Accuracy & Connectivity in Flare Gas Monitoring
Lana Ginns, Marketing Manager, Fluenta Fluenta

Accurate measurement is critical to safety and profitability in the Oil & Gas industry. Lana Ginns, Marketing Manager at Fluenta, discusses the importance of flare gas measurement and how operators can ensure monitoring is accurate, effective and meaningful.

The Deepwater Horizon oil spill of 2010 is estimated to have released 210 million gallons of oil into the environment around the Gulf of Mexico. The cost of the tragedy was measured in human lives, environmental damage, broken businesses and reputational disaster, aside from the billions in compensation.

Oil exploration is dangerous. While reducing risk is the most critical element to the industry, central to understanding and managing risk is access to accurate information. In the Oil & Gas Industry, the difference between delivering success 99.9 per cent of the time and 99.999 per cent of the time could be a matter of life and death.

Flare gas measurement
The extraction of highly flammable liquids and gases from the earth involves precise technology combined with experience and expertise developed over decades and stringent safety regimes. Despite well publicised incidents that occasionally take place, the industry is safe and consistently getting safer. The publicity that comes with oil and gas explosions demonstrates how rare these incidents are.

Burning excess gas by flare is a critical part of any operator’s safety regime. Flare stacks are often used for burning flammable gas released by pressure relief valves during unplanned over-pressuring of plant equipment. This often takes place during start-ups and shutdowns in production when the volume of gas being extracted can be uncertain. Flare stacks provide a critical means to ensure safety – not allowing the gas to escape would cause a significant build-up of pressure and increase the risk of explosion.

But gas is not only flared for safety reasons. When crude oil is extracted and produced from onshore or offshore oil wells, raw natural gas also comes to the surface. In areas of the world lacking pipelines and other gas transportation infrastructure, this gas is commonly flared.

The question of emissions
Flaring has long been recognised as a leading contributor to greenhouse gas (GHG) emissions, and consequently global warming. Associated gas from the oil extraction process produces more than 300 million tons of CO2 emissions annually. A 2015 report released by the Western Values Project (WVP), a non-profit organisation focused on sustainable land development, estimates that taxation lost from gas flaring in the US alone amounts to more than $50 million annually.

While the Oil & Gas Industry has come a long way in its recognition and reduction of emissions, increasing regulatory focus and additional public and media attention means the industry must make more progress in the way it measures and manages GHG emissions.

Flaring gas is subject to regulation in many parts of the world. Penalties, taxes and fines for flaring are common around the globe and flaring itself is an issue that is being addressed by the European Union, the United Nations and the World Bank.

How can operators ensure accuracy?
Accurate measurement is required to demonstrate both good practice and ensure a company’s carbon tax obligations are minimised. By employing the most accurate measurement technology, operators can ensure they are not paying more tax than needed while also demonstrating regulatory compliance.

Tools used to measure flare gas need to be reliable in some of the most ex treme environments on ear th, where exposure to environmental conditions cannot impact accuracy. The turndown ratio of equipment is a central consideration. This indicates the range of flow that a meter is able to measure with acceptable accuracy. If, for example, gas flow varies from 100,000m3 per day to 1,000,000m3 per day, a meter would require a turndown ratio of at least 10 to record accurately.

There are four primary technologies around gas measurement:

  • Differential Pressure (Dp) Devices:
    DP devices were used in the earliest days of flow measurement and were often deployed for transmission and distribution of gas. These devices have a limited turndown ratio and often need a long, straight line of piping to be effective. That piping, and the space it requires, is expensive.
  • Thermal M ass Measurement:
    Thermal meters use two sensors to determine flow rate: one of the sensors is constantly heated and flow is measured by monitoring the cooling effects of gas on the temperature of the sensor – the faster the flow, the cooler the sensor will become. With turndown ratios of up to 600, these meters are suitable for the unpredictable nature of flare measurement but require constant correction when gas composition changes. As a consequence, thermal meters can be expensive to maintain and make it difficult to ensure continuous accuracy.
  • Photo/Optical Technology:
    This method of measurement uses particles in the gas stream to reflect laser beams. The volume and velocity of gas is proportionate to the time it takes particles to travel between the laser beams. With a turndown ratio of 1500, this method of measurement is flexible enough for flow monitoring but does not work with clean gas, where there are few or no particles. It is also susceptible to degradation caused by moisture and condensation meaning there are high maintenance costs.
  • Ultrasonic:
    The most reliable measurement tool for gas is ultrasonic. This method measures the time it takes for ultrasonic waves to travel across a pipe both upstream and downstream. The difference between these two values provides the most accurate measurement of flow. Ultrasonic measurement has the highest turndown ratio of up to 4000 and is not impacted by the composition or cleanliness of gas. With no mechanical parts within the line, maintenance and support requirements are low, safety is increased, and accuracy is maintained, even at low velocities and varying compositions.
  • Measurement Automation
    The most forward thinking operators are now looking to the Internet of Things (IoT) – the global network of devices connected directly to the internet – to further improve measurement efficiency. Connecting flare gas meters to the internet means measurements can be monitored remotely and in real-time and data collected from on-site equipment can be streamed to any location around the world.

Cloud technology – where software is stored on a central server and accessed via the internet – has transformed how businesses access, pay for and utilise enterprise software. Access to software in this way is now fundamentally changing the Oil & Gas Industr y’s approach to asset management, empowering operators with increased visibility and analytics over plant data.

It gives operators the ability to monitor equipment installed on a variety of local assets – from offshore oil rigs to chemical production plants – and transmit the data in real-time to be analysed in a completely separate location. Flaring data from a number of sites can be fed into a continuous emission monitoring system (CEMS) to enable an operator to collect, record, analyse and report data from multiple sites remotely and in real time. This significantly reduces cost and removes the need for an on-site engineer to manage the hardware and record data. Data is more secure – stored on a remote server – and is not dependent on the reliability of the on-site machine.

Increased control and visibility over emissions data can also be used to gain business advantage. New revenues can be established from existing processes. For example, data can be collated and compared from every site in an operation to optimise the flaring process and support continuous improvement. Best practice from low-emission sites can be implemented in high-emission sites to improve overall efficiency.

Conclusion
Over the next 10 years connected measurement technology will become central to limiting global temperature rises caused by GHG emissions. High-emission industries, such as those that routinely flare gas, will need to drive adoption of this technology, but they can also harness its speed, flexibility and collaboration capabilities to drive new insight and revenues.

Global regulations and targets – such as those agreed at COP21 in Paris in 2015 – mean that emissions repor ting requirements will become increasingly stringent. Repor ting will become a national priority and businesses will need to adapt, becoming more efficient in the face of increasing administration costs and carbon taxation. Accurate measurement technology and remote asset monitoring to track flaring volumes can give operators the information and insight they need to inform business strategy during this transition.