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The distillation mechanism in steam displacement of oil

The distillation mechanism in steam displacement of oil. Dan Marchesin and Hans Bruining, . ECMOR X Sept 4-7, 2006. An example of all the pathological problems with conservation laws. Elliptic regions (Not discussed here) Non-Lax shocks (*) and uniqueness

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The distillation mechanism in steam displacement of oil

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  1. The distillation mechanism in steam displacement of oil Dan Marchesin and Hans Bruining, ECMOR X Sept 4-7, 2006

  2. 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

  4. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Volatile oil enhanced steam drive • Proposed by Dietz (1979) Amsterdam: ECMOR X: Sept. 4-7, 2006: 18 slides

  5. water dead oil Vol. oil Steamzone cold zone Steam+vol. oil Liq. Vol. oil initial oil Vol. oil vapor Zero oleic phase ES-SAGD (Ian Gates) Co-inject some volatile oil with steam Courtesy: Claes Palmgren Amsterdam: ECMOR X: Sept. 4-7, 2006: 17 slides

  6. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Laboratory tests showing the effect of coinjected volatile oil

  7. 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

  8. Shock velocity Sw(-) Sg(-) Sw(+) Darcy velocity (+) Water balance Oil balance Energy balance Welge shock condition Missing equation? MOC models complicated due to saddle to saddle connection in shocks (not a Lax shock) Sw,Sg,So=0,vov =0 Sw,So,vov =0 initial Steam 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. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Simulation gives unrealistic results due to numerical dispersion Sw,Sg,So=0,vov =0 Sw,So,vov >0 initial Steam Volatile oil bank Initial composition Amsterdam: ECMOR X: Sept. 4-7, 2006: 13 slides

  10. 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

  11. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Model • Injection steam and volatile oil vapor in core Sw=Swc, So=1-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 -> f = c – p + 2

  12. 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

  13. Formulations of interest • Analytical solution; without capillary and diffusion -> 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

  14. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Dodecane coinjected (num. sol.)

  15. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Cyclo-butane coinjected (num. sol.)

  16. Steam+Vol-oil Sw,Sg,So=0,vov >0 Sw,So,vov = 0 initial Volatile oil bank Initial composition Comparison numerical (left) and analytical solution; Medium boiling (heptane) volatile oil Saturations 0  S 1., vov: fraction of volatile oil in the oleic phase.

  17. 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

  18. 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

  19. 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

  20. 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

  21. 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

  22. 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

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