共查询到20条相似文献，搜索用时 46 毫秒
1.
Tingting Yao 《Mathematical Geology》2002,34(4):387-403
Clastic reservoir characterization starts typically with modeling lithofacies distribution and geometry. The architecture of the reservoir, governed by the lithofacies geometry, is a major source of heterogeneity in such clastic systems. Seismic data provide potentially valuable information about the areal distribution of different lithofacies, such as the averaged prior proportion of each lithofacies. However, seismic data are available only at coarse vertical resolution rather than the fine lithofacies sampling along wells, hence seismic is considered equivalent to 2D data while building 3D geological models. This scale difference between the seismic data and the lithofacies data available along the wells makes direct integration difficult. Different algorithms have been proposed to integrate the seismic data: (1) duplicate seismic data along the vertical line and use the prior proportions provided by the seismic data as prior local means; (2) integrate the 2D seismic data as collocated block averages; and (3) duplicate seismic data along the vertical line and integrate them using a Markov-Bayes algorithm. These three algorithms are applied on a data set originating from a real clastic reservoir. The results are compared with regard to how much kriging weight is applied to the seismic data and how well the information from seismic data is honored. 相似文献
2.
A stochastic channel embedded in a background facies is conditioned to data observed at wells. The background facies is a fixed rectangular box. The model parameters consist of geometric parameters that describe the shape, size, and location of the channel, and permeability and porosity in the channel and nonchannel facies. We extend methodology previously developed to condition a stochastic channel to well-test pressure data, and well observations of the channel thickness and the depth of the top of the channel. The main objective of this work is to characterize the reduction in uncertainty in channel model parameters and predicted reservoir performance that can be achieved by conditioning to well-test pressure data at one or more wells. Multiple conditional realizations of the geometric parameters and rock properties are generated to evaluate the uncertainty in model parameters. The ensemble of predictions of reservoir performance generated from the suite of realizations provides a Monte Carlo estimate of the uncertainty in future performance predictions. In addition, we provide some insight on how prior variances, data measurement errors, and sensitivity coefficients interact to determine the reduction in model parameters obtained by conditioning to pressure data and examine the value of active and observation well data in resolving model parameters. 相似文献
3.
Amilcar Soares 《Mathematical Geology》1992,24(2):149-160
A method is proposed for the characterization of the disjoint shapes of a multi-phase set. The method uses a global structural function and provides estimates of the complete mosaic of phases, honoring the individual volume proportions inferred from the experimental samples. The estimates of shapes can be improved by local conditioning to the covariance of each phase and to geometrical characteristics such as spatial orientation of the different strata. The mapping of uncertainty zones for individual phases is one advantage of using a geostatistical approach to characterize the morphology of qualitative (non-numerical) variables. 相似文献
4.
基于过程的分流平原高弯河道砂体储层内部建筑结构分析--以大庆油田萨北地区为例 总被引：4，自引：1，他引：3
河道砂体内部结构已成为影响剩余油分布的决定因素。本研究旨在弄清三角洲平原高弯曲河道砂体内部结构,指导开发调整。解剖分为复合河道、单一河道、基本结构要素及要素内部结构等四个层次。基于三角洲平原上高弯河流的形成过程,依据河泛沉积分布及河道沉积体内部沉积特征识别单一河道。依据砂体厚度分布及砂体测井响应所体现的砂体所处的河道位置识别最终废弃河道,依据测井响应特征识别中间废弃河道,通过中间废弃河道及最终废弃河道位置关系,分析河道摆动特征,追踪河道迁移演化。按照河道演化过程识别点坝及其平面展布。在点坝内部通过岩芯、对子井分析确定侧积体的垂向厚度、倾向、倾角,进而获取侧积体平面发育频率,建立点坝内部的结构模型。研究基于河流演化过程,将河流过程与沉积结果统一起来,从过程角度解释了砂体形成,使解剖结果更合理更准确,可很好地指导剩余油预测分析。 相似文献
5.
Mean flow and turbulence structure over fixed, two-dimensional dunes: implications for sediment transport and bedform stability 总被引：4，自引：0，他引：4
Detailed measurements of flow velocity and its turbulent fluctuation were obtained over fixed, two-dimensional dunes in a laboratory channel. Laser Doppler anemometry was used to measure the downstream and vertical components of velocity at more than 1800 points over one dune wavelength. The density of the sampling grid allowed construction of a unique set of contour maps for all mean flow and turbulence parameters, which are assessed using higher moment measures and quadrant analysis. These flow field maps illustrate that: (1) the time-averaged downstream and vertical velocities agree well with previous studies of quasi-equilibrium flow over fixed and mobile bedforms and show a remarkable symmetry from crest to crest; (2) the maximum root-mean-square (RMS) of the downstream velocity values occur at and just downstream of flow reattachment and within the flow separation cell; (3) the maximum vertical RMS values occur within and above the zone of flow separation along the shear layer and this zone advects and diffuses downstream, extending almost to the next crest; (4) positive downstream skewness values occur within the separation cell, whereas positive vertical skewness values are restricted to the shear layer; (5) the highest Reynolds stresses are located within the zone of flow separation and along the shear layer; (6) high-magnitude, high-frequency quadrant-2 events (‘ejections’) are concentrated along the shear layer (Kelvin-Helmholtz instabilities) and dominate the contribution to the local Reynolds stress; and (7) high-magnitude, high-frequency quadrant-4 events occur bounding the separation zone, near reattachment and close to the dune crest, and are significant contributors to the local Reynolds stress at each location. These data demonstrate that the turbulence structure associated with dunes is controlled intrinsically by the formation, magnitude and downstream extent of the flow separation zone and resultant shear layer. Furthermore, the origin of dune-related macroturbulence lies in the dynamics of the shear layer rather than classical turbulent boundary layer bursting. The fluid dynamic distinction between dunes and ripples is reasoned to be linked to the velocity differential across the shear layer and hence the magnitude of the Kelvin-Helmholtz instabilities, which are both greater for dunes than ripples. These instabilities control the local flow and turbulence structure and dictate the modes of sediment entrainment and their transport rates. 相似文献
6.
应用研究区丰富的密井网和邻近露头资料,探讨了新疆克拉玛依油田三叠系克下组冲积扇内部构型单元的层次划分系统,并建立相应的沉积构型模式。在冲积扇的扇根、扇中和扇缘各亚相带,进一步划分了3个级次的构型要素以表达其内的沉积复杂性。扇根亚相主要由主槽、片流带和漫洪带组成,其中,在主槽内主要发育槽流砾石（岩）体（可细分为砾石坝和流沟）与泥石流沉积,在片流带内主要发育片流砂砾体（可细分为砾石坝和流沟）,在漫洪带主要发育漫洪砂体和漫洪细粒沉积,总体构型样式以广泛分布的砾石坝夹含流沟和漫洪沉积的“泛连通体”为特征;扇中亚相主要由辫流带和漫流带组成,其中,辫流带的主体构型要素为辫流水道（可细分为砂坝和沟道）,总体构型样式为复合宽带状辫流水道砂体与漫流细粒沉积侧向相间、垂向互层为特征;扇缘亚相主要由径流带和漫流带组成,其中,径流带的主体构型要素为径流水道,总体构型样式以窄带状径流水道和漫流砂体镶嵌于漫流—湿地泥岩之中为特征。 相似文献
7.
The Ichamati River drains the east and south side of the North 24 Parganas district which belongs to the Ganga-Brahmaputra Delta (GBD), covered by deep Quaternary sediments produced under tropical monsoon climate in India. The district is densely populated. The river has huge impact on its population. In this paper, particular attention has been paid to a new method, named optimum cross section index (OCI), which is a numerical representation of a river cross section with respect to its optimum condition. To establish the validity and reliability of OCI, as circumstantial evidences, we have measured and analyzed the geometric parameters, such as width, depth, hydraulic radius, wetted perimeter, and bank profile at 22 points, and applied the areal difference asymmetric index (ADAI). The paper considers that the changing characters of the geometric form of the cross sections and ADAI stand for the OCI. All the techniques reveal that (1) the area of channel decreases abruptly upstream downward, (2) the upstream channel is more symmetrical than the lower reach, and (3) the area of optimum channel gradually increases upstream downward. Results of the study show that the river is going to be deteriorating from upstream downward. OCI has been constructed based on width and depth, which are relatively easily available data. So, this model may be well assessable to identify the optimum channel for a river management. 相似文献
8.
河口坝地下储层构型的分析及建模研究甚少,至今未能建立完整的3~5级界面层次模型,迫切需要建立一套完整的三角洲河口坝构型界面层次模型。为此,本文提出了分级控制下的界面识别与井间预测相结合的河口坝储层构型建模方法。结果显示,在人机互动的共同作用下,完整的河口坝模型可以为实际生产提供空间理论上的支持。研究区各构型单元不断向前推移,形成了明显前积的三角洲模式,河口坝增生体夹角范围为0.2°~3.43°,主物源方向延伸距离为1.64km,垂直物源方向为0.89km,整体上看,河口坝增生体呈席状分布、连续性好。这一研究不仅完善了河口坝地下储集体理论的研究,而且对提高油田开发效率具有重要意义。 相似文献
9.
Pierre Goovaerts 《Mathematical Geosciences》2008,40(1):101-128
This paper presents a methodology to conduct geostatistical variography and interpolation on areal data measured over geographical units (or blocks) with different sizes and shapes, while accounting for heterogeneous weight or kernel functions within those units. The deconvolution method is iterative and seeks the point-support model that minimizes the difference between the theoretically regularized semivariogram model and the model fitted to areal data. This model is then used in area-to-point (ATP) kriging to map the spatial distribution of the attribute of interest within each geographical unit. The coherence constraint ensures that the weighted average of kriged estimates equals the areal datum.This approach is illustrated using health data (cancer rates aggregated at the county level) and population density surface as a kernel function. Simulations are conducted over two regions with contrasting county geographies: the state of Indiana and four states in the Western United States. In both regions, the deconvolution approach yields a point support semivariogram model that is reasonably close to the semivariogram of simulated point values. The use of this model in ATP kriging yields a more accurate prediction than a naïve point kriging of areal data that simply collapses each county into its geographic centroid. ATP kriging reduces the smoothing effect and is robust with respect to small differences in the point support semivariogram model. Important features of the point-support semivariogram, such as the nugget effect, can never be fully validated from areal data. The user may want to narrow down the set of solutions based on his knowledge of the phenomenon (e.g., set the nugget effect to zero). The approach presented avoids the visual bias associated with the interpretation of choropleth maps and should facilitate the analysis of relationships between variables measured over different spatial supports. 相似文献
10.
Goovaerts P 《Mathematical Geology》2008,40(1):101-128
This paper presents a methodology to conduct geostatistical variography and interpolation on areal data measured over geographical units (or blocks) with different sizes and shapes, while accounting for heterogeneous weight or kernel functions within those units. The deconvolution method is iterative and seeks the pointsupport model that minimizes the difference between the theoretically regularized semivariogram model and the model fitted to areal data. This model is then used in area-to-point (ATP) kriging to map the spatial distribution of the attribute of interest within each geographical unit. The coherence constraint ensures that the weighted average of kriged estimates equals the areal datum.This approach is illustrated using health data (cancer rates aggregated at the county level) and population density surface as a kernel function. Simulations are conducted over two regions with contrasting county geographies: the state of Indiana and four states in the Western United States. In both regions, the deconvolution approach yields a point support semivariogram model that is reasonably close to the semivariogram of simulated point values. The use of this model in ATP kriging yields a more accurate prediction than a na?ve point kriging of areal data that simply collapses each county into its geographic centroid. ATP kriging reduces the smoothing effect and is robust with respect to small differences in the point support semivariogram model. Important features of the point-support semivariogram, such as the nugget effect, can never be fully validated from areal data. The user may want to narrow down the set of solutions based on his knowledge of the phenomenon (e.g., set the nugget effect to zero). The approach presented avoids the visual bias associated with the interpretation of choropleth maps and should facilitate the analysis of relationships between variables measured over different spatial supports. 相似文献
11.
安塞油田坪桥水平井区沉积微相三维建模研究 总被引：4，自引：0，他引：4
以安塞油田坪桥水平井区为例,探讨了应用水平井和露头资料及标点过程(示性点过程)方法进行沉积微相三维建模的思路与方法,同时对研究区三角洲前缘分流河道的定量结构模式进行了深入的研究。研究表明,坪桥水平井区三角洲分流河道单砂体宽度一般为40～100m左右。砂体结构呈两种模式,其一为“迷宫状”,砂体离散地分布于湖相泥岩中,其二为“拼合板状”,多个砂体在侧向上叠置而形成连片分布的砂体,但部分单砂体间可被泥质或钙质薄层侧积层所隔挡。应用水平井资料和露头资料,可有效地提取三维建模所必须的地质统计学参数。研究表明,采用标点过程方法,可建立符合地质实际的沉积微相三维模型。 相似文献
12.
Computer-aided geometric design of geologic surfaces and bodies 总被引：2，自引：0，他引：2
Bivariate quadratic simplicial B-splines are employed to obtain aC
1-smooth surface from scattered positional or directional geological data given over a two-dimensional domain. Vertices are generated according to the areal distribution of data sites, and polylines are defined along real geological features. The vertices and the polylines provide a constrained Delaunay triangulation of the domain. Note that the vertices do not generally coincide with the data sites. Six linearly independent simplex B-splines are associated with each triangle. Their defining knots and finite supports are automatically deduced from the vertices. Specific knot configurations result in discontinuities of the surface or its directional derivatives. Coefficients of a simplex spline representation are visualized as geometric points controlling the shape of the surface. This approach calls for geologic modeling and interaction of the geologist up front to define vertices and polylines, and to move control points initially given by an algorithm. Thus, simplex splines associated with irregular triangles seem to be well-suited to approximate and allow further geometrically modeling of geologic surfaces, including discontinuities, from scattered data. Applications to mathematical test as well as to real geological data are given as examples. 相似文献
13.
Due to the notorious lack of data, stochastic simulation and conditioning of distributed parameter fields is generally acknowledged
as a major task in order to produce realistic prognoses for groundwater flow phenomena, thus honouring the maximum of information
available. In this paper, a new conditioning approach is presented which treats the distributed parameters directly without
projection onto lower dimensional spaces and preserves certain desired statistical properties by explicitly stating them as
constraints for the conditioning optimization problem. Typically, the conditioning task must be performed very often and the
conditioning optimization problems are highly dimensional. Therefore, a second main focus of the paper is on the presentation
of efficient multigrid methods for the solution of the conditioning problems. Numerical results are given for a practical
application problem.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Marta Cosma Na Yan Luca Colombera Nigel P. Mountney Andrea D&#x;Alpaos Massimiliano Ghinassi 《Sedimentology》2021,68(1):449-476
Low rates of lateral migration (centimetres to decimetres per year) combined with relatively high rates of vertical accretion (millimetres to centimetres per year) recorded in microtidal channels of the Venice Lagoon (Italy) give rise to point‐bar geometries and internal facies arrangements that differ substantially from widely accepted models of point‐bar sedimentary architecture. In this study, field data from the Venice Lagoon are combined with a three‐dimensional forward stratigraphic model, the ‘Point‐Bar Sedimentary Architecture Numerical Deduction’ (PB‐SAND), to predict the stratal geometries of point bars formed in aggradational settings. The PB‐SAND uses a combined geometric and stochastic modelling approach that can be constrained by field evidence. The model applied determines the geometry of four point bars generated by 9 to 11 m wide channels cutting through salt marshes. An iterative best‐fit modelling approach has been used to obtain multiple simulations for each case study, each of which fits the observations derived from the analysis of time‐series historical aerial photographs and 44 sedimentary cores. Results demonstrate how the geometry of the bars is determined by the development of two key stratal surfaces: the point‐bar brink and channel‐thalweg surfaces. These surfaces are defined by the progressive translation and vertical shift of the point‐bar brink (i.e. break of slope between bar top and bar slope) and the channel thalweg (i.e. deepest part of the channel) during bar evolution. The approach is used to: (i) reconstruct three‐dimensional point‐bar geometries; (ii) propose alternative reconstructions; (iii) provide insight to drive the acquisition of additional data to better constrain the proposed models; and (iv) provide insight into the mechanism of bar growth for slowly migrating channels in settings subject to relatively high rates of aggradation. This study highlights how interaction between styles of planform transformation and latero‐vertical shifts of meandering channels can determine the geometry of related sedimentary bodies. 相似文献
15.
16.
Modeling of Fluvial Reservoirs with Object Models 总被引：16，自引：0，他引：16
An object model for fluvial reservoirs that has been developed from 1985 to present is described. It uses a formal mathematical object model (marked point process) describing the distributions of four facies: channel, crevasse, barrier, and background. Realisations from the model are generated using the Metropolis-Hastings simulation algorithm with simulated annealing conditioning on the volume ratios and well observations. The main challenge has been to find a suitable parameterization of the geology of fluvial reservoirs, and to find and implement the generating function of the channels in the simulation algorithm. The model and simulation algorithm can be conditioned on arbitrary well paths including horizontal wells and paths with partly missing observations, well test data, well contacts, seismic data, and general geological knowledge. 相似文献
17.
针对地基隔振控制,提出了一类新型的空沟?波阻板联合隔振屏障,并对其隔振性能进行了数值分析。首先,利用复伸展坐标变换,在频域内建立了完全匹配层（perfect matched layer, PML）吸收边界的控制方程;其次,利用Galerkin近似技术,给出了以位移为基本未知量的二阶非分裂格式PML的频域有限元计算列式;最后,通过数值算例分析了空沟?波阻板联合隔振屏障的物性参数（地基与波阻板的模量比）、几何参数（空沟深度、波阻板深度）以及载荷参数（振动波频率）等对其隔振性能的影响规律。结果表明,空沟?波阻板联合隔振屏障结合了空沟和波阻板各自的优势,可以有效地控制不同频率振源引起的地基振动。 相似文献
18.
Field and laboratory methods have been used to determine the hydraulic properties in a multiple-layer aquifer–aquitard system that is hydrologically connected to a river. First, hypothetical pumping tests in aquifer–aquitard systems were performed to evaluate the feasibility of MODFLOW-PEST in determining these parameters. Sensitivity analyses showed that: the horizontal hydraulic conductivity in the aquifer has the highest composite sensitivity; the vertical hydraulic conductivity has higher composite sensitivity than the horizontal hydraulic conductivity in the aquitard; and a partial penetration pumping well in an aquifer layer can improve the quality of the estimated parameters. This inverse approach was then used to analyze a pumping-recovery test conducted near the Platte River in southeastern Nebraska, USA. The hydraulic conductivities and specific yield were calculated for the aquitard and aquifer. The direct-push technique was used to generate sediment columns; permeameter tests on these columns produced the vertical hydraulic conductivities that are compatible with those obtained from the pumping-recovery test. Thus, the combination of the direct-push technique with permeameter tests provides a new method for estimation of vertical hydraulic conductivity. The hydraulic conductivity, determined from grain-size analysis, is smaller than the horizontal one but larger than the vertical one determined by the pumping-recovery test. 相似文献
19.
A.P. Tarkov 《Tectonophysics》1980,65(1-2)
Consideration of the Voronezh Crystalline Massif shows that three-layered seismic models and velocity profiles with a characteristic distribution of layer velocities and their gradients in each layer, reflect a crystalline crust and uppermost mantle structure formed through regional metamorphism and magmatism processes.Velocity and seismic parameter vertical gradients from the lithosphere profile are several times higher than those for homogeneous compression of minerals and rocks.For the identified layers the contribution of different factors for each seismic parameter gradient value is estimated. Anomalously high rates of increase with depth for Vp, Vs and ø are shown to be caused by the combined effects of structure-phase transformations and substance composition variations in lithospheric complex mineral parageneses. 相似文献
20.
Atsushi Saotome Ryunoshin YoshinakaMasahiko Osada Hiroyasu Sugiyama 《Engineering Geology》2002,64(1):1-17
Volcanic breccia is a representative heterogeneous rock. As a preliminary study for determining its mechanical properties in laboratory and field experiments, its material properties and structural features were described. Three-dimensional clast-size distribution was also estimated for the study site using the theory of stereology. With this distribution determined, a numerical simulation was performed to investigate the relationship between the volumetric proportion of clasts in a sample and the areal proportion and maximum length of clasts on a lateral surface of the sample. The following observations were made: (1) coefficients of variation for volumetric proportion are dependent on the size of the sample, and became large when the size of the sample is small; (2) samples with a small coefficient of variation can be selected at any size if a restriction is placed on the ratio, Dmax/D0, of the maximum length of clasts to the size of the sample; and (3) the volumetric proportion of clasts in each sample can be estimated from the observed areal proportions within an error range that depends on the whole volumetric proportion. 相似文献