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Institute of Petroleum Engineering,
Heriot-Watt University
Edinburgh, UK
Contact:
+44(0)131 451 3568
AN OVERVIEW OF HEAVY OIL RECOVERY STUDIES AT THE CENTRE FOR ENHANCED OIL RECOVERY AND CO2 SOLUTIONS OF
HERIOT-WATT UNIVERSITY
IEAEOR 33rd Annual Symposium, Regina, Saskatchewan, Canada
Prof. Mehran Sohrabi
28 August 2012
1
Outline 2
Introduction & Objectives
Experimental Facilities
Visualization Experiments
Coreflood Experiments
Conclusions
3
Heavy Oil Recovery
Thermal methods are applied in the field but there
are limitations: - thin and deeper reservoirs - energy intensive - environmental issues e.g. carbon footprint
Non-thermal recovery methods provide a solution for reservoirs in which thermal methods are impractical or uneconomical also offer advantages on capital cost, energy consumption, environmental pollution etc.
Very low primary production (5% to 10%) and
poor waterflood performance.
Objective 4
The objective of the Non-Thermal Enhanced Oil Recovery JIP
at Heriot-Watt is to investigate potential of improving heavy
oil recovery by:
Water/CO2 combinations (focus of this presentation)
Chemical Injection, and
Mobility control techniques.
Mechanisms of Oil Recovery by CO2 Injection
5
Light Oil Systems Heavy Oil Systems
Klins, 1984
Interactions of CO2 and crude oil are different in heavy oil
compared to conventional oil
CO2 Dissolution and Viscosity Reduction
6
While miscibility would be absent, large drops in heavy oil
viscosity takes place upon mixing with CO2.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0% 20% 40% 60% 80% 100%
Vis
co
sit
y R
ati
o (
% v
isc
os
ity o
f o
il/C
O2
mix
ture
to
ori
gin
al o
il v
isc
os
ity)
CO2 content, saturation frac.
Crude "J"
Crude "C"
7
Our research approach:
Investigate pore-scale physics by performing visualization experiments
Quantify level of additional oil recovery by each method by core flood
experiments under reservoir conditions.
Performed simulation and modelling at core and field scales.
Outline 8
Introduction & Objectives
Experimental Facilities
Visualization Experiments
Coreflood Experiments
Conclusions
Work Reported in Thesis
Eight heavy crude oil samples were provided by sponsor companies from reservoirs
around the world. The viscosity range was from 5 to 10000 cp at their test
conditions. The focus of this presentation is on the following two heavy oils.
Experimental Work
Fluid Characterization: Viscosity, composition, Wettability, IFT, Acid number , etc
Flow Visualization Experiments: Using the transparent micromodels to investigate the
displacement mechanisms at the pore scale,
Displacement Experiments: Using Sandpack and consolidated cores to up-scale
and quantify the observations in the micromodel.
9
Crude APIº Viscosity
(cp)
Pressure
(psig)
Temperature
(ºC)
“C” 10 8700 600 50
“J” 16 617 1500 28
Flow Visualization Rig 10
High-pressure micromodels allow detailed investigation of
pore-scale mechanisms under reservoir conditions.
Coreflood Rig 11
Outline 12
Introduction
Experimental Facilities
Visualization Experiments
Coreflood Experiments
Conclusions
Low Pressure (gaseous) Application of CO2 (Crude C)
Initial Waterflood Flood – poor oil recovery CO2 Flood at CO2 Breakthrough
CO2 Flood after 2 days – note change of
colour of oil due to dilution with CO2
Water injection after CO2 flood resulted in
significant additional oil recovery
Initial Oil saturation Initial Water Flood
CO2 Flood at Breakthrough CO2 Flood after 1 day 2nd Waterflood (post CO2 Flood)
High Pressure (Super Critical) Application of CO2 (crude J)
Initial Oil Saturation
CO2-Foam, 2 hrs CO2-Foam, 10 hrs
Water Flood Surfactant Flood CO2-Foam BT
CO2-Foam, 5 hrs CO2-Foam, 1 day
CO2-Foam, 1 hr
Mobility Control by CO2-Foam (Crude C)
Oil Recovery Comparison (Crude C)
CO2 Flood after 2 days CO2-Foam injection 1 day CO2 and Water injection (slugs)
Outline 17
Introduction
Experimental Facilities
Visualization Experiments
Coreflood Experiments
Conclusions
Oil Recovery by Waterflood (Heavy Oil vs. Light Oil)
18
0
10
20
30
40
50
60
70
80
0 0.5 1 1.5 2 2.5
Oil R
ec
ove
ry (
%O
OIP
)
Inj Brine (PV)
Heavy oil - 617 cp
Light Oil - 1 cp
Water BT
Crude J – 617 cp
Heavy Oil Recovery by CO2 Injection (Tertiary Vs Secondary)
19
0
10
20
30
40
50
60
70
80
0 1 2 3 4 5
Oil R
ec
ove
ry (
%O
OIP
)
Inj Fluids (PV)
Tertiary CO2 Flood
Secondary CO2 Flood
CO2 BT
Tertiary CO2 Flood
Secondary CO2 Flood
Secondary Waterflood
Crude J – 617 cp (medium heavy oil)
Mobility Control by CO2-Foam (CO2 inj Vs CO2Foam)
20
0
10
20
30
40
50
60
70
80
90
0 1 2 3 4 5 6 7
Oil R
ec
ove
ry (
%O
OIP
)
Inj Fluids (PV)
Tertiary CO2 Flood
CO2-Foam Flood
Waterflood
CO2/CO2-Foam Flood
Crude C – 8670 cp (extra heavy oil)
CO2 storage in light vs. heavy oil Reservoirs
21
While in conventional oil reservoirs the amount of CO2 that can be stored
in water flooded reservoirs (tertiary) is much lower than secondary. In
heavy oil systems, CO2 storage capacity is almost the same for secondary
and tertiary CO2 injection.
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.5 1 1.5 2
Ave
rag
e G
as
Sa
tura
tio
n
Gas Injected (Core PV)
2Phase, Gas Injection
3 Phase, 1st Gas Injection
Secondary Gas Injection
Tertiary Gas Injection
0
0.1
0.2
0.3
0.4
0.5
0.6
0 0.5 1 1.5 2
CO
2 S
tora
ge
(P
V)
Inj Fluids (PV)
Secondary CO2 Flood
Tertiary CO2 Flood
Heavy Oil (Crude J )
617 cp
Light Oil
µ <1 cp
Mobeen Fatemi and Mehran Sohrabi, Water Alternating Gas Injection
JIP, Steering meeting Oct. 2011
Outline 22
Introduction
Experimental Facilities
Visualization Experiments
Coreflood Experiments
Conclusions
Conclusions 23
The results of this study show significant potential for
enhanced oil recovery and CO2 storage in heavy oil
reservoirs.
The coreflood results show that the performance of
CO2 is, to a large extent, dependent on reservoir
conditions, the state of CO2 under reservoir
conditions, and physical properties of the heavy
crude oil.
Conclusions 24
Comparison of recovery data during secondary and
tertiary injection of CO2 reveals that secondary CO2
injection provides much better recovery efficiency at
early injection times.
While CO2 storage capacity in light oil systems is a
strong function of injection mode (pre- or post-
waterflood), heavy oil systems show much less
sensitivity to CO2 injection strategy.
Conclusions 25
The results of micromodel and coreflood experiments
revealed that when the CO2 flood process is boosted
by a appopriate mobility control technique (e.g. in-
situ formation of foam), heavy oil displacement
process takes place in a much shorter time period and
more efficiently.
Acknowledgment 26
This work was carried out as part of the ongoing Enhanced
Heavy Oil Recovery joint industry project (JIP) at the Institute
of Petroleum Engineering of Heriot-Watt University and was
equally supported by: Total Exploration and Production UK,
ConocoPhillips, Petrobras, PEMEX, and PTT Ltd. which is
gratefully acknowledged.
