February 2011, Vol. 238 No. 2
Features
Advances In Wireless Monitoring Increase Intelligence Of Assets
Recent developments in process automation, wireless and information technology – and real-time data management systems – have helped make oil and gas field operations more intelligent.
Pipeline managers and technicians are continually working to make operations more efficient and safe. Process automation plays a key role, as it provides an up-to-date view of the entire field of operation and has the ability to warn of impending issues. Process automation has traditionally been restricted to operations hubs, but new technology and an ever-increasing push for more efficient operations is driving automation to the more remote parts of a field.
That, and the fact that oil and gas operations have become gradually more remote over the last several decades as operators stretch their reach for resources, means that the need for wireless technology has increased. Operations, such as those in West Africa, are so remote and often in impenetrable terrain that wired forms of communication (e.g. fiber optic lines) become extremely expensive, if not impossible. Wireless technology offers the prospect of extending process automation and real-time monitoring to the most remote parts of operations.
Remote monitoring and process automation applications aim to enhance operational efficiencies (improve production rate, reduce downtime and boost recovery rates). In addition, some remote monitoring applications can help improve worksite safety. Warnings, such as of pressure buildup in a wellhead, are monitored and can be reported before the problem occurs.
Wireless Systems
The use of wireless technology has significantly moved into remote monitoring applications in the last decade, but it is important to note that not all wireless technologies are created equal. The key characteristics of a wireless system that determine its overall applicability are:
* Range: The system’s ability to transmit a signal over a long distance.
* Capacity: This can be defined in two terms. First, there is the actual application throughput (“good put”) from a single end device (such as a pressure sensor) in the network. Second, the overall network capacity must also be considered. This refers to the ability of a concentrator (or access point) to process data from nodes in the network. This is what we call the overall throughput capacity.
* Power consumption: In remote monitoring applications, many end points must rely on batteries as the main source of power. The preference is for lower power consumption to extend the span between battery replacements. In some installations solar or other renewable sources can be used to supplement a main battery.
* Latency: This term relates to the time it takes for information to move through the system in either direction (from the remote device to a central collection system and the other way around).
* Communication type: Wireless (or any communication system for that matter) operates as either simplex (communication only one way), half-duplex (communication both ways but not at the same time), or full-duplex (same time, bi-directional communication).
Wireless spectrum allocation is another concern that must be addressed. Wireless systems perform over a wide range of frequencies, from a few kilohertz to high frequency gigahertz systems. Many frequencies are licensed and typically bought by private companies through public auctions.
Other frequencies are designated unlicensed and can be used free of charge. The unlicensed frequencies, however, come with a set of conditions. These are rules and regulations about how the free spectrum can be used by various different private operators. Rules such as these, e.g., guide use of popular technologies such as Wi-Fi and Bluetooth.
The rules and guidelines address the amount of power output and the occupied bandwidth that can be applied in the allocated free spectrum. The rules vary from country to country, and it is important for operators to observe and comply with local restrictions. Many remote monitoring applications operate in the free and unlicensed frequencies. This is mainly due to cost concerns as many of these applications do not warrant the high cost of dedicated frequencies or the monthly recurring fees incurred when renting this spectrum of a third-party operator.
It is important to recognize that different wireless systems mix and match these characteristics in various ways. This also means there isn’t a “one size fits all” wireless system that is ideal for any application. The unique application requirements of a flow measurement system, for example, are very different from a low latency, factory-floor SCADA application, which may require millisecond response times. Some applications will require very high data rates while others just process a trickle of index data throughout the day. Pick any of the above-mentioned system characteristics and the same kind of comparisons could be made.
Most remote monitoring applications fall into a category where range and low power consumption is prioritized. Range, in this sense, should be understood as either great distance (e.g. >10 km), or as the ability to penetrate obstacles, like vegetation, building, etc. Low power is key, as many remote devices will require monitoring without accessing a continuous power source (i.e. battery-operated). Relatively small amounts of data are typically transmitted and capacity therefore tends to be a minor concern.
Finally, one needs to consider the communication type. Some applications can survive with simplex communication. This would be the case when all the application is intended to do is to collect data from a remote point. For an application where two-way communication is needed (resetting alarms on remote devices or changing configurations) a duplex system must be deployed.
Backhaul Options
Another concern is backhaul from the remote site to a central data processing site. Most remote operation is far from the main hubs for IT infrastructure. When a private wireless system is installed (as opposed to using public infrastructure like a carrier-based global system for mobile communications network), it is up to the user to provide all connectivity links in the system.
A wireless system that uses unlicensed spectrum will typically terminate in a set of wireless access points or gateways, which then need to be connected to the overall company network. This can be done in various ways, but the most commonly used methods are a direct connection to the local area network (if available), backhaul via a public cellular network (again, if available), and finally through satellite links. These options are listed in terms of preference and cost.
Finally, integration with a process automation platform has to be considered. For a wireless remote monitoring system to be useful, it has to present the collected data in an industry standard format. An end-to-end wireless remote monitoring application will provide every step in the process, from integration of the wireless module with the remote sensor, wireless networking and networking infrastructure and conversion of the data to a standard format, such as Modbus or Profibus. This allows for simple integration, both with on-site process automation systems and backend historical data storage.
Recent breakthroughs in wireless signal processing have provided new options for remote monitoring applications. These systems are designed from the ground-up to address exactly the type of applications discussed in this article and thus combine the right set of wireless system parameters in order to provide maximum amount of coverage, penetration, reliability and power performance. This opens the door for new and lower cost applications. Some examples are pressure monitoring in areas that were previously out of reach, detection of hazardous gases and personnel tracking in remote fields to enhance safety.
Ultimately, remote monitoring is about enhanced efficiency, thorough minimization of loss from leakage and theft and about safety in the field. Wireless systems can help expand the reach of remote monitoring applications and provide a cost-effective means of enhancing operations.
Author
Jonas N. Olsen is vice president, Strategic Marketing for On-Ramp Wireless. He has extensive experience in technology consulting and business development. Most recently, he served as VP of Business Development at Blue Sky Network, a pioneer in global satellite-based asset tracking. In that capacity, he oversaw early product development and won contracts with ExxonMobil and Royal Dutch Shell, as well as military entities like the Royal Air Force. He has a M.S. degree in business administration and computer science from Copenhagen Business School in Denmark. He can be reached at jonas.olsen@onrampwireless.com.
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