A new era in oil and gas flow computing

Consolidating oil and gas flow measurement and control on a single and secure platform improves productivity and profitability.

Traditionally, most oil and gas production sites used a flow computer at the wellhead for measurement and simple control functions, and a PLC at a central facility for more sophisticated control. Operational and measurement data was collected from the well site once an hour and that was good enough. Some of these flow computers performed quite well in the harsh environments of the field, while others — and most PLCs — did not. No-one was thinking about cybersecurity at the wellhead and if any security was implemented, it was external to the flow computer or PLC.

Over the last 10 years, however, the CSG and shale gas boom and changing oil and gas markets have driven an evolution in oil and gas production, much of which is being enabled by a revolution in communications and computing technology. Wellhead measurement and automation will never be the same. In this article we look at the forces driving the change and how control and communications architectures are evolving to help producers take advantage of emerging opportunities to increase security and profitability from their operations.

Complexity and consolidation

Where traditional production site designs were calling for one or two wells per pad, today’s production well pad designs are calling for numerous wells, each of which may produce oil, natural gas and water. Where wellhead and facility controls were once performed in separate locations, many more sites are performing everything at the same location: the well pad. The economics of the modern oil and gas field require concentrating measurement and control in a single location.

With the concentration at the wellhead comes increasing demand for a single platform for measurement supported by sophisticated control algorithms and the ability to provide real-time and historical data to multiple users. As more and more users discover the competitive advantage and productivity improvement they can gain from better data analysis and the requirements to collect, store, process and transmit data, this demand will only increase. There is no longer any reason to accept measurement technology and automation equipment that isn’t rugged enough to handle harsh oilfield environments or secure enough to survive today’s growing cyber-threat landscape.

Consolidating flow measurement and control

With the new well pad designs, consolidating all flow measurement and control into a single platform makes sense because everything is at the pad. Such a modern digital field platform should perform best-in-class, API-compliant oil and gas measurement as well as DCS/PLC class control. The measurement functionality and control capability should be accessible in an integrated programming environment so that the controls have easy access to measurement data. The automation platform’s operating system should actively protect the measurement application from anything that might affect the accuracy and validity of the measurement.

More power to the process

Additionally, processor speeds and RAM must be many times better than current legacy flow computers and PLC/RTUs. A custody transfer application, for example, may involve up to 24 simultaneous measurement calculations, along with the wellhead and facility controls. Taking full advantage of these powerful microprocessors requires a robust and secure real-time operating system (RTOS).

A measurement application, by its very nature, requires a lot of non-volatile memory to store the measurement history and configuration data. Although traditional wellhead and facility controls have not been very memory intensive, the need to perform more sophisticated control and edge computing at the wellhead is changing that. Taking advantage of the business and productivity benefits of measurement and automation consolidation requires orders of magnitude more non-volatile memory than has been available on legacy flow computers and PLCs.

Open connectivity

Consolidating measurement, well controls and facility controls in a single and secure platform also changes communication requirements.

In the traditional flow computer installation, where there is a single well with minimal controls, it is not unusual for communications to occur as seldom as once an hour. The measurement collection system collects the historical data, event logs and configuration data from the flow computers as required. At the facilities, a local HMI typically provides real-time access to the facility PLC data, but only a subset of that data is available to the SCADA system.

A multi-well pad, however, requires near real-time data for both measurement and control. Legacy communication architectures, in which the flow computers and PLCs communicate directly with each SCADA system or HMI, may not have the bandwidth required for more complex, demanding data flows. These new data flow models require newer, open protocols such as the Open Platform Communications Unified Architecture (OPC UA) and Message Queuing Telemetry Transport (MQTT).

OPC UA is fast becoming an important communication standard for managing open communications across multivendor applications and devices across a network. To access data, an OPC UA client program, for example, a SCADA system connects to OPC UA servers and allows multiple SCADA HMI or other clients to connect and exchange data. OPC UA also allows for secure communications, unlike legacy protocols.

MQTT is a publish/subscribe protocol with true report-by-exception capabilities built in. It is designed to optimise connections from remote locations with minimal code. MQTT can support both real-time and historical data. The field device simply publishes data to an MQTT server once, on change. Any number of other devices can also subscribe to the data, which is published on the MQTT server, making the data available to the subscribers automatically. This approach simplifies the design of the SCADA network and makes providing data for other applications easier than ever. MQTT is also a secure communications protocol.

Intrinsic cybersecurity

With openness comes vulnerability, so achieving the benefits of openness requires embedding advanced, cyber-secure public key infrastructures (PKIs) into all devices starting at the chip level. This makes the device responsible for its own security. The system is no longer dependent on an external, bolted-on network of firewalls, intrusion detection devices, etc to parse out whether incoming signals can be trusted. This provides an entirely new level of depth to the defence. While elite hackers can bypass firewalls, breaking properly implemented strong cryptography that is enabled by a PKI is not a practical possibility. It presents the attacker with a whole new set of barriers along multiple signal paths, not just one. The controller essentially has an immune system.

In a PKI, all trusted parties have unique certificates that identify them. The certificates also include data that defines each party’s system roles and privileges. Certificates are issued and managed by a certificate authority (CA). PKI mechanisms allow all members of the trust web to recognise other members and exclude imposters automatically.

In a controller module with an integrated flow computer and PLC, this security makes it possible to know that the actor is an engineer who is authorised to change the user programming or an operator who has permission to change a set point. If the actor has the proper PKI credentials, the controller allows the action. If not, the controller automatically blocks it.

Protection in challenging physical environments

Traditional flow computers have a temperature specification of -40 to +70°C, and their simplified construction — typically one or two circuit boards housed in a plastic or metal housing — has been adequate for the wellhead. PLCs traditionally have an even narrower temperature specification of 0 to +60°C because they are typically installed in a more controlled environment. However, neither flow computers nor PLCs were designed to withstand high-voltage incidents.

Technological advancements have made reliable measurement and control possible in hazardous and extreme physical environments. New designs are pushing the temperature envelope as high as +80°C. Replacing plastic enclosures with sealed all-metal helps prevent physical damage, ingress of dust and moisture, and for advanced designs, even intrinsic hardening to extreme electromagnetic pulse threats (EMP interference).

Beyond the wellhead

The demand for a single, rugged platform with consolidated measurement and controls, edge computing, advanced connectivity and intrinsic cybersecurity exists across the entire oil and gas market: production, transmission and distribution. The platform needs to be scalable in order to meet the needs of every environment.

Some locations need many runs of measurement, with relatively little control. This requires the capability to communicate to many transmitters via HART or other fieldbuses but may not require many physical I/O points. Other locations may need one, two or three runs of measurement, but may need more control and the ability to interface with many external devices.

For instance, a LACT unit may only require one or two runs of measurement, but will also perform unit controls, communicate with HART and Modbus devices, interface with access control readers, drive local printers for printing tickets, allow access via a local HMI and need to support legacy SCADA protocols. These protocols include Enron Modbus as well as the latest open standards protocols such as OPC UA and MQTT. This application typically requires 10 to 20 physical I/O points, yet requires robust communications to many other field devices, all while ensuring the reliability and security of the measurement and control platform.

Conclusion

Ever-present volatility in both the supply and demand for petroleum products is pushing petroleum and natural gas producers to find new solutions to manage operations profitably. Consolidating measurement and control at the well pad provides heightened availability to real-time and historical data that is enabling a new generation of efficiency and profitability optimisation.

Taking full advantage of these opportunities requires an automation and measurement platform significantly more open, more secure and powerful than even the latest technology that the flow computer market leaders are offering. The openness is critical to enabling oil and gas producers to deploy and integrate best-in-class technologies that they can configure to their specific needs to get a true competitive edge. Intrinsic cybersecurity is essential to eliminate any vulnerability that open standards may introduce, and the computational power is necessary to provide the bandwidth for running advanced flow calculations at high speeds.

Top image: ©stock.adobe.com/au/TTstudio