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

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Presentation on theme: "1 SAGD ELift Applications Canadian Artificial Lift School November 2006 Ken Kisman Ph.D., P.Eng. www.rangewest.ca."— Presentation transcript:

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

2 2 Low-pressure SAGD with artificial lift: Reasons (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 3 Low-Pressure SAGD with artificial lift: Reasons (C) Improved SOR & economics n Less natural gas required n Less facilities for steam generation & water treatment n Lower capital cost for piping & vessels (D) Environmental benefits n Reduced emissions (Kyoto) n Less source water needed (E) Improved operations n Reduced H 2 S, CO 2, silica, scaling, & may eliminate sulphur plant

4 4 Low-Pressure SAGD with artificial lift: Reasons (F) More oil from same plant Example Plant Oil SOR Production High pressure: ,000 b/d Low pressure: ,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 5 SAGD artificial lift completion requires production tubing to toe (to maintain full length of well hot & maximize steam chamber development all along the well pair)

6 6 SAGD steam-trap control Definition of subcool

7 7 Reference “mixed subcool” & additional potential subcool locations

8 8 Cartoon of Local & Mixed Subcool Values Along a SAGD Horizontal Well Low mixed subcool requires lifting harder & increases the oil production rate Local subcool Mixed subcool Low mixed subcool minimizes the local subcools, maximizes height of steam chamber & maximizes steam chamber development along the well pair

9 9 Low Subcool  Low subcool (ie vigorous lift) is particularly important at low pressure  Low subcool is more important for lower quality reservoirs

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

11 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 12 Low Pressure Challenge: Saturated steam conditions reached prior to pump inlet for a standard pump configuration

13 13 Examples of low-pressure challenges: (a) 1000 kPaa versus (b) 3500 kPaa

14 14 Steam chamber may reach pump due to axial growth or from another well pair

15 15 SAGD Artificial Lift Standard Bottomhole Pump Configuration

16 16 SAGD Artificial Lift Standard Bottomhole Pump Configuration Difficult Conditions 1)High temperature fluids 2)Saturated steam conditions with flashing to steam and gas breakout 3)High lift rates required to achieve low subcool values in the production liner 4)Scaling in pump 5)Unstable flow  slugging between bitumen & water  inflow rates varying with time

17 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 18 Current SAGD lift status Some SAGD operators are: n satisfied that electrical submersible pumps (ESPs) are providing adequate lift n expecting improving run life for ESPs n not unduly concerned about subcool and reservoir performance issues.

19 19 A fully successful SAGD lift system n To be fully successful, a SAGD lift system must demonstrate the following Combination:  Low steam chamber pressures  Low mixed subcool  Long service life

20 20 ELift™: a patented 2-stage lift system Concentric configuration

21 21 Summary of ELift features

22 22 Concentric ELift Simplest instrumentation configuration

23 23 ELift control functions

24 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 1 st 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 1 st stage.

25 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 26 ELift simulation ELift performance can be predicted with the QFlow** thermal wellbore simulator ** Mike McCormack Fractical Solutions Inc

27 27 ELift concentric QFlow simulation example CALS 1 ► low subcool in liner ► conditioning of fluids at the pump inlet

28 28 ELift concentric QFlow simulation example CALS 2 ► low subcool in liner ► conditioning of fluids at the pump inlet

29 29 ELift parallel configuration

30 30 ELift parallel QFlow simulation example CALS 3

31 31 Choice of Concentric ELift or Parallel ELift (a) Concentric can be installed in small 9 5 / 8 ” od intermediate casing »for low or moderate flow rates »careful design required (b) For large intermediate casing, both concentric and parallel configurations should be considered

32 32 ELift benefits: (a) Subcool & Recovery ELift uses natural lift in 1 st stage to an intermediate elevation n Provides vigorous lift with low mixed subcool at low bottomhole pressures n Provides substantial recovery, facility & environmental benefits due to low pressure SAGD with low subcool n Increased feasibility for development of lower quality reservoirs (which require optimization)

33 33 ELift benefits: (b) Pump Potential to reduce pump costs by half or better n Can use standard, less expensive pumps n 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 34 ELift benefits: (c) ELift isolates the steam chamber during pump changes

35 35 ELift benefits: (d) downhole gas/liquid separation n Complete downhole gas/liquid separation provided by ELift n Eliminates the need for surface multiphase group separators n Allows good measurement of liquid production rates for each well & hence allows optimization of each well pair

36 36 ELift field demonstration Parallel ELift, with gas lift in 2 nd stage, was used for 3 years in ConocoPhillip’s Surmont SAGD pilot  Main principles of ELift were demonstrated  Very low mixed subcool values were obtained

37 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 38 Recommendation: Use Large Intermediate Casing in 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 39 Main Conclusions re: SAGD artificial lift with ELift 1)Any current or future SAGD pump should work better with ELift 2)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 3)Optimization with ELift is particularly important for lower quality reservoirs

40 40 Main Conclusions SAGD artificial lift with ELift has benefits under five main headings (a)Improved recovery performance  due to vigorous lift with low subcool in liner (b)Pump savings  less expensive pumps & longer pump life (c)Isolates steam chamber during workovers (d)Good downhole gas-liquid separation (e)Makes low-pressure SAGD more feasible  Economic, environmental, operations benefits


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