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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

Advancements and New Frontiers in offshore Seismic exploration Technology

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Journal of Earth Science 2024年第5期35卷 1749-1757页

作者： Yuhong Xie Yunfei Ye Xiaogang Huang Wenbo Sun Yanwen Wei China national offshore oil Corporation Beijing 100010China CNOOC Nanhai oil and gas Energy Academician Workstation Haikou 570312China CNOOC research Institute Ltd. Beijing 100028China national engineering research center of offshore oil and gas exploration Beijing 100028China

0 INTRODUCTION China's external dependence on oil and gas remains high,making the independent exploration and development of oil and gas resources crucial for ensuring national energy security and the sustainable development of the economy and *** 2023,China continued to step up its efforts in offshore oil and gas exploration and development,with offshore crude oil production surpassing 62 million tons,accounting for about 70%of the national increase in crude oil *** offshore oil and gas exploration and development is of great significance for guaranteeing national energy security.

关键词： offshore guarantee continued

Rheological study of methane gas hydrates in the presence of micron-sized sand particles

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Chinese Journal of Chemical engineering 2024年第6期70卷 149-161页

作者： Bohui Shi Shangfei Song Yuchuan Chen Shunkang Fu Lihao Liu Xinyao Yang Haihao Wu Guangjin Chen Jing Gong national engineering research center of oil and gas Pipeline Transportation Safety MOE Key Laboratory of Petroleum EngineeringBeijing Key Laboratory of Urban Oil and Gas Distribution TechnologyChina University of Petroleum-BeijingBeijing 102249China China's oil and gas exploration and Development Company(CNODC) Beijing 100034China China national Petroleum Corporation Mozambique LDA MaputoMozambique PipeChina West East Pipeline Company Shanghai 200122China

Natural gas hydrates,intricate crystalline structures formed by water molecules and small gas molecules,have emerged as a significant and globally impactful clean energy ***,their commercial exploitation faces challenges,particularly operational disruptions caused by sand-related *** the rheological properties of hydrate slurry,especially in the presence of micron-sized sand particles,is imperative for ensuring the flow assurance of subsea hydrate *** study extensively investigates the rheological properties of sand-containing hydrate *** findings reveal that these slurries exhibit non-Newtonian fluid characteristics,including yield stress,thixotropy,and shear-thinning ***-like elastic features are observed in sand-containing hydrate slurries before yielding,transitioning to viscous behavior after *** with a minimal amount of sand,both static yield stress and yield strain experience substantial changes,correlating with the increase in sand *** research conclusively establishes the thixotropic nature of sand-hydrate slurries,where the viscosity decay rate is directly influenced by the shear *** insights aim to contribute comprehensively to the development of effective flow assurance strategies,ensuring the safe and stable operation of subsea hydrate exploitation.

关键词： Natural gas hydrate production Sand-containing hydrate slurries Yield stress Thixotropy Shear-thinning behavior

Reservoir characteristics of Donghe well No.1 in Tarim Basin

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International Journal of Mining Science and Technology 2014年第5期24卷 719-724页

作者： Liao Taiping Hu Jingjing Lai Fuqiang Duan Yonggang School of Petroleum engineering Chongqing University of Science and Technology national oil and gas exploration and Development Corporation Well Completion center Southwest Petroleum University

Based on the techniques of X-ray diffraction analysis, identification of the thin sections of core cast, phys- ical analysis and scanning electron microscopy analysis, this paper studied the reservoir characteristics of the Carboniferous strata in Donghe well No.1 of Tarim region. The results show that the reservoir lithology is mainly the fine-grained quartz sandstone with ferrocalcite and pyrite, mud cement-based, the permeability concentrated in 5-40 × 10-3 μm2, a small part of the high permeability up to 150-327 ×10-3 μm2 and porosity ranged from 10% to 20%. The most part of the reservoirs is low perme- ability with a small part of the layer in moderate-high permeability. The types of reservoir space include intergranular pores, intra particle-molding pores, micro-pores and cracks, which mainly are intergranular pores with the pore diameter of 15-200 μm, 95.5μm on average. And the types of the throats are comolex with the main tvne of constricted l：hroats in this area and large contribution to the permeability.

关键词： Tarim Basin Carboniferous system Sandstone reservoir Physical characteristics Features of pore throats

Experimental Study on Response Performance of VIV of A Flexible Riser with Helical Strakes

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China Ocean engineering 2015年第5期29卷 673-690页

作者：高云付世晓曹静陈一帆 State Key Laboratory of oil and gas Reservoir Geology and exploration Southwest Petroleum University State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Collaborative Innovation center for Advanced Ship and Deep-Sea exploration Shanghai Jiao Tong University CNOOC research center Mechanical engineering School of engineering University of Kansas

Laboratory tests were conducted on a flexible riser with and without helical strakes. The aim of the present work is to further understand the response performance of the vortex induced vibration（VIV） for a riser with helical strakes. The experiment was accomplished in the towing tank and the relative current was simulated by towing a flexible riser in one direction. Based on the modal analysis method, the displacement responses can be obtained by the measured strain. The strakes with different heights are analyzed here, and the response parameters like strain response and displacement response are studied. The experimental results show that the in-line（IL） response is as important as the cross-flow（CF） response, however, many industrial analysis methods usually ignore the IL response due to VIV. The results also indicate that the response characteristics of a bare riser can be quite distinct from that of a riser with helical strakes, and the response performance depends on the geometry on the helical strakes closely. The fatigue damage is further discussed and the results show that the fatigue damage in the CF direction is of the same order as that in the IL direction for the bare riser. However, for the riser with helical strakes, the fatigue damage in the CF direction is much smaller than that in the IL direction.

关键词： flexible riser vortex-induced vibration helical strake response performance fatigue damage

research and Application of Joint Interpretation Using P-Wave and PS-Wave in Tight gas exploration

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Journal of Earth Science 2024年第4期35卷 1402-1406页

作者： Dong Wang Meng Zhang Jing Wang Dan Chen Yao Zhao Jing Bai BGPInc. China National Petroleum CorporationZhuozhou 072751China Institute of Geophysics Chengdu University of TechnologyChengdu 610059China national engineering research center of oil and gas exploration Computer Software Zhuozhou 072751China

The exploration and development of tight sandstone gas reservoirs are controlled by high-quality river channel sand bodies on a large scale in Sichuan *** order to improve the accu-racy of sand body prediction and characterization,Multi-component exploration technology research has been carried out in Northwest Sichuan ***,based on the array acoustic logging data,a for-ward modeling has been established to analyze the seismic response characteristics of the PS-wave data and P-wave *** result shows that the response characteristics of the P-wave and PS-wave to the sand bodies with different impedance are *** then through the analysis of logging data,the effectiveness of the forward modeling has been *** the sandstone velocity is close to the sur-rounding rocks,the P-wave performs as a weak reflection,which may lead to reduce the identification range of the sand ***,the PS-wave exhibits strong reflection,which can identify this type of sand ***,by comparing and explaining the PS-wave data and P-wave data,and integrat-ing their attributes,the prediction accuracy of sand bodies is *** with the interpreta-tion of a single P-wave,the results can significantly expand the distribution range of sand bodies,lay-ing a foundation for improving the production capacity of single wells and reserve submission.

关键词： multi-component exploration tight gas sand body identification

Petrophysical parameters inversion for heavy oil reservoir based on a laboratory-calibrated frequency-variant rock-physics model

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Petroleum Science 2023年第6期20卷 3400-3410页

作者： Xu Han Shang-Xu Wang Zheng-Yu-Cheng Zhang Hao-Jie Liu Guo-Hua Wei Gen-Yang Tang CNPC Key Laboratory of Geophysical Prospecting China University of Petroleum(Beijing)Beijing102249China engineering research center of the Ministry of Education for exploration and Development of Complex oil and gas Reservoirs China University of Petroleum(Beijing)Beijing102249China Shengli oilfield Geophysical exploration research Institute SinopecDongying257000ShandongChina

Heavy oil has high density and viscosity, and exhibits viscoelasticity. gassmann's theory is not suitable for materials saturated with viscoelastic fluids. Directly applying such model leads to unreliable results for seismic inversion of heavy oil reservoir. To describe the viscoelastic behavior of heavy oil, we modeled the elastic properties of heavy oil with varying viscosity and frequency using the Cole-Cole-Maxwell (CCM) model. Then, we used a CCoherent Potential Approximation (CPA) instead of the gassmann equations to account for the fluid effect, by extending the single-phase fluid condition to two-phase fluid (heavy oil and water) condition, so that partial saturation of heavy oil can be considered. This rock physics model establishes the relationship between the elastic modulus of reservoir rock and viscosity, frequency and saturation. The viscosity of the heavy oil and the elastic moduli and porosity of typical reservoir rock samples were measured in laboratory, which were used for calibration of the rock physics model. The well-calibrated frequency-variant CPA model was applied to the prediction of the P- and S-wave velocities in the seismic frequency range (1–100 Hz) and the inversion of petrophysical parameters for a heavy oil reservoir. The pre-stack inversion results of elastic parameters are improved compared with those results using the CPA model in the sonic logging frequency (∼10 kHz), or conventional rock physics model such as the Xu-Payne model. In addition, the inversion of the porosity of the reservoir was conducted with the simulated annealing method, and the result fits reasonably well with the logging curve and depicts the location of the heavy oil reservoir on the time slice. The application of the laboratory-calibrated CPA model provides better results with the velocity dispersion correction, suggesting the important role of accurate frequency dependent rock physics models in the seismic prediction of heavy oil reservoirs.

关键词： Heavy oil Rock physics Velocity dispersion Pre-stack inversion Reservoir prediction