频率域航空电磁数据变维数贝叶斯反演研究   总被引：5，自引：2，他引：3       下载免费PDF全文

殷长春  齐彦福  刘云鹤  蔡晶 《地球物理学报》2014,57(9):2971-2980

传统的梯度反演方法已经广泛应用于频率域航空电磁数据处理中,然而此类方法受初始模型影响较大,且容易陷入局部极小.为解决这一问题,本文采用改进的变维数贝叶斯反演方法实现航空电磁数据反演.该方法根据建议分布对反演模型进行随机采样,并依据接受概率筛选合理的候选模型,最终获得反演模型的概率分布和不确定度信息.为解决贝叶斯反演方法对深部低阻层反演效果不佳的问题,本文通过引入合理加权系数,调整对反演模型约束强度,在很大程度上改善了反演效果.通过对模型统计方法进行改进,在遵循原有模型采样方法和接受标准的基础上,将满足数据拟合要求的模型纳入统计范围,削弱不合理模型对统计结果的干扰.本文最后通过对含有高斯噪声的理论数据和实测数据进行反演,并与Occam反演结果进行对比,验证了该方法的有效性.  相似文献   

Anisotropic permeability in fractured reservoirs from frequency‐dependent seismic Amplitude Versus Angle and Azimuth data     

Aamir Ali  Morten Jakobsen 《Geophysical Prospecting》2014,62(2):293-314

Attempts have previously been made to predict anisotropic permeability in fractured reservoirs from seismic Amplitude Versus Angle and Azimuth data on the basis of a consistent permeability‐stiffness model and the anisotropic Gassmann relations of Brown and Korringa. However, these attempts were not very successful, mainly because the effective stiffness tensor of a fractured porous medium under saturated (drained) conditions is much less sensitive to the aperture of the fractures than the corresponding permeability tensor. We here show that one can obtain information about the fracture aperture as well as the fracture density and orientation (which determines the effective permeability) from frequency‐dependent seismic Amplitude Versus Angle and Azimuth data. Our workflow is based on a unified stiffness‐permeability model, which takes into account seismic attenuation by wave‐induced fluid flow. Synthetic seismic Amplitude Versus Angle and Azimuth data are generated by using a combination of a dynamic effective medium theory with Rüger's approximations for PP reflection coefficients in Horizontally Transversely Isotropic media. A Monte Carlo method is used to perform a Bayesian inversion of these synthetic seismic Amplitude Versus Angle and Azimuth data with respect to the parameters of the fractures. An effective permeability model is then used to construct the corresponding probability density functions for the different components of the effective permeability constants. The results suggest that an improved characterization of fractured reservoirs can indeed be obtained from frequency‐dependent seismic Amplitude Versus Angle and Azimuth data, provided that a dynamic effective medium model is used in the inversion process and a priori information about the fracture length is available.  相似文献   

半隐式半拉格朗日动力框架的动能谱分析   总被引：10，自引：2，他引：8  

郑永骏  金之雁  陈德辉 《气象学报》2008,66(2):143-157

大量的观测事实表明自由大气动能谱与波数之间满足如下关系:在大尺度区域满足E∝k-3关系,过渡到中尺度区域表现为E∝k-5/3关系.数值模式动能谱是测量模式动力框架的耗散的直接度量,而耗散对模式的性能有着重要影响,因此动能谱是研究和评估模式动力框架的非常规的有效方法.文中使用基于半隐式半拉格朗日动力框架的全球/区域一体化模式GRAPES进行数值模拟试验,然后计算GRAPES模式的动能谱并与实际观测得到的大气动能谱比较,得到GRAPES模式能够很好地复制出实际大气动能谱的分布特征,包括从大尺度区域的E∝k-3关系向中尺度的E∝k-5/3关系的过渡特征.并且发现GRAPES模式存在最大有效时间步长,当时间步长小于最大有效时间步长时,模式动能谱随时间步长增大而逐渐衰减;当时间步长大于最大有效时间步长时,模式动能谱随时间步长增大而虚假增长.同时通过与实际大气动能谱比较,发现模式动能谱在5Δx波长附近开始明显衰减,因此将5Δx波长定义为GRAPES模式的最高有效分辨尺度;当空间分辨率提高与时间步长等相协调时,中小尺度模式动能谱向中小尺度延伸而更接近实际大气动能谱;当空间分辨率提高与时间步长等不相协调时,中小尺度模式动能谱存在较大误差,相应的大尺度模式动能谱亦存在较大误差.此外,时间步长对模式spin up过程有着重要的影响,较小时间步长时,spin up过程能够很好发展出合理的动能谱结构,在物理空间上表现为模式能够在spin up时间内生成和发展出合理的中小尺度系统;而较大时间步长时,spin up过程很难发展出合理的动能谱结构,在物理空间上表现为模式未能在spin up时间内生成和发展出合理的中小尺度系统.最后,GRAPES模式动能谱与WRF模式动能谱具有一致性,GRAPES全球中期模式能够完美地模拟出大尺度的E∝k-3动能谱特征.综上所述,本文通过研究GRAPES模式动力框架的动能谱得到了一些有意义的结果,为进一步研究、完善、优化和应用模式提供了科学的指导,可见动能谱是评估模式动力框架的有效方法.  相似文献   

层序地层学在油田开发中的应用实践   总被引：10，自引：2，他引：8  

尹太举  张昌民  李中超  毛立华  邓宏文 《沉积学报》2005,23(4):664-671

总结了依据地层基准面原理进行开发调整阶段储层精细对比和油藏精细描述的方法。以湖泛面为层序界面,在濮城油田沙三中6-10油藏内识别出超短期、短期、中期和长期四级界面和基准面旋回,短期旋回是油藏细分开发调整的最小单元。短期基准面上升期,形成向上物性变差、高渗段位于砂层下部的层内非均质模式,而短期基准面下降期,形成向上物性变好、高渗段位于中上部的层内非均质模式。中长期基准面较低部位沟道较为发育,砂体厚度大、分布广、物性较好,而在中长期基准面较高部位沟道不发育,砂体厚度薄、面积小、储层物性较差。中长期基准面上升旋回内形成向上物性变差的层间非均质格局,而在中长期下降期则形成向上物性变好的非均质性格局。在水下扇前缘区,近湖心剖面砂体中的沟道成份较小,砂体连通性、连续性及物性较差,而向岸方向储层相对较连续,物性较好。基准面低位处的砂体油气储量和储量丰度均较高,而基准面高位处砂体油气储量和丰度较低。基准面低位处砂体物性较好,较易动用,采出油气数量和采出程度较高,但由于其本身的储量较大,剩余油仍占据着主要的地位。基准面高位处砂体物性较差,储量较难动用,采出油量和采出程度均较小,但受其本身储量的限制,剩余油量在剩余可采储量中的比例较小。  相似文献   

中国西部陆内前陆盆地沉积特征与层序格架   总被引：16，自引：2，他引：14  

顾家裕  张兴阳 《沉积学报》2005,23(2):187-193

中国西部陆内前陆盆地发育于造山带与克拉通之间,是板块碰撞后陆内远程效应引起冲断作用所形成的一种盆地。它与国外典型前陆盆地有一定的差异,不存在被动陆缘所形成的海相生油岩系及海相磨拉石建造。陆内前陆盆地同样富集油气,近年来广泛地受到石油地质界的关注。文章从多个方面研究分析了陆内前陆盆地与典型前陆盆地的差异性,认为其主要沉积特点是冲断作用期粗粒沉积物的叠加可形成连续的裙边状沉积体;冲断作用松懈期发育的煤系地层及泥质岩可形成良好的烃源岩;沉降中心的不断迁移与沉降中心和沉积中心的偏移现象普遍。根据沉积物叠加样式将陆内前陆盆地分为前展型、上叠型和后退型三类,并建立了相应的沉积层序格架。最后据不同类型的盆地分析了其油气生成、储集和保存条件,这将有利于根据不同的样式针对性地进行油气勘探,从而提高勘探效率。  相似文献   

基于随机地震反演的Russell流体因子直接估算方法          下载免费PDF全文

孙瑞莹  印兴耀  王保丽  张广智 《地球物理学报》2016,59(3):1143-1150

本文研究了一种基于随机地震反演的Russell流体因子直接估算方法,该方法是一种基于蒙特卡罗的非线性反演,能够有效地融合测井资料中的高频信息,提高反演结果的分辨率.本文应用贝叶斯理论框架,首先通过测井数据计算井位置处的Russell流体因子,利用序贯高斯模拟方法(sequential Gaussian simulation,SGS)得到流体因子的先验信息;然后构建似然函数;最后利用Metropolis抽样算法对后验概率密度进行抽样,得到反演的Russell流体因子.其中对每道数据进行序贯高斯模拟时,采用一种新的逐点模拟方式,具有较高的计算速度.数值试验表明:反演结果与理论模型和实际测井数据吻合较好,具有较高的分辨率,对于判识储层含流体特征具有较好的指示作用.  相似文献   

An efficient probabilistic back-analysis method for braced excavations using wall deflection data at multiple points     

《Computers and Geotechnics》2017

This paper presents an efficient Bayesian back-analysis procedure for braced excavations using wall deflection data at multiple points. Response surfaces obtained from finite element analyses are adopted to efficiently evaluate the wall responses. Deflection data for 49 wall sections from 11 case histories are collected to characterize the model error of the finite element method for evaluating the deflections at various points. A braced excavation project in Hang Zhou, China is chosen to illustrate the effectiveness of the proposed procedure. The results indicate that the soil parameters could be updated more significantly for the updating that uses the deflection data at multiple points than that only uses the maximum deflection data. The predicted deflections from the updated parameters agree fairly well with the field observations. The main significance of the proposed procedure is that it improves the updating efficiency of the soil parameters without adding monitoring effort compared with the traditional method that uses the maximum deflection data.  相似文献   

佛山市税源地图大数据展示系统的设计与实现     

谢辉荣  钱佩  谢刚生 《测绘通报》2017,(10):133-136

在智慧时空大数据与云平台建设工作中,如何进一步挖掘分析海量空间数据是实现高效应用的一项关键任务。针对佛山市税务机关的业务需求,研究了基于Hadoop框架的大数据技术,结合GIS数据,利用互联网云平台对海量税务数据进行存储、计算、分析的佛山市税源地图大数据展示系统的设计与实现。  相似文献   

Annot Sandstone in the Peïra Cava basin: An example of an asymmetric facies distribution in a confined turbidite system (SE France)     

《Marine and Petroleum Geology》2017

High-resolution physical stratigraphy and detailed facies analysis have been carried out in the foredeep turbidites of Annot Sandstone in the Peïra Cava basin (French Maritime Alps) in order to characterize the relationship between facies and basin morphology. Detailed correlation patterns are evidence of a distinction between a southern bypass-dominated region, coincident with a channel-lobe transition and a north-eastern depositional zone, represented by sheet-like basin plain. These depositional elements are characterized by three main groups of beds related to the downcurrent evolution of bipartite flows. These facies groups are: 1) pebbly coarse-grained massive sandstones with rip-up mudstone clasts and impact mudstone breccias (Type I and II beds) deposited by basal dense flows, 2) coarse-grained massive sandstone overlain by tractive structures (Type III and IV beds) indicating the bypass of overlying turbulent flows and 3) massive medium-grained and fine-grained laminated sandstones related to the deposition of high and low density turbidity currents (Type V and VI beds). Ponding and reflection processes, affecting the upper turbulent flows, can characterize all type beds, but especially the beds of the third group. As described in other confined basins of the northern Apennines (Italy), the lateral and vertical distribution of these type of beds, together with other important sedimentary characteristics, - such as the sandstone/mudstone ratio, bed thicknesses, amalgamation surfaces and paleocurrents - reveal that the deposition of the Annot Sandstone in the Peïra Cava basin was controlled by an asymmetric basin with a steep western margin. This margin favored, on the one hand, basal dense flow decelerations and impacts, as well as bypass and deflection of the upper turbulent flows towards the north east.  相似文献   

Progress in refining the global radiocarbon calibration curve using New Zealand kauri (Agathis australis) tree-ring series from Oxygen Isotope Stage 3     

《Quaternary Geochronology》2015

Ancient kauri (Agathis australis) buried in bogs across Northland, New Zealand, provide potential for a continuous high-precision radiocarbon calibration curve that extends to the full chronologic range of the dating method. Here we report four new tree-ring series which in addition to previous work represent some 5312 years across Oxygen Isotope Stage 3, a period during which human evolution, migration and extinction took place against a backdrop of extreme and abrupt global climate and environmental change. We compare our radiocarbon-dated series against three different calibration datasets and find considerable differences in the wiggle-matched solutions, demonstrating the difficulty in undertaking high-precision correlation between ice, marine and terrestrial sequences. One way around the apparent impasse is the use of ¹⁰Be in the Greenland and Antarctic ice cores to precisely link to kauri ¹⁴C from which a decadally/bidecadally-resolved floating ‘calibration’ dataset can be generated.  相似文献