... of 4D FWI on field data have only been seen in a few surveys, either with high repeatability or with large velocity changes. We propose a new workflow to tackle some challenges in 4D FWI, such as cycle-skipping and amplitude mismatch between modeled synthetic data and recorded field data and water-layer...

... full-waveform inversion fwi artificial intelligence attenuation amplitude information full waveform inversion estimation propagation métivier vp 2500 velocity change Q estimation by full-waveform inversion: analysis and mis t functions comparison Peng Yong1 , Romain Brossier1, Ludovic Me...

.... A narrow band of frequencies are sensitive to near-surface hydrologic state, also accurately predicted by the model. Even though the estimated velocity changes are lower than experimentally measured, we believe that with better model calibration, perturbations in velocity can be accurately inverted...

... to inversion algorithms, the improvements in 3D illumination and 4D amplitudes, and adjoint operators from both Kirchhoff and RTM yield analyze the effects of velocity changes on 4D. images that are more susceptible to poor illumination and migration artifacts. Least-squares migration (LSM) reframes...

... of 4D velocity changes. A realistic synthetic study shows that a workflow of 4D JFWI followed by 4D FWI leads to an improved data fit as well as a more accurate estimate and better resolution of velocity changes than classical 4D FWI methods, in a reservoir zone that is not penetrated by diving waves...

... difference target-oriented time-lapse waveform inversion exploration geophysicist 10 vertical profile wavefield inversion result inversion robustness overburden model alkhalifah velocity change datum level Target-oriented time-lapse waveform inversion using redatumed data: Feasibility...

... velocity change seawater change Non-repeatability Effects on Time-Lapse 4D Seismic Full Waveform Inversion Wei Zhou, David Lumley, The University of Texas at Dallas SUMMARY 4D FWI which can better overcome NR errors. However, these studies are based on acoustic synthetic data, whereas the real Full...

..., but only predicted velocity changes. The numerical results sample very limited areas laterally. The well information demonstrate that the proposed method is capable of can be correlated to the inversion result from TLFWI using inverting for the time-lapse changes effectively in the target deep learning...

... of the velocity change. Here we show that, with a dense seismic array and intense spatial averaging, we can retrieve ballistic P-waves and Rayleigh waves from daily ambient-noise correlations. Measuring their time-shift in the time vs. offset domain for subsequent days allows us to monitor and locate velocity...

... the resulting optimization problem using differential evolution (DE), which allows us to have complete control over the allowable velocity changes and thus to guarantee that the measured borehole observations are honored well. Another key feature of the method is that, in contrast to manual tying and some...

... stratum heterogeneous media waveform upstream oil & gas density 2 coda wave velocity change physical model reservoir zero-offset data seg international exposition reservoir characterization An , S. P. , T. Y. , Hu , Y. F. , Cui , W.-S. , Duan , and G.-X...

...: Oral reservoir characterization upstream oil & gas nakata refracted wave surface wave velocity variation correlation campillo ambient seismic noise fundamental mode seg international exposition monitoring geophysical research letter annual meeting ambient noise velocity change...

... velocity changes induced by stimulation. Since distributed acoustic sensing allows high spatial and temporal sampling, these guided waves can be measured with high resolution, allowing them to be used for imaging and analysis. Presentation Date: Monday, September 16, 2019 Session Start Time: 1:50 PM...

... event in the data showed a much longer delay-time and could be a mode-converted and reflected S-wave below the well. The estimated velocity change from a traveltime simulation showed that the decrease in S-wave velocity could be higher than the P-wave velocity. These observations are investigated...

... ABSTRACT Time-lapse full waveform inversion (4D-FWI) is a key contender technology for high resolution characterisation of production related changes in complex subsurface. Typical recovered time-lapse velocity changes suffer from a poor signalto-noise ratio, e.g. due to acquisition...

... resolved. Both fundamental and first overtone Rayleigh waves are used to localise such changes, which correspond nicely to known geology to within 100 m. overtone correlation upstream oil & gas passive seismic ambient noise reservoir characterization velocity model velocity change velocity...

... noise correlation functions (NCFs) throughout the 18 months of recording to test whether the array’s NCFs were sensitive to near-surface velocity changes tied to seasonal saturation cycles. During rainier winter months, we see higher signal-to-noise ratios (SNR) in one-bit cross-correlations...

... of shear wave velocity change suggests that proppant did not reach the Upper Hamilton and Tully formations, and therefore these fractures did not remain connected to the borehole. Significant rock property changes were introduced in the Lower Hamilton, evidenced by the change in the shear velocities...

... the delays is not yet well-understood. Here, P-wave velocity changes caused by changing stress around fractures are investigated as a possible cause. Using an analytic 2D stress field and an empirical relation of velocity and effective stress, it is shown that time delays comparable to observed data can...

... velocity change. The regularization promote the velocity change to have the similar shape as the geomechanical attributes, overcoming the challenge of unknown scaling factors between different attributes. We show the potential of the proposed methods on synthetic models with both noise free data and noisy...