2.

Petroleum activity on the Norwegian Continental Shelf

11
 2. Petroleum activity
on the Norwegian Continental Shelf

In May 1963, the Norwegian govern- ing the 1980s. Only a limited number of nities in the southern part of the North exploration area, new types of reservoirs
ment proclaimed sovereignty over the blocks were announced for each licensing Sea are linked to the chalk reservoirs in have also been discovered during the last
Norwegian continental shelf (NCS). A round, and the most promising areas were this area. The area is a mature petroleum couple of years. These discoveries will be
new act stipulated that the State was explored first. This led to world class dis- province, and the majority of today’s pro- developed together under the name of the
the landowner, and that only the King coveries. duction comes from the Ekofisk, Eldfisk, Johan Sverdrup field. This field might con-
(Government) could grant licences for Currently, 78 fields are in production Tor, Valhall and Hod chalk fields. Together, tain so much oil that it enters the top 10 list
exploration and production. Licences on on the Norwegian continental shelf (NCS). these fields still contain very significant oil of discoveries on the NCS and might prove
the NCS are awarded in mature areas dur- In addition, there are 12 abandoned fields, volumes. Some chalk fields in the area have the biggest discovery here since the 1980s.
ing APA (Awards in Predefined Areas) or all in the North Sea. Production from the been shut down, and some discoveries are The Sleipner field is an important hub for
during ordinary licensing rounds in frontier North Sea has been dominated by large not yet developed. the Norwegian gas transport system, as
areas. The discovery of the Ekofisk field in fields such as Ekofisk, Statfjord, Oseberg, The central part of the North Sea also both UK and the Continental Europe can be
1969 started the Norwegian oil and gas Gullfaks and Troll. These fields have been, has a long history of petroleum activity, reached. In addition, this field has facilities
adventure, and production from the field and still are, very important for the devel- and here discoveries have been made in designed to reduce the CO2 content of the
began 15 June 1971. During the following opment of petroleum activities in Norway. several types of petroleum reservoirs. The gas. For nearly 18 years, CO2 extracted from
years, several large discoveries were made The large field developments have led to first development in the area was the Frigg the Sleipner Vest well stream has been
in the North Sea. In the 1970s exploration the establishment of infrastructure, ena- gas field, which produced for 27 years stored under the seabed, yielding impor-
activity was concentrated in this area, bling tie-in of a number of other fields. before it was shut down in 2004. At the tant experience and knowledge about
but gradually expanded northwards dur- Current production and future opportu- Utsira High, which is considered a mature subsurface storage of CO2. Oil and gas have

Petroleum resources and uncertainty in the estimates for the Norwegian Historical petroleum production of oil and gas, and prognosis for production in
Continental Shelf per 31.12.2013. (Source: Norwegian Petroleum Directorate) coming years (Source: Norwegian Petroleum Directorate)

co2storageATLAS
norwegian continental shelf
12
2. Petroleum activity
on the Norwegian Continental Shelf

been produced in the northern part of the and Ormen Lange field are mature areas pipeline to Kårstø in Rogaland County, and between the fields in the Norwegian
North Sea since the late 1970s. There are with considerable oil and gas production in Haltenpipe to Tjeldbergodden in Møre Sea, and affects how the individual fields
significant remaining reserves and resourc- along with well-developed infrastructure. and Romsdal County. The gas from Ormen are produced. The Vøring area in the
es in the area, both in fields and discov- There are also areas in the Norwegian Sea Lange runs in a pipeline to Nyhamna, Norwegian Sea currently has no infrastruc-
eries. The northern part of the North Sea that have not yet been developed or even which is also in Møre and Romsdal, and ture, but several gas discoveries have been
consists of several petroleum provinces: opened up for exploration activity. Oil further to the United Kingdom. The CO2 made in the area.
with fields like Statfjord, Gullfaks, Snorre, production from the major fields in the content in the gas produced from several The Barents Sea is part of the Arctic
Oseberg and Troll. area is declining. The gas export capacity of these fields is relatively high, and that is Ocean and is considered an immature
The Norwegian Sea was opened for from Haltenbanken, through the Åsgard also the case for some other discoveries in petroleum province. The area covers 1.3
exploration activity in 1980, and the first transport system (ATS), is fully booked for the area. Gas from these fields is therefore million km2, and the water depth varies
field in the area to commence production several decades into the future. This could mixed with gas containing lower amounts between 200 and 500m. The southern part
was Draugen in 1993. A number of fields affect the timing for phase-in of new dis- of CO2 to achieve compliance with gas of the Barents Sea is in general opened for
have since been developed. Several smaller coveries on Haltenbanken. The Norwegian quality requirements. The blending takes petroleum activities, with the first licensing
fields that are located around existing infra- Sea has also been proven to contain signif- place from fields both in the Norwegian round announced in 1979. The first wildcat
structure have been put into production in icant volumes of gas. Produced gas from Sea and from fields located further south. wells in the Barents Sea were spudded in
recent years. Today, the Haltenbanken area the fields is transported through the ATS This process creates interdependence 1980, and the first discovery was made by

Norwegian North Sea, fields and discoveries Norwegian Sea, fields and discoveries Barents Sea, fields and discoveries
(red= gas, green= oil), per March 2014. (red= gas, green= oil) per March 2014. (red= gas, green= oil) per March 2014.

13
 2. Petroleum activity
on the Norwegian Continental Shelf

the third wildcat, 7120/8-1 Askeladd. Upper Triassic to Lower Cretaceous seventh largest exporter of oil and 16° 14° 12° 10° 8° 6° 4° 2° 0° 2° 4° 6° 8° 10° 12°

The biggest gas discovery is 7121/4-1 plays along the Ringvassøya-Loppa the third largest exporter of natural Aasta Hansteen

Snøhvit, drilled in 1984 with Statoil and Bjørnøyrenna fault complexes gas. Oil production declined after

ED
ARL
POL
as operator. The Snøhvit gas field are also relatively unexplored, with a peak in 2001, but it is expected 62° Norne
Skarv Sandnessjøen
started production in 2007 and is only about 16 wildcat wells. More that future production of oil will Åsgard
Kristin
Heidrun 66°

the only field developed so far. The than half of these were dry. The first be relative stable for some years to Draugen

PI PE
gas from Snøhvit is transported to well to test these plays was drilled come. Gas production has increased Faroe Njord

H A LT EN
RT
SPO
Islands
a land terminal at Melkøya, where in 1983, and the first gas discovery, steadily since 1995, and the total Ormen Lange

AN
60° 64°

TR
Tjeldbergodden Trondheim

RD
it is refrigerated into LNG (liquefied 7019/1-1, was made in 2000. This production on the shelf is expected

GA
Nyhamna

ÅS
natural gas) and forwarded by ship. discovery contained gas with a very to stabilize for the next five years. Murchison
Statfjord
Snorre
Visund Gjøa Florø
As in many gas discoveries in the high CO2 content. The North Sea is the most mature Shetland
TAMPEN LINK
Gullfaks Kvitebjørn
Valemon Veslefrikk 62°
Huldra
Norwegian Sea, the CO2 content Today there are 53 active licences area on the NCS with regard to 58°
The Orkneys
Martin Linge Brage
Oseberg OT Troll
S
Mongstad
Stura
Kollsnes
in the Snøhvit area is high. CO2 is in the Barents Sea. Approximately petroleum activity. About 615 wells

S TA
Bergen
Norway

TPI
S Heimdal
AG

PE
FL Beryl
therefore separated from the gas 100 exploration wells have been have been drilled, and the geology
Alvheim l A
LED El

ll B
Grane
TER PIP

IPE
V E S A Edvard Grieg ZEE Kårstø

EP
stream onshore on the Melkøya ter- drilled and they have resulted in is well known. Consequently, there is FUK Brae

ZE
60°
S AG
E Sleipner P IP E Stavanger
St. Fergus Rev S TAT Grenland
Armada Draupner S/E
minal, transported through a 153 km about 35 discoveries. less uncertainty in our estimates of 56° Cruden Bay
Forties

pipeline on the seabed and injected Norway’s gas pipelines have undiscovered resources in the North
Ula Sweden
into the Stø formation in the Snøhvit a total length of about 8000 kilo- Sea than in our estimates for the

ED
L A N ATS
Gyda

GEL
58°

C
Ekofisk

field. The Upper Triassic to Middle metres. The gas flows from pro- Norwegian Sea or the Barents Sea. NORP
IP E Valhall
Hod
54°
Jurassic play in the Hammerfest duction installations to process As seen from the estimates of undis-

EUROPIPE ll
Teesside
Denmark

EURO
Basin is the most thoroughly plants where natural gas liquids covered resources in the NCS, the

P IP E
NOR
56°

l
explored play in the Barents Sea. are separated out and exported seabed offshore Norway still hides

P IP E
Easington
This play has been proved by both by ship. The remaining dry gas is significant volumes of oil and gas. 52°

F R A IP E l
E
N P IP
the Snøhvit discovery and the Goliat piped on to receiving terminals The year 2014 marks the 48th Great

P
Bacton

ZEE
Dornum
Britain Emden

CO NN
oil field, which is currently under in continental Europe and the UK. anniversary of the arrival of Ocean

IN T E O R
54°
Germany

EC T
R-
development with Norwegian Eni as There are four receiving terminals Traveler in Norway and the spudding The
Netherlands
operator. for Norwegian gas on the Continent; of the first well on the Norwegian 50°
Zeebrugge
Existing gas pipeline
Projected gas pipeline
Dunkerque
The Lower to Upper Triassic play two in Germany, one in Belgium Continental Shelf (NCS). Since France Belgium Other pipelines
52°
on the Bjarmeland Platform is less and one in France. In addition, there then, the geological knowledge 2° 0° 2° 4° 6° 8° 10° 12° 14°

explored. The first well to test this are two receiving terminals in the of the shelf has increased greatly. Gas pipelines (NPD 2013)
play was drilled in 1987, and the UK. Norwegian gas is important for Exploration activity on the NCS is
following five wells were dry. In addi- the European energy supply and still high, with extensive seismic sur-
tion, a couple of discoveries were is exported to all the major con- veys and a large number of explora-
significantly smaller than expected. sumer countries in Western Europe. tion wells. Maintaining a high level
Approximately 10 wildcat wells have Norwegian gas export covers close of exploration activity will also be
been drilled and three gas discover- to 20 per cent of European gas con- necessary in the years to come, in
ies made, with 7225/3-1 (Norvarg) as sumption. The transport capacity in order to clarify the potential of the
the largest. The Norvarg discovery the Norwegian pipeline system is undiscovered resources and to make
is encouraging, and the estimate of currently about 120 billion scm per new discoveries which can be
undiscovered resources shows that year. developed.
the play potential remains large. The Norway was in 2012 the world’s

co2storageATLAS
norwegian continental shelf
14
 -50° -40° -30° -20° -10° 0° 10° 20° 30° 40° 50° 60° 70°

Open for petroleum activity

70°
Greenland Svalbard

75°
BARENTS SEA NORTH

Jan Mayen BARENTS SEA SOUTH

65° 70°

Iceland

NORWEGIAN SEA Russia 65°

60°
Faeroe Islands
Finland
Sweden
Shetland

Norway 60°

NORTH
55°
Great Britain SEA

Denmark
0° 10° 20° 30°
Area status for the Norwegian Continental Shelf March 2012 (Source: NPD Facts 2013)

15
 2. Petroleum activity
on the Norwegian Continental Shelf Gas hydrates

Gas hydrates in the Barents Sea phase diagram. The limits of the stability zone are deter- been drilled in the Vestnesa Ridge area west of Spitsbergen,
by Rune Mattingsdal, Alexey Deryabin (NPD) and mined by bottom water temperature, sea level, geothermal and there are good geophysical indications of gas hydrates
professor Arne Graue (UiB) gradient, gas composition and pore water salinity. in the Bjørnøya Basin.
The Barents Sea is a relative deep continental shelf with
Natural gas hydrate is a solid, consisting mostly of methane water depths of up to 500 metres, mainly due to several epi- CO2 storage in hydrates
and water. It form crystals where gas molecules are trapped sodes of glacial erosion. This, combined with bottom water CO2 may be stored in gas hydrates. Exposing methane
in cage-like structures formed by water molecules. Gas temperatures that can be as low as 0°C or colder, results in a hydrate to CO2 will cause a solid exchange of CO2 and CH4
hydrates can be found in Arctic regions below permafrost GHSZ thickness which might vary from a few tens of metres as guest molecules within the hydrate; an exchange caused
and in the marine subsurface at deep water, high pressure to 400 metres, depending on the gas composition and by the fact that it is thermodynamically more favourable for
conditions and low temperatures (typically above 60 bar geothermal gradient (Chand et al, 2008). The figure below water to form hydrates with CO2 than with methane. CO2
and below 100°C). Hydrate is a highly condensed form of shows a modelled GHSZ thickness map. Within this zone, sequestration in hydrates is a win-win process, since associ-
natural gas bound with water; one cubic metre of hydrate gas hydrates can form in areas where there is sufficient flux ated natural gas will be produced as CO2 and is sequestered
corresponds to ca. 160 cubic metres of natural gas at atmo- of thermogenic methane or deposits of biogenic methane. in the form of CO2 hydrates. The regenerated CO2 hydrate is
spheric conditions. The zone where gas hydrates can form In the southwestern Barents Sea, the thickest GHSZ gen- thermodynamically more stable than the methane hydrate;
is referred to as the gas hydrate stability zone (GHSZ). In erally coincide with the deeper parts of the shelf. Here gas thus the replacement of natural gas hydrate with CO2
the marine environment, the GHSZ is located between the hydrates might in theory act as a seal for hydrocarbons in hydrate will increase the stability of hydrate formations.
sea floor and the base of the stability zone defined by the shallow reservoirs. In the Barents Sea, gas hydrates have From an energy perspective, natural gas hydrates may

Seafloor
Depth

GHSZ

BGHSZ

Temperature

Left: Conceptual model of the gas hydrate stability zone (GHSZ) for a marine setting. BGHSZ is the CO2 storage in hydrate formations, as demonstrated in the
bottom of the GHSZ. Right: GHSZ thickness map calculated assuming 96% methane + 3% ethane Alaskan Injection test by ConocoPhillips and USDOE (Courtesy
+ 1% propane and sea water with a geothermal gradient of 31 °C/km, adapted from Chand et al. ConocoPhillips)
(2008). Fields, discoveries, faults and boundaries are indicated.

co2storageATLAS
norwegian continental shelf
16
 2. Petroleum activity
on the Norwegian Continental Shelf Gas hydrates

represent an enormous energy potential (Boswell and Collett Arctic sandstones under
2006). Some authors claim that the total energy of natural gas existing infrastructure (~10’s of Tcf in place)
entrapped in hydrate reservoirs worldwide might be more
than twice the energy of all known coal, oil and gas energy Arctic sandstones away from infrastructure (100s of Tcf in place)
sources. To store CO2 in natural gas hydrate reservoirs by Deep-water sandstones (~1000s of Tcf in place)
replacing the CH4 in the hydrate with CO2 may become very
attractive, compared to other methods of producing natural Non-sandstone marine reservoirs with permeability (unknown)
gas from hydrates. Besides the CO2 storage potential, this Massive surficial and shallow nodular hydrate (unknown)
method benefits from little or no associated brine produc-
Marine reservoirs with limited permeability
tion, which has been a severe limitation in previous attempts (100.000s of Tcf in place)
to produce natural gas from hydrates by depressurization and
heat injection. Another benefit is its ability to maintain the Reserves (200 Tcf )
geomechanical stability to avoid formation collapse or sub- Reserves growth & undiscovered
sidence. A field pilot in Alaska performed by ConocoPhillips (1.500 Tcf recoverable)
and US DOE in 2012 concluded that CO2 was stored and
methane successfully produced during a huff and puff opera- Remaining unrecoverable
(unknown)
tion injecting 200 000 scf of CO2 and nitrogen.
Storage of CO2 as hydrates below the sea floor is a pos-
sible trapping mechanism, but it has not been considered Boswell, R. and Collett, T.S.: "The gas hydrate resource pyramid", Fire in the ice, Netl fall newsletter, 5-7, 2006
here because the long term behaviour of such hydrates in
shallow sediments is not well known. It should be noted that
within the gas hydrate stability zone, a seepage of CO2 will be
trapped as hydrates before reaching the sea floor.

100 10000
Phase diagram for water, methane
and CO2. The scale to the right
shows approximate water depth con-
verted from the pressure scale. CO2
Stable CO2 and CH4 hydrate
hydrate is more stable than methane
Stable CH4 hydrate hydrate at depths shallower than
10 1000
700 m. The blue line shows pressure
and temperature below the sea bed
assuming a sea water temperature of
Pressure (MPa)

2 oC and a gradient of 40 oC/km.

Stable CO2 hydrate

Gas and water

0.1 10 m
-5 0 5 10 15
Temperature oC

Natural Gas Hydrate on Fire; "Fiery Ice" (Courtesy USGS)

17