepping errors, here we adopt the -space concept to the solver of DFL viscoacoustic wave equation. Different from the existing -space methods, the proposed k-space method for DFL viscoacoustic wave equation contains two correctors, which are designed to compensate for the time-stepping errors in the dispersion-dominated operator and the loss-dominated operator, respectively. Both theoretical analyses and numerical experiments show that the proposed k-space approach is superior to the traditional PS method mainly in three aspects. First, the proposed approach can effectively compensate for the time-stepping errors. Second, the stability condition is more relax, which makes the selection of sampling intervals more flexible. Finally, the k-space approach allows us to conduct high-accuracy wavefield extrapolation with larger time steps. These features make the proposed scheme be appealing for seismic modeling and imaging problems. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Start Time: 8:55 AM Location: 304A Presentation Type: Oral
- Geophysics > Seismic Surveying > Seismic Modeling (0.90)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.31)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
Fractional Laplacian visco-acoustic wave equation temporal extrapolation using a staggered-grid low-rank method
Jiang, Shuqi (China University of Petroleum (Beijing)) | Chen, Hangming (China University of Petroleum (Beijing)) | Zhou, Hui (China University of Petroleum (Beijing)) | Huang, Hua (China University of Petroleum (Beijing)) | Jiang, Chuntao (China University of Petroleum (Beijing)) | Zhang, Mingzhu (China University of Petroleum (Beijing))
ABSTRACT We develop a first-order fractional Laplacian visco-acoustic wave equation system in terms of pressure and particlevelocity. The first-order wave equation is more favored than the traditional second-order wave equation, because of its flexibility to incorporate the perfectly matched layer (PML) absorbing boundary condition and a spatial variable density. We derive an analytical temporal extrapolation formula under the staggered-grid configuration. The analytical extrapolation formula ensures an absolutely stable simulation result without numerical dispersion in homogeneous media. When simulating wave-propagation in heterogeneous media, we adopt the low-rank decomposition to approximate the k-space mixed-domain wave-propagator. The visco-acoustic staggered-grid low-rank extrapolation is more accurate than the conventional pseudo-spectral extrapolation method, and is subjected to a looser stability condition. Numerical examples verify the effectiveness of our visco-acoustic staggered-grid low-rank simulation method. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Start Time: 9:45 AM Location: 304A Presentation Type: Oral
Q-compensated viscoelastic reverse time migration using mode-dependent adaptive stabilization scheme
Wang, Yufeng (State Key Lab of Petroleum Resources and Prospecting) | Zhou, Hui (State Key Lab of Petroleum Resources and Prospecting) | Zhao, Xuebin (State Key Lab of Petroleum Resources and Prospecting) | Zhang, Qingchen (Chinese Academy of Geosciences) | Chen, Yangkang (Zhejiang University)
ABSTRACT The -compensated viscoelastic reverse time migration (-ERTM) method counteracts the subsurface quality-factor () filtering effect for attenuated multicomponent seismic data to produce high-quality migrated images. Compared with -compensated viscoacoustic reverse time migration (-ARTM), -ERTM provides more informative geologic and structural characterization of the subsurface, but it poses greater challenges on viscoelastic wavefield decomposition and stabilization. On the basis of our previously proposed stabilization operator for -ARTM, we have developed a mode-dependent adaptive stabilization scheme for -ERTM, which has the ability to handle the numerical instability issue arising from viscoelastic compensation. The stabilization scheme exhibits superior properties of time variance and dependence over the commonly used low-pass filtering method. In the context of the viscoelastic wave equation with decoupled fractional Laplacians, we have thoroughly investigated the staggered-grid pseudospectral approach for viscoelastic simulation, vector-based wavefield decomposition for imaging, and mode-dependent adaptive stabilization for compensation. These indispensable modules eventually form the whole framework for stable and accurate -ERTM. The -ERTM results including PP- and PS-images from synthetic and field data sets are provided to verify the feasibility and superiority of our approach in terms of fidelity and stability.
A stable approach for Q-compensated viscoelastic reverse time migration using excitation amplitude imaging condition
Zhao, Xuebin (China University of Petroleum-Beijing) | Zhou, Hui (China University of Petroleum-Beijing) | Wang, Yufeng (China University of Petroleum-Beijing) | Chen, Hanming (China University of Petroleum-Beijing) | Zhou, Zheng (China University of Petroleum-Beijing) | Sun, Pengyuan (BGP Research and Development Center of CNPC) | Zhang, Jianlei (BGP Research and Development Center of CNPC)
ABSTRACT The earth filtering causes poor illumination of the subsurface. Compensating for the attenuated amplitude and distorted phase is crucial during elastic reverse time migration (ERTM) to improve the imaging quality. Conventional -compensated ERTM (-ERTM) methods tend to boost the attenuated energy to inverse the effects. These methods usually suffer from severe numerical instability because of the unlimited amplification of the high-frequency noise. Low-pass filtering is generally used to stabilize the process, however, at the expense of precision. We have developed a stable compensation approach in this paper. Based on the decoupled fractional Laplacians viscoelastic wave equation, two compensation operators are obtained by extrapolating wavefield in the dispersion-only and viscoelastic media. Because no explicit amplification is included, these two operators are absolutely stable for implementation. To improve the division morbidity for calculating the compensation operators, we use the excitation amplitude criterion and embed the operators into a vector-based -compensated excitation amplitude imaging condition. With the derived imaging condition, we could compensate for the absorption accurately without needing to concern the stability issue. The -ERTM results for noise-free data are carried out over a simple layered model and a more realistic Marmousi model with an attenuating area to verify the feasibility of the proposed approach. The migration results for noisy data from the Marmousi model further prove that the proposed method performs better fidelity, adaptability, and antinoise performance compared with conventional compensation method with low-pass filtering.
Recovering the most from big gaps using least-squares inversion
Zu, Shaohuan (China University of PetroleumโBeijing) | Pan, Xiao (China University of PetroleumโBeijing) | Shuwei, Gan (China University of PetroleumโBeijing) | Zhou, Hui (China University of PetroleumโBeijing) | Chen, Yangkang (University of TexasโAustin) | Zhang, Dong (China University of PetroleumโBeijing) | Xie, Chunlin (E&D Research Institute, Daqing Oilfield Company)
ABSTRACT Seismic data are inadequately or irregularly sampled, particularly when there are big gaps, which will produce artifacts in the seismic imaging. The reconstruction can be posed as an inverse problem, which is known to be ill-posed and requires constraints to achieve unique and stable solutions. In this abstract, we propose an iterative scheme to reconstruct big gaps using least-squares method with slope constraint. In the proposed method, the slope estimation is a very important step. We apply an iterative scheme to estimate the slope field. In the first iteration, the smooth radius must be large to estimate smooth dip from the decimated data to guarantee the stability of inversion. In the later iterations, the smooth radius will be shortened in order to get more accurate dip estimation and good reconstruction result. We compare the proposed method and the well-known projection onto convex sets (POCS) method on the synthetic and field data examples. The interpolation results illustrate the advantage of the proposed method in constructing big gaps. Presentation Date: Tuesday, October 18, 2016 Start Time: 3:45:00 PM Location: 148 Presentation Type: ORAL
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Mingshui Formation (0.99)
A periodically varying code for improving deblending of simultaneous sources in marine acquisition
Zu, Shaohuan (China University of Petroleum) | Zhou, Hui (China University of Petroleum) | Chen, Yangkang (The University of Texas at Austin) | Qu, Shan (Delft University of Technology) | Zou, Xiaofeng (China University of Petroleum) | Chen, Haolin (BGP Inc.) | Liu, Renwu (BGP Inc.)
ABSTRACT We have designed a periodically varying code that can avoid the problem of the local coherency and make the interference distribute uniformly in a given range; hence, it was better at suppressing incoherent interference (blending noise) and preserving coherent useful signals compared with a random dithering code. We have also devised a new form of the iterative method to remove interference generated from the simultaneous source acquisition. In each iteration, we have estimated the interference using the blending operator following the proposed formula and then subtracted the interference from the pseudodeblended data. To further eliminate the incoherent interference and constrain the inversion, the data were then transformed to an auxiliary sparse domain for applying a thresholding operator. During the iterations, the threshold was decreased from the largest value to zero following an exponential function. The exponentially decreasing threshold aimed to gradually pass the deblended data to a more acceptable model subspace. Two numerically blended synthetic data sets and one numerically blended practical field data set from an ocean bottom cable were used to demonstrate the usefulness of our proposed method and the better performance of the periodically varying code over the traditional random dithering code.
- Asia > China (0.68)
- North America > United States > Texas (0.28)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
A k-space operator-based least-squares staggered-grid finite-difference method for modeling scalar wave propagation
Chen, Hanming (China University of Petroleum) | Zhou, Hui (China University of Petroleum) | Zhang, Qingchen (China University of Petroleum) | Xia, Muming (China University of Petroleum) | Li, Qingqing (China University of Petroleum)
ABSTRACT Two staggered-grid finite-difference (SGFD) schemes with fourth- and sixth-order accuracies in time have been developed recently based on new SGFD stencils. The SGFD coefficients of the two schemes are determined by a Taylor-series expansion (TE) approach, which is accurate only near a zero wavenumber. We have adopted the same SGFD stencils and determined the SGFD coefficients by minimizing the errors between the wavenumber responses of the SGFD operators and the first-order (wavenumber)-space operator in a least-squares (LS) sense. We solved the LS problems by performing a weighted pseudoinverse of nonsquare matrices to obtain the SGFD coefficients and to yield LS-based SGFD methods. We have developed an efficient LS implementation by using a small number of representative wavenumbers, which makes the computational time for estimating the coefficients negligible. Dispersion analysis and numerical examples demonstrate that our LS-based SGFD methods can preserve the original temporal accuracy and achieve better spatial accuracy than the existing TE-based SGFD methods. Extensive numerical tests proved that our LS-based methods do not damage the stability of the corresponding TE-based methods significantly.
- Geophysics > Seismic Surveying > Seismic Processing (0.93)
- Geophysics > Seismic Surveying > Seismic Modeling (0.93)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Data Science & Engineering Analytics (0.68)
- Reservoir Description and Dynamics > Reservoir Simulation (0.67)