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 engineers 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
Well model matched with actual flowing gradient
9
Gas Lift Historical Performance
Low Pressure Gas Lift (850 psig) PI lt 7 ,
Average drawdown 400 psi PI gt 7 , Average
drawdown 90 psi PI 5 - 10 , WC 65 ?
Lifting depth 2000 - 3000 ft High Pressure Gas
Lift (1250 psig) PI lt 7 , Average drawdown
500 psi PI gt 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
Demulsifier
No 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