Update on ELift™ SAGD artificial lift

1. 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

2. 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

3. 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)

4. 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)

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

6. 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

7. Concentric ELift configuration

8. Concentric ELiftchanges 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)

9. Advantages of Concentric ELift over Parallel ELift • Can be installed in 9 5/8” intermediate casing • 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 • Concentric option allows simpler wellhead, easier installation of tubulars, & more room for a pump & motor • There is very little pressure drop across the packer

10. 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

11. Concentric ELift simulation example 1 with QFlow

12. Concentric ELift simulation example 2 with QFlow

13. Concentric ELift tubing sizes • Example configurations

14. 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

15. 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

16. Concentric ELiftSimplest 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

17. Current ELift royalty rate • $800 per well-pair per month

18. Artificial lift field pilot • Need to demonstrate the following: • COMBINATION of: • Low steam chamber pressures • Low mixed subcool • Long pump service life

19. 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