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SAGD ELift Applications

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Title: AEUB Gas/Bitumen Inquiry Effect of Gas Production on SAGD Performance at Surmont Author: Preferred Customer Last modified by: Kenneth Kisman – PowerPoint PPT presentation

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Title: SAGD ELift Applications


1
SAGD ELift Applications
  • Canadian Artificial Lift School
  • November 2006
  • Ken Kisman Ph.D., P.Eng.

www.rangewest.ca
2
Low-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

3
Low-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

4
Low-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)

5
SAGD artificial lift completionrequires
production tubing to toe
(to maintain full length of well hot maximize
steam chamber development all along the well pair)
6
SAGD steam-trap controlDefinition of subcool
7
Reference mixed subcool additional potential
subcool locations
8
Cartoon 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
9
Low Subcool
  • Low subcool (ie vigorous lift) is particularly
    important at low pressure
  • Low subcool is more important for lower quality
    reservoirs

10
Cartoon showing how low subcool might increase
steam chamber development along a well pair
  • .

11
Evidence 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

12
Low Pressure ChallengeSaturated steam
conditions reached prior to pump inlet for a
standard pump configuration
13
Examples of low-pressure challenges (a) 1000
kPaa versus (b) 3500 kPaa
14
Steam chamber may reach pump due to axial growth
or from another well pair
15
SAGD Artificial Lift Standard Bottomhole Pump
Configuration
16
SAGD 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

17
What 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

18
Current 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.

19
A 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

20
ELift a patented 2-stage lift system Concentric
configuration
21
Summary of ELift features
22
Concentric ELift Simplest instrumentation
configuration
23
ELift control functions
24
Cooling 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.

25
Concentric ELift tubing sizes
  • Example configurations

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
26
ELift simulation
  • ELift performance can be predicted with the
    QFlow thermal wellbore simulator
  • Mike McCormack
  • Fractical Solutions Inc

27
ELift concentric QFlow simulation example CALS 1
? low subcool in liner ?
conditioning of fluids at the pump inlet
28
ELift concentric QFlow simulation example CALS 2
? low subcool in liner ?
conditioning of fluids at the pump inlet
29
ELift parallel configuration
30
ELift parallel QFlow simulation example CALS 3
31
Choice 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

32
ELift 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)

33
ELift 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
35
ELift 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

36
ELift 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

37
Artificial 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

38
RecommendationUse 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

39
Main 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

40
Main 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
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