Groningen gas field
Encyclopedia
The Groningen gas field is a giant natural gas field
located near Slochteren
in Groningen province
in the northeastern part of the Netherlands
. Discovered in 1959, it is the largest natural gas field in Europe
and the tenth largest in the world.
sandstone formation, which is 130 metres (426.5 ft) to 140 metres (459.3 ft) thick and 45 kilometres (28 mi) long from north to south by 25 kilometres (15.5 mi) long from east to west. The field started production in 1963 and produced around 100 billion cubic meters (3.57 trillion cubic feet) per year in the first decade of production but gradually the annual production fell to around 35 billion cubic meters (1.25 trillion cubic feet) per year. the Groningen gas field has produced around 1,700 billion cubic meters (60.7 trillion cubic feet) which represents 60% of the total reserves of the field but the remaining 1,100 billion cubic meters (39.3 trillion cubic feet) are expected to last for another 50 years.
The Groningen gas field is operated by the Nederlandse Aardolie Maatschappij BV (NAM), a joint venture between Royal Dutch Shell
and ExxonMobil
with each company owning a 50% share. The field accounts for 50% of the natural gas
production in the Netherlands
, the other 50% being supplied by around 300 smaller gas fields, most of them located offshore in the North Sea
.
, which extends from the eastern coast of England to Poland. Within this area large volumes of gas have been discovered, mainly reservoired in the Rotliegend sandstone, with producing fields in England, the Netherlands, Germany, Denmark and Poland.
), Rotliegend
Slochteren sandstone. The Rotliegend reservoir at Groningen is mainly an aeolian sand
with local development of fluvial
wadi
sands.
Porosities
lie generally in the range 15–20% with permeabilities in the range 0.1–3000 mD
.
for the gas at Groningen are coals and carbonaceous shales within the Westphalian coal measures sequence
that lies unconformably
beneath the Rotliegend. These sources are dominated by type III kerogen
.
, particularly during the Late Jurassic
to early Cretaceous
. It has an overall horst
geometry, lying between the Ems Graben to the east and the Lauwerszee Trough to the west.
evaporite sequence, consisting of carbonate, anhydrite
and halite
, which provides an effective seal to the gas accumulations within the underlying sandstone.
Natural gas field
Oil and natural gas are produced by the same geological process according fossil fuel suggestion: anaerobic decay of organic matter deep under the Earth's surface. As a consequence, oil and natural gas are often found together...
located near Slochteren
Slochteren
Slochteren is a municipality in the northeastern Netherlands.The municipality can be characterized as a chain of small villages dividing a mostly agricultural landscape. Having an agricultural background for at least a thousand years, the community houses for the most part commuters to nearby...
in Groningen province
Groningen (province)
Groningen [] is the northeasternmost province of the Netherlands. In the east it borders the German state of Niedersachsen , in the south Drenthe, in the west Friesland and in the north the Wadden Sea...
in the northeastern part of the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
. Discovered in 1959, it is the largest natural gas field in Europe
Giant oil and gas fields
The world's 932 giant oil and gas fields are considered those with of ultimately recoverable oil or gas equivalent. Geoscientists believe these giants account for 40 percent of the world's petroleum reserves. They are clustered in 27 regions of the world, with the largest clusters in the Persian...
and the tenth largest in the world.
History
After two previous unsuccessful wells were commissioned to search for oil and gas, on July 22, 1959, the Slochteren 1 well, drilling to a depth of 3000 metres (9,842.5 ft), discovered the huge 2.8 trillion cubic meters (100 trillion cubic feet) gas field in the porous RotliegendRotliegend
The Rotliegend or Rotliegendes is a lithostratigraphic unit of Cisuralian age that is found in the subsurface of large areas in western and central Europe. The Rotliegend mainly consists of sandstone layers...
sandstone formation, which is 130 metres (426.5 ft) to 140 metres (459.3 ft) thick and 45 kilometres (28 mi) long from north to south by 25 kilometres (15.5 mi) long from east to west. The field started production in 1963 and produced around 100 billion cubic meters (3.57 trillion cubic feet) per year in the first decade of production but gradually the annual production fell to around 35 billion cubic meters (1.25 trillion cubic feet) per year. the Groningen gas field has produced around 1,700 billion cubic meters (60.7 trillion cubic feet) which represents 60% of the total reserves of the field but the remaining 1,100 billion cubic meters (39.3 trillion cubic feet) are expected to last for another 50 years.
The Groningen gas field is operated by the Nederlandse Aardolie Maatschappij BV (NAM), a joint venture between Royal Dutch Shell
Royal Dutch Shell
Royal Dutch Shell plc , commonly known as Shell, is a global oil and gas company headquartered in The Hague, Netherlands and with its registered office in London, United Kingdom. It is the fifth-largest company in the world according to a composite measure by Forbes magazine and one of the six...
and ExxonMobil
ExxonMobil
Exxon Mobil Corporation or ExxonMobil, is an American multinational oil and gas corporation. It is a direct descendant of John D. Rockefeller's Standard Oil company, and was formed on November 30, 1999, by the merger of Exxon and Mobil. Its headquarters are in Irving, Texas...
with each company owning a 50% share. The field accounts for 50% of the natural gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
production in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
, the other 50% being supplied by around 300 smaller gas fields, most of them located offshore in the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
.
Regional setting
The Groningen field lies within the Southern Permian BasinPermian Basin (Europe)
The European Permian Basin is a thick sequence of sedimentary rocks deposited in a large sedimentary basin during the Permian period in North Europe. The basin underlies northern Poland, northern Germany, Denmark, The Netherlands and under a significant portion of the North Sea to Scotland...
, which extends from the eastern coast of England to Poland. Within this area large volumes of gas have been discovered, mainly reservoired in the Rotliegend sandstone, with producing fields in England, the Netherlands, Germany, Denmark and Poland.
Reservoir
The main reservoir in the Groningen field is the Cisuralian (Lower PermianPermian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
), Rotliegend
Rotliegend
The Rotliegend or Rotliegendes is a lithostratigraphic unit of Cisuralian age that is found in the subsurface of large areas in western and central Europe. The Rotliegend mainly consists of sandstone layers...
Slochteren sandstone. The Rotliegend reservoir at Groningen is mainly an aeolian sand
Aeolian
Aeolian or Eolian may refer to:* things related to Aeolus, the Greek God of wind or the patriarch of Greeks of Aeolia* Aeolian harp, a harp that is played by the wind* Aeolian processes, wind generated geologic processes...
with local development of fluvial
Fluvial
Fluvial is used in geography and Earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them...
wadi
Wadi
Wadi is the Arabic term traditionally referring to a valley. In some cases, it may refer to a dry riverbed that contains water only during times of heavy rain or simply an intermittent stream.-Variant names:...
sands.
Porosities
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
lie generally in the range 15–20% with permeabilities in the range 0.1–3000 mD
Darcy
A darcy and millidarcy are units of permeability, named after Henry Darcy. They are not SI units, but they are widely used in petroleum engineering and geology. Like other measures of permeability, a darcy has the same units as area.-Definition:Permeability measures the ability of fluids to...
.
Source
The main source rockSource rock
In petroleum geology, source rock refers to rocks from which hydrocarbons have been generated or are capable of being generated. They form one of the necessary elements of a working petroleum system. They are organic-rich sediments that may have been deposited in a variety of environments including...
for the gas at Groningen are coals and carbonaceous shales within the Westphalian coal measures sequence
Westphalian (stage)
The Westphalian is a stage in the regional stratigraphy of northwest Europe with an age between roughly 313 and 304 Ma . It is a subdivision of the Carboniferous system or period and the regional Silesian series. The Westphalian is named for the region of Westphalia in western Germany where strata...
that lies unconformably
Unconformity
An unconformity is a buried erosion surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval of time before deposition of the younger, but the term is used to describe...
beneath the Rotliegend. These sources are dominated by type III kerogen
Kerogen
Kerogen is a mixture of organic chemical compounds that make up a portion of the organic matter in sedimentary rocks. It is insoluble in normal organic solvents because of the huge molecular weight of its component compounds. The soluble portion is known as bitumen. When heated to the right...
.
Trap
The Groningen structure is a NNW-SSE trending intrabasinal high formed by normal faulting during the MesozoicMesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
, particularly during the Late Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
to early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. It has an overall horst
Horst
Horst is a Germanic word meaning "eagle's nest" and "man from the forest" . It may refer to:-Given name:* Horst * Horst Buchholz, a German actor* Horst Bulau, a Canadian ski jumper...
geometry, lying between the Ems Graben to the east and the Lauwerszee Trough to the west.
Seal
The Rotliegend is covered by the Late Permian ZechsteinZechstein
The Zechstein is a unit of sedimentary rock layers of Middle to Late Permian age located in the European Permian Basin which stretches from the east coast of England to northern Poland...
evaporite sequence, consisting of carbonate, anhydrite
Anhydrite
Anhydrite is a mineral – anhydrous calcium sulfate, CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium and strontium sulfates, as might be expected from the...
and halite
Halite
Halite , commonly known as rock salt, is the mineral form of sodium chloride . Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount and type of impurities...
, which provides an effective seal to the gas accumulations within the underlying sandstone.