July 8, 2013
ETC Plunger Lift Controllers and SCADA – A standalone controller is a smarter investment than plunger lift programming on a PLC. Here’s why:
Production Engineers are regularly making the decision to move away from standalone plunger lift controllers and make use of programmable logic controllers (PLCs) to operate their plunger wells. At first glance, this may seem like the obvious choice, since in most cases, there is already a PLC or flow computer on site that can be programmed to perform the basic valve operations that are required for plunger lift. The real advantage is that these systems incorporate a communication network that allows operators to remotely monitor and control the plunger lift system, greatly reducing the amount of travel time required. The problem, however, is that most people don’t realize that they are giving up some critical functionality, and while going purely with a PLC looks like it is saving them money, quite the opposite is happening.
The controller and radio panel in a SCADA system is typically classified as Div 2/Zone 2, meaning that it has to be located away from the well head. The problem is that common pieces of a plunger system, such as the plunger arrival sensor and solenoid must be located in the Div 1/Zone 1 area. You are left with no choice but to either add an intrinsic safety (IS) barrier between the SCADA panel and these devices, or use explosion proof rated devices. In either case this adds thousands of dollars in equipment and installation costs.
Another drawback is the lack of programming space for advanced algorithms. Due to these limitations, quite often features that provide enhanced safety or greater gas production are left out. Even if some of the features can be added, quite often the system architect has to make choices about what features will be available at which sites. This leads to custom builds for each individual wellsite. Add this to the already cumbersome task of maintaining the current program, adding new device types, and adding new features, and costs can quickly spiral out of control.
One of the biggest inconveniences in going to a PLC based control system for plunger lift is the lack of a proper user interface. Many of these systems don’t have a local display, and when they do, it is hard to navigate and is often very limited. Operators and technicians are forced to either call a control room or connect over the cell network with a laptop in order to see what is happening with their system. Most companies don’t allow field technicians to have access to the SCADA system because they don’t want them having access to the production system. This just causes more delays which leads to higher service costs.
The solution is to combine the best of both worlds by connecting trusted ETC plunger lift controllers to existing and new SCADA installs. Often the radio network can be re-used, meaning that the only extra investment is in the controller package and IS barrier to safely connect across the divisions/zones. The controller resides in the Div 1/Zone 1 location, so intrinsically safe solenoids that come as part of the package are used instead of expensive explosion proof solenoids. In addition, now IS arrival sensors can be used without an IS barrier, further decreasing costs.
The local interface of an ETC plunger lift controller can be used by operators and technicians right on site; Well performance information is available instantly, and setting changes can be made without having to wait on control room staff. At the same time, data is being brought back to the control room to provide remote operators historical logs, current operational information, and the ability to change settings without having to always visit the well site.
ETC plunger lift controllers have an extensive collection of safety and optimization features that can be easily reconfigured to enable the options you want to use on a given well. ETC is actively maintaining the software so that you don’t have to. We work with our customers to quickly resolve any issues, to implement new features, and to add support for new, leading edge devices. As new releases become available, they can easily be programmed into any existing controller. Headaches that come with maintaining custom builds on PLCs are eliminated.
Before making the decision to spend hundreds of thousands of dollars building a custom application, consider using ETC plunger lift controllers to simplify your operation, save you maintenance costs, and increase your production.