混合本征模型的多视SAR影像海冰密度检测

目的 SAR影像中像素光谱测度的空间相关性蕴含着海洋表面和海冰更加丰富的空间特性及其变化信息,因此合理建模这种相关性是高分辨率SAR影像海冰精准解译的关键。提出一种利用随机模型及空间统计学测度刻画海冰空间结构的方法。方法 本文首先,在空间统计学框架下,SAR影像被表示为多值Gamma模型和泊松线Mosaic模型线性加权构建的混合模型,其中多值Gamma模型用于描述海洋表面雷达信号背向散射变化的连续性,而泊松线Mosaic模型则用于表征不同类型海冰表面雷达信号背向散射变化的区域性。利用上述混合模型的一阶、二阶变异函数,建模蕴含在SAR影像中海冰空间结构的变化。结果 对RADARSAT-1影像海冰结构建模并反演其密度。实验区域真实海冰密度分别为20%,80%等,运用本文方法反演所得海冰密度与真实海冰密度误差正负不超过10%。结论 本文提出混合本征模型用以刻画SAR强度影像中海冰像素强度变化的空间关系,能够较好地反演Ungava湾海冰密度分布。为利用遥感影像检测空间机构提供一种全新的方法。     

利用遗传算法拟合实验变差函数

理论变差函数模型的获取是地质统计学中的基础性工作,它是描述储层非均质性、进行储层随机模拟必不可缺的关键环节.针对现有的拟合实验变差函数方法:人工拟合法、非线性回归最小二乘法、加权多项式拟合法等的不足之处,充分利用遗传算法在求解非线性优化问题时具有的全局寻优的特点,提出实验变差函数的遗传算法拟合方法;在常规遗传算法中引入了模拟退火算法,加速了遗传算法的收敛速度.以川中某气藏的孔隙度变差函数为例进行了计算,结果表明:利用遗传算法可以简单、快速地实现实验变差函数的参数估计.     

DESIGN OF GROUNDWATER LEVEL MONITORING NETWORK WITH ORDINARY KRIGING

The primary network of groundwater level observation wells aims at realizing a regional groundwater management policy. It may give a regional picture of groundwater level with emphasis on the natural situation. Observation data from the primary network can be used to estimate the actual state of groundwater system. Since the cost of the installation and maintenance of a groundwater monitoring network is extremely high, the assessment of effectiveness of the network becomes very necessary. Groundwater level monitoring networks are the examples of discontinuous sampling on variables presenting spatial continuity and highly skewed frequency distributions. Anywhere in the aquifer, ordinary kriging provides estimates of the variable sampled and a standard error of the estimate. In this article, the average Kriging standard deviation was used as a criterion for the determination of network density,and the GIS-based approach was analysized. A case study of groundwater level network simulation in the Chaiwopu Basin, Xinjiang Uygur Autonomous Region, China, was presented. In the case study, the initial phreatic water observation wells were 18, a comparison of the three variogram parameters of the three defferent variogram models shows that the Gaussian model is the best. Finally, a network with 55 wells was constructed.     

普通克里格法在铜曼矿区储量估算中的应用

以铜曼矿区勘探数据为基础,建立三维地质矿床模型和三维块体模型,利用3DMine矿业软件实现变异函数模型的拟合、椭球体参数、估值参数的确定。利用克里格估值方法对铜曼矿区进行储量估算,结果表明,基于3DMine软件的克里格法储量估算结果相对准确,可作为矿山资源储量管理和开发利用的依据。     

地质统计学在曼家寨锡锌多金属矿床中的应用

简述了地质统计学的理论和方法,并在此基础上应用大型矿业软件Surpac建立了曼家寨锡锌多金属矿床的矿床数学模型,模拟了锌元素的变异函数,建立了矿床的三维实体模型和品位模型,用克立格法进行了储量计算。     

SURPAC平台下基于克里格估值理论的勘探网度优化

阐述了应用地质统计学法进行勘探网度优化的基本原理及方法,以焦家金矿为例,利用大型矿山软件SURPAC建立了该金矿床的三维模型,结合钻孔和刻槽的样品数据,采用普通克里格法对金品位进行了估值及储量估算,形象地展现了矿体的空间赋存情况和矿石品位的分布情况,并对其变异规律进行分析和评价,模拟出最佳勘探网度,同时在该矿中深部中段进行了实际应用,为采矿设计提供了可靠的地质资料。     

基于DIMINE软件的三维可视化技术及其工程应用

为了对矿山地质条件和开采环境有准确的认识,运用DIMINE三维矿业软件,根据三维建模理论和原始地质资料建立某铁矿的地质数据库、矿体、地表和井巷工程模型.采用距离幂反比法和普通克里格法进行了品位估值和储量计算.与传统方法相比,距离幂反比法和克里格法的矿石量都相差2.5%,品位分别相差0.2%和0.28%.结果表明,运用三维可视化软件对地质体进行三维表达和相关属性计算,可提高现场工作人员的工作效率,可对采矿方法选择、设计和生产组织等提供参考,对提高矿山生产效率有非常重要的意义.     

Reservoir history matching using constrained ensemble Kalman filtering

The high heterogeneity of petroleum reservoirs, represented by their spatially varying rock properties (porosity and permeability), greatly dictates the quantity of recoverable oil. In this work, the estimation of the spatial permeability distribution, which is crucial for predicting the future performance of a reservoir, is carried out through a history matching technique based on constrained ensemble Kalman filtering (EnKF). The main contribution in this work is the novel implementation of hard and soft constraints in the recursive EnKF estimation methodology for petroleum reservoirs. Hard data is obtained from the actual values of the reservoir parameters at discrete locations obtained by core sampling and well logging, while the soft data considered is obtained from correlograms, which characterize the spatial correlation of the rock properties in a reservoir. In each time update, the parameter estimates obtained from the unconstrained EnKF are modified by one of two novel algorithms. In the first, the correlation matrix obtained after the unconstrained EnKF update is transformed to honour the true correlation structure from the correlogram by applying a projection‐based method. The second algorithm involves the use of a technique for soft constrained covariance localization. We observe that the soft data constrained localization method results in the best estimates of the permeability and also reduces the computational time significantly. We quantify the improvement in estimation performance of each of the constrained methods over unconstrained estimation. The method, while developed for estimation in petroleum reservoirs, is also generally applicable to systems with spatial heterogeneity and underlying spatial correlations.     

A FREQUENCY DOMAIN APPROACH FOR THE ESTIMATION OF PARAMETERS OF SPATIO‐TEMPORAL STATIONARY RANDOM PROCESSES

A frequency domain methodology is proposed for estimating parameters of covariance functions of stationary spatio‐temporal processes. Finite Fourier transforms of the processes are defined at each location. Based on the joint distribution of these complex valued random variables, an approximate likelihood function is constructed. The sampling properties of the estimators are investigated. It is observed that the expectation of these transforms can be considered to be a frequency domain analogue of the classical variogram. We call this measure frequency variogram. The method is applied to simulated data and also to Pacific wind speed data considered earlier by Cressie and Huang (1999). The proposed method does not depend on the distributional assumptions about the process.     

秦皇岛32-6油田北区三维相控地质统计建模与反演

秦皇岛32-6油田主要含油层系是被断层复杂化了的明化镇组下段河流相储层,由于薄夹层规模小,砂体薄厚极不稳定且横向变化大,井间可对比性差。常规确定性反演方法受地震频带限制,对目的层段出现频次最多的3~5 m砂体无法准确表征,造成钻前、钻后砂体的变化比较大。为了提高河流相储层预测的分辨率和精度,文中发展应用了相控地质统计学反演方法。具体实现过程是,首先反演出高分辨率的砂泥岩性模型,将它与基于目标的方法模拟出的沉积微相模型合并,然后在新的相模型约束下,按照双重变差函数分析思想,实现对薄储层物性的高精度反演。实际应用表明,井点预测砂体厚度误差较小,井间预测砂体连通、接触关系符合地震趋势和地质统计规律。由此得到的阻抗、优势相和物性三维地质模型,其垂向网格间距可达到1 ms,既能在平面上很好地表现地质认识,又能在纵向上合理划分出隔、夹层。