Gas Flaring in the Niger Delta
Embed Size (px)
Transcript of Gas Flaring in the Niger Delta
Gas Flaring In the Niger Delta
The disposal of associated gases through flaring has been a major problem for the Nigerian oil and gas industries and most of these gases are flared due to the lack of commercial out lets. The resultant effects of gas flaring are the damaging effect of the environment due to acid rain formation, green house effect, global warming and ozone depletion.
BLANKSON EYITUOYO .R (060409015) ANIMASHAUN OLANRENWAJU (050409011) NDIGWE EMEKA (060409022) ADEYINKA ADESHOLA (050409007)
SUBMITTED TO THE UNIVERSITY OF LAGOS
PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE DEGREE OF BACHELOR OF SCIENCE
DEPARTMENT OF PETROLEUM AND GAS ENGINEERING, FACULTY OF ENGINEERING
ABSTRACT The disposal of associated gases through flaring has been a major problem for the Nigerian oil and gas industries and most of these gases are flared due to the lack of commercial out lets. The resultant effects of gas flaring are the damaging effect of the environment due to acid rain formation, green house effect, global warming and ozone depletion. This write up is aimed at evaluating the situation of gas flaring in the Niger Delta, the effects of gas flaring, measures and attempts being made to stop/reduce gas flaring in the area and possible solutions to put an end to gas flaring in the country.
TABLE OF CONTENT Title Page Abstract10 INTRODUCTION 20 THEORETICAL PRINCIPLES 2.1 Gas Flaring Systems 2.1.1 Open Flare Systems 2.1.2 Enclosed Flare Systems 30 GAS FLARING IN THE NIGER DELTA 3.1 Effects of Gas Flaring in the Niger Delta 3.2 Attempts to stop/reduce gas flaring in the Niger Delta 3.2.1 Domestic Gas Market 3.2.2 Export-oriented Gas Market 3.2.3 Escravos Gas Project 3.2.4 Oso NGL Project 3.2.5 LNG Project 3.2.6 Ekpe Gas Compression Project 3.2.7 Oso 2Y2 Project 3.2.8 Belema Gas Injection Project 3.2.9 Odigbo Node Gas Project 3.2.10 Cawthorne channel Gas Pipeline Project 3.2.11 The West African Gas Pipeline project 40 CONCLUSION
i 1 2 2 3 3 4 4 6 7 7 7 7 7 8 8 8 8 8 8 10
1.0 INTRODUCTION A gas flare or flare stack is an elevated vertical stack or pipe found on oil & gas wells, oil & gas drilling rigs, natural gas well completion activities, in refineries, chemical plants, natural gas processing plants and landfills used for combusting waste gas released by pressure relief valves during unplanned over-pressuring of plant equipment and also for releasing the excess amount of natural gas that cannot be used so we burn this gas and carbon dioxide formed is released to atmosphere landfills. Its primary purpose is to combust waste methane gas which results from the decomposition of organic materials in the landfill. On oil production rigs, in refineries and chemical plants, its primary purpose is to act as a safety device to protect vessels or pipes from over-pressuring due to unplanned upsets. This acts just like the spout on a tea kettle when it starts whistling as the water in it starts boiling. Whenever plant equipment items are over-pressured, the pressure relief valves on the equipment automatically release gases (and sometimes liquids as well) which are routed through large piping runs called flare headers to the flare stacks. The released gases and/or liquids are burned as they exit the flare stacks. The size and brightness of the resulting flame depends upon how much flammable material was released. Steam can be injected into the flame to reduce the formation of black smoke. The injected steam does however make the burning of gas sound louder, which can cause complaints from nearby residents. Compared to the emission of black smoke, it can be seen as a valid trade off. In more advanced flare tip designs, if the steam used is too wet it can freeze just below the tip, disrupting operations and causing the formation of large icicles. In order to keep the flare system functional, a small amount of gas is continuously burned, like a pilot light, so that the system is always ready for its primary purpose as an overpressure safety system. The continuous gas source also helps diluted mixtures achieve complete combustion. Enclosed ground flares are engineered to eliminate smoke, and contain the flame within the stack. Flaring and venting of natural gas from oil & gas wells is a significant source of greenhouse gas emissions. Its contribution to greenhouse gases has declined by three-quarters in absolute terms since a peak in the 1970s of approximately 110 million metric tons/year and now accounts for 0.5% of all anthropogenic carbon dioxide emissions. This flaring is highly concentrated: 10 countries account for 75% of emissions, and twenty for 90%. The largest flaring operations occur in the Niger Delta region of Nigeria. The leading contributors to gas flaring are (in declining order): Nigeria, Russia, Iran, Algeria, Mexico, Venezuela, Indonesia, and the United States. In spite of a ruling by the Federal High Court of Nigeria (that forbade flaring) in 2005, 43% of the gas retrieval was still being flared in 2006. The number for Nigeria is 23 billion cubic meters.
2.0 THEORITICAL PRINCIPLES Natural Gas could be either associated gas or non-associated gas. This depends on whether it is produced together with crude oil or produced from a defined gas reservoir. In cases where crude oil is the only resource of interest, natural gas becomes not only an unwanted figure but also an embarrassment. As a result it has become imperative to put together a means of collection for the accompanying hydrocarbon. On the other hand, the lack of availability of gas resources in gas producing countries like Nigeria has made this hydrocarbon resource somewhat useless. Thus, natural gas becomes a waste and a profit reduction term. Waste gases are uneconomical to recover/retain. This leaves such a country with only one option: Gas Flaring. 2.1 Gas Flaring Systems The flare system fills a key role in the overall safety and environmental compliance of a hydrocarbon processing plant or production facility. A Flare system consists of: Staging/Control System Liquid Seal Elevated Stack
Due to the facts that flare applications ranges, there are different types of flares. Flares could be broad categorized into the following: Open Flares Enclosed Flares 2.1.1 Open Flare Systems Open flares burn waste gases as open flames, though a windshield is normally fitted. If provided, combustion control is rudimentary. Open flares are also known as elevated flares.
FIG 2: Open Flare System 2.1.2 Enclosed Flare Systems
Enclosed flares burn waste gases in a vertical, cylindrical or rectilinear enclosure. Some means of combustion control is normally provided, and the enclosure is often insulated to reduce heat losses and allow operation at higher temperatures. Enclosed flares are also known as ground flares.
A Typical Enclosed Flare System
3.0 GAS FLARING IN THE NIGER DELTA Nigeria holds 11,700 square kilometers of mangrove forest: the third largest in the world and the largest in Africa. Most of this mangrove is found in the Niger Delta. She is also a major oil producer and most oil extraction takes place in the Niger Delta. Here, petroleum or crude oil abounds in rock formations. The complex mixture of hydrocarbons and other organic compounds that make up the flammable liquid fossil fuel is extracted from oil wells found in those oil fields. When crude oil is pumped out it also drags associated gas with it. Such natural gas could be separated from the oil and be used but oil companies prefer to burn it off. Shell-BP was the first one to start with this practice in the 1960s. Nigeria is Africas most populated country, with significant oil, and even more gas, reserves. Oil production began in the Niger Delta about 45 years ago and so did the practice of flaring associated gas. The waste involved in the practice, and the expected controversy, was recognized early on. Following the oil-fuelled 1967-1970 civil war, the industry developed via joint ventures with the governments Nigerian National Petroleum Corporation in which companies such as Shell, ExxonMobil, ChevronTexaco and TotalFinaElf are the operators, but hold minority interests.
There is confusion over how much oil and associated gas is produced in Nigeria. The most recent and independent information source suggests that over 3.5 billion standard cubic feet (SCF) of associated gas was produced in 2000, of which more than 70 per cent was burnt off, ie flared. As oil production has increased, Nigeria has become the worlds biggest gas flarer, both proportionally and absolutely, with around 2 billion scf, perhaps 2.5billion SCF/day being flared. This is equal to about 25 per cent of the UKs gas consumption. The single biggest flarer is the Shell Petroleum Development Company of Nigeria Ltd (SPDC). A recent report estimates flaring to represent an annual economic loss to the country of about US $2.5 billion. 3.1 EFFECTS OF GAS FLARING IN THE NIGER DELTA The impact of gas flared is of local and global concern. The main components of this flared gas include carbon (iv) oxide (CO2), methane (CH4), nitrous oxide (NO2), water vapour and sulphur dioxide (SO2). It is estimated that the Nigerian gas flared has released 35 million tons of carbon dioxide and 12 million tons of methane in a year. The low combustion efficiency of Nigerian flare stack (60 80%) results in a large portion of the gas emitted being methane and since methane has a higher global warming potential (64 against 1 for CO2). The Nigerian oil industry probably contributes more than any other company of these serious global commons environmental problems. As carbon dioxide and methane are the main green house effect and consequently, this phenomenon has been confirmed to raise the average global temperature by about 0.5C within t