Transcript AEUB Gas/Bitumen Inquiry Effect of Gas Production on SAGD

Update on ELift™
SAGD artificial lift
Presentation to
Artificial Lift & Low-Pressure SAGD Subcommittees
Nov 2004
Ken Kisman Ph.D., P.Eng.
www.rangewest.ca
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Update on ELift
Since my last presentation to the Artificial Lift
Subcommittee on June 17, 2003:

An artificial lift paper was published in JCPT, August
2003

A presentation was made to the 2004 Slugging it Out
conference which is available at
www.petsoc.org/SIO_2004/Kisman.pdf
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Low-pressure SAGD summary
Advantages (even in absence of thief zones):
 Reduced heat requirements
 Reduced emissions (Kyoto)
 Less source water needed
 Less facilities for steam generation & water treatment
 Lower capital cost for piping & vessels

Improved operations (reduced H2S, CO2, silica, scaling, & may
eliminate sulphur plant)
Disadvantages
 Drilling of more well pairs initially although total number needed
is approx. the same (or less)
 Artificial lift may add extra cost (or reduce costs when surface
fluid separators not needed)
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Subcool Issues
 Examples of Low-Pressure Challenges
 Flashing to steam is triggered by a much smaller ∆P in the
liner & up to the pump (eg 59 kPa versus 230 kPa)
 Flowing bitumen viscosity is much higher (eg 61 cp versus 9
cp)
 Higher mixed subcool for a given liquid head over a pump
 Bitumen rates per well are lower so it is more important to
optimize operations
 Low subcool (ie vigorous lift) is particularly important
at low pressure
(for more details, see 2004 Slugging it Out presentation)
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Cartoon showing how low subcool might increase
steam chamber development along a well pair
.
High
mixed
subcool
Low
mixed
subcool
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The next major SAGD advance
The only way to be sure that bitumen rate,
SOR, recovery factor, emissions & water
use are optimized is
Use low-pressure SAGD
Use vigorous lift, with low subcool values,
for extended periods
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Concentric ELift configuration
Liquid production
Gas
production
Second stage (inner) production tubing
Top of 1st stage in (outer) casing annulus
Liquid pool in (inner) tubing annulus
Port
Insulated (outer) tubing
Inlet to 2nd stage bottomhole pump
Optional downhole motor
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Concentric ELift
changes from parallel operation

Concentric inner & outer tubing are installed instead
of parallel tubing strings

The outer tubing is insulated (substantially from the
base to the port)

1st stage flow up to the port is between the outer
tubing and the casing

The liquid pool flowing down to the pump is between
the inner and outer tubing.

2nd stage flow to the surface is up the inner tubing.
(parallel ELift operation is described in JCPT paper August 2003)
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Advantages of Concentric ELift
over Parallel ELift
a) Can be installed in 9 5/8” intermediate casing
b) Both configurations provide good performance at
moderate flow rates but concentric ELift allows
higher flow rates because flow area in 1st stage can
readily be larger
c) Concentric option allows simpler wellhead, easier
installation of tubulars, & more room for a pump &
motor
d) There is very little pressure drop across the packer
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Concentric ELift simulation
The QFlow** thermal wellbore simulator has
been modified to allow SAGD simulation with
concentric ELift as well as parallel ELift
**Mike McCormack
Fractical Solutions Inc
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Concentric ELift simulation example 1
with QFlow
Liquid
production
Gas
production
P = 499 kPaa
T = 152 °C
Steam quality
= 5.2 %
Port
Depth of liner = 127 m
Elevation of pump above liner = 5 m
Elevation of port above liner = 75 m
Steam chamber pressure = 1000 kPaa
Liner toe pressure = 800 kPaa
P = 1134 kPaa
T = 152 °C
Subcool = 34 °C
Subcool at toe = 2 °C
Water rate = 300 m3/d
Oil rate = 150 m3/d
P = 706 kPaa
T = 165 °C
Steam present: quality = 1.8 %
Pump
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Concentric ELift simulation example 2
with QFlow
Liquid
production
Gas
production
P = 302 kPaa
T = 134 °C
Steam quality
= 9.5%
Port
Depth of liner = 360 m
Elevation of pump above liner = 10 m
Elevation of port above liner = 200 m
Steam chamber pressure 1000 kPaa
Liner toe pressure = 800 kPaa
P = 2025 kPaa
T = 133 °C
Subcool = 79 °C
Subcool at toe = 2 °C
Water rate = 300 m3/d
Oil rate = 150 m3/d
P = 706 kPaa
T = 165 °C
Steam present: Quality = 1.8%
Pump
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Concentric ELift tubing sizes
Example configurations
Casing
od
9 5/8”
9 5/8”
Insulated outer tubing
od
(id)
7 5/8”
(~6.0”)
7 ¾”
(~6.5”)
Inner tubing
od
11 ¾”
13 3/8”
9 5/8”
10 ¾”
3 ½”
4 ½”
(~8.0”)
(~9.0”)
2 7/8”
2 7/8”
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A downhole motor
adds heat to fluids prior to pump intake
Standard single-stage pump configuration

A downhole motor adds heat to the fluids prior to
the pump intake and increases flashing
ELift shroud option for motor

A shroud around the motor may be used so flow of
the liquid pool cools the motor. This will cause the
same heating of the pumped fluids but the high
pump subcool provided by ELift will prevent
flashing

Optionally insulate the section of 2nd stage tubing from the
pump to the elevation of the port.

Note the shroud benefits from liquid-only flow
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ELift option can prevent heating
of pumped fluids by a downhole motor
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.

Optionally, a heat transfer fluid can be used around the motor at
base of tubing for increased thermal conduction to the outer tubing
»

eg commercial heat transfer fluids or liquid fusible alloys
Simulations show that the subcool at the pump inlet is almost
unchanged by the use of the downhole motor. Hence, the full
subcool benefit provided by ELift is maintained even with a
downhole motor
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Concentric ELift
Simplest instrumentation configuration
Pressure in liquid pool

An electronic pressure sensor string (attached to the pump
cable) is landed above the pump. This enables control of the
liquid level (by controlling the gas production rate at the surface)
Liner temperature

A thermocouple string (attached to the pump cable) extends
below the downhole motor to measure bottomhole heel
temperature for (indirect) subcool measurement & control
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Current ELift royalty rate
$800 per well-pair per month
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Artificial lift field pilot
Need to demonstrate the following:
COMBINATION of:
 Low steam chamber pressures
 Low mixed subcool
 Long pump service life
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Main overall ELift advantages
 Improved recovery performance due to
vigorous lift with low subcool in liner
 Choice of pumps & the pumps have longer
service life
 Good downhole gas-liquid separation in each
well
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