基于贝叶斯框架的各向异性页岩储层岩石物理反演技术   总被引：1，自引：0，他引：1       下载免费PDF全文

刘财  符伟  郭智奇  刘喜武  刘宇巍 《地球物理学报》2018,61(6):2589-2600

页岩岩石物理建模旨在建立页岩矿物组分、微观结构、流体填充与岩石弹性参数的关系.对四川盆地龙马溪组页岩进行岩石物理建模研究，针对页岩黏土含量高、层间微裂缝发育等特点，利用Backus平均理论描述页岩黏土矿物弹性参数，利用Chapman理论计算与水平微裂缝有关的VTI各向异性，并利用Bond变换考虑地层倾角的影响.提出以黏土矿物纵、横波速度和孔隙纵横比为拟合参数进行岩石物理反演的方法，并引入贝叶斯框架减小反演的多解性.由已知的黏土矿物纵、横波速度和孔隙纵横比作为先验信息，并以测井纵、横波速度作为约束条件建立反演的目标函数，同时利用粒子群算法进行最优化搜索.计算结果表明，基于先验约束和粒子群算法的反演方法能够较准确地反演黏土矿物的弹性参数、孔隙形态参数以及裂缝密度等参数.计算得到的黏土纵、横波速度较高，并且在一定范围内变化，这可能与龙马溪组页岩的黏土矿物组分中具有较高弹性模量的伊利石含量较高有关，同时也与黏土定向排列等微观物性特征有关.反演得到的裂缝密度与纵波各向异性参数ε呈明显的正相关，而与横波各向异性参数γ相关性较小.另外，页岩各向异性参数与黏土垂向的纵横波速度有较强的相关性.  相似文献   

基于回归模型的热带气旋条件下的海表降温参数化方案设计     

韦骏  刘欣  蒋国庆 《海洋学报(英文版)》2018,37(1):1-10

Combining a linear regression and a temperature budget formula, a multivariate regression model is proposed to parameterize and estimate sea surface temperature(SST) cooling induced by tropical cyclones(TCs). Three major dynamic and thermodynamic processes governing the TC-induced SST cooling(SSTC), vertical mixing, upwelling and heat flux, are parameterized empirically using a combination of multiple atmospheric and oceanic variables:sea surface height(SSH), wind speed, wind curl, TC translation speed and surface net heat flux. The regression model fits reasonably well with 10-year statistical observations/reanalysis data obtained from 100 selected TCs in the northwestern Pacific during 2001–2010, with an averaged fitting error of 0.07 and a mean absolute error of 0.72°C between diagnostic and observed SST cooling. The results reveal that the vertical mixing is overall the pre dominant process producing ocean SST cooling, accounting for 55% of the total cooling. The upwelling accounts for 18% of the total cooling and its maximum occurs near the TC center, associated with TC-induced Ekman pumping. The surface heat flux accounts for 26% of the total cooling, and its contribution increases towards the tropics and the continental shelf. The ocean thermal structures, represented by the SSH in the regression model,plays an important role in modulating the SST cooling pattern. The concept of the regression model can be applicable in TC weather prediction models to improve SST parameterization schemes.  相似文献   

黄河现行清水沟流路汊河运用方案探讨   总被引：1，自引：1，他引：0  

王开荣  凡姚申  韩沙沙  杜小康 《海洋科学》2020,44(10):91-100

对黄河河口现行清水沟流路范围内不同汊河的形成、演化及其特征进行了梳理总结，围绕汊河不同运用方案的影响效应进行了论证分析。研究表明：现行清水沟流路范围内的汊河运用方案不适用于多汊河轮流行河模式、同时行河与轮流行河联合模式和同时行河模式，而采用单一汊河轮流行河模式可以充分发挥海洋输沙动力，保证河口海域向外海的较大输沙量，对延长清水沟流路使用年限更有利，更为科学和经济合理。在现行清8汊河达到改道标准后，应优先使用老河道汊河，该方案不仅有利于未来海岸线的均衡发展，而且更有利于延长清水沟流路的使用年限。  相似文献   

Non-point source pollution estimation in the Pingqiao River Basin,China, using a spatial hydrograph-separation approach     

Han Xue  Kaoru Takara  Bin He  Guangwei Huang  Weili Duan 《水文科学杂志》2019,64(8):962-973

For efficient and targeted management, this study demonstrates a recently developed non-point source (NPS) pollution model for a year-long estimation in the Pingqiao River Basin (22.3 km²) in China. This simple but physically reasonable model estimates NPS export in terms of land use by reflecting spatial hydrological features and source runoff measurements under different land-use types. The NPS export was separately analysed by a distributed hydrological model, a spatial hydrograph-separation technique, and an empirical water quality sub-model. Simulation results suggest that 57 890 kg of total nitrogen (TN) and 1148 kg of total phosphorus (TP) were delivered. The results, validated with observed stream concentrations, show relative errors of 23.3% for TN and 47.4% for TP. Countermeasures for urban areas (5.3% of total area) were prioritized because of the high contribution rate to TN (14.1%) and TP (26.2%) which is caused by the high degree of runoff (8.5%) and pollution source.  相似文献   

Hydrological impact of a reservoir network in the upper Gan River Basin,China     

Ningpeng Dong  Zhongbo Yu  Chuanguo Yang  Mingxiang Yang  Wenzhuo Wang 《水文研究》2019,33(12):1709-1723

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Numerical modeling of lock-exchange gravity/turbidity currents by a high-order upwinding combined compact difference scheme     

Liang Zhao  Ching-Hao Yu  Zhiguo He 《国际泥沙研究》2019,34(3):240-250

This study presents two-dimensional direct numerical simulations for sediment-laden current with higher density propagating forward through a lighter ambient water. The incompressible NavierStokes equations including the buoyancy force for the density difference between the light and heavy fluids are solved by a finite difference scheme based on a structured mesh. The concentration transport equations are used to explore such rich transport phenomena as gravity and turbidity currents. Within the framework of an Upwinding Combined Compact finite Difference (UCCD) scheme, rigorous determination of weighting coefficients underlies the modified equation analysis and the minimization of the numerical modified wavenumber. This sixth-order UCCD scheme is implemented in a four-point grid stencil to approximate advection and diffusion terms in the concentration transport equations and the first-order derivative terms in the Navier-Stokes equations, which can greatly enhance convective stability and increase dispersive accuracy at the same time. The initial discontinuous concentration field is smoothed by solving a newly proposed Heaviside function to prevent numerical instabilities and unreasonable concentration values. A two-step projection method is then applied to obtain the velocity field. The numerical algorithm shows a satisfying ability to capture the generation, development, and dissipation of the Kelvin-Helmholz instabilities and turbulent billows at the interface between the current and the ambient fluid. The simulation results also are compared with the data in published literatures and good agreements are found to prove that the present numerical model can well reproduce the propagation, particle deposition, and mixing processes of lock-exchange gravity and turbidity currents.  相似文献   

海气动量通量研究综述   总被引：1，自引：0，他引：1  

冯兴如  李水清  尹宝树 《海洋科学》2018,42(10):103-109

海气界面动量通量也称为风应力,是海流和表面海浪的主要驱动力,是海洋从大气获得动量的重要途径。因此,合理可靠的海洋表面风应力的参数化对于海洋、大气和波浪以及气候模式的准确预报都具有非常重要的科学意义和实用价值。对风应力拖曳系数的参数化是风应力参数化的主要内容。近来的观测发现,风应力拖曳系数随着风速的增加出现了先增后减的趋势,同时还与海面的波浪状态以及海流有关。基于观测或理论分析,目前已经得到了一系列的风应力拖曳系数计算方法或公式,有的考虑了海浪的作用,有的没有,但这些方案大都是适合中低风速,在高风速下的适用性还有待检验。本文回顾了目前在海气动量通量观测和参数化方面的研究进展,并建议应增加高风速下风速、海流以及海浪等的同步观测,以进一步完善风应力参数化方案。  相似文献   

Reply to comments on “Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth” (Int. J. Numer. Anal. Methods Geomech., 2019, 43 (6), 1300–1315)” by Prof. Linkov     

Haseeb Zia  Brice Lecampion 《国际地质力学数值与分析法杂志》2020,44(18):2524-2526

We reply to Prof. Linkov comments on our article entitled “Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth” (Int. J. Numer. Anal. Methods Geomech., 2019, 43 (6), 1300–1315). We present additional results indicating that both the implicit and explicit front advancement schemes are robust even in the case of a large stress contrast.  相似文献   

小区域消费级无人机倾斜摄影像控点布设及建模精度研究   总被引：1，自引：0，他引：1  

桑文刚  李娜  韩峰  赵培华  李玉斌 《测绘通报》2019,(10):93-96

像控点布设是无人机倾斜摄影施测阶段的重要环节，直接决定后期三维实景模型的精度。本文面向校园等小区域环境，利用消费级单镜头多旋翼无人机航摄系统获取影像数据，重点设计了不同像控点布设方案，基于全自动数据处理系统进行空三加密及三维模型的构建，并对模型成果进行精度分析，为实际工作中小区域像控点的布设提供建议和指导。  相似文献   

滇西实验场地震中短临动态跟踪综合预测方案及其实践运用     

杨芬  李孝宾  薛艳 《震灾防御技术》2014,9(S1):590-599

对滇西实验场1992年以来地下流体前兆观测资料进行分析研究，选取应震效果通过R信度检验（对应MS≥5.0级地震）的8条单项前兆指标。综合考虑单项前兆指标虚报率和漏报率对指标信度的影响，对单项前兆指标利用数学模型进行综合处理，减少了虚报和漏报的次数，预测效果明显提高。利用分级预警模式分别建立了中期（T≤6个月）和短临（T≤3个月）预测模型。综合预测方案还提供了地点判定原则和震级估算原则。最终提供地震短临预测三要素。运用本综合预测方案对2011年腾冲5级双震、2013年洱源5级双震和德钦两次5级地震作用了较为成功的短临预测。  相似文献