共查询到20条相似文献，搜索用时 203 毫秒
1.
A probabilistic parametrization for geological uncertainty estimation using the ensemble Kalman filter (EnKF) 总被引：2，自引：0，他引：2
In the past years, many applications of history-matching methods in general and ensemble Kalman filter in particular have been proposed, especially in order to estimate fields that provide uncertainty in the stochastic process defined by the dynamical system of hydrocarbon recovery. Such fields can be permeability fields or porosity fields, but can also fields defined by the rock type (facies fields). The estimation of the boundaries of the geologic facies with ensemble Kalman filter (EnKF) was made, in different papers, with the aid of Gaussian random fields, which were truncated using various schemes and introduced in a history-matching process. In this paper, we estimate, in the frame of the EnKF process, the locations of three facies types that occur into a reservoir domain, with the property that each two could have a contact. The geological simulation model is a form of the general truncated plurigaussian method. The difference with other approaches consists in how the truncation scheme is introduced and in the observation operator of the facies types at the well locations. The projection from the continuous space of the Gaussian fields into the discrete space of the facies fields is realized through in an intermediary space (space with probabilities). This space connects the observation operator of the facies types at the well locations with the geological simulation model. We will test the model using a 2D reservoir which is connected with the EnKF method as a data assimilation technique. We will use different geostatistical properties for the Gaussian fields and different levels of the uncertainty introduced in the model parameters and also in the construction of the Gaussian fields. 相似文献
2.
3.
A Simple Approach to Account for Radial Flow and Boundary Conditions When Kriging Hydraulic Head Fields for Confined Aquifers 总被引：2，自引：0，他引：2
The estimation and mapping of realistic hydraulic head fields, hence of flow paths, is a major goal of many hydrogeological studies. The most widely used method to obtain reliable head fields is the inverse approach. This approach relies on the numerical approximation of the flow equation and requires specifying boundary conditions and the transmissivity of each grid element. Boundary conditions are often unknown or poorly known, yet they impose a strong signature on the head fields obtained by inverse analysis. A simpler alternative to the inverse approach is the direct kriging of the head field using the measurements obtained at observation wells. The kriging must be modified to incorporate the available information. Use of the dual kriging formalism enables simultaneously estimating the head field, the aquifer mean transmissivity, and the regional hydraulic gradient from head data in steady or transient state conditions. In transient state conditions, an estimate of the storage coefficient can be obtained. We test the approach on simple analytical cases, on synthetic cases with solutions obtained numerically using a finite element flow simulator, and on a real aquifer. For homogeneous aquifers, infinite or bounded, the kriging estimate retrieves the exact solution of the head field, the exact hydrogeological parameters and the flow net. With heterogeneous aquifers, kriging accurately estimates the head field with prediction errors of the same magnitude as typical head measurement errors. The transmissivities are also accurately estimated by kriging. Moreover, if inversion is required, the kriged head along boundaries can be used as realistic boundary conditions for flow simulation. 相似文献
4.
基于TOUGH2数值模拟器中存在处理复杂地质条件难的问题,提出了将三维地质模型与TOUGH2数值模型耦合的具体思路和方法,并在Windows平台上编制了相应的程序,利用该程序可以直接将地质模型（如GMS和Petrel建立）与TOUGH2的数值模型进行有机融合,并进行了算法验证。通过CO2地质储存的实例,可以看出地层构造对CO2的空间运移起着控制作用,模拟结果显示CO2会沿着背斜面地层进行运移扩散。因此通过此转换程序,能够增强TOUGH2模拟器处理地层起伏、断层、褶被等常见地质构造,以及地质属性随空间变化的地质体,提高了模拟器的使用效率。 相似文献
5.
Application of the EnKF and Localization to Automatic History Matching of Facies Distribution and Production Data 总被引：3，自引：3，他引：0
The performance of the ensemble Kalman filter (EnKF) for continuous updating of facies location and boundaries in a reservoir model based on production and facies data for a 3D synthetic problem is presented. The occurrence of the different facies types is treated as a random process and the initial distribution was obtained by truncating a bi-Gaussian random field. Because facies data are highly non-Gaussian, re-parameterization was necessary in order to use the EnKF algorithm for data assimilation; two Gaussian random fields are updated in lieu of the static facies parameters. The problem of history matching applied to facies is difficult due to (1) constraints to facies observations at wells are occasionally violated when productions data are assimilated; (2) excessive reduction of variance seems to be a bigger problem with facies than with Gaussian random permeability and porosity fields; and (3) the relationship between facies variables and data is so highly non-linear that the final facies field does not always honor early production data well. Consequently three issues are investigated in this work. Is it possible to iteratively enforce facies constraints when updates due to production data have caused them to be violated? Can localization of adjustments be used for facies to prevent collapse of the variance during the data-assimilation period? Is a forecast from the final state better than a forecast from time zero using the final parameter fields?To investigate these issues, a 3D reservoir simulation model is coupled with the EnKF technique for data assimilation. One approach to enforcing the facies constraint is continuous iteration on all available data, which may lead to inconsistent model states, incorrect weighting of the production data and incorrect adjustment of the state vector. A sequential EnKF where the dynamic and static data are assimilated sequentially is presented and this approach seems to have solved the highlighted problems above. When the ensemble size is small compared to the number of independent data, the localized adjustment of the state vector is a very important technique that may be used to mitigate loss of rank in the ensemble. Implementing a distance-based localization of the facies adjustment appears to mitigate the problem of variance deficiency in the ensembles by ensuring that sufficient variability in the ensemble is maintained throughout the data assimilation period. Finally, when data are assimilated without localization, the prediction results appear to be independent of the starting point. When localization is applied, it is better to predict from the start using the final parameter field rather than continue from the final state. 相似文献
6.
Luis Manuel de Vries Jesus Carrera Oriol Falivene Oscar Gratacós Luit Jan Slooten 《Mathematical Geosciences》2009,41(1):29-42
Simulation of flow and solute transport through aquifers or oil reservoirs requires a precise representation of subsurface
heterogeneity that can be achieved by stochastic simulation approaches. Traditional geostatistical methods based on variograms,
such as truncated Gaussian simulation or sequential indicator simulation, may fail to generate the complex, curvilinear, continuous
and interconnected facies distributions that are often encountered in real geological media, due to their reliance on two-point
statistics. Multiple Point Geostatistics (MPG) overcomes this constraint by using more complex point configurations whose
statistics are retrieved from training images. Obtaining representative statistics requires stationary training images, but
geological understanding often suggests a priori facies variability patterns. This research aims at extending MPG to non-stationary
facies distributions. The proposed method subdivides the training images into different areas. The statistics for each area
are stored in separate frequency search trees. Several training images are used to ensure that the obtained statistics are
representative. The facies probability distribution for each cell during simulation is calculated by weighting the probabilities
from the frequency trees. The method is tested on two different object-based training image sets. Results show that non-stationary
training images can be used to generate suitable non-stationary facies distributions. 相似文献
7.
Continuous Facies Updating Using the Ensemble Kalman Filter and the Level Set Method 总被引：1，自引：1，他引：0
We present a methodology based on the ensemble Kalman filter (EnKF) and the level set method for the continuous model updating of geological facies with respect to production data. Geological facies are modeled using an implicit surface representation and conditioned to production data using the ensemble Kalman filter. The methodology is based on Gaussian random fields used to deform the facies boundaries. The Gaussian random fields are used as the model parameter vector to be updated sequentially within the EnKF when new measurements are available. We show the successful application of the methodology to two synthetic reservoir models. 相似文献
8.
基于MatDEM的砂土侧限压缩试验离散元模拟研究 总被引：2，自引：2，他引：0
离散元法基于非连续介质力学理论,尤其适用于砂土等离散介质体的数值模拟研究。利用岩土体离散元模拟软件MatDEM的二次开发功能,研发了砂土侧限压缩试验三维离散元模拟器。对三个不同级配砂土试样进行了侧限压缩试验,并且进行了与之相对应的数值模拟,通过分析对比试验结果与数值模拟结果验证了所开发模拟器的有效性。模拟结果表明:离散元法可以很好地反应砂土压缩过程中的配位数变化;每个模拟样品中,粒径较小的单元受到较大的平均压力,导致平均位移较大;数值计算结果的主要误差是由离散元颗粒自身的泊松比引起的。研究突破了常规土力学研究方法的局限性,为今后岩土工程离散元模拟研究提供了参考。 相似文献
9.
油气储层相控随机建模技术的约束方法 总被引：31，自引：4，他引：27
提出根据相控随机建模技术描述油气储层特征,并用已知地质数据和沉积微相的研究成果,如平面展布方向、宽厚比等来指导相控建模,文章提出“多层分级控制,同级套合管理”的相控随机建模策略,并将相序、概率、定量知识库或变差函数三个方面相结合来表征油气储层的非均质特性。具体则是从沉积形成与演化的成因角度指导沉积储层随机建模的过程,应用多参数协同、分层次约束的方法,运用沉积相带的平面展布和垂向演化来控制建模的结果,并用宝力格油田的实际地质和钻井数据验证优选得到的多个模型实现。结果表明:优选模型真实地反映了地下油气储层的非均质特性和连通性展布特征,并经新钻井数据验证确实有效。 相似文献
10.
A statistical method for estimating rates of soil development in a given region based on calibration from a series of dated soils is used to estimate ages of soils in the same region that are not dated directly. The method is designed specifically to account for sampling procedures and uncertainties that are inherent in soil studies. Soil variation and measurement error, uncertainties in calibration dates and their relation to the age of the soil, and the limited number of dated soils are all considered. Maximum likelihood (ML) is employed to estimate a parametric linear calibration curve, relating soil development to time or age on suitably transformed scales. Soil variation on a geomorphic surface of a certain age is characterized by replicate sampling of soils on each surface; such variation is assumed to have a Gaussian distribution. The age of a geomorphic surface is described by older and younger bounds. This technique allows age uncertainty to be characterized by either a Gaussian distribution or by a triangular distribution using minimum, best-estimate, and maximum ages. The calibration curve is taken to be linear after suitable (in certain cases logarithmic) transformations, if required, of the soil parameter and age variables. Soil variability, measurement error, and departures from linearity are described in a combined fashion using Gaussian distributions with variances particular to each sampled geomorphic surface and the number of sample replicates. Uncertainty in age of a geomorphic surface used for calibration is described using three parameters by one of two methods. In the first method, upper and lower ages are specified together with a coverage probability; this specification is converted to a Gaussian distribution with the appropriate mean and variance. In the second method, absolute older and younger ages are specified together with a most probable age; this specification is converted to an asymmetric triangular distribution with mode at the most probable age. The statistical variability of the ML-estimated calibration curve is assessed by a Monte Carlo method in which simulated data sets repeatedly are drawn from the distributional specification; calibration parameters are reestimated for each such simulation in order to assess their statistical variability. Several examples are used for illustration. The age of undated soils in a related setting may be estimated from the soil data using the fitted calibration curve. A second simulation to assess age estimate variability is described and applied to the examples. 相似文献
11.
Effects of Microparameters on Macroparameters of Flat-Jointed Bonded-Particle Materials and Suggestions on Trial-and-Error Method 总被引：1，自引：1，他引：0
Peng-yu Chen 《Geotechnical and Geological Engineering》2017,35(2):663-677
The aims of this paper are to analyze the effects of microparameters on macroparameters of flat-jointed bonded-particle materials of particle flow code in two dimensions (PFC2D) and improve the efficiency of trial-and-error method in calibration of microparameters. The trial-and-error method is always used to calibrate the microparameters for a PFC2D model, but it is time-consuming and empirical. To improve the efficiency of the trial-and-error method, the effects of microparameters on macroparameters need to be analyzed. By using the trial-and-error method, a desirable set of microparameters for a uniaxial compression PFC2D model (with a flat-joint contact model as the contact model) of limestone were calibrated to match the macroscopic properties obtained from laboratory tests. Based on the calibration set of microparameters, effects of microparameters on macroparameters of the PFC2D model were studied by the orthogonal design method. On this basis, a flowchart of calibrating microparameters via trial-and-error method was proposed. This flowchart was used to calibrate the microparameters of granite. The macroparameters and failure characteristics determined from numerical simulation were very similar to those of laboratory tests, confirming the effectiveness of the proposed flowchart. 相似文献
12.
E. S. Zakirov I. M. Indrupskiy O. V. Liubimova I. M. Shiriaev D. P. Anikeev 《Doklady Earth Sciences》2017,476(2):1120-1124
An approach for geostatistically consistent matching of 3D flow simulation models and 3D geological models is proposed. This approach uses an optimization algorithm based on identification of the parameters of the geostatistical model (for example, the variogram parameters, such as range, sill, and nugget effect). Here, the inverse problem is considered in the greatest generality taking into account facies heterogeneity and the variogram anisotropy. The correlation dependence parameters (porosity-to-log permeability) are clarified for each single facies. 相似文献
13.
Fresh-water lenses are the major sources of water supply in many atoll islands in the Pacific and Indian Oceans, particularly
in dry seasons. Several two- and three-dimensional models are currently available for the simulation of atoll-island aquifers;
however, 2D models cannot include 3D spatial variability of material properties, they must simplify the boundary conditions,
and they cannot correctly simulate pumping wells. In an attempt to overcome these difficulties, a 3D model, SALTFLOW, was
adopted for the simulation of Home Island in the Indian Ocean. This exercise required a discretisation on the order of a few
metres and time steps of a few hours requiring significantly high CPU times. High CPU demand proved to be a difficult challenge
but cannot be considered a serious practical limitation with today's advanced computers. The exhaustive data demands of the
model (e.g., 3D distributions of hydraulic conductivity, porosity, dispersivities, and spatial and temporal variations of
recharge and extraction rates) proved to be more problematical. Although the Home Island data set is unusually comprehensive
by any standards, nonetheless the quality and quantity of the available data proved inadequate to meet the calibration needs
of a highly karstic aquifer system. The Home Island modeling demonstrates the practical limitations of 3D models. It raises
the concern that our ability to develop computer codes capable of simulating complex systems now exceeds our ability to supply
the input data necessary for reliable calibration. Finally, the paper demonstrates the importance of the transient calibration
in reliable simulation of various management options and emphasises that transient calibration should be considered as an
integral part of any similar 2D or 3D modeling.
Electronic Publication 相似文献
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15.
M. Le Ravalec-Dupin L. Y. Hu F. Roggero 《地学前缘》2008,15(1):176-186
计算机能力的提升和历史拟合方面的最新进展促进了对先前建立的储层模型的重新检验。为了节省工程师和CPU的时间,我们开发了4种独特的算法,来允许无需重新进行储层研究而重建现有模型。这些算法涉及的技术包括:优化、松弛、Wiener滤波或序贯重构。基本上,它们被用来确定一个随机函数和一系列随机数。给定一个随机函数,一族随机数将产生一个实现,这个实现和现有的储层模型十分接近。一旦随机数已知,现有的储层模型将被提交到一个历史拟合过程中,以此来改进数据拟合度或者考虑新收集到的数据。我们关注的是先前建立的相储层模型。虽然我们对模型模拟的方式一无所知,但是我们可以确定一系列随机数,再用多点统计模拟方法来建造一个和现有储层模型十分接近的实现。然后运行一种新的历史拟合程序来更新现有的储层模型,使其拟合两口新生产井的流量数据。 相似文献
16.
三维大地电磁测深(MT)资料用于沉积相分布的研究中,弥补了野外露头、测井和地震等传统识别和研究方法的不足.通过对三维MT资料进行去噪、编辑与平滑和静态位移校正等预处理和三维反演处理,使三维MT数据更加准确地反映研究地区岩石的电阻率.在野外露头观察和测井解释成果的基础上,利用岩芯或岩屑对电阻率进行标定,界定出库车组不同岩性的电阻率值范围,然后将三维MT剖面与相对应的地震剖面叠合,进行电震同平台解释,建立构造样式,最终在建立的地层格架内对沉积相分布特征进行精细的识别和研究,该方法在库车坳陷库车组沉积相识别及分布研究中取得了良好的应用效果,解决了井间相带变化和地震相特征不明显带来的研究困难,对研究沉积相带分布和沉积相演化等基础石油地质研究具有重大的意义. 相似文献
17.
二维颗粒流数值模拟（PFC2D）是目前研究裂隙岩石裂纹扩展特征的重要手段。在大量已有相关研究文献的基础上做了以下分析和总结:从颗粒接触本构模型、细观参数的标定和裂隙模拟方法3个方面对当前PFC2D的主要模拟方法进行了总结;根据PFC2D模拟裂隙岩石裂纹扩展特征的研究现状,重点对单裂隙、断续双裂隙岩石在不同加载方式下的裂纹扩展特征进行了深入总结。在此基础上,指出当前研究中存在如下不足:裂隙岩石的PFC2D模型未考虑断裂韧度是否符合实际、平行黏结模型模拟结果与室内试验结果存在差异、模拟裂隙与真实裂隙存在差异。结合研究中存在的不足,提出了相应的解决办法并进行展望,以期有助于裂隙岩石PFC2D模拟方法的发展。 相似文献
18.
F. O. Alpak F. Gray N. Saxena J. Dietderich R. Hofmann S. Berg 《Computational Geosciences》2018,22(3):815-832
Digital rock physics (DRP) is a rapidly evolving technology targeting fast turnaround times for repeatable core analysis and multi-physics simulation of rock properties. We develop and validate a rapid and scalable distributed-parallel single-phase pore-scale flow simulator for permeability estimation on real 3D pore-scale micro-CT images using a novel variant of the lattice Boltzmann method (LBM). The LBM code implementation is designed to take maximum advantage of distributed computing on multiple general-purpose graphics processing units (GPGPUs). We describe and extensively test the distributed parallel implementation of an innovative LBM algorithm for simulating flow in pore-scale media based on the multiple-relaxation-time (MRT) model that utilizes a precise treatment of body force. While the individual components of the resulting simulator can be separately found in various references, our novel contributions are (1) the integration of all of the mathematical and high-performance computing components together with a highly optimized code implementation and (2) the delivery of quantitative results with the simulator in terms of robustness, accuracy, and computational efficiency for a variety of flow geometries including various types of real rock images. We report on extensive validations of the simulator in terms of accuracy and provide near-ideal distributed parallel scalability results on large pore-scale image volumes that were largely computationally inaccessible prior to our implementation. We validate the accuracy of the MRT-LBM simulator on model geometries with analytical solutions. Permeability estimation results are then provided on large 3D binary microstructures including a sphere pack and rocks from various sandstone and carbonate formations. We quantify the scalability behavior of the distributed parallel implementation of MRT-LBM as a function of model type/size and the number of utilized GPGPUs for a panoply of permeability estimation problems. 相似文献
19.
The spatial continuity of facies is one of the key factors controlling flow in reservoir models. Traditional pixel-based methods
such as truncated Gaussian random fields and indicator simulation are based on only two-point statistics, which is insufficient
to capture complex facies structures. Current methods for multi-point statistics either lack a consistent statistical model
specification or are too computer intensive to be applicable. We propose a Markov mesh model based on generalized linear models
for geological facies modeling. The approach defines a consistent statistical model that is facilitated by efficient estimation
of model parameters and generation of realizations. Our presentation includes a formulation of the general framework, model
specifications in two and three dimensions, and details on how the parameters can be estimated from a training image. We illustrate
the method using multiple training images, including binary and trinary images and simulations in two and three dimensions.
We also do a thorough comparison to the snesim approach. We find that the current model formulation is applicable for multiple training images and compares favorably to
the snesim approach in our test examples. The method is highly memory efficient. 相似文献