The distillation mechanism in steam displacement of oil

1
The distillation mechanism in steam displacement
of oil

• Dan Marchesin and Hans Bruining,

ECMOR X Sept 4-7, 2006
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An example of all the pathological problems with
conservation laws

• Elliptic regions (Not discussed here)
• Non-Lax shocks () and uniqueness
• Small diffusion is dominating efficiency of
  process

E. Isaacson. D. Marchesin, and B. Plohr ,
Transitional waves for conservation laws, SIAM J.
Math. Anal. 21, 831-866 (1990)
Amsterdam ECMOR X Sept. 4-7, 2006 20 slides
3
Steam injection
Steam injection is commercially applied to
recover viscous oils
Amsterdam ECMOR X Sept. 4-7, 2006 19 slides
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Volatile oil enhanced steam drive

• Proposed by Dietz (1979)

Amsterdam ECMOR X Sept. 4-7, 2006 18 slides
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ES-SAGD (Ian Gates)
Co-inject some volatile oil with steam
Courtesy Claes Palmgren
Amsterdam ECMOR X Sept. 4-7, 2006 17 slides
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Laboratory tests showing the effect of coinjected
volatile oil
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Contents

• Reasons why modeling of this process is complex
• Formulation including capillary and diffusion
  effects
• Dodecane, cyclo butane and heptane Bifurcations
  depending on boiling points
• Importance of diffusion processes
• Peak wave and effect on recovery

Amsterdam ECMOR X Sept. 4-7, 2006 15 slides
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MOC models complicated due to saddle to saddle
connection in shocks (not a Lax shock)
Sw,Sg,So0,vov 0
initial
Sw,So,vov 0
Steam

• Shock velocity
• Sw(-)
• Sg(-)
• Sw()
• Darcy velocity ()

• Water balance
• Oil balance
• Energy balance
• Welge shock condition
• Missing equation?

Bruining, J., Duijn, C.J. van, "Uniqueness
Conditions in a Hyperbolic Model for Oil Recovery
by Steamdrive, Computational Geosciences" No 4,
pp 65-98 (2000), Traveling waves in a finite
condensation rate model for steam injection,
ibid. 2006
9
Simulation gives unrealistic results due to
numerical dispersion
Sw,Sg,So0,vov 0
initial
Sw,So,vov gt0
Steam
Volatile oil bank
Initial composition
Amsterdam ECMOR X Sept. 4-7, 2006 13 slides
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Motivation of combined analytical and numerical
approach

• Simulators overemphasize diffusion/ capillary
  diffusion are the solutions realistic?
• Are we allowed to disregard diffusion all
  together?
• Does the form of the diffusion e.g. saturation
  dependence affect the global solution even if it
  is small?
• Existence and uniqueness? We are using empirical
  relations to describe the convection flow
• Possible bifurcations analysis i.e. solutions
  change behavior if parameters cross critical
  values ().
• Discovery of new recovery mechanisms

Bruining, J. and Marchesin, D. , Nitrogen and
steam injection in a porous medium with water,
TIPM (March 2006), 62 (3), 251-281
Amsterdam ECMOR X Sept. 4-7, 2006 12 slides
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Model

• Injection steam and volatile oil vapor in core
  SwSwc, So1-Swc
• No dissolution of water in the oleic phase.
• Volatile oil vapor mixes in all proportions with
  steam. Liquid volatile oil mixes with dead oil.
  Dead oil only occurs in the oleic phase.
• Viscosities depend on T and the composition vov .
  
• No volume effects on mixing
• Capillary forces and diffusional effects
  incorporated
• Local thermodynamic equilibrium -gt f c p 2

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Four conservation laws water, dead oil, volatile
oil, energy

• ?ov(T) volatile oil concentration in oleic phase
• ?gv(T) volatile oil concentration in gaseous
  phase
• uov(T) Darcy velocity volatile oil in oleic phase
• ugv(T) Darcy velocity volatile oil in gaseous
  phase

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Formulations of interest

• Analytical solution without capillary and
  diffusion -gt hyperbolic problem (solution
  discussed here) details in paper submitted to
  Phys. Rev. E
• Numerical solution with capillary and diffusion
  (see Figs. 1, 2, 3.) details in paper submitted
  to Phys. Rev. E
• Traveling wave solution in steam
  condensation zone (formulation presented in
  paper)

Bruining, J. and Marchesin, D. , Maximal Oil
Recovery by simultaneous condensation of alkane
and steam, Submitted to Phys Rev E
Amsterdam ECMOR X Sept. 4-7, 2006 9 slides
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Dodecane coinjected (num. sol.)
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Cyclo-butane coinjected (num. sol.)
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Comparison numerical (left) and analytical
solution Medium boiling (heptane) volatile oil
Saturations 0 ?? S?? ? 1., vov fraction of
volatile oil in the oleic phase.
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Numerical (left) and analytical solution, Medium
boiling volatile oil initially present
Saturations 0 ?? S?? ? 1., vov fraction of
volatile oil in the oleic phase.
Amsterdam ECMOR X Sept. 4-7, 2006 5 slides
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Medium volatile oil slug injection problem.
Rescaled temperature 0 ?? T ? 1., vov is
fraction of volatile oil in the oleic phase.
Amsterdam ECMOR X Sept. 4-7, 2006 4 slides
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Blow up of previous plot
Structure of the transition zone consisting of a
3- and a 2-phase part. Rescaled temperature 0
?? T ? 1. Volatile oil peak indicated by vov
between hot steam zone and cold liquid zone .
Amsterdam ECMOR X Sept. 4-7, 2006 3 slides
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Stability of diffusion bank
First 7 time intervals volatile oil is
coinjected with the steam. Second 7 time
intervals pure steam injection. volatile oil
peak is essentially preserved ensuring high
recovery of oil
Amsterdam ECMOR X Sept. 4-7, 2006 2 slides
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Conclusions

• During steam injection with co-injection of
  volatile oil a volatile oil peak is formed
  between the steam zone and the liquid zone
• The volatile oil peak is a component of a
  traveling wave solution this is a new type of
  wave
• After turning to pure steam injection the
  volatile oil peak remains more or less unchanged
• A steady volatile oil peak is capable of reducing
  the residual oil during steam drive and hence
  enhances the oil recovery
• These conclusions must still be rigorously
  validated by solving the traveling wave problem

Amsterdam ECMOR X Sept. 4-7, 2006 last slide
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Conclusions

• Finite volume methods can give erroneous results
  when describing non-Lax shocks
• Only medium range boiling volatile oils added to
  the steam help to improve the oil recovery low
  range boiling oils form a 3-ph zone beyond the
  SCF. High range boiling oils stay behind.
• Molecular diffusion plays an important role in
  determining the efficiency of volatile oil
  enhanced steam drive recovery.
• (un) stable nodal points