Upscaling, Gridding, and Simulation Using Streamtubes

Portella, Ricardo Cunha Mattos; Hewett, Thomas T.

doi:10.2523/49071-ms

Cited by 8 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They are usually nonzero for only a few values of i. Press et al (1992) list values of h k for many wavelets. Based on our previous simulations and experience, we utilized the DB4 wavelet in order to compute the results, for which,…”

Section: The Wavelet Functionsmentioning

confidence: 99%

“…The scale and wavelet functions are interrelated (Daubechies 1988(Daubechies , 1992Press et al 1992). …”

Section: Generation Of the Initial Upscaled Gridmentioning

confidence: 99%

“…In some sense, the WT method, which has been developed by our group over the past few years (Mehrabi and Sahimi 1997;Ebrahimi and Sahimi 2002Sahimi 2008, 2009a,b), is also based on the minimization of the local variations in the permeabilities. The WTs represent relatively recent developments in mathematics (Daubechies 1988(Daubechies , 1992Press et al 1992), which have found a broad and diverse set of applications, including data processing, reservoir engineering and simulations, and upscaling (Sahimi 2003).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, numerous techniques have also been developed for upscaling of the GM. Some of such methods rely on the dynamic response of the reservoir, in order to identify the sectors in the grid in which a relatively resolved structure must be used, while the rest of the GM is upscaled and is represented by coarsened (enlarged) grid blocks (see, for e.g., Verma and Aziz 1997;Durlofsky et al 1997;Edwards et al 1998;Wallstorm et al 1999;Portella and Hewett 2000;Castellini et al 2000). Such dynamics-based upscaling methods are effective in accurately preserving the flow response of the fine-scale regions in the cases in which the boundary conditions remain relatively constant.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Upscaled Unstructured Computational Grids for Efficient Simulation of Flow in Fractured Porous Media

et al. 2009

View full text Add to dashboard Cite

Discrete fracture modeling (DFM) is currently the most promising approach for modeling of naturally fractured reservoirs and simulation of multiphase fluid flow therein. In contrast with the classical double-porosity/double permeability models, in the DFM approach all the interactions and fluid flow in and between the fractures and within the matrix are modeled in a unified manner, using the same computational grid. There is no need for computing the shape factors, which are crucial to the accuracy of the double-porosity models. We have exploited this concept in order to develop a new method for the generation of unstructured computational grids. In the new approach the geological model (GM) of the reservoir is first generated, using square or cubic grid blocks. The GM is then upscaled using a method based on the multiresolution wavelet transformations that we recently developed. The upscaled grid contains a distribution of the square or cubic blocks of various sizes. A map of the blocks' centers is then used with an optimized Delauney triangulation method and the advancingfront technique, in order to generate the final unstructured triangulated grid suitable for use in any general reservoir simulator with any number of fluid phases. The new method also includes an algorithm for generating fractures that, contrary to the previous methods, does not require modifying their paths due to the complexities that may arise in spatial distribution of the grid blocks. It also includes an effective partitioning of the simulation domain that results in large savings in the computation times. The speed-up in the computations with the new upscaled unstructured grid is about three orders of magnitude over that for the initial GM. Simulation of waterflooding indicates that the agreement between the results obtained with the GM and the upscaled unstructured grid is excellent. The method is equally 123 196 M. Sahimi et al. applicable to the simulations of multiphase flow in unfractured, but highly heterogeneous, reservoirs.

show abstract

Section: The Wavelet Functionsmentioning

confidence: 99%

“…The scale and wavelet functions are interrelated (Daubechies 1988(Daubechies , 1992Press et al 1992). …”

Section: Generation Of the Initial Upscaled Gridmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Upscaled Unstructured Computational Grids for Efficient Simulation of Flow in Fractured Porous Media

et al. 2009

View full text Add to dashboard Cite

show abstract

“…However, it is limited because the coarser grid is constrained to be aligned with the fine grid. Other researchers (Verma and Aziz 1997;Edwards 2002;Portella and Hewett 2000;Castellini et al 2000;Castellini 2001;He 2004) presented techniques based on the use of streamlines computed from a single phase flow solution of the fine scale problem. Alternate gridding procedures based on the grouping of cells of similar permeability were suggested by Garcia et al (1992) and Ebrahimi and Sahimi (2004).…”

mentioning

confidence: 98%

Flexible Unstructured Gridding for 2D Reservoir Coarse Scale Modeling using Fine Scale Permeability Filtering

Hesami

Dabir

2011

Transp Porous Med

View full text Add to dashboard Cite

Accurate up-scaling is an essential part of creating a valid reservoir coarse scale dynamic model. In this article, unstructured discretization of spatial domain is accompanied by numerical permeability up-scaling in order to construct an accurate coarse scale model. A new technique for generating a course scale triangular mesh is presented in which the density of elements in key flow regions is kept high to capture accuracy. The fine scale permeability map is investigated using image processing techniques, especially steerable filters, and the results are converted into a high-resolution element size map. This element size map will be refined by the integration of other important factors such as well-position effects and used to construct a coarse triangular mesh. The combination of flux-continuous pressure approximation and mass conservative, total variation diminishing finite volume schemes have been considered to solve two phase flow equations on the control volume finite element mesh. Fine scale simulations results are compared with the coarse scale ones for a series of water flooding examples to investigate the efficiency and accuracy of the presented gridding methodology. This method is developed for 2D cases, but can be easily extended to 3D problems.

show abstract

Well-Included Flowbased Grid Generation for Heterogeneous Reservoirs

Gherabati

Dabir²,

Hesami

2008

SPE Annual Technical Conference and Exhibition

View full text Add to dashboard Cite

Fine grid geocellular reservoir characterizations often include detailed description of geological and geometric complexity. Since this volume of details cannot be handled by commercial reservoir simulators, some degree of coarsening is necessary. The fundamental agenda in coarse grid generation includes development of finer grids in regions with higher flow. Available methods in literature suffer from draw back of inability to consider both the well and geological features which mostly affect the flow response. This study introduces a new method of grid coarsening (flow based) procedure. The procedure encompasses tracing streamline from boundary to the well, monitoring velocity trend along streamline to identify high flow region and selection of appropriate points on streamlines as grid nodes. Differentiating the analytical equation of the streamline path results in developing velocity vectors and adding them up will yield a new term called cumulative velocity. Using this term, the grid points are easily identified which after implementation of Delaunay triangulation and Laplacian smoothing algorithms the main CVFE (Control Volume Finite Element) grid is produced. In addition, a robust up-scaling technique was used to calculate the tensor of permeability. Flux-continuous finite volume scheme was used to solve the associated flow equation in the coarse block. The generated grid pattern is finer in high flow regions and can successfully adapt itself based on type of geological features presented. Pressure was the main criteria for comparison the results of this study with those of Cartesian coarse grid. The results indicated that the response of the model with coarse grids (flow based) is more consistent with a fine model. The major advantage of the introduced method is its capability in handling the geological features within the grid. It is worthy to mention that the positioning of the well and adjustment of the required refinements around it are done automatically. Introduction Reservoir simulation is an important tool for the management of oil fields. Geological characterization and equations governing flow through porous media is used to simulate reservoir flow numerically. But where to consider geological variations and how much detail to consider when dealing with them, are questions that challenge engineers. During the process of griding and discritization physical properties are assigned to each grid block. Concentration of grid blocks represents the degree of detail we have considered and its location in the domain shows where geological variations have more importance. This indicates that grid generation method plays an important role when regarding number of grid produced. Geological models contain as much as grid blocks that cannot be handled by commercial reservoir simulators software due to computational cost. These models are called fine grid models or geostatistical models which contain fine scale geological variation. In order to reduce the number of blocks we should use coarser blocks. But petrophysical properties like permeability are defined in fine grid model. There should be a process to assign fine grid properties to the coarse grid. This process is called upscaling. In the process of griding and upscaling the tendency is to preserve critical reservoir features as much as possible. In this paper, we tried to take into account this fact by concentrating grid nodes in important regions to capture reservoir features. Different attempts have been performed so far in this area. The first one was the idea of local grid refinement (Ciment and sweet 1973; Pedrosa and Aziz 1985). Local grid refinement involves using fine grid inside coarse base grid. This is done in selected regions like near well regions or highly heterogeneous regions.

show abstract

Upscaling, Gridding, and Simulation Using Streamtubes

Cited by 8 publications

References 0 publications

Upscaled Unstructured Computational Grids for Efficient Simulation of Flow in Fractured Porous Media

Upscaled Unstructured Computational Grids for Efficient Simulation of Flow in Fractured Porous Media

Flexible Unstructured Gridding for 2D Reservoir Coarse Scale Modeling using Fine Scale Permeability Filtering

Well-Included Flowbased Grid Generation for Heterogeneous Reservoirs

Contact Info

Product

Resources

About