Accelerating Flash Calculation using Compositional Space for Compositional Simulation

Bicheng Yan, Yuhe Wang, Hadi Nasrabadi, John E. Killough, Keliu Wu

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Compositional simulation is often required for modeling complex oil recovery processes, such as CO2 enhanced oil recovery (). Flash calculation using Equation of State (EOS) is very CPU expensive in compositional simulation. Conventional approaches for initial guess of K-values usually have several levels of limitations. This paper reports our research motivated to provide trustworthy initial guess for flash calculation and further improve flash performance in isothermal processes. Reservoir fluid composition changes are categorized into two different scenarios: (a) slightly varying or constant composition changes in depletion process; and (b) sharp varying composition in gas injection process. Scenario (a) is reasonably parameterized as a compositional space of K-value and vapor mole fraction varied with pressure. Considering the actual simulation of gas injection process, a compositional space is defined via introducing a key pseudo composition as a controlling variable in addition to pressure. Flash calculation is formulated through direct solution of those non-linear equations in phase-split calculation, and solved by combining successive substitution iteration (SSI) and Newton-Raphson (NR) method. Using interpolation from the constructed compositional space, it is found that the initial guess of K-values for flash calculation are always obtained with safeguard. A variety of fluid samples has been applied for testing this new flash technique. The results show that initial guesses of K-values based on Wilson's correlation results cause much more flash iterations and even failures in some gas injection examples. On the other hand, the proposed method shows significant advantages in reducing the number of flash iterations in all examples. In addition, the SSI procedure in flash can even be bypassed and only NR procedure and a simple Rachford-Rice Equation Preconditioning is sufficient.

Original languageEnglish
JournalJournal of Petroleum Science and Engineering
DOIs
Publication statusAccepted/In press - 24 Dec 2016
Externally publishedYes

Fingerprint

simulation
Chemical analysis
substitution
Substitution reactions
gas
Recovery
Fluids
fluid composition
enhanced oil recovery
Newton-Raphson method
Equations of state
equation of state
Nonlinear equations
Program processors
interpolation
Interpolation
rice
Vapors
calculation
fluid

Keywords

  • CO2 flooding
  • Compositional simulation
  • Compositional space
  • Enhanced oil recovery
  • Flash calculation
  • Miscible gas injection

ASJC Scopus subject areas

  • Fuel Technology
  • Geotechnical Engineering and Engineering Geology

Cite this

Accelerating Flash Calculation using Compositional Space for Compositional Simulation. / Yan, Bicheng; Wang, Yuhe; Nasrabadi, Hadi; Killough, John E.; Wu, Keliu.

In: Journal of Petroleum Science and Engineering, 24.12.2016.

Research output: Contribution to journalArticle

@article{e607772dddd9484aa8bcf243e29b04c8,
title = "Accelerating Flash Calculation using Compositional Space for Compositional Simulation",
abstract = "Compositional simulation is often required for modeling complex oil recovery processes, such as CO2 enhanced oil recovery (). Flash calculation using Equation of State (EOS) is very CPU expensive in compositional simulation. Conventional approaches for initial guess of K-values usually have several levels of limitations. This paper reports our research motivated to provide trustworthy initial guess for flash calculation and further improve flash performance in isothermal processes. Reservoir fluid composition changes are categorized into two different scenarios: (a) slightly varying or constant composition changes in depletion process; and (b) sharp varying composition in gas injection process. Scenario (a) is reasonably parameterized as a compositional space of K-value and vapor mole fraction varied with pressure. Considering the actual simulation of gas injection process, a compositional space is defined via introducing a key pseudo composition as a controlling variable in addition to pressure. Flash calculation is formulated through direct solution of those non-linear equations in phase-split calculation, and solved by combining successive substitution iteration (SSI) and Newton-Raphson (NR) method. Using interpolation from the constructed compositional space, it is found that the initial guess of K-values for flash calculation are always obtained with safeguard. A variety of fluid samples has been applied for testing this new flash technique. The results show that initial guesses of K-values based on Wilson's correlation results cause much more flash iterations and even failures in some gas injection examples. On the other hand, the proposed method shows significant advantages in reducing the number of flash iterations in all examples. In addition, the SSI procedure in flash can even be bypassed and only NR procedure and a simple Rachford-Rice Equation Preconditioning is sufficient.",
keywords = "CO2 flooding, Compositional simulation, Compositional space, Enhanced oil recovery, Flash calculation, Miscible gas injection",
author = "Bicheng Yan and Yuhe Wang and Hadi Nasrabadi and Killough, {John E.} and Keliu Wu",
year = "2016",
month = "12",
day = "24",
doi = "10.1016/j.petrol.2017.03.045",
language = "English",
journal = "Journal of Petroleum Science and Engineering",
issn = "0920-4105",
publisher = "Elsevier",

}

TY - JOUR

T1 - Accelerating Flash Calculation using Compositional Space for Compositional Simulation

AU - Yan, Bicheng

AU - Wang, Yuhe

AU - Nasrabadi, Hadi

AU - Killough, John E.

AU - Wu, Keliu

PY - 2016/12/24

Y1 - 2016/12/24

N2 - Compositional simulation is often required for modeling complex oil recovery processes, such as CO2 enhanced oil recovery (). Flash calculation using Equation of State (EOS) is very CPU expensive in compositional simulation. Conventional approaches for initial guess of K-values usually have several levels of limitations. This paper reports our research motivated to provide trustworthy initial guess for flash calculation and further improve flash performance in isothermal processes. Reservoir fluid composition changes are categorized into two different scenarios: (a) slightly varying or constant composition changes in depletion process; and (b) sharp varying composition in gas injection process. Scenario (a) is reasonably parameterized as a compositional space of K-value and vapor mole fraction varied with pressure. Considering the actual simulation of gas injection process, a compositional space is defined via introducing a key pseudo composition as a controlling variable in addition to pressure. Flash calculation is formulated through direct solution of those non-linear equations in phase-split calculation, and solved by combining successive substitution iteration (SSI) and Newton-Raphson (NR) method. Using interpolation from the constructed compositional space, it is found that the initial guess of K-values for flash calculation are always obtained with safeguard. A variety of fluid samples has been applied for testing this new flash technique. The results show that initial guesses of K-values based on Wilson's correlation results cause much more flash iterations and even failures in some gas injection examples. On the other hand, the proposed method shows significant advantages in reducing the number of flash iterations in all examples. In addition, the SSI procedure in flash can even be bypassed and only NR procedure and a simple Rachford-Rice Equation Preconditioning is sufficient.

AB - Compositional simulation is often required for modeling complex oil recovery processes, such as CO2 enhanced oil recovery (). Flash calculation using Equation of State (EOS) is very CPU expensive in compositional simulation. Conventional approaches for initial guess of K-values usually have several levels of limitations. This paper reports our research motivated to provide trustworthy initial guess for flash calculation and further improve flash performance in isothermal processes. Reservoir fluid composition changes are categorized into two different scenarios: (a) slightly varying or constant composition changes in depletion process; and (b) sharp varying composition in gas injection process. Scenario (a) is reasonably parameterized as a compositional space of K-value and vapor mole fraction varied with pressure. Considering the actual simulation of gas injection process, a compositional space is defined via introducing a key pseudo composition as a controlling variable in addition to pressure. Flash calculation is formulated through direct solution of those non-linear equations in phase-split calculation, and solved by combining successive substitution iteration (SSI) and Newton-Raphson (NR) method. Using interpolation from the constructed compositional space, it is found that the initial guess of K-values for flash calculation are always obtained with safeguard. A variety of fluid samples has been applied for testing this new flash technique. The results show that initial guesses of K-values based on Wilson's correlation results cause much more flash iterations and even failures in some gas injection examples. On the other hand, the proposed method shows significant advantages in reducing the number of flash iterations in all examples. In addition, the SSI procedure in flash can even be bypassed and only NR procedure and a simple Rachford-Rice Equation Preconditioning is sufficient.

KW - CO2 flooding

KW - Compositional simulation

KW - Compositional space

KW - Enhanced oil recovery

KW - Flash calculation

KW - Miscible gas injection

UR - http://www.scopus.com/inward/record.url?scp=85018781084&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85018781084&partnerID=8YFLogxK

U2 - 10.1016/j.petrol.2017.03.045

DO - 10.1016/j.petrol.2017.03.045

M3 - Article

AN - SCOPUS:85018781084

JO - Journal of Petroleum Science and Engineering

JF - Journal of Petroleum Science and Engineering

SN - 0920-4105

ER -