GAS LIFT APPLICATION FOR HEAVY CRUDE WITH EMULSION Dacion Field, Venezuela

1. GAS LIFT APPLICATIONFOR HEAVY CRUDE WITH EMULSION Dacion Field, Venezuela Harryson Huang Schlumberger Artificial Lift Engineering Venezuela Topics: 1. Dacion well completion, fluid and reservoir characteristics 2. Gas lift design for heavy crude with emulsion 3. Lesson learned

2. DACION FIELD - VENEZUELA Fluid and Reservoir Characteristic: • More than 500 sandstone reservoir layers. Strong water drive • Reservoir depth = ± 4000 ft TVD (upper sands), ± 6000 ft TVD (lower sands) • Sand thickness = 10-60 ft TVD • Reservoir pressure = ± 1600 psia (upper sands), ± 2500 psia (lower sands) • Reservoir temperature = ± 160 oF (upper sands), ± 200 oF (lower sands) • Ke = 200-4500 mD (mostly 2500 mD) • GOR = 50-500 scf/bbl (mostly 200) • API gravity = 16 - 23 deg (mostly 18-20 deg) • Emulsion, asphaltene, paraffin • Sand (common). Scale (carbonate, barium. Minor) • Production rate 100-3000 bfpd

3. Completion: • Multi zone, single selective gravel pack completion (most common) • 3-1/2” in tubing (most common) • Gas lift system (90% of the lift system)

4. GAS LIFT DESIGN FOR HEAVY CRUDE WITH EMULSION 1. Effective for gravity above 16 degrees API 2. Full design, no generic design 3. Normal GL design procedure applied: • Use reservoir inflow model to determine PI • Casing pressure drop use “Ptmin-Ptmax method” • Use design bias according to engineer’s degree of confidence 4. Use oil viscosity & emulsion viscosity correction 5. Select multiphase flow correlation from offset wells

5. Gas Lift Design Flexibility 1. Anticipate higher water cut / emulsion 2. Anticipate reservoir pressure / PI decline 3. Anticipate demulsifier chemical injection 4. Anticipate temperature rise 5. Design for more prolific zone, anticipate other zone(s) characteristics.

6. Important Fluid Properties

7. Gas Lift Design Example Alternative lifting points Assigned lifting point

8. Gas Lift Design Example, Cont’ KO Pressure OP Pressure Well model matched with actual flowing gradient

9. Gas Lift Historical Performance Low Pressure Gas Lift (850 psig): PI < 7 , Average drawdown* = 400 psi PI > 7 , Average drawdown* = 90 psi PI = 5 - 10 , WC = 65 %  Lifting depth 2000 - 3000 ft High Pressure Gas Lift (1250 psig): PI < 7 , Average drawdown* = 500 psi PI > 7 , Average drawdown* = 125 psi PI = 5 - 10 , WC = 65 %  Lifting depth 3500 - 4500 ft *from 112 QLBU data

10. Effectiveness of Gas LiftGL vs ESP

11. Effectiveness of Gas LiftGL vs ESP, Cont’ No Demulsifier Demulsifier

12. Optimum Production Rate at Different WC without Emulsion Effect

13. Optimum Production Rate at Different WC with Emulsion Effect

14. Actual Data

15. Lesson Learned

16. Lesson Learned, Cont’ HPGL Conversion Case: GG-210 Study: Matched current rate: 1133 BFPD Estimated rate with HPGL: 1541 BFPD Actual Result: June 30, 2000 (LPGL): 909 BFPD August 1, 2000 (HPGL): 1531 BFPD Note: LPGL: 850 psig system HPGL: 1250 psig system

17. Lesson Learned, Cont’ Benefit of Demulsifier Chemical

18. Lesson Learned, Cont’ • Temperature lock problem • Accurate temperature profile prediction. Anticipate WC rise. • Multi-point injection problem • More conservative approach in design. • Accurate temperature profile prediction. Anticipate WC rise. • Controlled well unloading rate 100 psi / 10 minutes. • Valve change out • Prepare different type of latches in stock (eq. Camco M latches). • Displace tubing volume with diesel before GLV CO. • Use neoprene packing element with brass backup rings. • Deviation • Use orienting style mandrel for deviation above 15 degree.

19. Q & A