Associated petroleum gas (APG), or associated gas, is a form of
natural gas
Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...
which is found with deposits of
petroleum
Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...
, either dissolved in the oil or as a free "gas cap" above the oil in the reservoir. The gas can be utilized in a number of ways after processing: sold and included in the natural-gas distribution networks, used for on-site electricity generation with
engine
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ge ...
s or
turbine
A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...
s, reinjected for
secondary recovery and used in
enhanced oil recovery
Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted after primary and secondary recovery methods have been completely exhausted. Whereas primary and se ...
, converted from
gas to liquids producing
synthetic fuels, or used as feedstock for the
petrochemical industry
file:Jampilen Petrochemical Co. 02.jpg, 300px, Jampilen Petrochemical co., Asaluyeh, Iran
The petrochemical industry is concerned with the production and trade of petrochemicals. A major part is constituted by the plastics industry, plastics (poly ...
, but much of it worldwide is
flared.
Composition
APG is primarily a mixture of
hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...
molecules that are classified as
alkanes. The following table lists typical percentages of the major alkanes in APG, and includes the typical levels of nitrogen and carbon dioxide. Water (
wet gas) and
hydrogen sulfide
Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is toxic, corrosive, and flammable. Trace amounts in ambient atmosphere have a characteristic foul odor of rotten eggs. Swedish chemist ...
(
sour gas) contaminate APG at more varied levels.
Helium
Helium (from ) is a chemical element; it has chemical symbol, symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert gas, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is ...
is present in significant amounts in some cases, and is a relatively valuable by-product. APG is processed to separate out most other components before the methane-rich gas is sold into natural-gas distribution networks.
Uses
Like crude oil, APG is both a
primary energy resource and a
primary commodity that enables much of the modern
world economy
The world economy or global economy is the economy of all humans in the world, referring to the global economic system, which includes all economic activities conducted both within and between nations, including production (economics), producti ...
. Statistics from the
International Energy Agency
The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organization, established in 1974, that provides policy recommendations, analysis and data on the global energy sector. The 31 member countries and 13 associatio ...
show that the natural-gas supplies steadily increased during 1990-2017 to meet the demands of expanding global
population
Population is a set of humans or other organisms in a given region or area. Governments conduct a census to quantify the resident population size within a given jurisdiction. The term is also applied to non-human animals, microorganisms, and pl ...
and
consumerism
Consumerism is a socio-cultural and economic phenomenon that is typical of industrialized societies. It is characterized by the continuous acquisition of goods and services in ever-increasing quantities. In contemporary consumer society, the ...
. APG is nevertheless a finite
fossil fuel
A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geolog ...
, and the crossing of
planetary boundaries could impose earlier limits on its value and usefulness.
Following extraction, petroleum companies prefer to transport both crude oil and APG to their respective refiners for processing and distribution to consumers. Most modern wells are planned to include gas
pipeline transport
A pipeline is a system of Pipe (fluid conveyance), pipes for long-distance transportation of a liquid or gas, typically to a market area for consumption. The latest data from 2014 gives a total of slightly less than of pipeline in 120 countries ...
, but some oil wells are drilled only to get the more lucrative oil, in which case the options are to locally use, process, or dispose of the APG. A traditional local use is to re-inject the gas for storage, and to re-pressurize the well to extend the oil production lifetime. On-site processing with various mobile systems also exist for producing
natural gas liquids (NGL),
compressed natural gas (CNG),
liquified natural gas (LNG), and
gas to liquids (GTL) fuels that can be transported by truck or ship. Electricity generation from on-site
microturbines and
engines
An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.
Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...
is also compatible with minimally processed APG.
Flaring
Historically APG was, and still may be, a waste product from the petroleum extraction industry. It may be a
stranded gas reserve due to the remote location of the oil field, either at sea or on land. The gas is then simply
vented or, preferably, burnt off in
gas flare
A gas flare, alternatively known as a flare stack, flare boom, ground flare, or flare pit, is a gas combustion device used in places such as petroleum refineries, chemical plants and natural gas processing plants, oil or gas extraction sites ha ...
s. When this occurs it is referred to as flare gas.
APG flaring is controversial since it is a pollutant, a source of global warming and a waste of a finite fuel source. APG is flared in many countries where there are significant power shortages. In the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
, gas may not be flared without written consent from the UK government to prevent unnecessary waste and protect the environment. Russia is the world leader and contributed 30 percent of total global APG flared in 2009.
The
World Bank
The World Bank is an international financial institution that provides loans and Grant (money), grants to the governments of Least developed countries, low- and Developing country, middle-income countries for the purposes of economic development ...
estimates that over 150 billion cubic metres of natural gas are flared or vented annually. Flared natural gas is worth approximately 30.6 billion dollars and equivalent to 25 percent of the United States' yearly gas consumption or 30 percent of the European Union's annual gas consumption.
See also
*
Coalbed methane — Methane associated with coal deposits
*
Landfill gas
Landfill gas is a mix of different gases created by the action of microorganisms within a landfill as they decompose organic waste, including for example, food waste and paper waste. Landfill gas is approximately forty to sixty percent methane, ...
— Methane associated with municipal landfills
References
{{DEFAULTSORT:Associated Petroleum Gas
Fuel gas
Natural gas
sv:Fettgas