Flaring is the controlled burning of natural gas during oil and gas production. While necessary for safety, flaring wastes a resource and harms the environment. It is in industry's interest to minimize flaring by commercializing gas when possible. When gas cannot be utilized, reinjection underground or flaring with high-efficiency systems are preferable to venting. Governments must provide policies to encourage alternative approaches tailored to local conditions, in order to reduce flaring impacts.

1. FLARING PRACTICES IN PETROLEUM INDUSTRYVINITA AGARWAL (R020208043VISHAL PARASHAR (R020208044)VIVEK ZAVERI (R020208045)KUHU SHARMA (R020208047)

2. Introduction The option to release gas to the atmosphere by flaring or venting is a necessary practice in the production of oil and gas. Most developing countries that produce oil also flare and vent large volumes of associated gas, a blend of hydrocarbons released when crude oil is brought to the surface. This practice of burning gas or releasing it into the atmosphere not only harms the environment, including by adding significantly to greenhouse gas emissions.The World Bank estimates the annual volume of natural gas being flared and vented worldwide at about 110 billion cubic meters (bcm), enough to provide for the annual gas consumption of Central and South America or that of Germany and Italy.

3. Ideally, the associated gas will be sold to a customer as a fuel or petrochemical feedstock. However, unlike oil, gas is not an easily transportable fuel.A customer must be reasonably physically close in order for the additional expense of gas processing and transportation to be economically justifiable.The customer must also be willing to enter into the necessary commercial arrangements.The political will also needs to exist within government to provide an appropriate fiscal regime which will allow the project to go ahead.

4. However, these conditions can be difficult to achieve in practice becauseThe government may have other national priorities that conflict with developing a supportive financial regime.Potential customers may have other projects they wish to pursue. Technology may also offer new ways to commercialize associated gas reserves. Although gas itself is relatively difficult to transport, it can be liquefied and then transported more easily.

5. In recent years, the exploration and production industry has significantly improved gas liquefaction technologies - technologies which until recently could only be applied to the largest gas reserves.In the situation where the associated gas cannot be commercialized, only three options remain vent it, flare it, orre-inject and store it in the underground formations from which the oil is being recovered.

6. FlaringFlaring is the controlled burning of natural gas in the course of routine oil and gas production operations.This burning occurs at the end of a flare stack or boom. A complete flare system consists of the flare stack or boom and pipes which collect the gases to be flared.The flare tip at the end of the stack or boom is designed to assist entrainment of air into the flare to improve burn efficiency.Depending on the design, one or more flares may be required at a production location. A flare is normally visible and generates both noise and heat.During flaring, the burned gas generates mainly water vapor and carbon dioxide.The percentage combustion efficiency of a well-designed and operated flare is in the high ninety percent range.Recent work by the U.S. Environmental Protection Agency has shown that combustion efficiencies are often greater than 98%.

7. Sources of Gas FlaringIt may be excess to that which can be supplied commercially to customers.It may be unburned process gas from the processing facilities. It may be vapors collected from the tops of tanks as they are being filled. Sometimes, the gas may be from process upsets, equipment changeover or maintenance. Occasionally, a production shutdown may require the temporary flaring of all the gas stored on or arriving at a facility, to release high pressure and avoid a catastrophic situation occurring.

8. It is in the oil company’s interest to realize as much value as possible from the hydrocarbon accumulations the company is producing. Therefore, it is also in the company’s interest to minimize the amount of gas being flared. In this respect, the commercial aims of the company are consistent with good environmental practice.

9. FLARING ALTERNATIVESIf operated properly, incinerators generally have more efficient combustion than flares because combustion occurs in an enclosed chamber, away from the effects of wind and weather, and the air to fuel ratio required for complete combustion can be precisely controlled. Although they can be highly efficient, incinerators are mainly used at sour gas processing plants and not for routine waste gas flaring. The reasons are that incinerators are more costly to install, they require more frequent maintenance and monitoring, and they are difficult to install and operate in remote locations.

10. Other alternatives to flaring include:Conserving the waste gas for processing at natural gas facilities,Re-injecting the waste gas underground to maintain reservoir pressure during production,Connecting well test gases to existing pipeline systems for in-line well testing,Using the gas to power micro-turbine generators for electricity production,Ensuring flare systems are properly designed, constructed and maintained through guidelines, codes of practice, or regulation.

11. FLARING EFFICIENCYThe efficiency of a flare is a measure of how effective that flare is in converting all of the carbon in the fuel to C02. Previous studies have indicated that flares have highly variable efficiencies, on the order of 62-99%.

12. FACTORS AFFECTING FLARING EFFICIENCYThe tips of the flare can be exposed to wind, humidity, and temperature variations that reduce efficiency and increase variability.The composition of the waste gas stream entering the flare, which varies from site to site.Improper flaring practices that cause unsteady combustion conditions.

13. Low efficiency flares do not completely combust all of the fuel gas and unburned hydrocarbons and carbon monoxide are emitted from the flare with the carbon dioxide.If the waste fuel entering the flare contains impurities and/or liquid droplets, many other by-products can also be emitted from the flare stack. These products include: particulate matter, volatile organic compounds (VOCs) such as benzene, toluene and xylene, polycyclic aromatic hydrocarbons (PAH), and small quantities of sulfur compounds such as carbon disulfide (CS2) and carbonyl sulfide (COS).

14. Reinjection is a practicable option for some oilfields, but not in all cases. In some situations, the geological nature of the underground formations is such that the injected gas would migrate back to the oil production wells too easily, leading to inefficient and energy intensive gas recycling.Even for formations where reinjection is geologically practicable, the oilfield itself may be too small in economic terms to support the additional reinjection infrastructure.Although the current viability of underground gas storage is limited by geology and economics, some companies are investigating ways of making underground storage more attractive.

15. VentingVenting is the release of gases directly to the atmosphere either intentionally to get rid of unwanted waste gases or unintentionally through equipment leaks and failures. Venting can occur from the following:Oil and natural gas production and transport,Oil and gas well drilling and servicing,Accidental equipment failures,Equipment leaks from bleed valves, fuel gas operated pneumatic equipment, imperfect seals, and Surface casing vents, blows, and gas migration.

16. SAFETY & ENVIRONMENTAL ASPECTSFlaring is both a concern to the public and a government priority because of the potential health risks and environmental concerns associated with the activity and also because it wastes a valuable nonrenewable resource. Furthermore, the noise, odor, and smoke produced from flaring activities can interfere with nearby residents and their enjoyment of the outdoors. Flaring is an environmental concern with regards to global warming and acid deposition. Emissions of carbon dioxide and unburned natural gas from flares contribute to the greenhouse gas effect and global warming.Acid deposition is the combination of nitrogen, sulfur oxides (released from flaring), and water in the atmosphere to form acids that are deposited either directly or with precipitation. The acids can fall near flaring activities or be carried for hundreds or thousands kilometers before being deposited. Acid deposition can lead to lakes and streams becoming acidified and it is harmful to the environment.

17. The United Nations Environment Program's (UNEP) Information Unit on Climate Change (IUCC) states that global emissions of C02 from gas flaring peaked during the mid-1970s and has been declining since.Gas that previously was flared is now increasingly captured for use as a fuel due to improvements in technology, higher gas prices and demand.Global emissions of carbon dioxide for 1989 from gas flaring were estimated at 202 million tones, or approximately 0.8 percent of anthropogenic (man made) carbon dioxide emissions.The majority of emissions due to gas flaring are from the oil-producing countries of Africa and Asia, as well as in the former USSR.

18. Concerns in safetyEven where associated gas is being sold or re-injected, small amounts of gas will still need to be flared or vented for safety reasons. Oil and gas processing and storage equipment is often operated at high pressures and temperatures. When abnormal conditions occur, the control and safety systems must release gas to the emergency flare or vent to prevent hazards to the employees or public.

19. Good maintenance and operating strategies are the main mechanisms used to keep this already small volume as low as practicable. Emergency flares are normally fitted with pilot systems maintaining a small flame as the ignition source in case the full size flare is activated.Recently, new flare equipment designed to operate without a pilot flame, and hence without emission when not active, was installed on a number of Statoil’s production facilities in Norway.

20. Another safety issue in the application of flaring and venting is the toxicity of the gases being disposed. In some situations, the toxicity of the gas relative to the toxicity of its combustion products may need to be considered when choosing between flaring and venting as a means of disposal.

21. ConclusionThe option to release gas to the atmosphere by flaring and venting is an essential practice in oil and gas production, primarily for safety reasons.The availability of a flare or a vent ensures that associated natural gas can be safely disposed of in emergency and shut down situations. Where gas cannot be stored or used commercially, the risk of fire and explosion must be reduced by either flaring or venting.For environmental and resource conservation reasons, flaring and venting should always be minimized as much as practicable, consistent with safety considerations. Flaring and venting can have local environmental impacts, as well as producing emissions which have the potential to contribute to global warming.

22. Available data indicate that, on a worldwide basis, gas flaring contributes only 1% of anthropogenic carbon dioxide emissions, and flaring and venting contribute only 4% of anthropogenic methane emissions.Industry needs to be able to choose from among a variety of creative and common sense approaches to address flaring and venting concerns in specific operations.To achieve this, governments need to provide an energy policy framework which will encourage and allow companies to select from among very different approaches in order to achieve the best practicable outcome in particular circumstances.

23. BIBLIOGRAPHYFlare efficiency Study, EPA-600/2-83-052, U.S. Environmental Protection Agency, Cincinnati, OH, July1983.IEA Report No. PH2/7 (Jan 1997), Methane Emissions from the Oil and Gas Industry.www.cdm.unfccc.inGGFR (Global Gas Flaring Reduction Public-Private Partnership). 2002. “Report on Consultations with Stakeholders.” World Bank–GGFR Report 1. Washington, D.C. 2004a. “Regulation of Associated Gas Flaring and Venting: A Global Overview and Lessons from International Experience.” World Bank–GGFR Report 3. Washington, D.C.2004b. “A Voluntary Standard for Global Gas Flaring and Venting Reduction.” World Bank– GGFR Report 4. Washington, D.C.

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