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Source wavefield reconstruction based on an implicit staggered-grid finite-difference operator for seismic imaging

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Petroleum Science 2022年第5期19卷 2095-2106页

作者： Zhi-Ming Ren Xue Dai qian-Zong bao Chang'an University College of Geological Engineering and GeomaticsXi'anShaanxi710064China National Engineering Research Center of Offshore Oil and Gas Exploration Beijing100028China

Reverse time migration and full waveform inversion involve the crosscorrelation of two wavefields,propagated in the forward-and reverse-time directions,*** a result,the forward-propagated wavefield needs to be stored,and then accessed to compute the correlation with the backward-propagated ***-value methods reconstruct the source wavefield using saved boundary wavefields and can significantly reduce the storage ***,the existing boundary-value methods are based on the explicit finite-difference(FD)approximations of the spatial *** FD methods exhibit greater accuracy and thus allow for a smaller operator *** develop two(an accuracy-preserving and a memory-efficient)wavefield reconstruction schemes based on an implicit staggered-grid FD(SFD)*** former uses boundary wavefields at M layers of grid points and the spatial derivatives of wavefields at one layer of grid points to reconstruct the source wavefield for a(2M+2)th-order implicit SFD *** latter applies boundary wavefields at N layers of grid points,a linear combination of wavefields at M–N layers of grid points,and the spatial derivatives of wavefields at one layer of grid points to reconstruct the source wavefield(0≤N

关键词： Finite difference Reverse time migration Source wavefield reconstruction Implicit Staggered grid

Truncated Gauss-Newton full-waveform inversion of pure quasi-P waves in vertical transverse isotropic media

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Petroleum Science 2024年第5期21卷 3102-3124页

作者： Zhi-Ming Ren Lei Wang qian-Zong bao College of Geological Engineering and Geomatics Chang'an UniversityXi'an710064ShaanxiChina National Engineering Research Center of Offshore Oil and Gas Exploration Beijing100028China

Full-waveform inversion(FWI) uses the full information of seismic data to obtain a quantitative estimation of subsurface physical parameters. Anisotropic FWI has the potential to recover high-resolution velocity and anisotropy parameter models, which are critical for imaging the long-offset and wideazimuth data. We develop an acoustic anisotropic FWI method based on a simplified pure quasi P-wave(qP-wave) equation, which can be solved efficiently and is beneficial for the subsequent *** the inverse Hessian operator to precondition the functional gradients helps to reduce the parameter tradeoff in the multi-parameter inversion. To balance the accuracy and efficiency, we extend the truncated Gauss-Newton(TGN) method into FWI of pure qP-waves in vertical transverse isotropic(VTI) media. The inversion is performed in a nested way: a linear inner loop and a nonlinear outer *** derive the formulation of Hessian-vector products for pure qP-waves in VTI media based on the Lagrange multiplier method and compute the model update by solving a Gauss-Newton linear system via a matrix-free conjugate gradient method. A suitable preconditioner and the Eisenstat and Walker stopping criterion for the inner iterations are used to accelerate the convergence and avoid prohibitive computational cost. We test the proposed FWI method on several synthetic data sets. Inversion results reveal that the pure acoustic VTI FWI exhibits greater accuracy than the conventional pseudoacoustic VTI FWI. Additionally, the TGN method proves effective in mitigating the parameter crosstalk and increasing the accuracy of anisotropy parameters.

关键词： Full waveform inversion Anisotropy Pure quasi-P wave Gauss-Newton Hessian

Target-oriented Q-compensated reverse-time migration by using optimized pure-mode wave equation in anisotropic media

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Petroleum Science 2023年第2期20卷 866-878页

作者： Shi-Gang Xu qian-Zong bao Zhi-Ming Ren Chang'an University School of Geological Engineering and GeomaticsDepartment of GeophysicsXi'anShaanxi710064China National Engineering Research Center of Offshore Oil and Gas Exploration Beijing100028China

Research on seismic anisotropy and attenuation plays a significant role in exploration geophysics. To enhance the imaging quality for complicated structures, we develop several effective improvements for anisotropic attenuation effects in reverse-time migration (Q-RTM) on surface and vertical seismic profiling (VSP) acquisition geometries. First, to suppress pseudo-shear wave artifact and numerical instability of the commonly used anisotropic pseudo-acoustic wave equations, an optimized pure P-wave dispersion relation is derived and the corresponding pure-mode wave equation is solved by combining the finite-difference and Possion methods. Second, a simplified anisotropic pure-mode visco-acoustic wave equation (PVAWE) based on standard linear solid model is established. Third, a time-dispersion correlation strategy is applied to improve the modeling accuracy. Fourth, we extend a target-oriented scheme to anisotropic attenuated modeling and imaging. Instead of the conventional wavefield modeling and RTM, the proposed approach can extract available wavefield information near the target regions and produce high imaging resolution for target structures. Last, both anisotropic surface and VSP Q-RTMs are executed by combining optimized PVAWE, time-dispersion correlation and target-oriented algorithm. Modeling examples demonstrate the advantages of our schemes. Moreover, our modified Q-compensated imaging workflow can be regarded as a supplement to the classical anisotropic RTM.

关键词： Anisotropy Attenuation Reverse-time migration Wave equation Optimized algorithm Target-oriented

Survivin:Potential role in diagnosis,prognosis and targeted therapy of gastric cancer

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World Journal of Gastroenterology 2007年第20期13卷 2784-2790页

作者： Ting-Ting Wang Xiao-Ping qian bao-Rui Liu (Department of Oncology Affiliated Gulou Hospital Medical School of Nanjing University Nanjing 210008 Jiangsu Province China )

Survivin is a protein that is highly expressed in a vast number of malignancies,but is minimally expressed in normal tissues. It plays a role as an inhibitor of cell death in cancer cells,thus facilitating the growth of these cells. In the case of gastric cancer,survivin is over-expressed in tumor cells and plays a role in the carcinogenesis process. Several studies on gastric cancer have indicated that there is a relationship between survivin expression and the ultimate behavior of the carcinoma. Since the expression pattern of survivin is selective to cancer cells,it has been described as an "ideal target" for cancer therapy. Currently,several pre-clinical and clinical trials are on-going to investigate the effects of interfering with survivin function in cancer cells as a biologic therapy. Survivin is a potentially significant protein in the diagnosis,prognosis and treatment of gastric tumors.

关键词： Survivin Gastric neoplasm Diagnosis Prognosis Targeted therapy

DLSLA 3-D SAR imaging algorithm for off-grid targets based on pseudo-polar formatting and atomic norm minimization

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Science China(Information Sciences) 2016年第6期59卷 225-239页

作者： qian bao Kuoye HAN Xueming PENG Wen HONG Bingchen ZHANG Weixian TAN Science and Technology on Microwave Imaging Laboratory (MITL) Institute of ElectronicsChinese Academy of Sciences (IECAS) School of Electronic and Communication Engineering University of Chinese Academy of Sciences (UCAS) Information System Technology Institute Information Science Academy of China Electronics Technology Group Corporation Global RD Centre (Shanghai) Carestream Health Incorporated College of Information Engineering Inner Mongolia University of Technology

This paper concerns the imaging problem for downward looking sparse linear array three-dimensional synthetic aperture radar(DLSLA 3-D SAR) under the circumstance of sparse and non-uniform cross-track dimensional virtual phase centers configuration. Since the 3-D imaging scene behaves typical sparsity in a certain domain, sparse recovery approaches hold the potential to achieve a better reconstruction performance. However,most of the existing compressive sensing(CS) algorithms assume the scatterers located on the pre-discretized grids, which is often violated by the off-grid effect. By contrast, atomic norm minimization(ANM) deals with sparse recovery problem directly on continuous space instead of discrete grids. This paper firstly analyzes the off-grid effect in DLSLA 3-D SAR sparse image reconstruction, and then introduces an imaging method applied to off-gird targets reconstruction which combines 3-D pseudo-polar formatting algorithm(pseudo-PFA) with ANM. With the proposed method, wave propagation and along-track image reconstruction are operated with pseudo-PFA, then the cross-track reconstruction is implemented with semidefinite programming(SDP) based on the ANM model. The proposed method holds the advantage of avoiding the off-grid effect and managing to locate the off-grid targets to accurate locations in different imaging scenes. The performance of the proposed method is verified and evaluated by the 3-D image reconstruction of different scenes, i.e., point targets and distributed scene.

关键词： atomic norm minimization DLSLA 3-D SAR sparse recovery off-grid targets pseudo-PFA 3-D imaging

Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

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Petroleum Science 2021年第2期18卷 546-564页

作者： Jing Wang Hui-Qing Liu Gen-bao qian Yong-Can Peng State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China Shaanxi Cooperative Innovation Center of Unconventional Oil and Gas Exploration and Development Xi’an Shiyou UniversityXi’an710065ShaanxiChina CNPC Xinjiang Oilfield Karamay834000XinjiangChina

Huff-n-puff by water has been conducted to enhance oil recovery after hydraulic fracturing in tight/shale oil ***,the mechanisms and capacity are still unclear,which significantly limits the application of this *** order to figure out the mechanisms,the whole process of pressurizing,high-pressure soaking,and depressurizing was firstly discussed,and a mechanistic model was ***,the simulation model was verified and employed to investigate the significances of high-pressure soaking,the contributions of different mechanisms,and the sensitivity analysis in different *** results show that high-pressure soaking plays an essential role in oil production by both imbibition and elasticity after hydraulic *** contribution of imbibition increases as the increase in bottom hole pressure(BHP),interfacial tension,and specific surface area,but slightly decreases as the oil viscosity *** addition,it first decreases and then slightly increases with the increase in matrix *** optimal soaking time is linear with the increases of both oil viscosity and BHP and logarithmically declines with the increase in matrix permeability and specific surface ***,it shows a rising tendency as the interficial tension(IFT)***,a general model was achieved to calculate the optimal soaking time.

关键词： Enhanced oil recovery High-pressure soaking Huff-n-puff Imbibition Tight/shale oil

Time to tackle clonorchiasis in China

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Infectious Diseases of Poverty 2013年第1期2卷 23-26,22页

作者： Men-bao qian Ying-Dan Chen Fei Yan National Institute of Parasitic Diseases Chinese Center for Disease Control and PreventionWHO Collaborative Center for MalariaSchistosomiasis and FilariasisKey Laboratory of Parasite and Vector BiologyMinistry of HealthShanghaiPeople’s Republic of China School of Public Health Fudan UniversityShanghaiPeople’s Republic of China

Recent publication of the global epidemiology of clonorchiasis and its relationship with cholangiocarcinoma in the journal of Infectious Diseases of Poverty has stressed the importance of Clonorchis sinensis *** further demonstrate its threat on public health,especially in China,comparisons between clonorchiasis and hepatitis B are made in terms of epidemiology,clinical symptoms and carcinogenicity,disability,as well as changing ***,major problems and prioritized researches are argued,from basic biology to *** between the majority of infected population and the minority of researches in China urges for more work from Chinese scientists and international cooperation.

关键词： Clonorchis sinensis Clonorchiasis Hepatitis B virus Liver cancer Research

Enhancement of ductility and improvement of abnormal Goss grain growth of magnetostrictive Fe–Ga rolled alloys

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International Journal of Minerals,Metallurgy and Materials 2018年第4期25卷 444-452页

作者： Ji-heng Li Chao Yuan Xing Mu Xiao-qian bao Xue-xu Gao State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing

The influences of initial microstructures on the mechanical properties and the recrystallization texture of magnetostrictive 0.1 at% Nb C-doped Fe83 Ga17 alloys were investigated. The directionally solidified columnar-grained structure substantially enhanced the tensile elongation at intermediate temperatures by suppressing fracture along the transverse boundaries. Compared with tensile elongations of 1.0% at 300℃ and 12.0% at 500℃ of the hot-forged equiaxed-grained alloys, the columnar-grained alloys exhibited substantially increased tensile elongations of 21.6% at 300℃ and 46.6% at 500℃. In the slabs for rolling, the introduction of 〈001〉-oriented columnar grains also promotes the secondary recrystallization of Goss grains in the finally annealed sheets, resulting in an improvement of the saturation magnetostriction. For the columnar-grained specimens, the inhomogeneous microstructure and disadvantage in number and size of Goss grains are improved in the primarily annealed sheets, which is beneficial to the abnormal growth of Goss grains during the final annealing process.

关键词： magnetostriction iron-gallium alloys columnar grain ductility abnormal grain growth

Analysis of temporal and spatial distribution characteristics of ammonium chloride smoke particles in confined spaces

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Defence Technology（防务技术） 2022年第7期18卷 1269-1280页

作者： Chen-youshi Xu Bing-ting Zha Jia-qian bao He Zhang Hong-xia Li ZNDY of Ministerial Key Laboratory Nanjing University of Science and TechnologyJiangsuNanjing210094China

In response to the demand for short-range detection of anti-smoke environment interference by laser fuzes,this study proposes a smoke environment simulation of non-uniform continuous point source diffusion and investigates an experimental laboratory smoke environment using an ammonium chloride smoke *** particle size distribution,composition,and mass flow distribution of the smoke were *** on a discrete phase model and a kεturbulence model,a numerical simulation was developed to model the smoke generation and diffusion processes of the smoke agent in a confined *** temporal and spatial distribution characteristics of the smoke mass concentration,velocity,and temperature in the space after smoke generation were analyzed,and the motion law governing the smoke diffusion throughout the entire space was *** with the experimental verification of the smoke environment laboratory,the results showed that the smoke plume changed from fan-shaped to umbrella-shaped during smoke generation,and then continued to spread ***,the mass concentration of smoke in the space decreased from the middle outward;the changes in temperature and velocity were small and *** the diffusion stage(after 900 s),the mass concentration of smoke above 0.8 m was relatively uniform across an area of smoke that was 12 m *** concentration decreased over time,following a consistent decreasing trend,and the attenuation was negligible in a very short ***,this system was suitable for conducting experimental research on laser fuzes in a smoke *** to the stability of the equipment and facilities,the setup could reproduce the same experimental smoke environment by artificially controlling the smoke emission of the smoke ***,this work provides a theoretical reference for subsequent research efforts regarding the construction of uniform smoke environments and evaluating laser transmission characteristics in smoky envir

关键词： Laser fuze Smoke environment Temporal distribution Spatial distribution Confined space Smoke agent