| 1. |
- Liu, Yanrong, et al.
(författare)
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Cascade utilization of lignocellulosic biomass to high-value products
- 2019
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Ingår i: Green Chemistry. - : Royal Society of Chemistry. - 1463-9262 .- 1463-9270. ; 21:13, s. 3499-3535
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Tidskriftsartikel (refereegranskat)abstract
- Lignocellulosic biomass is a potential sustainable feedstock to replace fossil fuels. However, the complex structure of biomass makes it difficult to convert into high-value products. Utilization of lignocellulosic biomass in a green and effective way is of great significance for sustainable development. Based on the analysis of different options, we proposed that cascade utilization according to its composition, characteristics, and nature is the best way to utilize the lignocellulosic biomass. To promote the cascade utilization of lignocellulosic biomass, this article provides a review of the latest research results from the aspect of cascade utilization of lignocellulosic biomass covering the whole chain from pretreatment to high-value products, and the research on the non-conventional pretreatments including microwave irradiation, supercritical fluids, ultrasonic irradiation, electric field, hydrodynamic cavitation, and ionic liquids are presented in detail and evaluated by 4 proposed levels, and the newly developed high-value applications were further overviewed for lignin (carbon/graphene/carbon nano-tubes, dye dispersants, bioplastics, and aerogels), cellulose (cellulose-based ionic liquids, functional composites, adsorbent materials, carbon, and aerogels), and hemicellulose (films and pharmaceutical carriers), respectively. Finally, perspectives on the future research on the cascade utilization of lignocellulosic biomass are highlighted.
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| 2. |
- Zhang, Fengjiao, et al.
(författare)
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Passive seismic interferometry imaging : An example from the Ketzin pilot CO2 geological storage site
- 2022
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Ingår i: Journal of Applied Geophysics. - : Elsevier. - 0926-9851 .- 1879-1859. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- Ketzin is a well-known onshore CO2 geological storage test site. Injection started in June 2008 and ended in August 2013. About 67 kt of CO2 was injected into a saline aquifer reservoir. Numerous geophysical surveys have been conducted at the site, including passive seismic ones. Passive seismic interferometry can be applied in many seismic exploration investigations to image the underground structures. This study compares several passive seismic interferometry imaging methods to a data set acquired at Ketzin. The passive data set consist of 5 lines with 20 h of recordings in total. First, we apply the autocorrelation method to obtain zero offset stacked sections directly. Secondly, we test different interferometry methods to generate virtual shot gathers. These virtual shot gathers are then processed to obtain CDP stacked sections. Results from these methods are compared with an active data set recorded at the site. The processed passive sections have relatively less coherent reflections compared with the active stacked sections. However, the passive sections obtained by autocorrelation show good agreement with the active stacked sections. The stacked sections obtained by processing virtual shot gathers using crosscorrelation show similar features to the active stacked sections, but with poorer coherence in the reflections and are noisier than the autocorrelation sections.
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| 3. |
- Bergmann, Peter, et al.
(författare)
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Review on geophysical monitoring of CO2 injection at Ketzin, Germany
- 2016
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Ingår i: Journal of Petroleum Science and Engineering. - : Elsevier BV. - 0920-4105. ; 139, s. 112-136
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Tidskriftsartikel (refereegranskat)abstract
- Geophysical monitoring activities were an important component of the CO2 injection program at the Ketzin site, Germany. Here we report on the seismic and electrical resistivity tomography (ERT) measurements performed during the period of the site development and CO2 injection. Details on the site geology, the history of the CO2 injection operation, and petrophysical models relevant for the interpretation of the geophysical data are presented. The seismic measurements comprise 2D and 3D surface seismic surveys, vertical seismic profilings, and crosshole measurements. Apart from the measurements, results from advanced processing methods, such as impedance inversion and full-waveform inversion are also presented. In addition, results from crosshole ERT and surface-downhole ERT are presented. If operational efforts are taken into consideration we conclude that a combination of several geophysical methods is preferable given the demands of a spatiotemporally comprehensive monitoring program. We base this conclusion on that the different imaging characteristics and petrophysical sensitivities of different methods can complement each other. An important finding is, based on signal quality and reduced operational costs, that the use of permanent installations is promising. Generally, specific monitoring layouts will depend on site-specific characteristics, such as reservoir depth, availability of wells, petrophysical characteristics, and accessibility of surface locations. Given the comprehensive range of methods applied, the reported results are not only relevant to the operation of CO2 storage sites, but are also of interest to other monitoring projects dealing with fluid injection or production.
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| 4. |
- Duan, Chaoran, et al.
(författare)
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COMPRESSED FWI INVERSION WITH NON-MONOTONE LINE SEARCH LBFGS
- 2017
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Ingår i: Journal of Seismic Exploration. - : GEOPHYSICAL PRESS. - 0963-0651. ; 26:6, s. 561-586
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Tidskriftsartikel (refereegranskat)abstract
- Full waveform inversion (FWI) is a high quality seismic imaging method. It is a nonlinear inversion problem which usually needs the monotone line search method to be solved. However, the speed of convergence for such a simple search technique is relatively slow. In this paper, we combine the non-monotone line search technique with the LBFGS method and apply them to the frequency-domain FWI. We test this new method on a two-dimensional Marmousi model. The results show that the method is robust. Comparing with the monotone line search method, the new method could improve the convergence rate of FWI. We also test the new method with a two-dimensional conventional streamer data set and the results show some improvements compared with the conventional FWI method.
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| 5. |
- Fei, Huang, 1987-, et al.
(författare)
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DMO processing on the Ketzin 3D seismic data
- 2014
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Konferensbidrag (refereegranskat)abstract
- The Dip-moveout (DMO) correction is a process which attempts to make the finite offset data closer to zero offset data after the normal-moveout (NMO) correction. The NMO correction is then dip independent and reflections with different dips will stack coherently. DMO plays a critical role in seismic processing by enhancing the final image quality of the seismic data. In this study, we apply 3D Squeezing DMO (Hale and Artley, 1993) to seismic data from the Ketzin pilot CO2 site after NMO to study the impact of DMO on time-lapse seismic imaging and to investigate if it enhances the CO2 seismic monitoring technique. This 3D DMO method is based on an integral approach and incorporates Hale and Artley’s (1993) modifications for variable velocity with time. A constant velocity algorithm is used with a gamma correction function which depends on the velocity function. An anti-alias velocity of 3000 m/s is used for the DMO. After DMO the data are stacked and F-XY deconvolution is applied. Finally, 3D finite-difference migration using the final smoothed NMO velocities is performed for each data set.We then apply a time-lapse analysis to the 3D seismic data sets and compare the results with and without DMO processing. The most important aspect of the DMO processing is determining the velocity field for the NMO step. This is done by using the initial smoothed velocity field obtained from the conventional velocity analysis before DMO as a first estimate. The data are input into the DMO process and then inverse NMO is applied. These data are then subjected to a new velocity analysis and the velocity field is updated and used as input for the NMO process. A number of iterations are generally required until the velocity field does not need further updating. In this study velocities were picked at every 20th CDP in the inline and crossline directions. Compared to the velocity spectrum without DMO processing, the velocity trend is improved and the ambiguity in the velocity picks is eliminated after DMO correction. The improved accuracy of velocity picking makes it easier to interpret the velocity spectrum and obtain correct interval velocities. Considering the stacked section, DMO suppresses the random noise to a greater extent and thus the signal-to-noise ratio is enhanced. From the comparison of the amplitude difference horizon at the reservoir level, the shape of the anomaly observed in the data with DMO processing is similar to that observed in the data without DMO processing. However, the amplitude anomalies of the former are stronger than those of the latter, especially close to the injection well. In addition, one stronger amplitude anomaly in the DMO time-lapse horizon indicates a preferred trend of the CO2 migration in WNW direction due to the reservoir heterogeneity.
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| 6. |
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| 7. |
- Huang, Fei, 1987-, et al.
(författare)
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Application of seismic complex decomposition on thin layer detection of the CO2 plume at Ketzin, Germany
- 2015
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Konferensbidrag (refereegranskat)abstract
- The seismic complex decomposition technique is a spectral decomposition method using inversion strategies to decompose a seismic trace into its constituent frequencies and corresponding complex coefficients. This method has high time-frequency resolution and it is not necessary to select a signal window in comparison to conventional spectral decomposition methods. The thickness of the reservoir at the Ketzin pilot site is relatively thin, making it difficult to resolve seismically due to the band-limited seismic spectrum. This study presents an application of seismic complex decomposition to the time-lapse 3D seismic datasets at the Ketzin pilot site for estimating the temporal thickness of the injected CO2 within the thin reservoir via frequency tuning. Quantitative analysis for CO2 thickness and mass is investigated. Comparison between the real recorded data and the estimates shows that our results are reliable in assessing the amount of the CO2 in the plume at the Ketzin pilot site.
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| 8. |
- Huang, Fei, et al.
(författare)
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Feasibility of utilizing wavelet phase to map the CO2 plume at the Ketzin pilot site, Germany
- 2017
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Ingår i: Geophysical Prospecting. - : Wiley. - 0016-8025 .- 1365-2478. ; 65:2, s. 523-543
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Tidskriftsartikel (refereegranskat)abstract
- Spectral decomposition is a powerful tool that can provide geological details dependent upon discrete frequencies. Complex spectral decomposition using inversion strategies differs from conventional spectral decomposition methods in that it produces not only frequency information but also wavelet phase information. This method was applied to a time‐lapse three‐dimensional seismic dataset in order to test the feasibility of using wavelet phase changes to detect and map injected carbon dioxide within the reservoir at the Ketzin carbon dioxide storage site, Germany. Simplified zero‐offset forward modelling was used to help verify the effectiveness of this technique and to better understand the wavelet phase response from the highly heterogeneous storage reservoir and carbon dioxide plume. Ambient noise and signal‐to‐noise ratios were calculated from the raw data to determine the extracted wavelet phase. Strong noise caused by rainfall and the assumed spatial distribution of sandstone channels in the reservoir could be correlated with phase anomalies. Qualitative and quantitative results indicate that the wavelet phase extracted by the complex spectral decomposition technique has great potential as a practical and feasible tool for carbon dioxide detection at the Ketzin pilot site.
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| 9. |
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| 10. |
- Huang, Fei, et al.
(författare)
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Modeling 3D time-lapse seismic response induced by CO2 by integrating borehole and 3D seismic data - A case study at the Ketzin pilot site, Germany
- 2015
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Ingår i: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 36, s. 66-77
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Tidskriftsartikel (refereegranskat)abstract
- In order to simulate the 3D time-lapse seismic response from real data in a consistent manner detailed 3D property models at the Ketzin pilot site were constructed by robustly integrating borehole and 3D reflection seismic data. The spatial CO2 distribution and the detailed CO2 density in the reservoir were derived from dynamic flow simulations that had been history-matched to the site monitoring data. Changes in velocity and density after CO2 injection were estimated utilizing the CO2 saturation distributions at two repeat times and fluid substitution models. 4D seismic data were generated by convolving the property models at different times with an extracted wavelet. Time-lapse analysis was performed to qualitatively and quantitatively investigate the changes in reflection amplitude after CO2 injection. Comparison between the synthetic and real data at the corresponding time indicates that the 3D property models were built successfully and model the 3D time-lapse seismic response induced by CO2 injection. A synthetic experiment with two different source wavelets was implemented to investigate the impact of source non-repeatability on the seismic amplitude anomaly. Analysis shows that the same or similar sources should be used in time-lapse seismic monitoring to minimize the impact of source non-repeatability on the monitoring.
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