Re-sampling the Ensemble Kalman Filter for Improved History Matching and Characterizations of Non-gaussian and Non-linear Reservoir Models

Re-sampling the Ensemble Kalman Filter for Improved History Matching and Characterizations of Non-gaussian and Non-linear Reservoir Models
Author: Siavash Nejadi
Publisher:
Total Pages: 203
Release: 2014
Genre: Reservoirs
ISBN:

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Reservoir simulation models play an important role in the production forecasting and field development planning. To enhance their predictive capabilities and capture the uncertainties in model parameters, stochastic reservoir models should be calibrated to both geologic and flow observations. The relationship between production performance and model parameters is vastly non-linear, rendering history matching process a challenging task. The Ensemble Kalman Filter (EnKF) is a Monte-Carlo based technique for assisted history matching and real-time updating of reservoir models. EnKF works efficiently with Gaussian variables, but it often fails to honor the reference probability distribution of the model parameters where the distribution of model parameters are non-Gaussian and the system dynamics are strongly nonlinear. In this thesis, novel sampling procedures are proposed to honor geologic information in reservoirs with non-Gaussian model parameters. The methodologies include generating multiple geological models and updating the uncertain parameters using dynamic flow responses using iterative EnKF technique. Two new re-sampling steps are presented for characterization of multiple facies reservoirs. After certain number of assimilation steps, the updated ensemble is used to generate a new ensemble that is conditional to both the geological information and the early production data. Probability field simulation and a novel probability weighted re-sampling scheme are introduce to re-sample a new ensemble. After the re-sampling step, iterative EnKF is again applied on the ensemble members to assimilate the remaining production history. A new automated dynamic data integration workflow is implemented for characterization and uncertainty assessment of fracture reservoir models. This new methodology includes generating multiple discrete fracture network (DFN) models, upscaling the models for flow simulation, and updating the DFN model parameters using dynamic flow responses. The assisted history matching algorithm entails combining a probability weighted sampling with iterative EnKF. The performances of the introduced methodologies are evaluated by performing various simulation studies for different synthetic and field case studies. The qualities of the final matching results are assessed by examining the geological realism of the updated ensemble using the reference probability distribution of the model parameters and computing the predicted dynamic data mismatch.

Streamline Assisted Ensemble Kalman Filter - Formulation and Field Application

Streamline Assisted Ensemble Kalman Filter - Formulation and Field Application
Author: Deepak Devegowda
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:

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The goal of any data assimilation or history matching algorithm is to enable better reservoir management decisions through the construction of reliable reservoir performance models and the assessment of the underlying uncertainties. A considerable body of research work and enhanced computational capabilities have led to an increased application of robust and efficient history matching algorithms to condition reservoir models to dynamic data. Moreover, there has been a shift towards generating multiple plausible reservoir models in recognition of the significance of the associated uncertainties. This provides for uncertainty analysis in reservoir performance forecasts, enabling better management decisions for reservoir development. Additionally, the increased deployment of permanent well sensors and downhole monitors has led to an increasing interest in maintaining 'live' models that are current and consistent with historical observations. One such data assimilation approach that has gained popularity in the recent past is the Ensemble Kalman Filter (EnKF) (Evensen 2003). It is a Monte Carlo approach to generate a suite of plausible subsurface models conditioned to previously obtained measurements. One advantage of the EnKF is its ability to integrate different types of data at different scales thereby allowing for a framework where all available dynamic data is simultaneously or sequentially utilized to improve estimates of the reservoir model parameters. Of particular interest is the use of partitioning tracer data to infer the location and distribution of target un-swept oil. Due to the difficulty in differentiating the relative effects of spatial variations in fractional flow and fluid saturations and partitioning coefficients on the tracer response, interpretation of partitioning tracer responses is particularly challenging in the presence of mobile oil saturations. The purpose of this research is to improve the performance of the EnKF in parameter estimation for reservoir characterization studies without the use of a large ensemble size so as to keep the algorithm efficient and computationally inexpensive for large, field-scale models. To achieve this, we propose the use of streamline-derived information to mitigate problems associated with the use of the EnKF with small sample sizes and non-linear dynamics in non-Gaussian settings. Following this, we present the application of the EnKF for interpretation of partitioning tracer tests specifically to obtain improved estimates of the spatial distribution of target oil.

An Ensemble Kalman Filter Module for Automatic History Matching

An Ensemble Kalman Filter Module for Automatic History Matching
Author: Baosheng Liang
Publisher:
Total Pages: 0
Release: 2007
Genre: Hydrocarbon reservoirs
ISBN:

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The data assimilation process of adjusting variables in a reservoir simulation model to honor observations of field data is known as history matching and has been extensively studied for few decades. However, limited success has been achieved due to the high complexity of the problem and the large computational effort required by the practical applications. An automatic history matching module based on the ensemble Kalman filter is developed and validated in this dissertation. The ensemble Kalman filter has three steps: initial sampling, forecasting through a reservoir simulator, and assimilation. The initial random sampling is improved by the singular value decomposition, which properly selects the ensemble members with less dependence. In this way, the same level of accuracy is achieved through a smaller ensemble size. Four different schemes for the assimilation step are investigated and direct inverse and square root approaches are recommended. A modified ensemble Kalman filter algorithm, which addresses the preference to the ensemble members through a nonequally weighting factor, is proposed. This weighted ensemble Kalman filter generates better production matches and recovery forecasting than those from the conventional ensemble Kalman filter. The proposed method also has faster convergence at the early time period of history matching. Another variant, the singular evolutive interpolated Kalman filter, is also applied. The resampling step in this method appears to improve the filter stability and help the filter to deliver rapid convergence both in model and data domains. This method and the ensemble Kalman filter are effective for history matching and forecasting uncertainty quantification. The independence of the ensemble members during the forecasting step allows the benefit of high-performance computing for the ensemble Kalman filter implementation during automatic history matching. Two-level computation is adopted; distributing ensemble members simultaneously while simulating each member in a parallel style. Such computation yields a significant speedup. The developed module is integrated with reservoir simulators UTCHEM, GEM and ECLIPSE, and has been implemented in the framework Integrated Reservoir Simulation Platform (IRSP). The successful applications to two and three-dimensional cases using blackoil and compositional reservoir cases demonstrate the efficiency of the developed automatic history matching module.

Reservoir History Matching Using Constrained Ensemble Kalman Filter and Particle Filer Methods

Reservoir History Matching Using Constrained Ensemble Kalman Filter and Particle Filer Methods
Author: Abhiniandhan Raghu
Publisher:
Total Pages: 126
Release: 2014
Genre: Ecological heterogeneity
ISBN:

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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 these rock properties, which is crucial for the future performance prediction of a reservoir, is carried out through a history matching technique using constrained ensemble Kalman filtering (EnKF) and particle filtering (PF) methods. The first part of the thesis addresses some of the main limitations of the conventional EnKF. The EnKF, formulated on the grounds of Monte Carlo sampling and the Kalman filter (KF), arrives at estimates of parameters based on statistical analysis and hence could potentially yield reservoir parameter estimates that are not geologically realistic and consistent. In order to overcome this limitation, hard and soft data constraints in the recursive EnKF estimation methodology are incorporated. Hard data refers to the actual values of the reservoir parameters at discrete locations obtained by core sampling and well logging. On the other hand, the soft data considered here is obtained from the variogram, which characterize the spatial correlation of the rock properties in a reservoir. In this algorithm, the correlation matrix obtained after the unconstrained EnKF update is transformed to honour the true correlation structure from the variogram by applying a scaling and projection method. This thesis also deals with the problem of spurious correlation induced by the Kalman gain computations in the EnKF update step, potentially leading to erroneous update of parameters. In order to solve this issue, a covariance localization-based EnKF coupled with geostatistics is implemented in reservoir history matching. These algorithms are implemented on two synthetic reservoir models and their efficacy in yielding estimates consistent with the geostatistics is observed. It is found that the computational time involved in the localization-based EnKF framework for reservoir history matching is considerably reduced owing to the reduction in the size of the parameter space in the EnKF update step. Also, the geostatistics-based covariance localization performs better in capturing the spatial heterogeneity and variability of the reservoir permeability than the traditional methods. In the second part of the thesis, we extend the history matching implementation using the particle filtering. Reservoir models, being nonlinear, the distributions of the noise and parameters are generally non-Gaussian in nature. Since the EnKF may fail to obtain accurate estimates when the distributions involved in the model are non-Gaussian, we attempt to use a completely Bayesian filter, the particle filter, to estimate reservoir parameters. In addition, the geostatistics-based covariance localization is also coupled with the particle filter and is found to perform better than the filter without any localization.

Petroleum Reservoir Modeling and Simulation: Geology, Geostatistics, and Performance Prediction

Petroleum Reservoir Modeling and Simulation: Geology, Geostatistics, and Performance Prediction
Author: Juliana Y. Leung
Publisher: McGraw Hill Professional
Total Pages: 465
Release: 2022-01-28
Genre: Technology & Engineering
ISBN: 1259834301

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Reservoir engineering fundamentals and applications along with well testing procedures This practical resource lays out the tools and techniques necessary to successfully construct petroleum reservoir models of all types and sizes. You will learn how to improve reserve estimations and make development decisions that will optimize well performance. Written by a pair of experts, Petroleum Reservoir Modeling and Simulation: Geology, Geostatistics, and Performance Prediction offers comprehensive coverage of quantitative modeling, geostatistics, well testing principles, upscaled models, and history matching. Throughout, special attention is paid to shale, carbonate, and subsea formations. Coverage includes: An overview of reservoir engineering Spatial correlation Spatial estimation Spatial simulation Geostatistical simulation constrained to higher-order statistics Numerical schemes for flow simulation Gridding schemes for flow simulation Upscaling of reservoir models History matching Dynamic data integration

Data Assimilation

Data Assimilation
Author: Geir Evensen
Publisher: Springer Science & Business Media
Total Pages: 285
Release: 2006-12-22
Genre: Science
ISBN: 3540383018

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This book reviews popular data-assimilation methods, such as weak and strong constraint variational methods, ensemble filters and smoothers. The author shows how different methods can be derived from a common theoretical basis, as well as how they differ or are related to each other, and which properties characterize them, using several examples. Readers will appreciate the included introductory material and detailed derivations in the text, and a supplemental web site.

Nonlinear Data Assimilation

Nonlinear Data Assimilation
Author: Peter Jan Van Leeuwen
Publisher: Springer
Total Pages: 130
Release: 2015-07-22
Genre: Mathematics
ISBN: 3319183478

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This book contains two review articles on nonlinear data assimilation that deal with closely related topics but were written and can be read independently. Both contributions focus on so-called particle filters. The first contribution by Jan van Leeuwen focuses on the potential of proposal densities. It discusses the issues with present-day particle filters and explorers new ideas for proposal densities to solve them, converging to particle filters that work well in systems of any dimension, closing the contribution with a high-dimensional example. The second contribution by Cheng and Reich discusses a unified framework for ensemble-transform particle filters. This allows one to bridge successful ensemble Kalman filters with fully nonlinear particle filters, and allows a proper introduction of localization in particle filters, which has been lacking up to now.

Reservoir Characterization of Non Gaussian Field Using Combined Ensemble Based Method

Reservoir Characterization of Non Gaussian Field Using Combined Ensemble Based Method
Author: Samson B. Folarin
Publisher:
Total Pages:
Release: 2020
Genre: Kalman filtering
ISBN:

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The proper reservoir characterization was a decade-long challenge for both geoscientists and reservoir engineers because of the complex subsurface structures. Ensemble Kalman filter was studied rigorously as a promising method for quantify the reservoir uncertainty quantification. Because of its computational efficiency and easy implementation on any simulator, petroleum engineers recommended ensemble Kalman filter (EnKF) as a useful history matching technique. It failed because of the Gaussian assumption and the inconsistency that exist between the updated static and dynamics parameters, which violate the field’s material balance. Wang et al., (2012) introduced an improved method called half iterative ensemble Kalman filter (HIEnKF) to overcome the shortcomings of the EnKF. The new method (HIEnKF) appears to be promising in the field of history matching but has its drawback. Mary Wheeler et al., (2013) introduced the ensemble smoother method to overcome the computational cost induced by HIEnKF. Various challenges arise from the existing methods that motivated us to propose new techniques that can give a promising result in petroleum engineering. We designed our first method by considering the advantage of half iterative EnKF and ensemble smoother. The combined half iterative EnKF and ensemble smoother (CoHIEnKFS) characterize a Gaussian field better than the existing methods. Previous work has shown poor characterization on reservoirs with non-Gaussian permeability distribution, which fails to satisfy HIEnKF Gaussian assumption. We apply a normal score transformation on (CoHIEnKFS) to meet this assumption. The new method (normal score combined half iterative EnKF and ES) produces a good result in the petroleum history matching field.

History Matching and Uncertainty Characterization

History Matching and Uncertainty Characterization
Author: Alexandre Emerick
Publisher: LAP Lambert Academic Publishing
Total Pages: 264
Release: 2012-04
Genre:
ISBN: 9783659107283

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In the last decade, ensemble-based methods have been widely investigated and applied for data assimilation of flow problems associated with atmospheric physics and petroleum reservoir history matching. Among these methods, the ensemble Kalman filter (EnKF) is the most popular one for history-matching applications. The main advantages of EnKF are computational efficiency and easy implementation. Moreover, because EnKF generates multiple history-matched models, EnKF can provide a measure of the uncertainty in reservoir performance predictions. However, because of the inherent assumptions of linearity and Gaussianity and the use of limited ensemble sizes, EnKF does not always provide an acceptable history-match and does not provide an accurate characterization of uncertainty. In this work, we investigate the use of ensemble-based methods, with emphasis on the EnKF, and propose modifications that allow us to obtain a better history match and a more accurate characterization of the uncertainty in reservoir description and reservoir performance predictions.

Streamline Simulation

Streamline Simulation
Author: Akhil Datta-Gupta
Publisher:
Total Pages: 418
Release: 2007
Genre: Business & Economics
ISBN:

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Streamline-Simulation emphasizes the unique features of streamline technology that in many ways complement conventional finite-difference simulation. It fills gaps in the mathematical foundations.