New Developments in Multiblock Reservoir Simulation: Black Oil Modeling, Nonmatching Subdomains and Near-Well Upscaling

Lee, S.H.; Wolfsteiner, C.; Durlofsky, L.J.; Jenny, P.; Tchelepi, H.A.

doi:10.2523/79682-ms

Cited by 2 publications

(2 citation statements)

References 16 publications

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“…The latter is what we are interested in. There have been studies of the non-orthogonality error in the literature 1,3 , focusing on the corner-point grids that exhibit strong areal non-orthogonality.…”

Section: Spe 92868mentioning

confidence: 99%

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Effect of Grid Deviation on Flow Solutions

Parashkevov

2005

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe two-point flux, finite volume method (FVM-2P) is the most widely used method for solving the flow equation in reservoir simulations. For FVM-2P to be consistent, the simulation grid needs to be orthogonal (or K-orthogonal if the permeability field is anisotropic). It is well known that cornerpoint grids can introduce large errors in the flow solutions due to the lack of orthogonality in general. Multi-point flux formulations that do not rely on grid orthogonality have been proposed, but these methods add significant computational cost to solving the flow equation.Recently, 2.5D unstructured grids that combine 2D Voronoi areal grids with vertical projections along deviated coordinate lines have become an attractive alternative to corner point gridding. The Voronoi grid helps to maintain orthogonality areally and can mitigate grid orientation effects. However, experience with these grids is limited.In this paper, we present an analytical and numerical study of these 2.5D unstructured grids. We focus on the effect of grid deviation on flow solutions in homogeneous but anisotropic permeability fields. In particular, we consider the grid deviation that results from gridding to sloping faults. We show that FVM-2P does not converge to the correct solution as grid refines. We further quantify the errors for some simple flow scenarios using a technique that combines numerical analysis and asymptotic expansions.Analytical error estimates are obtained. We find that the errors are highly flow dependent and they can be global with no strong correlation with local non-orthogonality measures. Numerical tests are presented to confirm the analytical findings and to show the applicability of our conclusions to more general flow scenarios.

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Section: Spe 92868mentioning

confidence: 99%

“…However, the effect can be strong near pinch-outs and if the dip angle is large. See e.g., Lee et al 3 for numerical examples.…”

Section: Spe 92868mentioning

confidence: 99%

Effect of Grid Deviation on Flow Solutions

Parashkevov

2005

All Days

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History-matching surface-based property models using the ensemble Kalman filter

Trani¹,

Graham²

2016

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Hydrocarbon reservoirs often contain thin and irregularly shaped low-permeability heterogeneities at the interface between sedimentary bodies that can act as barriers or baffles where they are aligned perpendicular to the flow. These heterogeneities are often not explicitly captured in simulation models because they occur over lengthscales smaller than a single simulation grid block and, as such, are ubiquitously captured in flow simulations using transmissibility multipliers. This parameterization implies that the properties of the fine-scale heterogeneities are a direct function of the properties in the adjacent grid cells. A new methodology is proposed where fine-scale heterogeneities are modelled using properties attached to surfaces and updated independently from other uncertain reservoir properties present during assisted history matching. This method is validated via a synthetic reservoir simulation model, using the ensemble Kalman filter to assimilate production history. The update of geometrical and petrophysical parameters related to fine-scale heterogeneity improves the history match and production forecast in comparison to traditional implicit techniques that do not honour the characteristics of the heterogeneity. The results indicate that, for history matching, it can be important to capture fine-scale heterogeneities independently from other uncertain reservoir properties even if the fine-scale heterogeneities do not exert a large control on reservoir response.

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New Developments in Multiblock Reservoir Simulation: Black Oil Modeling, Nonmatching Subdomains and Near-Well Upscaling

Cited by 2 publications

References 16 publications

Effect of Grid Deviation on Flow Solutions

Effect of Grid Deviation on Flow Solutions

History-matching surface-based property models using the ensemble Kalman filter

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