Issue #227 | March 4, 2010 | by Jim Gardner

When a natural gas well produces excessive fluid volumes, sometimes the natural gas pressure of the well is unable to overcome the weight of the fluid trapped in the tubing. It becomes unable to produce the natural gas.

Traditionally. to overcome heavy fluid loads, an operator was required to manipulate the equipment and build enough downhole pressure to lift the fluid to the surface. To improve this process, producers also utilize a plunger, or a valve, to assist with lifting the fluid. Incorrect use, or excessive plunger travel speed, could damage the equipment.

Sometimes operators must physically sit on a well location to monitor not just production volumes, but plunger activity too.

Artificial lift is a process that allows oil and gas producers to optimize well production while minimizing overall maintenance and life cycle costs. One solution has been to automate this process and allow electronics to self-optimize the plunger lift process. The controlling Electronic Flow Meter (EFM) learns and adapts to the changes in the well.



Now with the use of I/O technology, wireless plunger lift monitoring and control has helped producers to handle these problems remotely.

Wireless I/O—Input/Output control—is a mechanism by which analog signals (1 to 5 Volt inputs or 4 to 20 milliamp inputs), discrete inputs, or other raw signals may be transmitted via radio to and/or from a central processing device.

For the wells, the data transmitted includes level, flow, pressure, temperature, plunger arrival, alarms, and signals generated to final control devices, such as valves.

By monitoring the critical data points an operator can achieve maximum results. The problem is that wells change with time and what was the right formula on a new well may not be adequate for a one-year-old well.

There are several compelling reasons to do this wirelessly, but number one is cost savings. The other factors are:

• Faster installations – wireless can be up and running in 30 minutes versus several days with conventional wired methods.
• Less repair – a common source of irritation on well sites is the cut wire that was inadvertently severed when something was added later.
• No trenching – trenching is a slow, time-consuming and expensive process with cost of $20 per foot in many areas.
• No conduit – installing conduits is a slow process with costs running in excess of $60 per foot.
• Redeployable – wireless is not a “sunk cost.” It is transportable. If the tank moves, the radio can be relocated.

Many operators in the past few years have switched to “pad” wells where multiple wells are located on one pad reducing the foot print of the wells and allowing operators to share production facilities between multiple wells, again reducing the cost per wellhead. These new techniques also lend themselves easily to automated plunger and wireless control systems.

In the Rocky Mountain area, pad wells are rapidly becoming the norm. Major producers in Colorado, Montana and Wyoming are standardizing on wireless automation for the wellhead. Many operators are taking advantage of this technology and are also monitoring and controlling tank levels, flow rates, pressures and temperatures, including water meter monitoring, sump or pit monitoring, flare monitors and chemical injection monitoring. Essentially, all process variables can be measured and controlled wirelessly.

While no well pad has thousands of points to be monitored, the idea of limitless control has intrigued producers to constantly push the envelope, and in turn, push radio manufacturers to constantly upgrade and expand their product offerings. Many of these manufacturers are now offering expandable “I/O radios.” These products come with a base set of I/O and then the user can add modules for an expanded I/O count where needed. Our FreeWave I/O radios run on 900MHz and 2.4GHz.





Another important criterion in selecting a wireless I/O device is whether it has a “fail safe” configuration. Many wireless I/O devices plan ahead for loss of signal. No device is immune to a loss of signal, and it is important that you be able to have the radio make the changes to the situation as you have preplanned for them.

If a wireless I/O device that monitors tank levels loses its signal, you should be able to choose what the “fail safe” condition will be. You can choose to have the valve close on loss of signal, open on loss of signal or do nothing on loss of signal. In most cases, you will choose to have the valve close to insure you do not overflow the tank, but the important issue is that you have a fail safe and that it is user selectable.

By utilizing one EFM per pad and switching to wireless I/O at the wellhead one major production company in Colorado’s Denver Julesburg Basin claims it saves $4,000 per well. This producer plans to automate 3,500 wells over the next four years. That is the equivalent of saving $4 million for every 1,000 wells it automates, a powerful argument for today’s high-powered flow computers that can handle 16 to 20 wells and the new radio technology of “wireless I/O” at the wellhead.

Jim Gardner is Business Development Manager, Oil and Gas, at FreeWave Technologies, a Boulder, Colo. manufacturer of spread spectrum and licensed wireless radios. www.freewave.com