A Negative-Flash Tie-Simplex Approach for Multiphase Reservoir Simulation

Iranshahr, Alireza; Voskov, Denis

doi:10.2118/141896-pa

Cited by 22 publications

(9 citation statements)

References 5 publications

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“…This global characteristic of thermodynamic problems (which cannot be solved robustly only from local information) can be also seen in multiphase flash; i.e., global minimization of the Gibbs free energy. Use of tie simplex information tabulated prior to simulation has been shown to be effective in speeding up fully implicit reservoir simulations (Voskov and Tchelepi 2009ab;Iranshahr et al 2012Iranshahr et al , 2013.…”

Section: Formulation and Solution Methodsmentioning

confidence: 99%

Numerical Simulation of Three-Hydrocarbon-Phase Flow with Robust Phase Identification

Xu¹,

Okuno²

2015

SPE Reservoir Simulation Symposium

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Low-temperature oil displacement by enriched-gas or carbon-dioxide (CO 2 ) can exhibit multiphase flow of three hydrocarbon phases; the oleic (L 1 ), solvent-rich liquid (L 2 ), and gaseous (V) phases. The L 2 phase can play a significant role in these oil recovery processes. Recently, oil displacement by three hydrocarbon phases was explained on the basis of interphase mass transfer on phase transitions in multiphase flow. However, systematic investigation into the complex interplay between phase behavior and mobilities has been hindered by issues in multiphase compositional flow simulation, such as incorrect phase identification.This paper presents the effect of relative permeability on oil displacement by three hydrocarbon phases. A new method for robust phase identification is developed and implemented in a 1D convective flow simulator with no volume change on mixing. The new method uses tie triangles and their normal unit vectors tabulated as part of the simulation input information. The extensions of the limiting tie triangles at the upper and lower critical endpoints (UCEP and LCEP) define three different regions in composition space; the super-UCEP, super-LCEP, and sub-CEP regions. The method can properly recognize five different two-phase regions surrounding the three-phase region; the two two-phase regions that are super-CEP, and the three different two-phase regions that originate with the corresponding edges of the three-phase region in the sub-CEP region. Multiphase behavior calculations are conducted rigorously by use of the Peng-Robinson equation of state with the van der Waals mixing rules during the flow simulation. Simulation case studies are presented with a quaternary model and the West Sak oil model with 15 components.Results show that the phase-identification method developed in this research can correctly solve for phase identities in three-hydrocarbon-phase flow simulation. The method can quantify the relative location of the current overall composition to the three-phase region in composition space. Simulation results are analyzed by use of the distance parameters that describe interphase mass transfer on multiphase transitions in oil displacement. In the case study for the West Sak oil displacement, the analysis confirms that the miscibility level of oil displacement increases with increasing methane dilution. The effect of relative permeability diminishes as the miscibility level increases owing to methane dilution. The distance parameters can properly represent the interaction of phase behavior and mobilities since they are derived from mass conservation, not only from thermodynamic conditions.

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Section: Formulation and Solution Methodsmentioning

confidence: 99%

Numerical Simulation of Three-Hydrocarbon-Phase Flow with Robust Phase Identification

Xu¹,

Okuno²

2015

SPE Reservoir Simulation Symposium

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“…In Eqs. (10) to (14), c r is rock compressibility and T ab is the transmissibility between grid blocks. The vector u contains well-control variables, ω is the set of state variables and ξ are the set of spatial coordinates.…”

Section: Operator-based Linearizationmentioning

confidence: 99%

“…A nearmiscible gas injection process usually involves a large number of species in solution, which significantly degrades simulation performance. In addition, in nonlinear iterations, thermodynamic equilibrium should be enforced in every grid block to check the phase behavior of the mixture; this adds to the performance penalty [10].…”

Section: Introductionmentioning

confidence: 99%

Optimization of CO2 injection using multi-scale reconstruction of composition transport

Chen

Voskov

2019

Comput Geosci

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The current situation with green gas emission requires the development of low-carbon energy solutions. However, a significant part of the modern energy industry still relies on fossil fuels. To combine these two contradictory targets, we investigate a strategy based on a combination of CO 2 sequestration with enhanced oil recovery (EOR) in the hydrocarbon reservoirs. In such technology, the development of miscibility is the most attractive strategy from both technological and economic aspects. Modeling of this process involves solving complex nonlinear problem describing compositional flow and transport in highly heterogeneous porous media. An accurate capture of the miscibility development usually requires an extensive number of components to be present in the compositional problem which makes simulation run-time prohibitive for optimization. Here, we apply a multi-scale reconstructing of compositional transport to the optimization of CO 2 injection. In this approach, a prolongation operator, based on the parametrization of injection and production tie-lines, is constructed following the fractional flow theory. This operator is tabulated as a function of pressure and pseudo-composition which then is used in the operator-based linearization (OBL) framework for simulation. As a result, a pseudo two-component solution of the multidimensional problem will match the position of trailing and leading shocks of the original problem which helps to accurately predict phase distribution. The reconstructed multicomponent solution can be used then as an effective proxy-model mimicking the behavior of the original multicomponent system. Next, we use this proxy-model in the optimization procedure which helps to improve the performance of the process several fold. An additional benefit of the proposed methodology is based on the fact that important technological features of CO 2 injection process can be captured with lower degrees of freedom which makes the optimization solution more feasible.

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“…Next, we show phase‐state identification in parameterized steam systems. The computational examples of three‐phase thermal‐compositional flow simulation are recently presented by Iranshahr et al…”

Section: Numerical Examplesmentioning

confidence: 99%

Tie‐simplex based compositional space parameterization: Continuity and generalization to multiphase systems

Iranshahr

Voskov

2012

AIChE Journal

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A theoretical analysis is provided of the continuity of multiphase compositional space parameterization for thermalcompositional reservoir simulation. It is shown that the tie-simplex space changes continuously as a function of composition, pressure, and temperature, and this justifies the Compositional Space Adaptive Tabulation (CSAT) framework, in which a discrete number of tie-simplexes are constructed, tabulated, and reused in the course of a simulation. The CSAT is extended for thermal-compositional displacements for mixtures that can form an arbitrary number of phases. In particular, the construction is described of three-phase tie-simplex tables, and it is shown how the degeneration of multiphase regions can be accurately captured over wide ranges of temperature and pressure. Several challenging multiphase examples are used to demonstrate the accuracy and effectiveness of phase-state identification using tabulated tie-simplexes.

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A Negative-Flash Tie-Simplex Approach for Multiphase Reservoir Simulation

Cited by 22 publications

References 5 publications

Numerical Simulation of Three-Hydrocarbon-Phase Flow with Robust Phase Identification

Numerical Simulation of Three-Hydrocarbon-Phase Flow with Robust Phase Identification

Optimization of CO2 injection using multi-scale reconstruction of composition transport

Tie‐simplex based compositional space parameterization: Continuity and generalization to multiphase systems

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