One of the primary reasons for flare measurement is to comply with international legislation around the venting or 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 venting and flaring has become clearer.
A measure of the issue
In June 2014, an article in The Guardian questioned the environmental credentials of natural gas over coal and oil production. The basis of the article was that any benefit to the environment of using gas instead of oil or coal was largely negated by the volume of gas flared or vented in the mining process.
A report, commissioned by the Environmental Defense Fund and carried out by environmental consulting group ICF International, estimated the amount of leaks from natural gas and oil production on federal and tribal land in the US at 65 billion cubic feet of natural gas – amounting to about $360 million of lost gas.
However the loss was not all economic. Methane, the main ingredient in natural gas, is 84 times more potent than carbon dioxide over short periods of time and 30 times more potent over the long term. Therefore venting this volume of gas is the equivalent to the greenhouse gases produced by 5.6 million additional cars.
Flare versus vent
This is one of the reasons why flaring gas is often preferred to venting gas. When gas is flared, it is burned, meaning that the methane is not released into the environment. A further reason for flaring over venting is where the release of gas is taking place over a long period of time. Where this occurs, safety as well as environmental reasons demand that the gas is burned.
In the U.S., mandatory reporting of greenhouse gases including CO2, Methane, and N2O is covered by Final Rule CFR 40 issued by the Environmental Protection Agency (EPA). In addition, the Bureau of Safety and Environmental Enforcement (BSEE) issued Final Rule CFR 30 in 2010 which limits flaring or venting of natural gas from facilities in the Gulf of Mexico and Outer Continental Shelf.
These regulations state that all flare and vented gas volumes must be measured to within 5% uncertainty for facilities producing more than 2,000 barrels of oil equivalent per day.
Elsewhere in North America, Alberta’s Energy and Utilities Board (AEUB) Directive 60 and Directive 17 govern measurement requirements for upstream oil and gas operations. The EUB sets maximum uncertainty for gas measurement at facilities where annual average total flare volumes exceed 500 m3/day as follows:
– Measurement uncertainty for flare gas ±5%
– Measurement uncertainty for dilution gas ±3%
– Measurement uncertainty for acid gas ±10%
In the UK key legislation in this area includes the Petroleum Act 1998 and the Petroleum Licensing Regulations (2004). This in turn is supported by the 2008 Climate Change Act, which set up a framework for the UK to achieve its long-term goals of reducing greenhouse gas emissions and to ensure steps are taken towards adapting to the impact of climate change. The combined legislation requires consent orders for flaring in certain circumstances as well as limits placed on flare volumes, requirements to report flare volumes and to ensure the accuracy of measurement.
Legislation and regulation in this area will continue to develop and it is expected that there will be further tightening of the rules in the future, probably to reduce measurement uncertainty. Organisations that are implementing new flare measurement solutions would be well advised to seek products that exceed current legislative guidelines.