Title: SAGD ELift Applications
1SAGD ELift Applications
- Canadian Artificial Lift School
- November 2006
- Ken Kisman Ph.D., P.Eng.
www.rangewest.ca
2Low-pressure SAGD with artificial liftReasons
- (A) Thief Zones
- Upper gas water sand thief zones and/or bottom
water are common in the Athabasca deposit - (B) SAGD Wind-down
- Requires low pressure and/or injection of
non-condensable gas
3Low-Pressure SAGD with artificial lift Reasons
- (C) Improved SOR economics
- Less natural gas required
- Less facilities for steam generation water
treatment - Lower capital cost for piping vessels
- (D) Environmental benefits
- Reduced emissions (Kyoto)
- Less source water needed
- (E) Improved operations
- Reduced H2S, CO2, silica, scaling, may
eliminate sulphur plant
4Low-Pressure SAGD with artificial lift Reasons
- (F) More oil from same plant
-
- Example
- Plant Oil SOR
Production - High pressure 2.5 30,000 b/d
- Low pressure 1.9 40,000 b/d
- with relatively modest extra facilities
- addition of artificial lift
- drilling of more well pairs initially (although
total number needed is approx. the same)
5SAGD artificial lift completionrequires
production tubing to toe
(to maintain full length of well hot maximize
steam chamber development all along the well pair)
6SAGD steam-trap controlDefinition of subcool
7Reference mixed subcool additional potential
subcool locations
8Cartoon of Local Mixed Subcool Values Along a
SAGD Horizontal Well
Local subcool
Mixed subcool
Low mixed subcool minimizes the local subcools,
maximizes height of steam chamber maximizes
steam chamber development along the well pair
Low mixed subcool requires lifting harder
increases the oil production rate
9Low Subcool
- Low subcool (ie vigorous lift) is particularly
important at low pressure - Low subcool is more important for lower quality
reservoirs
10Cartoon showing how low subcool might increase
steam chamber development along a well pair
11Evidence of need for low subcool values
- SAGD Field Projects
- UTF pilot Phase B used subcool values close to 0
C in the production liner - Surmont pilot reported much higher oil rates
improved SOR with low subcool (EUB Resource
Management Reports) - Simulations with real-life conditions
- Kisman JCPT Aug 2003
12Low Pressure ChallengeSaturated steam
conditions reached prior to pump inlet for a
standard pump configuration
13Examples of low-pressure challenges (a) 1000
kPaa versus (b) 3500 kPaa
14Steam chamber may reach pump due to axial growth
or from another well pair
15SAGD Artificial Lift Standard Bottomhole Pump
Configuration
16SAGD Artificial Lift Standard Bottomhole Pump
Configuration
- Difficult Conditions
- High temperature fluids
- Saturated steam conditions with flashing to steam
and gas breakout - High lift rates required to achieve low subcool
values in the production liner - Scaling in pump
- Unstable flow
- slugging between bitumen water
- inflow rates varying with time
17What if available artificial lift cannot lift
hard enough to provide low mixed subcool?
- Some bitumen recovery will still be obtained but
only part of the well may have a steam chamber - There is no way of knowing how much better the
bitumen rate, SOR, recovery factor would be
with low mixed subcool - The only way to be sure that field performance is
optimized is to use vigorous lift, with low
subcool values, for extended periods
18Current SAGD lift status
- Some SAGD operators are
- satisfied that electrical submersible pumps
(ESPs) are providing adequate lift - expecting improving run life for ESPs
- not unduly concerned about subcool and reservoir
performance issues.
19A fully successful SAGD lift system
- To be fully successful, a SAGD lift system must
demonstrate the following - Combination
- Low steam chamber pressures
- Low mixed subcool
- Long service life
20ELift a patented 2-stage lift system Concentric
configuration
21Summary of ELift features
22Concentric ELift Simplest instrumentation
configuration
23ELift control functions
24Cooling of motor when downhole motor is used
- (A) ELift shroud option for motor
- A shroud around the motor may be used so flow of
the liquid pool cools the motor. There is only
liquid flow in the shroud. The high pump subcool
provided by ELift will prevent flashing - (B) ELift 1st Stage Cooling Option for Motor
- Motor does not have a shroud. A section of outer
tubing at the elevation of the motor is left
uninsulated so the motor is cooled by concentric
flow up the 1st stage.
25Concentric ELift tubing sizes
Casing od Insulated outer tubing od (id) Inner tubing od
9 5/8 7 5/8 (6.0) 2 7/8
9 5/8 7 ¾ (6.5) 2 7/8
11 ¾ 9 5/8 (8.0) 3 ½
13 3/8 10 ¾ (9.0) 4 ½
26ELift simulation
- ELift performance can be predicted with the
QFlow thermal wellbore simulator - Mike McCormack
- Fractical Solutions Inc
27ELift concentric QFlow simulation example CALS 1
? low subcool in liner ?
conditioning of fluids at the pump inlet
28ELift concentric QFlow simulation example CALS 2
? low subcool in liner ?
conditioning of fluids at the pump inlet
29ELift parallel configuration
30ELift parallel QFlow simulation example CALS 3
31Choice of Concentric ELift or Parallel ELift
- Concentric can be installed in small 9 5/8 od
intermediate casing - for low or moderate flow rates
- careful design required
- For large intermediate casing, both concentric
and parallel configurations should be considered
32ELift benefits (a) Subcool Recovery
- ELift uses natural lift in 1st stage to an
- intermediate elevation
- Provides vigorous lift with low mixed subcool at
low bottomhole pressures - Provides substantial recovery, facility
environmental benefits due to low pressure SAGD
with low subcool - Increased feasibility for development of lower
quality reservoirs (which require optimization)
33ELift benefits (b) Pump
- Potential to reduce pump costs by half or
- better
- Can use standard, less expensive pumps
- Increased pump life
- Supported by indirect field evidence
- Whatever improvements are made over time to
pumps, pump life should always be longer when the
pump is used with ELift because of fluid
conditioning by ELift
34 ELift benefits (c) ELift
isolates the steam chamber during pump changes
35ELift benefits (d) downhole gas/liquid
separation
- Complete downhole gas/liquid separation provided
by ELift - Eliminates the need for surface multiphase group
separators - Allows good measurement of liquid production
rates for each well hence allows optimization
of each well pair
36ELift field demonstration
- Parallel ELift, with gas lift in 2nd stage, was
- used for 3 years in ConocoPhillips Surmont
- SAGD pilot
- Main principles of ELift were demonstrated
- Very low mixed subcool values were obtained
37Artificial lift field pilot
- New piloting is needed to demonstrate the
following - COMBINATION
- Low steam chamber pressures
- Low mixed subcool
- Long pump service life
- Note that pump performance when used at high
pressures does not translate down to low
pressures since all aspects are more challenging
at low pressures
38RecommendationUse Large Intermediate Casingin
future SAGD production wells
- Facilitates the option of 2-stage ELift
artificial lift - Otherwise, future operations could be jeopardized
if low pressure becomes necessary - Typical extra well drilling cost is modest for 13
3/8 casing
39Main Conclusionsre SAGD artificial lift with
ELift
- Any current or future SAGD pump should work
better with ELift - The benefit could be substantial even if the only
benefit considered is either - Increased pump life, or
- Isolation of the steam chamber during pump
changes etc - Optimization with ELift is particularly important
for lower quality reservoirs
40Main Conclusions SAGD artificial lift with ELift
has benefits under five main headings
- Improved recovery performance
- due to vigorous lift with low subcool in liner
- Pump savings
- less expensive pumps longer pump life
- Isolates steam chamber during workovers
- Good downhole gas-liquid separation
- Makes low-pressure SAGD more feasible
- Economic, environmental, operations benefits