Sparta deep water project is a planned offshore oil project in the US Gulf of Mexico. The project, previously known as the North Platte field, was discovered by Cobalt International Energy in 2012.

The offshore field is located in the Garden Banks area of the US Gulf of Mexico in 915, 916, 958, and 959 GB Blocks, in approximately 1,300m (4,265ft) of water depth.

The location is approximately 275km off the coast of Louisiana.

The front-end engineering and design (FEED) for the project, which was launched in December 2019, had matured.

The Sparta field is expected to produce 75,000 barrels of oil per day (bpd) at plateau level. The output will also include associated gas.

Ownership History

Cobalt International Energy had a 60% operating interest in the North Platte discovery, while TotalEnergies (then Total) held the remaining 40% stake.

In April 2018, after Cobalt’s bankruptcy auction sale, Total completed acquiring an additional 20% stake in North Platte and the remaining 40% of Cobalt’s holding in the field was transferred to Equinor (then Statoil).

In February 2022, TotalEnergies announced its decision of withdrawing from the project and relinquished its operatorship.

Shell agreed to acquire 51% interest in the North Platte deep water development in June 2022.

As per the deal, Shell will also become the new operator of the field and Equinor will retain 49% interest in the project. The completion of the transaction is subject to regulatory approval and other customary conditions.

To reflect the change in ownership, Equinor and Shell renamed the North Platte development as the Sparta development.

As of June 2022, the two companies are working together to review the FEED work and update the development plan.

North Platte: Discovery and Appraisal

Cobalt announced a significant oil discovery at North Platte prospect on Garden Banks Block 959 in December 2012.

The well was drilled in 4,400ft of water to a total measured depth of 34,500ft. It encountered more than 550ft of net oil pay. Preliminary hydrocarbon recovery estimate was 350-800 million barrels.

Cobalt planned to drill this prospect in May 2010 and brought ENSCO 8503 drilling rig to the location. However, Cobalt moved the rig off the well location after a moratorium on drilling activity was imposed by the US Department of the Interior in the Gulf.

As part of a two well package including the North Platte, Ensco 8503 returned to the location after two years to commence drilling for Miocene targets on the Lingurian #2 structure.

After discovery, the offshore field has been fully appraised with three drilled wells and multiple sidetracks.

In March 2013, Cobalt confirmed that the North Platte #1 exploratory well encountered more than 550ft of net oil pay in multiple high quality Inboard Lower Tertiary reservoirs.

The North Platte #3 appraisal well also encountered similar oil pay but indicated the presence of a better developed Inboard Lower Tertiary Wilcox reservoirs.

In January 2017, Cobalt announced the completion of drilling operations on the North Platte #4 appraisal well, which encountered approximately 650ft of net oil pay.

Project details

Sparta features a subsalt Paleogene reservoir at a water depth of 9,100m.

In December 2019, TotalEnergies announced that the development plan of the field includes eight subsea wells and two subsea drilling bases.

The wells will be tied back via two production loops to a new semi-submersible Floating Production Unit (FPU). The FPU will be designed to accommodate future tie-ins.

The production, which will include oil and associated gas, will be exported via existing subsea oil and gas networks.

The development of the project will require the use of 20 kpsi technologies.

Contractor Involved

In January 2020, Worley secured the FEED contract for the North Platte Deep Water Development Project. The work was led by Worley’s Houston Office with support from its Hyderabad office in India.

The pre-FEED phase of the project was also completed by Worley in August 2019.