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Plunger Lift and Gas Lift

Use the SCADASuite Plunger Lift application to optimize production from your gas well over the well's lifecycle, even before a plunger is actually installed in the well. Protect your asset from damage via protection settings. Reduce integration costs, training costs, and downtime by using the same application on all of your gas wells.

The Plunger Lift + Gas Lift application supports up to 4 completely independent wells. The application can be licensed for only as many wells as you need. Gas Lift is an optional, licensed feature that is added to each plunger control loop.

Most of the information on this page is summarized in an easy to read and distribute format in our Plunger Lift and Gas Lift App Note.

Plunger Lift Features

A summary of the features of the SCADASuite Plunger Lift application are highlighted below. For a complete list of features please see the material on the Resources page, especially the reference manual. Or, download the software from the Resources page and try it for yourself.

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Protection Settings
The SCADASuite Plunger Lift application includes configurable protection for the following situations. Protection can be enabled or disabled for each option. A diagnostic log entry is made when a protection mode is entered with the details of what caused the upset.

• High Energy. When the load ratio is too low, the well is in a high energy state and will be shut in until the high energy state no longer exists.
• Low Line and High Line Pressure. Shut the well in if the line pressure is less than the low pressure limit, or greater than the high pressure limit.
• Very Early Plunger Arrival. Shut the well in if the plunger arrives too soon for a consecutive number of control cycles.
• No Plunger Arrival. Shut the well in if the plunger doesn't arrive for a consecutive number of control cycles.
• User Protection. Trigger protection mode via a register based on your own ladder logic.

Condition Based Approach
The SCADASuite Plunger Lift application uses a condition based approach to determine when to open or close the sales valve and allow the well to flow or be shut in.

Each condition is enabled independently, and each condition also has a configurable delay between the time that the condition occurs and is accepted which allows for rejection of fleeting changes.

Flow Conditions
All enabled Flow Conditions must be met before the sales valve is opened and the well is allowed to flow. This is unlike Shut In Conditions, where any single shut in condition being met will cause the well to shut in.

• Minimum Off Time. The minimum amount of time to wait after the well is shut in.
• Maximum Load Ratio. The calculated load ratio must below this value.
• Minimum Tubing Pressure. The well's tubing pressure must be greater than this value.
• Minimum Casing Pressure. The well's casing pressure must be greater than this value.
• Maximum Line Pressure. The line pressure must be less than this value.
• Minimum Tubing/Line Pressure Difference. The difference between the tubing and line pressure must be greater than this value.
• Minimum Casing/Line Pressure Difference. The difference between the casing and line pressure must be greater than this value.
• User Flow Condition. Trigger a flow condition via a register based on your own ladder logic.

Shut In Conditions
Once any single enabled Shut In Condition is met the well will be shut in. This is unlike flow conditions, where all of the enabled flow conditions must be met to allow the well to flow.

• Maximum On Time. The maximum amount of time to wait after the well is flowing.
• Minimum Well Flow. The flow from the well must be less than this value.
• Casing Pressure Rise. The rise in casing pressure from the minimum measured value while the well is flowing must be greater than this value.
• Critical Flow. The actual flow from the well must be less than the calculated critical flow rate. This condition includes a multiplier so that the threshold can be set to some multiple of the critical flow rate. Both Turner and Coleman algorithms are supported for the critical velocity calculation.
• User Shut In Condition. Trigger a shut in condition via a register based on your own ladder logic.
• Minimum Casing Pressure. The casing pressure must be less than this value.
• Minimum Tubing Pressure. The tubing pressure must be less than this value.
• Casing/Line Pressure Difference. The difference between the casing and line pressure must be less than this value.

Automatic Optimization
When configured to do so, the SCADASuite Plunger Lift application will automatically adjust both flow condition and shut in condition set points to try to force normal plunger arrival. If the plunger arrival is early, the last flow condition that was met will be adjusted to make the well flow for longer on the next cycle. If the plunger arrival is late, the first shut in condition that was met will be adjusted to shut the well in for longer on the next cycle.

Conditions will only be adjusted within a user configurable range. Each condition has its own allowable range. This allows you to have complete control over how optimization works.

Gas Lift Features

The SCADASuite Gas Lift application allows you to inject gas down hole in a controlled fashion to increase production from your well. The application uses PID control to set the position of an injection valve to inject just the amount of gas that you want. The application supports multiple control modes, including a plunger mode where gas injection occurs at various times during the plunger cycle.

Gas Lift is an optional licensed feature to the Plunger Lift application. A summary of the features of the application are highlighted below.

For a complete list of features please see the material on the Resources page, especially the reference manual. Or, download the software from the Resources page and try it for yourself.

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Control Modes
The SCADASuite Gas Lift application supports the control modes listed below.

• Continuous Flow. Gas is continuously injected down hole at a fixed rate. The PID set point is a configured injection flow rate.
• Continuous Critical Flow. Gas is continuously injected down hole at a some rate to keep the well's flow rate above the well's calculated critical flow rate. The PID manipulates the position of the injection valve to control the well's flow rate.
• Injection Steps. Gas is injected at various rates to unload a well. Each step has its own injection flow rate and pressure drop settings. The system moves to the next step when the pressure in the well changes by a configured amount.
• Plunger. The Gas Lift application is aware of the state of the Plunger Lift application and injects gas at various stages of the plunger cycle. Gas can be injected in the following ways:
  • Shut In Injection. Inject gas when the sales valve is closed the pressure in the well is below some threshold.
  • Pre-Arrival Injection. Inject gas before the plunger arrives. Gas can be injected at different rates depending on the plunger arrival type (early, late or no-arrival) of the preceding plunger cycle.
  • Post-Arrival Injection. Inject gas after the plunger arrives.

PID Control
In all control modes, the Gas Lift application manipulates the position of the injection valve to control either the actual injection flow rate, or the flow rate of the well. The application uses the same PID control algorithms as logic on the SCADAPack RTU for maximum reliability.

The PID control loop can be configured for flow control, or for flow control with pressure override. When in flow control with pressure override mode, when the actual pressure exceeds a configured threshold, the PID algorithm will switch to controlling the pressure instead of flow to keep it under a safe value. Later on, if the pressure decreases, the PID will switch back to controlling flow.

Pre-Arrival Injection Rate Optimization
When in plunger mode, the Gas Lift application can adjust the pre-arrival injection set point automatically depending on the plunger arrival history. If the plunger consistently arrives late, more gas will be injected. If the plunger consistently arrives early, less gas will be injected. The goal is to adjust the injection set point so that the plunger always arrives normally.

Next Steps
What to know more? Dive into the details on the Resources page, or get in touch.

Let us know if you don't see a feature that you need. Using our framework based approach, we can add fully tested and documented features in days, often at no cost to you.