Accurate Flare Gas Measurement: The First Step to Net-Zero Carbon Emissions

Introduction

Flaring is a growing issue in the oil and gas industry, which is under pressure to minimise the practice in order to reduce the environmental impact and, where possible, put flared gas to better use.

Studies show an estimated 142 billion cubic metres of natural gas, worth $21 billion, is wasted through flaring each year worldwide.

In addition to wasting a valuable natural resource, gas flaring contributes to global warming, adding as much CO2 to the atmosphere per year as 200 million cars. Even though the practice cannot be avoided in some circumstances, there are several ways operators can monetise the natural resource, resulting in a win-win situation for themselves and the environment.

To curb the environmental and bottom-line implications of flaring, operators across upstream, midstream, and downstream must start with flare gas measurement. Gaining an understanding of the volumes of gas flowing through systems is the first port of call to manage emissions from flaring and support de-carbonisation plans to reach net-zero.

What is Gas Flaring?

Gas flaring is the process of burning off associated natural gas at oil extraction wells, refineries, chemical plants, coal mines and landfills, either as a means of disposal or as a safety measure.

The practice has persisted since the beginning of oil production over 160 years ago and takes place due to a range of issues – from economic constraints to a lack of infrastructure or appropriate regulation and political will.

The flame at the top of an oil rig is an iconic image of the oil and gas industry. Yet its purpose isn’t common knowledge, so let’s explore why gas is flared in the first place.

Reasons for Gas Flaring

Flaring excess gas is a critical part of the safety regime across rigs and installations. Flare stacks are often used to burn off flammable gas released by pressure relief valves during unplanned over-pressurisation of plant equipment.

Flaring often occurs during start-ups and shutdowns in production when the volume of gas extracted can be uncertain. In this respect, flare stacks provide a critical means by which to ensure safety – the alternative to allowing the gas to escape would be a significant build-up of pressure and the risk of explosion.

It is not always the case that gas is 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.

Flaring for Safety

By burning excess natural gas, flaring protects against the dangers of over-pressuring industrial equipment. Natural gas can be stored and transported instead of being flared.

In the U.S., there were 6,298 significant safety incidents at natural gas transmission pipelines between 2010 and 2019. These incidents led to 140 fatalities and 656 injuries, according to Fractracker Alliance. Transporting natural gas from a rig to homes and businesses is high risk, and many companies choose flaring as the alternative.

Flaring for Disposal

One of the main reasons for gas flaring is the disposal and burning of natural gas as waste. Typically, when there are large volumes of hydrogen sulphide in natural gas, it cannot be safely extracted. To dispose of this gas, it is burned off. When the gas is burned, the hydrogen is converted into water, and the sulphur becomes sulphur dioxide.

Flaring for Remote Locations

When petroleum crude oil is extracted and produced from onshore or offshore oil wells, natural gas associated with the oil is also brought to the surface. If companies do not have the infrastructure in place to capture natural gas and safely transport it – such as when oil rigs are in deep waters – natural gas is often flared.

Flaring for Economics

There is a significant gap between oil and natural gas prices. Natural gas costs more than oil to produce on an energy-equivalent basis. For this reason, drillers are searching for oil, not gas, and companies are reluctant to invest in costly projects to capture and transport natural gas from oil wells to the market.

Implications of Gas Flaring on the Environment

There have been numerous studies, such as the IPCC’s Climate Change 2022 Mitigation of Climate Change report, that show emissions from fossil fuels are one of the dominant causes of rising temperatures and the devastating effects of climate change. One source of these emissions is gas flaring.

Collectively, around 142 billion cubic meters of natural gas are flared each year, which is a colossal waste of a natural resource that could otherwise be conserved or used to generate power. For an idea of the scale of this waste, the volume of gas flared each year could power the whole of sub-Saharan Africa.

Aside from the energy waste, the incineration of the associated gas is a major environmental problem that’s contributing to increased levels of greenhouse gas emitted into our atmosphere.

According to the International Energy Agency (IEA), gas flaring pollutes the environment with about 400 million metric tonnes of CO2 per year; however, due to the mixture of gasses sent to flare, not all of it is burnt and converted to CO2. As well as carbon dioxide, a significant amount of methane (CH4 ) and black carbon (commonly known as soot) are also released into the atmosphere.

The Permian Methane Analysis Project recently released a study from the Permian tight-oil basin, noting that 11% of flares were unlit or working sub-optimally, resulting in more than 3.5 times more methane released than officially reported.

Methane often steals the show as the main culprit of global warming due to its potent ability to trap heat over time. But, black carbon, even though it remains in the atmosphere for no more than a few weeks, it also has a significant warming effect.

This is of particular concern in the Arctic, where black carbon deposits are believed to increase the rate at which snow and ice are melting. Research from the European Geosciences Union indicates that gas flaring emissions contribute to about 40% of the annual black carbon deposits in the Arctic.

Despite rising awareness of the problem and several initiatives aiming to curb flaring, the world now flares as much as it did 10 years ago, according to an IEA analysis.

What’s Being Done to Reduce the Impact of Emissions from Flare Gas

To curb the large volumes of greenhouse gas emissions from flaring, companies must understand how flare gas is handled in their installations and measure and report their emissions.

Governments around the world are recognising the negative impact of flare gas on business and the environment and are introducing policies to control their levels of emissions. Some of these policies require measurement accuracies within a certain threshold, typically ± 3 to 5%, and require companies to pay more for every ton of CO2 emitted beyond their yearly carbon allowance.

In our view at Fluenta, governments and regulatory bodies play a critical role in reducing flaring. They are uniquely positioned to introduce environmentally aware policies and financial incentives that encourage gas flaring reduction.

While several countries already have regulations addressing flaring, not all policy approaches have proved effective at reducing the polluting practice, as reported by the World Bank and the Global Gas Flaring Reduction Partnership (GGFR).

Several countries have opted into initiatives such as the World Bank’s Zero Routine Flaring initiative, the Global Methane Pledge, and other UN-led climate conferences and partnerships.

However, many international jurisdictions still have a very weak regulatory environment and enforcement capacity, so voluntary initiatives to reduce carbon emissions are highly encouraged.

The principle “what can be measured can be changed” holds true for flaring. Effective and accurate measurement is the first step in understanding where we are now and where we want to be.

Thankfully, governments aren’t left to work in isolation. Several initiatives provide governments with support and frameworks to issue the right policies to end routine flaring and promote the conservation or productive use of the associated gas.

Examples of initiatives count the World Bank’s Zero Routine Flaring by 2030 (ZRF) Initiative, the Global Gas Flaring Reduction Partnership (GGFR), the Global Methane Pledge, and UN-led climate conferences, to name a few. The commitment of governments and energy companies to manage the associated gas that comes with oil production is more important than ever before.

The protection of the environment is our moral responsibility, and energy companies shouldn’t wait for lawmakers to force them into action, even in jurisdictions with absent or limited regulation.

Legislations around Flare Gas Measurement

One of the primary reasons for flare measurement is to comply with international legislation around the flaring of gas from oil production facilities. In recent years, with the increase in environmental concerns, such legislation has become more common around the world as the scale of flaring has become clearer.

Regulatory Considerations

The Case for Accurate Flare Gas Measurement

As demonstrated recently by several COP summits, putting a limit on flaring requires a significant behavioural change prompted either through penalising legislation that taxes the volumes of gas flared and/or the introduction of incentives, including subsidies and funding, to accelerate change.

As outlined already in this paper, taking action to limit flaring starts with measurement. Currently, many regulatory regimes, including the U.S., Canada, the EU, the UK, and more, require operators to report their flare emissions to a degree of ± 3-5% measurement accuracy. These stipulated accuracies are expected to get tighter as the industry changes.

Both legislators and energy companies’ de-carbonisation efforts require an understanding of the volumes of associated gas routinely flared. Thankfully, there are several solutions available, the most effective and accurate of which is ultrasonic gas measurement technology.

Overview of Flare Gas Measurement

Flow meter requirements can vary depending on the application, but ultrasonic meters have become the go-to choice when it comes to measuring flare gas. Calculating and metering the volumes of natural gas expelled through flare systems is arguably the most challenging form of gas flow measurement.

Flare gas is subject to wildly fluctuating velocity ranges, varying atmospheric conditions, extreme temperatures, and mixed gas compositions, making it difficult to measure flow accurately. The challenge is increased further in large pipe sizes and when installations lack straight-run pipelines or have insufficient flow conditioning, for example, on offshore platforms.

Ultrasonic flowmeters rely on several physical, mechanical, and electrical principles to measure gas flow rate accurately over various conditions. As a result, they are particularly suitable for processes handling extreme cold and hot temperatures, low pressures, and high flow velocities found in applications such as natural gas pipelines, chemical plants, and oil and gas rigs.

The versatile working principles of ultrasonic flowmeters make them one of the fastest-growing types of flowmeters. They enable operators to accurately measure the volume and velocity of products such as flare gas. As a result, ultrasonic measurement devices are a valuable way to ensure compliance with regulatory requirements concerning greenhouse gas emissions and meet environmental and performance goals.

Beyond Measurement: Available Flare Gas Recovery Avenues

As outlined, flare gas is a colossal waste of a valuable natural resource that’s detrimental to our climate. The accurate measurement of flare gas is only the first step in reducing emissions. Operators can re-purpose flare gas through several flaring reduction methods, such as:

Power Generation Programmes

The natural gas recovered from oil wells and landfill sites can converted to generate heat and electricity. This can be achieved through:

• Gas driven turbines
• Steam driven turbines
• Reciprocating internal combustion engines

Re-injection in Secondary Oil Recovery

Flare gas could be injected into aged wells to restore declining natural formation pressure and to maintain production outputs. This is a self-sustaining cycle as it minimises waste and boosts overall process efficiency.

Feedstock for Petrochemical Plants

Petrochemical production processes rely heavily on natural gas as a core raw material. Flared gas from oil and gas wells can be converted into syngas, ammonia, hydrogen fuel for cars, rubber, glass, steel, and paint – instead of it being flared.

Liquefied Natural Gas

Gas liquefaction and storage are safer and more economical alternatives to gas flaring. Liquefied natural gas can be stored for industrial and domestic use following purification processes.

Compressed Natural Gas

Methane from oil wells and landfill sites can be stored in cylinders at high pressures ranging from 20-50 MPa. This process is commonly known as Compressed Natural gas (CNG), and it allows for flare gas to power vehicles that run on natural gas engines instead of flaring it.