12th May 2020
Matthew Hawkridge, Ovarro, UK, looks at how existing RTU technology can be applied to meet growing demand in the oil and gas sector for information from the field.
To turn a profit in a modern oil and gas company, management teams need to take into account a broader range of factors than ever before. The old method of increasing production whatever the cost is no longer a viable business strategy. Companies must now manage reliability and downtime to minimise interruptions and increase efficiency.
There is also a need to constantly monitor the environmental impact of any operations and above all else, ensure the safety of staff and the general public. The most valuable tool in meeting this new range of key performance indicators (KPIs) is information; and the most appropriate device to collect and process this information is the remote telemetry unit (RTU).
For decades now, RTUs have been a key component in the data chain from the I/O to the CEO. These devices have a longstanding track record of sitting on remote wellheads, pipelines and offshore platforms, collecting, storing and acting upon data, regardless of the surrounding environment.
To date, most RTUs have been used to collect and log operational data and perform local control. This very same device is also the ideal solution to collect and act upon the new wave of information that is needed for a modern, efficient and profitable organisation. The RTU is a field mount computer. It collects data locally, acts upon it immediately, reports data to the central supervisory control and data acquisition (SCADA) control room and maintains a local historical store as an additional backup.
In remote locations, communications may be slow, intermittent or unreliable. The RTU is the device at the edge, sitting between the control room and the field instruments, that provides a low latency response to changing site conditions as well as performing data filtering.
The RTU ensures that only key, critical information is passed via the narrow communications links, minimising data throughput but maximising information throughput. Within the downstream sector, refineries operate 24/7, which means firms need RTU systems that are robust, secure, reliable and flexible enough to be able to manage and monitor the plant’s diverse range of assets. RTUs are integrated with sensors across these sites and provide data to the SCADA system.
Working the other way, RTUs can receive commands from the supervisory system and transmit them to the end devices as well as retaining an ability to act autonomously. RTUs do this over large and remote downstream sites, handling the data acquisition portion of SCADA, providing early warning of impending issues – such as a rise in temperature of a holding tank, elevated temperature in a pump etc. – avoiding asset failure, and potential environmental incidents.
Tackling common issues
In practical terms, RTUs help operators overcome a wide range of issues in the oil and gas sector ranging from continuous monitoring of remote fixed assets, data logging (meaning critical data from the field is not missed and is available for analysis), through to managing complex remote automation and control applications without the need for operators in the field. Some of the specific issues that RTUs can help address include:
- Monitoring of flow, pressure, process equipment, temperature.
- Natural gas flow measurement.
- Optimisation and secondary recovery.
- Complete well site automation.
- Pipelines/transmission systems.
- Compressor and pump station automation
- Metering and regulating (M&R) station measurement and automation
- Cathodic protection monitoring systems.
- Storage facilities
- Pressure monitoring
A number of practical considerations must be accounted for when choosing an RTU system to deliver these benefits. The key features that are required in an RTU are resilience to the site environment, an ability to operate with minimal drain on local power resources, and the processing power to perform any local control algorithms autonomously.
It is also beneficial that an RTU has extensive diagnostics capability and a low meant time to repair (MTTR) to reduce the time required for technicians to spend on site, improving both efficiency and personnel safety.
An increased need for efficiency, environmental protection and safety are driving the market for data analysis and monitoring of assets in the oil and gas sector. RTUs facilitate these processes because they can be deployed on a vast range of assets. Once in place, the real value of an RTU is that it can perform autonomous control in real time and then report to SCADA that it has everything under control. Operators at the SCADA interface can ‘supervise’ the operations by setting new KPIs (set points) or updating instructions (open/close this, start/stop that, for example) for RTUs to then act upon and manage locally.
This ability to provide accurate, real-time data enables management teams to make better, more informed decisions. In addition, because RTUs do everything locally, it means if communications break down, they continue to run, maintaining a historical log, and reporting back later. In remote locations, communications will fail regularly, although RTUs can manage this. For instance, the data that the RTU collects can be used to support maintenance decisions, and to verify that environmental obligations are being adhered to. Currently, most RTUs are only used for operations, although they can support maintenance teams, health and safety initiatives and environmental management.
Below are some of the features and functionality of RTUs that make them particularly suitable to the oil and gas sector:
Resilience to the site environment
Easily accessible oil and gas reserves are becoming scarcer, meaning that assets are now located in remote geographical areas. These environments, because of their extremes of temperature can present challenges for technology, and specifiers are already demanding RTUs that can operate at temperatures between -40˚C and +70˚C.
In order to meet changing and ever more stringent operational, safety and environmental responsibilities, modern RTU systems should have built-in redundancy and resilience. This varies by RTU, from simple CPU backup to full redundancy of power supply, CPU, and communication paths.
High availability can also be achieved via redundant processors, redundant power supply and redundant communications modules. It means they are capable of managing intensive and future SCADA and telemetry applications, whilst avoiding system failure. Processor modules support hot standby redundancy; switchover from the primary to the backup processor will occur upon failure of I/O module scan, communications failure on selected ports.
Ability to operate with minimal drain on local power resources
A challenge in remote areas is power supply, which is the reason why the specified RTU should incorporate intelligent management of power consumption as well as battery or solar power sources.
Processing power
There has been a significant improvement in RTU processing power and memory recently, meaning that they are effectively a PC in the field. With that, they are capable of running and storing data in the most challenging of applications. This increased processing power is helping facilitate the Industrial Internet of Things (IIoT).
A significant area of opportunity is the ability of IIoT to create smart assets, even those that are part way through their lifecycle. For example, deploying the latest RTUs with processing power on an old asset can turn it into a ‘smart’ asset. This helps operators to make the most of their ageing equipment and reduce lifecycle costs.
Security
Historically, industrial networks were isolated from IT networks. However, they are now deeply interconnected and as such need to be robust against cyberattacks. As a result, RTUs need to incorporate a range of security measures such as Firewall SSL (authentication and encryption), HTTP, FTPS and SFTP, SMTPS and open VPN. Auditing is carried out regularly according to IEC 62443 4 2 and ISO 27019.
Low MTTR
Before specifying an RTU, an understanding of the MTTR should be gained. That is because RTUs with rugged reliability are in real need in today’s competitive oil and gas sector. Conversely, RTUs that are not proven in the field may be susceptible to failure, resulting in raised MTTR, which affects productivity for operators as well as having potentially serious environmental consequences. For example, as a result of subsequent equipment failure and spillages.
RTUs have come a long way in the last few years and as oil and gas companies face continued pressure to maintain efficiency, safety and deliver shareholder value, their use looks set to increase. Continued innovation will help drive this change; it is already possible to deploy RTUs on most equipment, whatever its size or age. Inbuilt redundancy and resilience are also helping to avoid system failures. At the same time, improvements in processing power and throughput are helping RTUs keep up with increasing demand for data.
Conclusion
Looking to the future RTUs, which are already ‘mini PCs in the field’, will help harness the power of IIoT by making older assets ‘smart’. Edge computing will come into the mix at some stage, although increased processing power of RTUs means they are already part of a distributed network, processed at the ‘edge’ of the network.
The benefit if this is low latency by computing the data where it is generated – essential for real-time monitoring. In addition, this edge capability provides linear scalability, which will be essential to support the increased deployment of communication devices that reduce pressure on the central network infrastructure.
With its geographically spread assets and multiple process that all generate massive amounts of data, key to ensuring these improvements help business performance is being able to capture and interpret it in real-time. The latest, ruggedised RTU technology focuses specifically on that, helping operators meet their investor and customer commitments.
This article was featured in Hydrocarbon Engineering.