89

Recovery strategy: The Oseberg field produces by pressure main-tenance with the injection of both gas and water, and by water alterna-ting gas injection (WAG). Massive up-flank gas injection in the main field has provided excellent oil displacement, and a large gas cap has now developed which will be recovered in the future. Injection gas was previously imported from Troll Øst (TOGI) and Oseberg Vest. Small parts of the field produce by pressure depletion.

Transport: The oil is sent through the Oseberg Transport System (OTS) to the Sture terminal. Gas export began in 2000 through a pipeline, Oseberg Gas Transport (OGT), to the Statpipe system via the Heimdal facility.

Status: The challenge on Oseberg will be to produce the remaining oil below the gas cap, and to balance the gas offtake with regard to oil recovery from the field. A module for low pressure production has been installed at the Oseberg Field Centre and the compressor has been upgraded. In addition, upgrades of the drilling facilities on Oseberg B and C are ongoing. Test production is ongoing from an overlying chalk reservoir in the Shetland Group on the Oseberg field to evaluate the flow characteristics.

Oseberg SørBlocks and production licences

Block 30/12 - production licence 171 B, awarded 2000Block 30/9 - production licence 079, awarded 1982Block 30/9 - production licence 104, awarded 1985

Development approval 10.06.1997 by the StortingOn stream 05.02.2000 Discovered 1984Operator Statoil Petroleum ASLicensees ConocoPhillips Skandinavia AS 2.40 %

ExxonMobil Exploration & Production Norway AS

4.70 %

Petoro AS 33.60 %Statoil Petroleum AS 49.30 %Total E&P Norge AS 10.00 %

Recoverable reserves Original Remaining as of 31.12.201052.6 million scm oil 13.0 million scm oil11.8 billion scm gas 5.7 billion scm gas1.5 million tonnes NGL 1.5 million tonnes NGL

Estimated prod. in 2011 Oil: 32 000 barrels/day, Gas: 0.45 billion scm, NGL: 0.15 million tonnes

Expected investment Total NOK 26.6 billion (2011 values)As of 31.12.2010 NOK 22.5 billion have been invested (2011 values)Main supply base Mongstad

Development: Oseberg Sør is an oil field located south of Oseberg in the northern part of the North Sea. The water depth in the area is appro-ximately 100 metres. The field has been developed with an integrated steel facility with accommodation, drilling module and first-stage separa-tion of oil and gas. In addition, several deposits included in the Oseberg Sør field have been developed with subsea templates tied back to the Oseberg Sør facility. Final processing of oil and gas takes place on the Oseberg Field Centre. The development of the Oseberg Sør J structure was approved on 15.05.2003 and production started in November 2006.

Reservoir: Oseberg Sør consists of several deposits with Jurassic sand-stone reservoirs. The reservoir depth is between 2 200 - 2 800 metres. The main reservoirs are in the Tarbert and Heather Formations. The reservoir quality is moderate.

Recovery strategy: Recovery mainly takes place by water and gas injec-tion. In parts of the field water alternating gas injection (WAG) is being used. Water used for injection is produced from the Utsira Formation.

Transport: The oil is transported from the Oseberg Sør facility by pipe-line to the Oseberg Field Centre where it is processed and transported through Oseberg Transport System (OTS) to the Sture terminal. The gas is transported via Oseberg Gas Transport (OGT) to Statpipe.

Status: Optimal use of available gas for re-injection and a strategy for blowdown of the Oseberg Sør reservoirs are evaluated. A strategy to combine smaller prospects and discoveries into clusters large enough to trigger new infrastructure has been established. The discovery 30/9-22 (Katla) proven in 2009 is being developed with direct tie-back to the Oseberg Sør facility.

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2000 2005 2010

Oseberg Sør

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