1. By Jayant Sadare Gas-Lift Optimization and Diagnosis by using
Wellflo and Dynalift Simulators By
Jayant Sadare
&
Dr. Faleh T. Al-Saadoon
Texas A&M University-Kingsville
ASME/API/ISO GAS-LIFT WORKSHOP-2004

2. Objectives
Optimization (Wellflo)
Advanced Gas Valve Modeling
Diagnosis and Verification (Dynalift)
Implementation

3. Wellflo Simulator (EPS)
USES Nodal Analysis for
Designing
Modeling
Optimizing
Troubleshooting

4. Input Data Summary Fluid Properties Well-bore Data
- Oil Gravity = deg. API
- Water Gravity = 1.03
- Gas Gravity = 0.70
- Produced Gas-Oil Ratio = scf/STB
- Percent Water (%) = 45
Well-bore Data
- Production Casing: inch OD × inch ID 7100 ft (TVD)
- Tubing : inch OD × inch ID ft (TVD)
- Well Injection Angle (with vertical) = 0

5. Contd….. Reservoir Data Gas-Lift Data
Reservoir shut-in pressure = ft
Reservoir Temperature = 206 deg F
Productivity Index (Straight line) = 2.00 STB/day/psi
Gas-Lift Data
Casing Head Pressure = 1450 psig
Operating valve Differential Pressure = psi
Well-head pressure = psig
Minimum Valve Spacing = 350 ft
Injection Gas Rate = MMscf/day

6. Why Artificial lift??

7. Continuous Gas Lift design - Point of Injection
Specify:
- Casing head pressure
- GLR or Qgi
- Pressure drop across valve
Calculates maximum depth of injection and well
performance for gas lift
Sensitivity to CHP, Qgi, GLR

8. Inflow / Outflow Performance Curve

9. Performance Analysis Curve

10. Pressure and Temperature Vs Depth Analysis

11. Gas Lift Design - valve spacing for continuous gas lift installations
Specify
- Casing head pressure
- GLR or Qgi - Pressure drop across valve
- Kill fluid gradient
- Maximum depth
- Target operating rate
- Design Margins
Calculates
- depth of unloading and operating valves (IPO/PPO)
- Corresponding tubing/casing pressures & temperatures

12. Gas-Lift Valve Spacing

13. Advanced Gas Valve Modeling (AGVM)
True performance of commercial gas lift valves
True operating point of system
Sensitivity to valve type, port size, valve settings
and gas injection parameters
Gas-charged and orifice valve performance

14. True Valve Performance Curve

15. Valve Performance Curve For Orifice Valve

16. Curve Showing Closed Unloading Valve No. 1

17. Dynalift Simulator (EPS)
Dynamic (Unsteady-State) simulation tool for
Verification
Troubleshooting
Learning

18. Dynamic Gas-Lift Simulation
This Dynamic simulator uses all the equations used by a steady-state simulator except it adds the dynamic variable (Time).
Uses real correlations to simulate the behavior of gas-lift valves under bottom-hole dynamic conditions.
By controlling the injection conditions, the production parameters are observed to define if the design will work with the selected gas-lift valves.
More realistic performance can be generated
Simulates the system by considering the casing head pressure, gas-injection rate and wellhead pressure at the same time.

19. Contd…… This Dynamic simulator is an excellent tool for
identifying operational problems with gas-lift
installations.
Also best tool to understand the causes for
unstable production conditions which not
understood with a steady state simulator
It is the best tool for gas lift valves to verify
its performance from the unloading operation
through all the production life.

20. Working Screen for Dynamic Simulator

21. Valve Data Screen

22. Comparison of Dynamic & Steady-state Performance Curve

23. Conclusion Combination of Wellflo and Dynalift is one of the best
tool for students to understand gas-lift simulation.
Advanced Gas Valve Modeling (AGVM) is the heart
of steady-state simulation.
Do we really need Dynamic Simulation?
- Accurately model the well unloading for better
design and diagnosis
- Minimize unloading time
- Accurate valve performance curves
- Improve operational procedures

24. Thank you