3D forward modeling and response analysis for marine CSEMs towed by two ships     

Bo Zhang  Chang-Chun Yin  Yun-He Liu  Xiu-Yan Ren  Yan-Fu Qi  Jing Cai 《应用地球物理》2018,15(1):11-25

A dual-ship-towed marine electromagnetic (EM) system is a new marine exploration technology recently being developed in China. Compared with traditional marine EM systems, the new system tows the transmitters and receivers using two ships, rendering it unnecessary to position EM receivers at the seafloor in advance. This makes the system more flexible, allowing for different configurations (e.g., in-line, broadside, and azimuthal and concentric scanning) that can produce more detailed underwater structural information. We develop a three-dimensional goal-oriented adaptive forward modeling method for the new marine EM system and analyze the responses for four survey configurations. Oceanbottom topography has a strong effect on the marine EM responses; thus, we develop a forward modeling algorithm based on the finite-element method and unstructured grids. To satisfy the requirements for modeling the moving transmitters of a dual-ship-towed EM system, we use a single mesh for each of the transmitter locations. This mitigates the mesh complexity by refining the grids near the transmitters and minimizes the computational cost. To generate a rational mesh while maintaining the accuracy for single transmitter, we develop a goal-oriented adaptive method with separate mesh refinements for areas around the transmitting source and those far away. To test the modeling algorithm and accuracy, we compare the EM responses calculated by the proposed algorithm and semi-analytical results and from published sources. Furthermore, by analyzing the EM responses for four survey configurations, we are confirm that compared with traditional marine EM systems with only in-line array, a dual-ship-towed marine system can collect more data.  相似文献   

Carbon fluxes in the China Seas: An overview and perspective     

Qian Liu  Xianghui Guo  Zhiqiang Yin  Kuanbo Zhou  Elliott Gareth Roberts  Minhan Dai 《中国科学:地球科学(英文版)》2018,61(11):1564-1582

This paper aims to provide an overview of regional carbon fluxes and budgets in the marginal seas adjacent to China.The "China Seas" includes primarily the South China Sea, East China Sea, Yellow Sea, and the Bohai Sea. Emphasis is given to CO_2 fluxes across the air-sea interface and their controls. The net flux of CO_2 degassing from the China Seas is estimated to be9.5±53 Tg C yr~(-1). The total riverine carbon flux through estuaries to the China Seas is estimated as 59.6±6.4 Tg C yr~(-1). Chinese estuaries annually emit 0.74±0.02 Tg C as CO_2 to the atmosphere. Additionally, there is a very large net carbon influx from the Western Pacific to the China Seas, amounting to ～2.5 Pg C yr~(-1). As a first-order estimate, the total export flux of particulate organic carbon from the upper ocean of the China Seas is 240±80 Tg C yr~(-1). This review also attempts to examine current knowledge gaps to promote a better understanding of the carbon cycle in this important region.  相似文献   

Facies-constrained prestack seismic probabilistic inversion driven by rock physics     

Li  Kun  Yin  Xingyao  Zong  Zhaoyun 《中国科学:地球科学(英文版)》2020,63(6):822-840

Seismic Rock physics plays a bridge role between the rock moduli and physical properties of the hydrocarbon reservoirs. Prestack seismic inversion is an important method for the quantitative characterization of elasticity, physical properties, lithology and fluid properties of subsurface reservoirs. In this paper, a high order approximation of rock physics model for clastic rocks is established and one seismic AVO reflection equation characterized by the high order approximation(Jacobian and Hessian matrix) of rock moduli is derived. Besides, the contribution of porosity, shale content and fluid saturation to AVO reflectivity is analyzed. The feasibility of the proposed AVO equation is discussed in the direct estimation of rock physical properties. On the basis of this, one probabilistic AVO inversion based on differential evolution-Markov chain Monte Carlo stochastic model is proposed on the premise that the model parameters obey Gaussian mixture probability prior model. The stochastic model has both the global optimization characteristics of the differential evolution algorithm and the uncertainty analysis ability of Markov chain Monte Carlo model. Through the cross parallel of multiple Markov chains, multiple stochastic solutions of the model parameters can be obtained simultaneously, and the posterior probability density distribution of the model parameters can be simulated effectively. The posterior mean is treated as the optimal solution of the model to be inverted.Besides, the variance and confidence interval are utilized to evaluate the uncertainties of the estimated results, so as to realize the simultaneous estimation of reservoir elasticity, physical properties, discrete lithofacies and dry rock skeleton. The validity of the proposed approach is verified by theoretical tests and one real application case in eastern China.  相似文献   

A fundamental theorem for eco-environmental surface modelling and its applications   总被引：2，自引：0，他引：2  

Yue  Tianxiang  Zhao  Na  Liu  Yu  Wang  Yifu  Zhang  Bin  Du  Zhengping  Fan  Zemeng  Shi  Wenjiao  Chen  Chuanfa  Zhao  Mingwei  Song  Dunjiang  Wang  Shihai  Song  Yinjun  Yan  Changqing  Li  Qiquan  Sun  Xiaofang  Zhang  Lili  Tian  Yongzhong  Wang  Wei  Wang  Ying’an  Ma  Shengnan  Huang  Hongsheng  Lu  Yimin  Wang  Qing  Wang  Chenliang  Wang  Yuzhu  Lu  Ming  Zhou  Wei  Liu  Yi  Yin  Xiaozhe  Wang  Zong  Bao  Zhengyi  Zhao  Miaomiao  Zhao  Yapeng  Jiao  Yimeng  Naseer  Ufra  Fan  Bin  Li  Saibo  Yang  Yang  Wilson  John P. 《中国科学:地球科学(英文版)》2020,63(8):1092-1112

We propose a fundamental theorem for eco-environmental surface modelling(FTEEM) in order to apply it into the fields of ecology and environmental science more easily after the fundamental theorem for Earth's surface system modeling(FTESM). The Beijing-Tianjin-Hebei(BTH) region is taken as a case area to conduct empirical studies of algorithms for spatial upscaling, spatial downscaling, spatial interpolation, data fusion and model-data assimilation, which are based on high accuracy surface modelling(HASM), corresponding with corollaries of FTEEM. The case studies demonstrate how eco-environmental surface modelling is substantially improved when both extrinsic and intrinsic information are used along with an appropriate method of HASM. Compared with classic algorithms, the HASM-based algorithm for spatial upscaling reduced the root-meansquare error of the BTH elevation surface by 9 m. The HASM-based algorithm for spatial downscaling reduced the relative error of future scenarios of annual mean temperature by 16%. The HASM-based algorithm for spatial interpolation reduced the relative error of change trend of annual mean precipitation by 0.2%. The HASM-based algorithm for data fusion reduced the relative error of change trend of annual mean temperature by 70%. The HASM-based algorithm for model-data assimilation reduced the relative error of carbon stocks by 40%. We propose five theoretical challenges and three application problems of HASM that need to be addressed to improve FTEEM.  相似文献   

河北赤城井水温对远场大震的响应特征研究     

尹宏伟  梁丽环  韩文英  李凤  刘静 《地震地磁观测与研究》2019,40(5):93-100

在河北赤城井井下30 m、53 m、58 m处分别安装了3个温度传感器,进行水温微动态观测。通过对2004年12月以来全球发生的22次M_S≥8.0地震时赤城井不同深度水温观测数据的变化进行研究发现,井下30 m处水温均无明显同震变化;而7次大震时53 m、58 m处水温有明显的同震变化,53 m处水温同震初始变化形态均为上升,58 m处均为下降。同时,对水温变化机理进行探讨发现,井下30 m处水温日变幅度偏大是记录不到地震的主要原因;水温同震初始变化是由井孔水体对流引起的,53 m处水温同震初始变化形态均为上升是由于该处位于负温度梯度带,井孔中水体受震荡激发而加速对流与掺混是导致58 m处水温同震初始下降的主要原因,赤城井水温同震初始变化的后效恢复过程为热传导作用的结果。  相似文献   

内蒙古自治区地震局震情上报系统   总被引：1，自引：1，他引：0  

宋晓燕  王鑫  安全  尹战军 《地震地磁观测与研究》2018,39(3):197-201

针对内蒙古自治区地震局人工震情上报过程中存在的弊端和问题,基于VC语言,设计并实现自动震情上报系统。该系统通过读取EQIM数据库中的相关数据,采用模拟操作,实现无接口情况下采集EQIM中相应地图,并利用Microsoft office Word通用API,按所需格式生成包含震情数据与地图的震情上报文档,同时提供核对和校验功能,通过自动传真方式实现震情上报与保存功能。该系统的实现,减少了人工干预造成的错误,提高了震情上报的准确性和高效性,真正实现了震情的自动传真上报。  相似文献   

Linearized amplitude variation with offset and azimuth and anisotropic poroelasticity     

Xinpeng Pan  Guangzhi Zhang  Xingyao Yin 《Geophysical Prospecting》2019,67(7):1882-1897

The normal-to-shear weakness ratio is commonly used as a fracture fluid indicator, but it depends not only on the fluid types but also on the fracture intensity and internal architecture. Amplitude variation with offset and azimuth is commonly used to perform the fluid identification and fracture characterization in fractured porous rocks. We demonstrate a direct inversion approach to utilize the observable azimuthal data to estimate the decoupled fluid (fluid/porosity term) and fracture (normal and shear weaknesses) parameters instead of the calculation of normal-to-shear weakness ratio to help reduce the uncertainties in fracture characterization and fluid identification of a gas-saturated porous medium permeated by a single set of parallel vertical fractures. Based on the anisotropic poroelasticity and perturbation theory, we first derive a linearized amplitude versus offset and azimuth approximation using the scattering function to decouple the fluid indicator and fracture parameters. Incorporating Bayes formula and convolution theory, we propose a feasible direct inversion approach in a Bayesian framework to obtain the direct estimations of model parameters, in which Cauchy and Gaussian distribution are used for the a priori information of model parameters and the likelihood function, respectively. We finally use the non-linear iteratively reweighted least squares to solve the maximum a posteriori solutions of model parameters. The synthetic examples containing a moderate noise demonstrate the feasibility of the proposed approach, and the real data illustrates the stabilities of estimated fluid indicator and dry fracture parameters in gas-saturated fractured porous rocks.  相似文献   

Multi-trace basis-pursuit seismic inversion for resolution enhancement     

Dongyong Zhou  Xingyao Yin  Zhaoyun Zong 《Geophysical Prospecting》2019,67(3):519-531

Seismic inversion is an important tool that transfers interface information of seismic data to formation information, which renders the seismic data easily understood by geologists or petroleum engineers. In this study, a novel multi-trace basis-pursuit inversion method based on the Bayesian theory is proposed to enhance the vertical resolution and overcome the lateral instability of inversion results between different traces occasionally seen in the traditional trace-by-trace basis-pursuit inversion method. The Markov process is initially introduced to describe the relationship between adjacent seismic traces and their correlation, which we then close couple in the equation of our new inversion method. A recursive function is further derived to simplify the inversion process by considering the particularity of the coefficient matrix in the multi-trace inversion equation. A series of numerical-analysis and field data examples demonstrates that both the traditional and the new methods for P-wave impedance inversion are helpful in enhancing the resolution of thin beds that are usually difficult to discern from original seismic profiles, thus highlighting the importance of acoustic-impedance inversion for thin bed interpretation. Furthermore, in addition to yielding thin bed inversion results with enhanced lateral continuity and high vertical resolution, our proposed method is robust to noise and cannot be easily contaminated by it, which we verify using both synthetic and field data.  相似文献   

白洋淀湿地表层土壤主要环境元素分布特征及来源     

刘雪松  王雨山  王旭清  尹德超 《湖泊科学》2022,34(2):496-505

白洋淀是雄安新区生态共同体的重要组成部分,在"白洋淀生态环境治理和保护规划"中,淀区内纯水村和耕地将被淹没,而上述陆地的土壤环境元素分布特征及来源仍缺乏系统调查和分析.本文以淀区内现有0～ 20 cm土壤为研究对象,以环境元素As、Hg、Cd、Cr、Pb、Ni、Cu、Zn、N、P和土壤类型、质地为研究要素,以统计描述、方差分析、相关分析和因子分析为研究手段对淀区内土壤主要环境元素分布特征和来源进行刻画和分析.结果 表明:淀区主要环境元素在不同土地类型的差异性分布是大气沉降和人类工农业活动综合作用的结果.除元素P外,其余环境元素的淀区背景值均高于区域背景值,呈富集趋势.大部分元素趋向于在农用地富集,在水田的富集最为突出,Hg元素则更易在村镇用地富集.淀区内土壤主要环境元素来源分3种类型:大气沉降型,代表元素为Ni、Cr、As、Pb、Cu和Cd,主要来自区域燃煤烟气的沉降输入;农业输入型,代表元素为P、N、Hg、Cd、Pb,主要来自本地农业施肥和人类生活垃圾输入;工业叠加型,代表元素为Zn、Cu、Cd、Pb,主要来自大气沉降和淀区临近的小冶炼的排放叠加,其中Pb、Cd、Cu为综合输入方式.  相似文献   

Adaptation strategies for mitigating agricultural GHG emissions under dual-level uncertainties with the consideration of global warming impacts     

Wencong?Yue  Yanpeng?CaiEmail author  Linyu?Xu  Qian?Tan  Xin’An?Yin 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(4):961-979

Agriculture plays a central role in maintaining food security and achieving sustainable development for human society. It is a challenge for the agricultural sector to mitigate greenhouse gas (GHG) emissions and maintain agricultural production. However, dual-level uncertainties exist in the processes of agricultural GHG accounting and emission reduction management. In this research, an integrated approach for identifying adaptation strategies in agricultural GHG emission reduction management was developed through incorporating life cycle analysis (LCA) of agricultural production into a general mathematical programming model. This approach strengthened the applicability of LCA and the comprehensiveness of programming models in generating agricultural adaptive actions under different GHG emission restriction targets. Also, dual-level uncertainties of LCA and adaptation management can be effectively addressed. A case study was proposed to illustrate application of the approach in Dalian City, China. The results indicated that farming patterns in eight districts would change significantly. The total area of maize fields would account for the primary proportion (i.e., 40–45 %) in its agricultural sector. Rice, peanut and cabbage fields would be the minor contributors in terms of GHG emissions. In addition to effective rainfall (i.e., [156, 259] mm/ha), a certain amount of water would be supplied for agricultural irrigation to maximize the city’s agricultural yields. Compared with other agricultural crops, rice fields would need the largest amount of irrigation water (i.e., [153.72, 277.98] Mt) to meet the requirements of local government plans.  相似文献