Using Gas Lift to Unload Horizontal Gas Wells

Transcription

1 Gas Well Deliquification Workshop Sheraton Hotel, Denver, Colorado February 27 March 2, 211 Using Gas Lift to Unload Horizontal Gas Wells Rob Sutton Marathon Oil Company

2 Conventional Gas Lift Application Predominately liquid producers Vertical/directional wells Above packer Reduce hydrostatic head Reduce FBHP Increase flow rate from reservoir Avoid increased friction Over injection of lift gas Reduces flow rate

3 Well Performance Analysis

4 Rate vs Total GLR Performance Optimum GLR

5 Conventional Gas Lift Observations Factors affecting optimum GLR Operating pressure Pipe size Reservoir pressure and deliverability Optimum GLR Typical range Formation GLR < Optimum GLR < 2, SCF/STB

6 Liquid Loading in Horizontal Gas Wells Clear liquid from horizontal section Terrain induced slugging Severe slugging Stratified liquid flow Impact on reservoir & completion Excessive drawdown may impair well Evidence from Haynesville Shale presented by Petrohawk Impaired productivity from liquid saturated hydraulic fractures Higher attrition rate compared to vertical wells

7 Horizontal Well Ideal Case

8 A Few Example Profiles Video

9 Fraction of Total Barnett Shale Horizontal & Vertical Wells 1. Barnett - Fraction of Annual Wells Drilled as Horizontal HDPI & SPE Year

10 Fraction of Total Wells Vertical vs Horizontal Well Attrition Barnett - Well Attrition 21 Wells 22 Wells 23 Wells 24 Wells 25 Wells 26 Wells 27 Wells 28 Wells HDPI & SPE Vertical Horizontal Months

11 Cleanup and Load Recovery in Vertical Fractures is Affected by Gravity, Viscous, and Capillary Forces Flow downward, co-current at any rate, assisted by gravity. Lower Sw, better recovery and gas perm. Possible water coning around well causing further damage? From Barree & Associates Flow upward, co-current at high rates, counter-current at low rates, hindered by gravity. Higher Sw, poor load recovery, and low gas perm.

12 Mobile Water ~ 14 gm Water Produced Shut-in min

13 True Vertical Depth, ft Complex Horizontal Well Profiles Example Horizontal Well Trajectories 7,5 Well 1 Well 2 7,6 7,7 7,8 7,9 8, 1, 2, 3, 4, 5, 6, Departure, ft

14 Turner Unloading Velocity v c N we r r l r 2 g g sin where Turner Adjustment TNO/Shell Angle Correction r g = gas phase density, lbm/ft 3 r L = liquid phase density, lbm/ft 3 N we Ө v c = surface tension, dynes/cm = Weber Number (use 6 for original Turner) = hole angle (Deg from vertical) = critical velocity of liquid droplet, ft/sec

15 Turner Modification TNO-Shell Angle Modification TNO/Shell Modification for Hole Angle 35% increase at Hole Angle, Deg

16 True Vertical Depth, ft Horizontal Well 1 Example Horizontal Well Trajectories 7,8 7,82 Well 1 Completion 7,84 7,86 7,88 7,9 7,92 7,94 7,96 7,98 8, 1, 2, 3, 4, 5, 6, Departure, ft

17 Measured Depth, ft Measured Depth, ft Horizontal Well 1 (EOT Placement 25 ) Velocity Profile Directional Profile Gas Velocity Critical Velocity Hole Angle EOT 2, 2, 4, 4, 6, 6, 9 - Horizontal 8, 8, 1, 1, 12, 12, 14, , Velocity, ft/sec Hole Angle, Deg

18 Gas Rate, MCFD Hole Angle, Degs Horizontal Well 1 (EOT Placement 25 ) Rate & Directional Profile 5, 4,5 4, Gas Rate Critical Rate Hole Angle EOT 9 - Horizontal ,5 7 3, 6 2,5 5 2, 4 1,5 1, 1 MCFD Form Gas , 1, Measured Depth, ft

19 Measured Depth, ft Measured Depth, ft Horizontal Well 1 (EOT Placement 85 ) Velocity Profile Directional Profile Gas Velocity Critical Velocity Hole Angle EOT 2, 2, 4, 4, 6, 6, 9 - Horizontal 8, 8, 1, 1, 12, 12, 14, , Velocity, ft/sec Hole Angle, Deg

20 Gas Rate, MCFD Hole Angle, Degs Horizontal Well 1 (EOT Placement 85 ) Rate & Directional Profile 5, 4,5 4, Gas Rate Critical Rate Hole Angle EOT 9 - Horizontal ,5 7 3, 6 2,5 5 2, 4 1,5 3 1, , 1, Measured Depth, ft

21 Measured Depth, ft Measured Depth, ft Horizontal Well 1 (EOT Placement 85 ) Casing Flow Annular Flow Velocity Profile Velocity Profile Gas Velocity Critical Velocity Gas Velocity Critical Velocity 2, 2, 4, 4, 6, 2.44-in Tubing 6, in Tubing 8, 8, Dead String 1, in Casing 1, x in Annulus 12, 12, 14, , Velocity, ft/sec Velocity, ft/sec

22 Observation Right-size completion velocity management Adjust setting depths and diameters to align flow velocity with velocity requirement to remove liquids Flowing well case place EOT at 85-9 Extending tubing (dead string) into horizontal modifies the flow velocity profile but does not adequately address liquid accumulation problems

23 AVE Gas Lift SPE 13256

24 Measured Depth, ft Measured Depth, ft Horizontal Well 1 (Gas Lift + Annular Flow with AVE x 4.778) Velocity Profile Directional Velocity Profile Gas Velocity Critical Velocity Gas Velocity Critical Velocity Hole Angle EOT 2, 2, 4, in Tubing 4, 6, 6, in Tubing 9 - Horizontal 8, AVE at 5 8, Dead String 1, x in Casing 1, x in Annulus 12, 12, 14, 14, Velocity, ft/sec Hole Velocity, Angle, ft/sec Deg

25 Gas Rate, MCFD Hole Angle, Degs Horizontal Well 1 (Gas Lift + Annular Flow with AVE x 4.778) Rate & Directional Profile 5, 4,5 4, Gas Rate Critical Rate Hole Angle EOT 9 - Horizontal ,5 7 3, 6 2,5 5 2, 4 1,5 3 1, , 1, Measured Depth, ft

26 Bottomhole Pressure, psia Horizontal Well 1 Outflow Performance - Flowing 2, 1,8 Effect of Gas Lift to Achieve Critical Rate Flowing 1,6 1,4 1,2 1, , 1,5 2, 2,5 Formation Gas Rate, MCFD

27 Bottomhole Pressure, psia Horizontal Well 1 Outflow Performance Flowing & Gas Lift 2, 1,8 Effect of Gas Lift to Achieve Critical Rate Flowing Gas Lift 1,6 1,4 1,2 1, 8 Gas lift to reach critical rate , 1,5 2, 2,5 Formation Gas Rate, MCFD

28 Horizontal Well 1 Putting It All Together Bottomhole Pressure, psia 2, 1,8 1,6 1,4 Effect of Gas Lift to Achieve Critical Rate Flowing Gas Lift IPR 1,2 1, Time Depletion Liquid Loading Effective Dewatering 5 1, 1,5 2, 2,5 Formation Gas Rate, MCFD

29 True Vertical Depth, ft Horizontal Well 2 Example Horizontal Well Trajectories 7,5 7,52 Well 2 Completion 7,54 7,56 7,58 7,6 7,62 7,64 7,66 7,68 7,7 1, 2, 3, 4, 5, 6, Departure, ft

30 Horizontal Well 2 (EOT Placement 89 ) Measured Depth, ft Measured Depth, ft Velocity Profile Directional Profile Gas Velocity Critical Velocity Hole Angle EOT 2, 2, 2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 9 - Horizontal 8, 8, 9 - Horizontal 8, 1, 8, 1, 1, 12, 1, 12, 12, 14, , 14, Velocity, ft/sec Hole Angle, Deg

31 Gas Rate, MCFD Hole Angle, Degs Horizontal Well 2 (EOT Placement 89 ) Rate & Directional Profile 5, Gas Rate 1 4,5 4, Critical Rate Hole Angle EOT 9 - Horizontal 9 8 3,5 7 3, 6 2,5 5 2, 4 1,5 3 1, , 4, 6, 8, 1, 12, Measured Depth, ft

32 Measured Depth, ft Measured Depth, ft Horizontal Well 2 (Gas Lift + Annular Flow with AVE x 4.) Velocity Profile Velocity Profile Gas Velocity Critical Velocity Gas Velocity Critical Velocity 2, 2, 4, in Tubing 4, in Tubing 6, 6, 8, AVE at 5 8, AVE at 5 Velocity Management 1, x 4.-in Casing 1, x 4.-in Casing 12, , Velocity, ft/sec Velocity, ft/sec

33 Conclusions Horizontal wells Complex flow geometries Higher attrition rate compared to verticals Cause - liquid loading??? Liquid Loading - General Additional backpressure on reservoir Reservoir/Completion Reduced gas permeability Water blocks Impaired completion efficiency

34 Conclusions Liquid Loading Horizontal Directional effects Complex geometries Terrain induced slugging Severe slugging AVE Gas Lift Provides flow velocity management Works in horizontal or vertical wells Effectively keeps well unloaded Avoids excessive drawdown in horizontal wells

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