Vapex (vapor extraction) is a nonthermal process that has significant potential in providing a more environmentally friendly and energy-efficient alternative to steam injection. Vaporized solvent injected in-situ dissolves into the oil and reduces oil viscosity, allowing the oil to flow to a horizontal production well via gravitational forces. While compositional simulators are available for assessing the Vapex performance, the simulation process may become difficult when taking into account the uncertainty due to reservoir heterogeneity. A semi-analytical proxy is proposed to model the process, in a way analogous to the steam-assisted gravity drainage (SAGD) model described by Butler, who demonstrated the similarity between two processes with a series of Hele-Shaw experiments and derived an analytical steady-state flow rate relationship that is comparable with the SAGD case. Solvent concentration and intrinsic diffusivity are introduced in this model instead of temperature and thermal diffusivity in SAGD. In this paper, analytical solutions and implementation details for the Vapex proxy are presented. The proposed approach is then applied to various reservoirs discretized with spatially varying rock porosity and permeability values; bitumen drainage rate and solvent penetration are calculated sequentially at grid blocks along the solvent–bitumen interface over incremental time steps. Results from this model are compared against experimental data available in the literature as well as detailed compositional simulation studies. Computational requirement of the proxy in comparison with numerical simulations is also emphasized. An important contribution from this work is that process physics are built directly into this proxy, giving it an advantage over other data-driven modeling approaches (e.g., regression). It can be used as an efficient alternative to expensive detailed flow simulations. It presents an important potential for assessing the uncertainty due to multiscale heterogeneity on effective mass transfer and the resulting recovery performance, as well as assisting decisions-making for future pilot and field development.

References

References
1.
Karim
,
G. A.
,
Hanafi
,
A.
, and
Mehta
,
S. A.
,
1989
, “
Volatilization and Ignition of Oil Sand Samples During Intermittent Exposure to Hot Low-Velocity Air Streams
,”
ASME J. Energy Resour. Technol.
,
111
(
2
), pp.
104
109
.10.1115/1.3231404
2.
Hubbard
,
M.
,
Krehbiel
,
D. K.
, and
Gollahalli
,
S. R.
,
1994
, “
A Laboratory-Scale Experimental Study of In-Situ Combustion Processes
,”
ASME J. Energy Resour. Technol.
,
116
(
3
), pp.
169
174
.10.1115/1.2906439
3.
Das
,
S. K.
, and
Butler
,
R. M.
,
1994
, “
Investigation of ‘VAPEX’ Process in a Packed Cell Using Butane as a Solvent
,”
Canadian SPE/CIM/CANMET International Conference on Recent Advances in Horizontal Well Applications
, Calgary, March 20–24.
4.
Forster
,
L. J.
,
2008
, “
Numerical Modeling of the VAPEX Process in Heterogeneous Media
,” M.Sc. thesis, University of Texas at Austin, Austin, TX.
5.
Das
,
S. K.
, and
Butler
,
R. M.
,
1998
, “Mechanism of the Vapor Extraction Process for Heavy Oil and Bitumen,”
J. Pet. Sci. Eng.
,
21
(
1–2
), pp.
43
59
.10.1016/S0920-4105(98)00002-
6.
Butler
,
R. M.
, and
Mokrys
, I
. J.
,
1989
, “
Solvent Analog Model of Steam Assisted Gravity Drainage
,”
AOSTRA J. Res.
,
5
(
1
), pp.
17
32
.
7.
Yazdani
,
A.
, and
Maini
,
B. B.
,
2008
, “
Modeling of the VAPEX Process in a Very Large Physical Model
,”
Energy Fuels
,
22
(
1
), pp.
535
544
.10.1021/ef700429h
8.
Yazdani
,
A.
, and
Maini
,
B. B.
,
2005
, “
Effect of Drainage Height and Grain Size on Production Rates in the Vapex Process: Experimental Study
,”
SPE Reservoir Eval. Eng.
,
8
(
3
), pp.
205
213
.10.2118/89409-PA
9.
Boustani
,
A.
, and
Maini
,
B. B.
,
2001
, “
The Role of Diffusion and Convective Dispersion in Vapour Extraction Process
,”
J. Can. Pet. Technol.
,
40
(
4
), pp.
68
77
.10.2118/89409-PA
10.
Das
,
S. K.
,
2005
, “
Diffusion and Dispersion in the Simulation of Vapex Process
,”
SPE/PS-CIM/CHOA International Thermal Operations and Heavy Oil Symposium
, Calgary, AB, Canada, Nov. 1–3.
11.
Das
,
S. K.
,
1998
, “
Vapex: An Efficient Process for the Recovery of Heavy Oil and Bitumen
,”
SPE J.
,
3
(
3
), pp.
232
237
.10.2118/50941-PA
12.
Chen
,
Q.
,
Gerritsen
,
M. G.
, and
Kovscek
,
A. R.
,
2008
, “
Effects of Reservoir Heterogeneities on the Steam-Assisted Gravity Drainage Process
,”
SPE Reservoir Eval. Eng.
,
11
(
5
), pp.
921
932
.10.2118/109873-PA
13.
Guan
,
L.
,
McVay
,
D. A.
,
Voneiff
,
G. W.
, and
Jensen
,
J. L.
,
2004
, “
Evaluation of a Statistical Method for Assessing Infill Production Potential in Mature, Low-Permeability Gas Reservoirs
,”
ASME J. Energy Resour. Technol.
,
126
(
3
), pp.
241
245
.10.1115/1.1781672
14.
Uddin
,
M.
,
Coombe
,
D.
,
Law
,
D.
, and
Gunter
,
B.
,
2008
, “
Numerical Studies of Gas Hydrate Formation and Decomposition in a Geological Reservoir
,”
ASME J. Energy Resour. Technol.
,
130
(
3
), p.
032501
.10.1115/1.2956978
15.
Ju
,
B.
,
Qiu
,
X.
,
Dai
,
S.
,
Fan
,
T.
,
Wu
,
H.
, and
Wang
,
X.
,
2008
, “
A Study to Prevent Bottom Water From Coning in Heavy-Oil Reservoirs: Design and Simulation Approaches
,”
ASME J. Energy Resour. Technol.
,
130
(
3
), p.
033102
.10.1115/1.2955560
16.
Vanegas
,
J. W. P.
,
Deutsch
,
C. V.
, and
Cunha
,
L. B.
,
2008
, “
Uncertainty Assessment of SAGD Performance Using a Proxy Model Based on Butler’s Theory
,”
SPE Annual Technical Conference and Exhibition
, Denver, CO, Sept. 21–24.
17.
Butler
,
R. M.
,
1985
, “
A New Approach to the Modeling of Steam-Assisted Gravity Drainage
,”
J. Can. Pet. Technol.
,
24
(
3
), pp.
42
51
.10.2118/85-03-01
18.
Azad
,
A.
, and
Chalaturnyk
,
R. J.
,
2010
, “
A Mathematical Improvement to SAGD Using Geomechanical Modeling
,”
J. Can. Pet. Technol.
,
49
(
10
), pp.
53
64
.10.2118/141303-PA
19.
Reis
,
J. C.
,
1992
, “
A Steam-Assisted Gravity Drainage Model for Tar Sands: Linear Geometry
,”
J. Can. Pet. Technol.
,
31
(
10
), pp.
14
20
.10.2118/92-10-01
20.
Lamb
,
H.
,
1932
,
Hydrodynamics
,
6th ed.
,
Dover Publications
,
New York
, p.
581
.
21.
Okazawa
,
T.
,
2009
, “
Impact of Concentration-Dependence of Diffusion Coefficient on VAPEX Drainage Rates
,”
J. Can. Pet. Technol.
,
48
(
2
), pp.
47
53
.10.2118/09-02-47
22.
Boustani
,
A.
,
2001
, “
Investigation of Interfacial Mass Transfer in Vapor Extraction Process
,” M. Sc. thesis. University of Calgary, Calgary, AB, Canada, pp.
22
23
.
23.
Burdine
,
N. T.
,
1953
, “
Relative Permeability Calculations From Pore Size Distribution Data
,”
J. Pet. Technol.
,
5
(
3
), pp.
71
78
.10.2118/225-G
24.
Kjosavik
,
A.
, and
Ringen
,
J. K.
,
2000
, “
Relative Permeability Correlation for Mixed-Wet Reservoirs
,”
SPE/DOE Improved Oil Recovery Symposium
, Tulsa, OK, April 3–5.
25.
Sandler
,
S. I.
,
1999
,
Chemical, Biochemical and Engineering Thermodynamics
,
4th ed.
,
John Wiley & Sons, Inc.
,
New York
.
26.
Sharma
,
G. D.
,
1994
, “
Study of Hydrocarbon Miscible Solvent Slug Injection Process for Improved Recovery of Heavy Oil From Schrader Bluff Pool
,” Department of Energy, Milne Point Unit, AK, Jan. 1–Dec. 31, Annual Report, No. DE-FG22-93BC14864.
27.
Computer Modelling Group
,
2011
,
GEM: Advanced Compositional Reservoir Simulator User’s Guide (Version 2011
),
Computer Modelling Group Limited
,
Calgary, AB
.
28.
Nghiem
,
L. X.
,
Kohse
,
B. F.
, and
Sammon
,
P. H.
,
2001
, “
Compositional Simulation of the Vapex Process
,”
J. Can. Pet. Technol.
,
40
(
8
), pp.
54
61
.10.2118/01-08-05
29.
Leung
,
J. Y.
,
2012
, “
Scale-up of Effective Mass Transfer in Vapor Extraction Process for Heterogeneous Reservoirs
,”
SPE Improved Oil Recovery Symposium
, Tulsa, OK, April 14–18.
You do not currently have access to this content.