Gas reinjection

Last updated

Gas reinjection is the reinjection of natural gas into an underground reservoir, typically one already containing both natural gas and crude oil, in order to increase the pressure within the reservoir and thus induce the flow of crude oil or else sequester gas that cannot be exported. This is not to be confused with gas lift, where gas is injected into the annulus of the well rather than the reservoir. After the crude has been pumped out, the natural gas is once again recovered. Since many of the wells found around the world contain heavy crude, this process increases their production. The basic difference between light crude and heavy crude is its viscosity and pumpability—the lighter the crude the easier it is to pump. Recovery of hydrocarbons in a well is generally limited to 50% (heavy crudes) and 75–80% (light crudes). Recycling of natural gas or other inert gases causes the pressure to rise in the well, thus causing more gas molecules to dissolve in the oil lowering its viscosity and thereby increasing the well's output. Air is not suitable for repressuring wells because it tends to cause deterioration of the oil, thus carbon dioxide or natural gas is used to repressure the well. The term 'gas-reinjection' is also sometimes referred to as repressuring—the term being used only to imply that the pressure inside the well is being increased to aid recovery.

Injection or reinjection of carbon dioxide also takes place in order to reduce the emission of CO2 into the atmosphere, a form of carbon sequestration. This has been proposed as a method to combat climate change, allowing mass storage of CO2 over a geological timescale. Reinjection of carbon dioxide in the Norwegian Sleipner gas field saves the operators 1 million Norwegian Kroners per day in national carbon taxes.

Listen to this article (3 minutes)
noicon
Sound-icon.svg
This audio file was created from a revision of this article dated 20 December 2012 (2012-12-20), and does not reflect subsequent edits.

Related Research Articles

Petroleum Naturally occurring hydrocarbon liquid found underground

Petroleum, also known as crude oil and oil, is a naturally occurring, yellowish-black liquid found in geological formations beneath the Earth's surface. It is commonly refined into various types of fuels. Components of petroleum are separated using a technique called fractional distillation, i.e., separation of a liquid mixture into fractions differing in boiling point by means of distillation, typically using a fractionating column. It consists of naturally occurring hydrocarbons of various molecular weights and may contain miscellaneous organic compounds. The name petroleum covers both naturally occurring unprocessed crude oil and petroleum products that are made up of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, mostly zooplankton and algae, are buried underneath sedimentary rock and subjected to both intense heat and pressure.

Oil well Well drilled to recover hydrocarbons

An oil well is a boring in the Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may be termed a gas well. Wells are created by drilling down into an oil or gas reserve that is then mounted with an extraction device such as a pumpjack which allows extraction from the reserve. Creating the wells can be an expensive process, costing at least hundreds of thousands of dollars, and costing much more when in hard to reach areas, i.e. when creating offshore oil platforms. The process of modern drilling for wells first started in the 19th century, but was made more efficient with advances to oil drilling rigs during the 20th century.

Fuel oil Petroleum product burned to generate power

Fuel oil is a fraction obtained from the distillation of petroleum. It includes distillates and residues.

Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure.

In the oil industry, waterflooding or water injection is where water is injected into the oil reservoir, to maintain the pressure, or to drive oil towards the wells, and thereby increase production. Water injection wells may be located on- and offshore, to increase oil recovery from an existing reservoir.

Repressuring is the method by which the pressure inside a crude oil well is increased so as to increase the output of the well. Pumping crude oil from a reservoir causes its pressure to drop, which further reduces pumpability. Returning the natural gas or other inert gases to the oil well increases the pumpability of the crude present inside the well by decreasing its viscosity and density. In one instance, slower rate of oil production and recycling of natural gas at 9.6 MPa enabled a net recovery of 70% of the oil originally present.

Unconventional oil is petroleum produced or extracted using techniques other than the conventional method. Industry and governments across the globe are investing in unconventional oil sources due to the increasing scarcity of conventional oil reserves. Unconventional oil and gas have already made a dent in international energy linkages by reducing US energy import dependency.

Heavy crude oil is highly-viscous oil that cannot easily flow from production wells under normal reservoir conditions.

Petroleum reservoir Subsurface pool of hydrocarbons

A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations.

Enhanced oil recovery, also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using primary and secondary recovery. According to the US Department of Energy, carbon dioxide and water are injected along with one of three EOR techniques: thermal injection, gas injection, and chemical injection. More advanced, speculative EOR techniques are sometimes called quaternary recovery.

Steam-assisted gravity drainage is an enhanced oil recovery technology for producing heavy crude oil and bitumen. It is an advanced form of steam stimulation in which a pair of horizontal wells is drilled into the oil reservoir, one a few metres above the other. High pressure steam is continuously injected into the upper wellbore to heat the oil and reduce its viscosity, causing the heated oil to drain into the lower wellbore, where it is pumped out. Dr. Roger Butler, engineer at Imperial Oil from 1955 to 1982, invented the steam assisted gravity drainage (SAGD) process in the 1970s. Butler "developed the concept of using horizontal pairs of wells and injected steam to develop certain deposits of bitumen considered too deep for mining". In 1983 Butler became director of technical programs for the Alberta Oil Sands Technology and Research Authority (AOSTRA), a crown corporation created by Alberta Premier Lougheed to promote new technologies for oil sands and heavy crude oil production. AOSTRA quickly supported SAGD as a promising innovation in oil sands extraction technology.

Carbon dioxide flooding

Carbon dioxide (CO2) flooding is a process whereby carbon dioxide is injected into oil reservoirs in order to increase output when extracting oil, especially in reservoirs where production rates have declined over time. The process was first attempted in 1977 in Scurrey County, Texas. Since then, the process has become extensively used in the Permian basin region of the US and is now more recently begun to be pursued in many different states, but still remains fairly uncommon outside of the United States.

Artificial lift refers to the use of artificial means to increase the flow of liquids, such as crude oil or water, from a production well. Generally this is achieved by the use of a mechanical device inside the well or by decreasing the weight of the hydrostatic column by injecting gas into the liquid some distance down the well. A newer method called Continuous Belt Transportation (CBT) uses an oil absorbing belt to extract from marginal and idle wells. Artificial lift is needed in wells when there is insufficient pressure in the reservoir to lift the produced fluids to the surface, but often used in naturally flowing wells to increase the flow rate above what would flow naturally. The produced fluid can be oil, water or a mix of oil and water, typically mixed with some amount of gas.

Extraction of petroleum

The extraction of petroleum is the process by which usable petroleum is drawn out from beneath the earth's surface location.

History of the petroleum industry in Canada (oil sands and heavy oil)

Canada's oil sands and heavy oil resources are among the world's great petroleum deposits. They include the vast oil sands of northern Alberta, and the heavy oil reservoirs that surround the small city of Lloydminster, which sits on the border between Alberta and Saskatchewan. The extent of these resources is well known, but better technologies to produce oil from them are still being developed.

Steam injection (oil industry)

Steam injection is an increasingly common method of extracting heavy crude oil. It is considered an enhanced oil recovery (EOR) method and is the main type of thermal stimulation of oil reservoirs. There are several different forms of the technology, with the two main ones being Cyclic Steam Stimulation and Steam Flooding. Both are most commonly applied to oil reservoirs, which are relatively shallow and which contain crude oils which are very viscous at the temperature of the native underground formation. Steam injection is widely used in the San Joaquin Valley of California (US), the Lake Maracaibo area of Venezuela, and the oil sands of northern Alberta (Canada).

Sleipner gas field

The Sleipner gas field is a natural gas field in the block 15/9 of the North Sea, about 250 kilometres (160 mi) west of Stavanger, Norway. Two parts of the field are in production, Sleipner West, and Sleipner East (1981). The field produces natural gas and light oil condensates from sandstone structures about 2,500 metres (8,200 ft) below sea level. It is operated by Equinor. The field is named after the steed Sleipnir in Norse mythology.

Heavy oil production is a developing technology for extracting heavy oil in industrial quantities. Estimated reserves of heavy oil are over 6 trillion barrels, three times that of conventional oil and gas.

The Batı Raman oil field (batı meaning west in Turkish) is located in Batman Province, in the Southeastern Anatolia Region of Turkey. With estimated reserves of 1.85 billion barrels (252×106 tonnes) and a production rate of around 7,500 barrels per day (1,190 m3/d) from 300 wells (as of 2007), it is the largest and most productive oil field in Turkey.

The Weyburn-Midale Carbon Dioxide Project is, as of 2008, the world's largest carbon capture and storage project. It is located in Midale, Saskatchewan, Canada.