75

EkofiskBlocks and production licences

Block 2/4 - production licence 018, awarded 1965

Development approval 01.03.1972On stream 15.06.1971 Discovered 1969Operator ConocoPhillips Skandinavia ASLicensees ConocoPhillips Skandinavia AS 35.11 %

Eni Norge AS 12.39 %Petoro AS 5.00 %Statoil Petroleum AS 7.60 %Total E&P Norge AS 39.90 %

Recoverable reserves Original Remaining as of 31.12.2010534.6 million scm oil 111.2 million scm oil158.1 billion scm gas 18.8 billion scm gas14.7 million tonnes NGL 2.0 million tonnes NGL

Estimated prod. in 2011 Oil: 161 000 barrels/day, Gas: 1.6 billion scm, NGL: 0.20 million tonnes

Expected investment Total NOK 189.4 billion (2011 values)As of 31.12.2010 NOK 146.7 billion have been invested (2011 values)Main supply base Tananger

Development: Ekofisk is an oil field located in the southern part of the North Sea. The water depth in the area is 70 - 75 metres. The field was initially produced to tankers until a concrete storage tank was installed in 1973. Since then, the field has been further developed with many facilities, including riser facilities for associated fields and export pipelines. Several of these have been decommissioned and are awaiting disposal. Today, the operative parts of the Ekofisk Centre consist of the accommodation facili-ties, Ekofisk H and Ekofisk Q, the production facility Ekofisk C, the drilling and production facility Ekofisk X, the processing facility Ekofisk J and the production and processing facility Ekofisk M. From the wellhead facility Ekofisk A, located in the southern part of the field, production goes to the riser facility Ekofisk FTP for processing at the Ekofisk Centre. The pipe-line from Ekofisk B in the northern part of the field is routed to Ekofisk M. Ekofisk K is a facility for water injection. A plan for water injection at Ekofisk was approved on 20.12.1983, a PDO for Ekofisk II was approved on 09.11.1994 and a PDO for Ekofisk Growth was approved on 06.06.2003. In June 2008 a subsea template for water injection wells was approved. These have replaced the water injection at Ekofisk W, which is no longer in use. In March 2010, the new accommodation facility, Ekofisk L, was approved. This will replace Ekofisk H and Ekofisk Q. Ekofisk L will be in operation from autumn 2013. Permanent cables have been installed on the seabed over the Ekofisk reservoir for acquisition of seismic data.

Reservoir: The Ekofisk field produces from naturally fractured chalk of the Ekofisk and Tor Formations of Early Paleocene and Late Cretaceous ages. The reservoir rocks have high porosity, but low permeability. The reservoir has an oil column of more than 300 metres and lies 2 900 - 3 250 metres below sea level.

Ekofisk

0

10

20

30

0

10

20

30

1970 1975 1980 1985 1990 1995 2000 2005 2010

GasOil,condensate,NGL

Mill.

scm

o.e

.

Recovery strategy: Ekofisk was originally developed by pressure depletion and had an expected recovery factor of 17 per cent. Since then, limited gas injection and comprehensive water injection have contributed to a substantial increase in oil recovery. Large scale water injection started in 1987, and in subsequent years the water injection area has been extended in several phases. Experience has proven that water displacement of the oil is more effective than expected, and the expected recovery factor for Ekofisk is now approximately 50 per cent. In addition to the water injection, compaction of the soft chalk provides extra force to the drainage of the field. The reservoir compaction has resulted in subsidence of the seabed, which is now more than 9 metres in the central part of the field. It is expected that the subsidence will continue for many years, but at a lower rate.

Transport: Oil and gas are routed to export pipelines via the processing facility at Ekofisk J. Gas from the Ekofisk area is transported via the Norpipe Gas pipeline to Emden, while the oil, which also contains NGL fractions, is sent via the Norpipe Oil pipeline to Teesside.

Status: Production from Ekofisk is maintained at a high level through continuous drilling of water injection and production wells from several facilities. A PDO for Ekofisk South was submitted to the authorities in February 2011. The project includes two new installations, Ekofisk Z which is a production facility, and Ekofisk VB, a subsea template for water injection wells.

TOR2/4E

COD7/11 A

ALBUSKJELL1/6 A

2/4 F

Edda2/7 C

37/4 A

36/22 A

2/4 B2/4 S

2/4 G 2/4 T2/4 H 2/4 C

2/4 Q2/4 FTP

2/4 W

2/4 X

2/4 M

2/4 J

2/4 AB-11

H-7

EMBLA2/7 D

ELDFISK

2/7 B

2/7 A

2/7 E

2/7 FTP

2/4 K

EKOFISK

ULA GYDA

WESTEKOFISK

2/4 D

Oil toTeesside

Gas toEmden

September 2009 Closed installations Third party installations

VA

LHA

LL and HO

D

VA

LHA

LL and HO

D

Figure 10.8 Facilities in the Ekofisk area(Source: ConocoPhillips)