US supermajor ExxonMobil could drill between 41 and 67 development wells to place the Yellowtail oil discovery on stream via the largest floating production, storage and offloading vessels to be deployed offshore Guyana to date.

The Greater Yellowtail area, comprising the Yellowtail-1, Yellowtail-2 and Redtail-1 finds, will provide a location for the fourth FPSO to be installed in the prolific Stabroek block, estimated to hold about 10 billion barrels of oil equivalent in recoverable resources, with exploration still continuing.

According to an environmental impact assessment study submitted to Guyanese regulators, ExxonMobil is looking at locations for scores of wells in Yellowtail, with the campaign scheduled to run from mid-2023 through 2032.

The EIA study included 67 possible locations, although permitting more wells than are actually executed is an acceptable strategy.

The company said development drilling operations may start as early as next year.

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ExxonMobil is currently undergoing pre-front-end engineering and design studies regarding the Yellowtail FPSO, which will feature topsides modules with processing capacity of 250,000 barrels per day of oil and 450 million cubic feet per day of natural gas.

The proposed floater is expected to produce first oil by the end of 2025 or early 2026, with operations continuing for at least 20 years.

“The FPSO will be new-built with double-hull protection, with the capacity to store 2 million barrels of stabilised crude oil,” said ExxonMobil.

Industry sources have previously suggested Netherlands-based SBM Offshore and Japan’s Modec are competing for the FPSO contract.

The subsea layout for the Yellowtail development will encompass six drilling centres, each equipped with separate oil production, water injection and gas injection wells linked to the spread-moored FPSO, to be situated at water depths between 1700 and 1900 metres.

ExxonMobil intends to use several drillships for the campaign.

The company currently has six such units on hire in Guyana, comprising four from Noble Corporation and two from Stena Drilling.

ExxonMobil is already producing from Stabroek via the Liza Destiny FPSO and intends to have two more floaters – Liza Unity and Prosperity – on stream in the Liza and Payara fields in 2022 and 2024, respectively. All three FPSOs are supplied by SBM.

The Liza Unity FPSO arrived in Guyanese waters on 26 October after travelling for about 53 days from Singapore, said the country’s Ministry of Natural Resources.

When the Yellowtail project comes on line in 2025, ExxonMobil will have four FPSOs in production in Guyana with a combined processing capacity of more than 800,000 bpd.