Erskine

Location and Discovery

The Erskine oil and gas field is located in the North Sea, approximately 150 miles east of Aberdeen, within blocks 23/26a and 23/26b of the U.K. Continental Shelf. The field was originally discovered in 1981 during the drilling of a north/south trending Jurassic sandstone reservoir.

Geology and Reserves

The Erskine field is characterized by three separate but generally overlying sandstone-producing horizons. The reservoir is a Jurassic sandstone, and the field's western flank, known as the beta terrace, remains unexplored. The well fluids present technical challenges, containing up to 33 ppm H2S, 5.5 mole % CO2, and 90,000 ppm chlorides, along with condensate that contains approximately 10% wt of wax-forming compounds.

Development History

The development of the Erskine field was delayed due to several factors, including the lack of export infrastructure, uncertainty about the field size, and technical concerns related to the well fluids and extreme downhole environment. The field's development was reconsidered in the early 1990s following changes to the Petroleum Revenue Tax rules and efficiencies from the CRINE initiative. Texaco, which later became part of Chevron, decided to proceed with the development.

• Infrastructure: The field uses a four-leg vertical tower steel jacket with pile foundations, designed to accommodate 12 wells. The jacket was installed in just nine months, following a fast-track program. The topsides facilities are specially adapted for high-pressure/high-temperature (HP/HT) service and remain unmanned to minimize personnel exposure to safety risks.
• Wells and Drilling: Six wells were drilled on a north/south trending line through the maximum thickness of the reservoir. Three of these wells were drilled before the field went on-stream to avoid the high cost of a platform rig.

Production and Export

• Production Rates: The field design production rates are 117 million cubic feet per day of gas and 30,650 barrels per day of fluids.
• Export: The Erskine platform is tied back to the Amoco Lomond platform 30 kilometers away via a 16-inch nominal bore multiphase pipeline. Gas and oil are transported into the existing CATS gas pipeline and the Forties liquids pipeline system, respectively.

Technological Innovations

The Erskine field is notable for several technological firsts:

• It was the first high-pressure, high-temperature (HPHT) field to be developed in the U.K. Continental Shelf.
• It was among the first platforms to implement full-scale NUI HP/HT wire line interventions from a mast rig, boat to platform coil tubing activities, and NUI HPHT deep hole coiling tubing activities. It also introduced the "Walk to Work" concept in the Central North Sea.

Current Operations

As of recent years, the Erskine field has celebrated significant milestones:

• 20th Anniversary: In 2017, Chevron marked 20 years since oil and gas first flowed from the Erskine field.
• 25th Anniversary: In 2022, Ithaca Energy, which now operates the field, celebrated the 25th year of production from the Erskine platform.
• Current Production: Net daily production from Erskine averaged 2,215 barrels of liquids and 13.92 million cubic feet of natural gas in recent years.

Partners and Ownership

The Erskine field is operated by Ithaca Energy, with partners including Serica Energy and Chrysaor. The ownership structure is as follows: Chevron (previously the operator) held 50%, Serica Energy holds 18%, and Chrysaor holds 32%.

Health, Safety, and Collaboration

The Erskine field is known for its commitment to health and safety, as well as its collaborative approach with various co-venturers. This collaboration has been pivotal in deploying new technologies and solving operational challenges over the years.