Ula

Ula Oil Field Profile

Location and Geology

The Ula oil field is located in the southern part of the Norwegian sector of the North Sea, specifically in block 7/12 (PL019A), at a water depth of approximately 70 meters (230 feet).

The main reservoir is situated at a depth of 3,345 meters in the Upper Jurassic Ula Formation sandstone. Additionally, there is production from the underlying Triassic reservoir at a depth of 3,450 meters, which is characterized as a tight sandstone reservoir with low effective permeability.

Discovery and Production History

The Ula field was discovered in 1976 by the 7/12-2 discovery well. The Plan for Development and Operation (PDO) was approved in 1980, and production commenced in October 1986.

Ownership and Operation

Aker BP operates the field with an 80% interest, while DNO Norge (previously DONG Energy) holds the remaining 20%. DNO Energy increased its stake from 5% to 20% by acquiring Svenska Petroleum's 15% share in 2008.

Infrastructure and Facilities

The Ula field development includes three conventional steel facilities:

• Drilling Platform: Built by Aker Verdal, installed in June 1985.
• Production and Processing Platform: Built by Kværner Brug Steel, installed in June 1985.
• Accommodation Platform: Built by Dragados Y Construcciones, installed in June 1985. These platforms are interconnected by bridges.

Production and Recovery Methods

Initially, oil recovery was achieved through pressure depletion. Later, water injection was implemented to improve recovery. In 1998, Water Alternating Gas (WAG) injection was introduced to further enhance oil recovery. The WAG program has been extended with gas from the Tambar field since 2001, Blane since 2007, and Oda since 2019. Gas lift is also used in some wells.

Reserves and Production

The Ula field has total recoverable reserves estimated at:

• 550 million barrels of oil
• 3.9 billion standard cubic meters (bscm) of gas
• 3.3 million tonnes of natural gas liquids (NGL).

As of 2021, Ula and Tambar have produced nearly 600 million barrels of oil equivalent. In 2022, the net production to Aker BP averaged 3,000 barrels of oil equivalent per day (mboepd).

Current Status and Future Plans

The Ula field is currently in its late-life phase and is expected to produce until 2028, when the production license is set to expire. Planning for field cessation and environmental impact assessments have been initiated, with the removal of installations expected in the years following 2028.

Production Hub

Ula serves as a production hub for the Tambar, Oda, and Blane fields. The Tambar/Tambar East satellite fields are remotely controlled from Ula, while Oda and Blane are developed with subsea structures.

Transportation

The oil produced is transported via a pipeline to the Ekofisk field and then to Teesside in the UK for refining.

Enhanced Oil Recovery (EOR)

The field has significantly benefited from EOR measures, particularly the WAG program, which has extended the field's lifetime and increased recovery beyond initial estimates. The positive effect of WAG has led to the drilling of additional WAG wells.

Environmental and Cessation Plans

Aker BP has proposed an Environmental Impact Assessment (EIA) program to cease operations at the Ula and Tambar fields at the end of their production licenses in 2028. Planning for the removal of the installations is underway.