1. 2002 Spring ASME/API Gas-Lift Workshop
Gas-Lift Surveillance
In Search of Hidden Production and Efficiency By
Dan Dees, AppSmiths
Cleon Dunham, Oilfield Automation Consulting
Burney Waring, Shell EP Technology
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

2. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance is a Process
It is a process of planning and designing for optimum operations; then continually looking for, finding, and addressing opportunities to overcome inefficiencies, weaknesses, and faults in these operations so that improvements can be made and maintained.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

3. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
True gas-lift surveillance is a comprehensive process that empowers trained gas-lift staff to optimize the artificial lifting of oil wells with gas-lift.
The difference between poor and optimized gas-lift systems and wells can be hundreds of barrels of oil, and therefore thousands of dollars of income per day.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

4. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Goal of gas-lift surveillance keep the entire gas-lift system (wells, gathering system, treating system, compression system, distribution system, and injection system) operating optimally, all of the time.
This can not be done by traditional means. It requires state-of-the-art tools and skilled personnel who are committed to and focused on the task.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

5. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Caution
This paper is intended to provide gas-lift operating companies with specific information on how to develop a comprehensive surveillance process to optimize their gas-lift operations.
In some cases, we mention specific goods, products, and services when, in our opinion, they represent state-of-the-art, yet field proven solutions that can be applied today. If we fail to mention other products and services that are also effective, we apologize.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

6. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Gas-lift surveillance is difficult but rewarding work.
Typical (field proven) gains can be:
10% or more oil production, plus
10% or more savings in lift gas, plus
Often reductions in CAPEX and other OPEX
For example:
Field with 100 wells capable of 600 BOPD per well
Produces 55,000 BOPD or less (potential 60,000 BOPD)
Potential gain is $100,000 per day ($35MM per year) or more
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

7. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Primary goals of gas-lift:
Continuous gas-lift
Inject as deep as possible
Inject on a continuous, stable basis
Inject at optimum rate
Intermittent gas-lift
Inject optimum volume of gas beneath a column of liquid
Inject each cycle at the optimum time (frequency)
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

8. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Continuous gas-lift surveillance
Most important goal --- depth of injection
Role of surveillance system
Assure mandrel spacing is correct, as well matures.
Assure valves support unloading & then close as needed.
Assure well works down and stays there.
Second goal --- stability
Detect any instability.
Assist in analyzing and trouble shooting cause(s) of instability.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

9. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Continuous gas-lift surveillance
Third goal --- optimum rate
Role of surveillance system
Always "know" the optimum rate(s) for the well and its gas-lift equipment --- they may not be the same.
If well changes (and it will), operation and/or equipment must also be changed to maintain optimum operation.
Keep the well as close to optimum as possible, while keeping system in balance.
Other goals
Continuously check for leaks, blockages, failed valves, etc.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

10. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Intermittent gas-lift surveillance
First goal --- system stability
Role of surveillance system
Keep system stable, even in face of inherent intermittent instability.
Second goal --- optimum injection volume and time
Precisely measure and control injection volume and time.
Adjust injection cycle (size and frequency) as needed.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

11. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Intermittent gas-lift surveillance
Third goal --- optimum liquid recovery per injection cycle
Role of surveillance system
Monitor, and if possible, measure each liquid slug.
Provide information to assist in optimizing intermittent injection cycle volume and frequency to maximize daily oil recovery.
Other goals
Continuously check for leaks, blockages, failed valves, etc.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

12. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is needed?
People --- the gas-lift team
Gas-lift champion
Gas-lift engineer(s)
Gas-lift technician(s) or programmer(s)
Well analyst(s)
Well services
Operators
Others
Whether these functions are performed by one or several people, by company or contract staff, they are all essential.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

13. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is needed?
Processes
Have an effective work process and work as a team.
Meet frequently --- in person or "electronically."
Provide an adequate training process.
Classroom
Training models --- both physical and computer-based
One-on-one mentoring
Train the trainer
On-line and web-based training
Conferences and workshops
There must be a complete, continuous training process for people to acquire and maintain needed skills.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

14. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is needed?
Information
Reservoir information --- PVT data, pressure, IPR
Well information --- physical well design
System information
Economics --- optimize income, not production
Pressure surveys
Pressure build-up
Static pressure
Flowing pressure survey to evaluate current performance
Flowing pressure survey to determine IPR
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

15. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is needed?
Information (Continued)
Well tests
Accurate well tests
Or if possible, continuous well production rate
Real-time information
Need to have
Distribution system gas pressure and availability
Well injection rate and injection pressure
Well production pressure
Nice to have
Manifold pressure
Downhole flowing bottom-hole pressure
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

16. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is needed?
Tools
Gas-lift design tools
Use modern, computer-based design tools.
But, know what they are doing.
Quality assurance
Check every valve before it is run and after it is pulled.
Monitoring system
Gather gas-lift information once per minute.
Process and summarize the data so people can be presented with actionable information.
Present it to people when and where they need it.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

17. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is needed?
Tools (Continued)
Control system
Keep system in balance, under all conditions.
Keep wells as close as possible to optimum at all times.
Keep wells stable during well tests.
Maintain required unloading rates.
Keep injection cycles as designed.
Analysis
Analyze the cause of each problem so it can be fixed correctly this time and prevented from happening again.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

18. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Good news
Excellent goods, tools, and services are available to help optimize each company's gas-lift operations.
See and
People
It is essential to have some "company" people who are focused on gas-lift --- this is "core" business.
And, there are several service companies that can provide excellent assistance --- either short or long term.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

19. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Processes
Work process
Each company must develop its own work process with which it is comfortable.
Classroom training
Several good courses are available --- check with Shell, Weatherford, EPS, and others.
Training models
Free computer-based training models are available --- check with Shell, Weatherford, Schlumberger, and others.
A physical model can be developed --- check with the authors.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

20. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Processes (Continued)
One-on-one training, and "train the trainer"
Each company should have at least one person --- company or contract --- who can train local staff on a one-on-one or one-on-few basis.
On-line, web-based training
Excellent tools are becoming available to provide highly leveraged training –-- when and where it is needed. Check with Shell and others.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

21. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Information
Each company must acquire the necessary information on its own reservoirs, systems, and wells.
Several important references are listed in the paper.
Especially refer to API RP 11V8 --- Recommended Practice for Gas-Lift System Design and Performance Prediction.
This is to be released in the near future.
It can be seen on the web site.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

22. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Tools
Design
We recommend the Shell WinGLUE program. There are other excellent design programs available from EPS, Baker Jardine, Petroleum Experts, and others.
WinGLUE uses gas-lift valve performance models developed by the Valve Performance Clearinghouse.
It uses an SQL database. All information, once entered, is kept on line for future use.
It uses "wizards" to assist in easily running the design process.
It supports designing with choked unloading valves, if desired.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

23. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Tools (Continued)
Quality assurance
We recommend fully testing every gas-lift valve, both before it is run and after it is pulled.
We recommend a new tool called the Gas-Lift Valve, Automatic Validation Tester.
Each valve can be fully tested in about five minutes.
Any faulty valve can be rejected before it is run.
Monitoring
Excellent real-time SCADA (production automation) systems are available from Shell and eProduction Solutions. Others are also available.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

24. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Surveillance process --- what is available?
Tools (Continued)
Control
These same systems can also provide the needed gas-lift system and well controls.
We have first-hand experience with the Shell system for controlling both large and small, complex gas-lift systems that contain both continuous and intermittent wells.
Analysis
The Shell WinGLUE program supports a full suite of tools for analyzing the performance of gas-lift wells and helping to determine the causes of problems with these wells.
There are other effective analysis tools available.
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop

25. Gas-Lift Surveillance In Search of Hidden Production and Efficiency
Conclusion
Comprehensive surveillance is essential
It is highly profitable
It is feasible and economic for any size company
It requires dedicated, motivated, highly trained staff
And it requires
Effective work processes
Excellent, on-going training
Good, current information
Excellent tools and the skills to use them
February 5 & 6, 2002
2002 Spring Gas-Lift Workshop