Jian-Yang Yuan Osum Oil Sands Corp. Richard McFarlane Alberta Research Council Inc.

Transcription

1 Steam Circulation Strategies for SAGD Start-Up Jian-Yang Yuan Osum Oil Sands Corp. Richard McFarlane Alberta Research Council Inc.

2 Objective Evaluate impact of operation parameters on SAGD start-up using steam circulation: Steam quality, circulation rate and circulation time Steam circulation vs. combination of circulation and injection induced by!p

3 Steam Circulation and!p P BHP, upper !P = P BHP, lower - P BHP, upper 5m apart vertically!p hydraulic " 50kPa P BHP, lower P 1 > P 2 > P 3 > P 4

4 Issues in SAGD Start Up Uniform heating along wellbore direction Establishing bitumen communication Avoid steam breakthrough or hot channels

5 !P and Instability of Fluid Front Analogue to water flooding Steam drive High pressure CSS Cold flow production SAGD start up

6 When!P Is Too Large Steam/hot water fingering Steam breakthrough causing sand problem Formation of hot channels which would have profound impacts on subsequent SAGD performance Low wellbore utilization factor Easier production of live steam jeopardizing production control Difficult to heal

7 Approach Employ discretized wellbore model in STARS 3D simulation 686m well pair with 5m separation Reservoir heterogeneity with log-normal distribution Initial reservoir pressure: 2000 kpa Initial reservoir temperature: 8 C Porosity = 0.34, K v = 3D; K h = 6D Initial saturations (o/w): 0.80/0.20 Steam circulation Steam injection in tubing at heel: 257 o C with % quality Min. BHP (annuli at heel): kpa

8 3D Reservoir Model z y x x = 7.5m, y = 700m, z = 13.5m Largest grid block: 1m x 7m x 1m Smallest grid block: 0.5m x 7m x 0.5m

9 Criteria for Well Communication Minimum temperature of 80 o C in blocks along mid-plane Except two end blocks that lie outside region bounded by well pair

10 Tubing and Liner Sizes Concentric tubing & annulus Tubing: OD m (3.5in.) ID m Liner: OD m (7in.) ID m

11 Tested Parameter Ranges!P: [0, 100] kpa Steam quality: [0, 100%]; more scenarios tested in above 60% Injection rate: [25, 200] m 3 /day

12 Impacts of!p 140 o C) between wells Min. Block Temperature ( R = 50, Q= 60, dp = 50 R = 50, Q= 60, dp = 100 R = 100, Q= 60, dp = 50 R =100, Q= 60, dp = 100 R = 200, Q= 60, dp = 50 R = 200, Q= 60, dp = 100 R = 50, Q= 80, dp = 50 R = 50, Q= 80, dp = 100 R = 100, Q= 80, dp = 50 R = 100, Q= 80, dp = 100 R = 200, Q= 80, dp = 50 R = 200, Q= 80, dp = 100 R = 50, Q= 100, dp = 50 R = 50, Q= 100, dp = 100 R = 100, Q= 100, dp = 50 R = 100, Q= 100, dp = 100 R = 200, Q= 100, dp = 50 R = 200, Q= 100, dp = 100 R = 50, Q= 100, dp = Time (days)

13 Example:!P=50kPa maximum Temperature ( o C) average minimum 20 R=200m 3 /d; Q=60% Time (days)

14 Example:!P=100kPa Steam Temperature ( o C) R=200m 3 /d; Q=60% Time (days)

15 Pressuring at Upper Well Preferred!P = 0 kpa R = 50 m 3 /day Q = 100%!P = 50 kpa!p = 100 kpa

16 Impacts of Steam Rate and Quality Q=60% Q=80% Q=100%!P=100 kpa; R=50(top), 100(mid), and 200(bot) m 3 /d

17 Asymmetric Steam Quality Q = 80%!P = 100kPa Rate = 100m 3 /d Time = 91 days Q = 80% Q = 40% Q = 80%

18 Asymmetric Steam Quality (80/40) 140 Min. Block Temperature ( o C) between wells R = 100, Q= 80/40, dp = 100 R = 100, Q= 60/60, dp = 100 R = 100, Q= 80/80, dp = 100 R = 100, Q= 100/100, dp = Time (days)

19 Summary For high steam quality, low flow rate is more preferable High pressure difference is not encouraged Pressuring from the upper well is preferred over from the bottom well Relatively lower quality steam in upper well may give faster initialization compared to equal quality in both wells

20 Recommendation The problem now of course is To simply hold your horses To rush would be a crime 'Cause nice and easy does it every time - F. Sinatra

21 Acknowledgment AACI Program JACOS ConocoPhillips Total CNRL Osum

22 Thank You