Near-well upscaling for three-phase flows

Nakashima, Toshinori; Li, Hangyu; Durlofsky, Louis J.

doi:10.1007/s10596-011-9252-4

Cited by 13 publications

(18 citation statements)

References 28 publications

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“…These results will appear in Nakashima (2009). In one of these cases, involving a portion of the highly channelized SPE 10 model (Christie and Blunt 2001), we observed an increase in the accuracy of the coarse-scale model when a larger LWM was used.…”

Section: Discussionmentioning

confidence: 65%

Accurate Representation of Near-well Effects in Coarse-Scale Models of Primary Oil Production

Nakashima

Durlofsky

2009

Transp Porous Med

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Near-well effects can have a strong impact on many subsurface flow processes. In oil production, because dissolved gas is released from the oil phase when the pressure falls below the bubble point, the detailed pressure field in the immediate vicinity of a production well strongly impacts gas (and thus oil) production. This effect is complicated by the interplay of fine-scale heterogeneity and two-phase flow physics, and can be difficult to capture in coarse-grid simulations. In this article, we develop and apply a new upscaling (coarsegraining) procedure to capture such near-well subgrid effects in coarse-scale flow simulation models. The method entails the use of preprocessing computations over near-well domains [referred to as local well models (LWM)] for the determination of upscaled single-phase and two-phase near-well parameters. These parameters are computed by minimizing the mismatch between fine and coarse-scale flows over the LWM. Minimization is accomplished using a gradient-based optimization procedure, with gradients calculated through solution of adjoint equations. The boundary conditions applied on the LWM can impact the upscaled parameters, but these boundary conditions depend on the global flow and are not, therefore, known a priori. In order to circumvent this difficulty, an adaptive local-global procedure is applied. This entails performing a global coarse-scale simulation with initial estimates for well-block parameters. The resulting pressure and saturation fields are then used to define local boundary conditions for the near-well computations. The overall procedure is applied to several example problems and is shown to provide results in close agreement with reference fine-scale computations. Significant improvement in accuracy over existing near-well upscaling treatments is demonstrated, particularly for a heavy oil case with oil viscosity of ∼10 4 cp.

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Section: Discussionmentioning

confidence: 65%

Accurate Representation of Near-well Effects in Coarse-Scale Models of Primary Oil Production

Nakashima

Durlofsky

2009

Transp Porous Med

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“…2) in the vicinity of the well. Consistent with previous work on near-well upscaling for nonlinear problems (e.g., [15,19,20]), we define a near-well region referred to as a local well model (LWM). The LWM for a given well typically comprises the domain corresponding to the coarse well blocks and a surrounding ring of coarse blocks.…”

Section: Numerically Upscaled Heater-well Modelmentioning

confidence: 99%

“…The general numerical procedure applied here for the heterogeneous and/or nonlinear case is similar to the near-well upscaling approach applied in [19]. Other near-well upscaling procedures for single-phase [9,10,18], two-phase [15] and three-phase [20] flow parameters have also been presented. Our numerically upscaled heater-well model uses a local-global approach to provide boundary conditions for the upscaling computations.…”

Section: Introductionmentioning

confidence: 99%

“…Our numerically upscaled heater-well model uses a local-global approach to provide boundary conditions for the upscaling computations. Local-global procedures for determining upscaled single-phase flow parameters are described in, e.g., [5,6,14] while approaches for computing two and three-phase flow parameters are presented in [7,19,20]. This paper proceeds as follows.…”

Section: Introductionmentioning

confidence: 99%

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New models for heater wells in subsurface simulations, with application to the in situ upgrading of oil shale

2011

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Downhole electrical heating can be used to achieve the high temperatures required for in situ upgrading of oil shale or oil sands. Heater-well models are needed if this process is to be simulated accurately. The traditional Peaceman approach used for fluid injection and production wells may not be applicable because it does not capture transient effects, which can be important in downhole heater models. Standard models also neglect the effects of heterogeneity and temperature dependence in the rock properties. Here, we develop two new models for representing heater wells in reservoir simulators. The first model is applicable for homogeneous systems with properties that are not temperature dependent. For such cases, we develop a semi-analytical procedure based on Green's functions to construct time-dependent heater-well indexes and heater-block thermal transmissibilities. For the general case, which can include both fine-scale heterogeneity and nonlinearity due to the temperature dependence of rock properties, we present a numerical procedure for constructing the heater-well model. This technique is essentially a near-well upscaling method and requires a local fine-scale solution in the near-well region. The boundary conditions are determined using a localglobal treatment. The accuracy of the new heater-well models is demonstrated through comparison to reference solutions for example problems. The approach is then applied for the coarse-scale modeling of the in situ upgrading of oil shale, which entails a thermalcompositional simulation with chemical reactions. The model is shown to provide an accurate and efficient solution for this challenging problem.

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“…Related work also includes a generalized pseudopressure well treatment (Fevang and Whitson, 1996), which was specifically applied to modeling the gas-condensate well deliverability. Most recently, Nakashima et al (2012) introduced a near-well multiphase (NWMP) upscaling procedure for general three-phase black-oil models. This approach entails solving local fine-scale welldriven flow problems in near-well regions to determine the appropriate multiphase flow functions.…”

Section: Introductionmentioning

confidence: 99%

Development and Application of Near-Well Multiphase Flow Upscaling for Forecasting of Heavy Oil Primary Production

Rojas

Kumar

et al. 2013

All Days

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Near-well effects can have a strong impact on reservoir flow. Current reservoir modeling practice often uses coarse-scale flow simulation models, which may lead to biased results, compared with fine-scale models. In this work, we extend and apply a recently developed near-well multiphase flow upscaling technique to the coarse-scale simulation of heavy-oil primary production. For heavy oils, oil viscosity is a strong function of pressure when the pressure is below the bubble point. Therefore, the upscaled mobility functions (from near-well multiphase upscaling) depend on both pressure and saturation, which cannot be directly input to general purpose reservoir simulators. This is very different than the upscaled mobility functions for typical black-oil fluids, in which oil viscosity does not vary significantly with pressure. Accordingly, the upscaled mobility functions are often equivalent to upscaled relative permeabilities (as functions of saturation only). In this work, we develop two procedures to derive either the upscaled relative permeability or viscosity functions from the phase mobility functions, thus decoupling the dependency on pressure and saturation. It is found that the upscaled oil viscosity provides more accurate predictions than the upscaled relative permeabilities, especially at early time. This is because that the rapid change of pressure at early stage is captured sufficiently in the upscaled oil viscosity (as a function of pressure). The use of upscaled viscosity function in multiphase upscaling is new, and has not been presented in previous studies. We also introduce a grouping technique to reduce the number of upscaled flow functions in coarse-scale models. This is based on an observation that there is a strong correlation between the upscaled flow functions and the coarse-scale well-block permeabilities. The proposed methods are applied to realistic models from heavy-oil fields. For cases considered, the nearwell multiphase flow upscaling considerably improves upon the standard coarse models. The use of upscaled relative permeability and viscosity functions, as well as the grouping of upscaled flow functions, provides practical applicability for fast and accurate forecast using coarse-scale models.

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Near-well upscaling for three-phase flows

Cited by 13 publications

References 28 publications

Accurate Representation of Near-well Effects in Coarse-Scale Models of Primary Oil Production

Accurate Representation of Near-well Effects in Coarse-Scale Models of Primary Oil Production

New models for heater wells in subsurface simulations, with application to the in situ upgrading of oil shale

Development and Application of Near-Well Multiphase Flow Upscaling for Forecasting of Heavy Oil Primary Production

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