The Exxon Mobil Corp.-led consortium has added to its oil discovery tally offshore Guyana with news Sept. 8 of the 18th find on the Stabroek Block along with more reservoir intervals at another well.

The latest discovery, which builds on gross discovered recoverable resources of more than estimated 8 billion barrels of oil equivalent, was made at the Redtail-1 well. Drilled by the Noble Don Taylor in about 6,164 ft of water about 1.5 miles northwest of the Yellowtail discovery, the well hit about 232 ft of high-quality oil-bearing sandstone, Exxon Mobil said in a news release.

“Our Stabroek Block exploration program continues to identify high-quality reservoirs in close proximity to previous discoveries, establishing efficient opportunities for new projects in Guyana,” Mike Cousins, senior vice president of exploration and new ventures at ExxonMobil, said in the release. “Developing these projects remains an integral part of ExxonMobil and our co-venturers’ long-term growth plans and a source of significant value for Guyana.”

In addition to the Redtail-1 discovery, the company said it hit 69 ft of net pay in new reservoir intervals at the Yellow-1 discovery. Exxon and partners are evaluating the resource for development along with other discoveries nearby.

Exxon operates the block alongside partners Hess Corp. and China’s CNOOC Ltd.

“The Redtail-1 and Yellowtail-2 discoveries further demonstrate the significant exploration potential of the Stabroek Block and will add to the recoverable resource estimate of more than 8 billion barrels of oil equivalent,” CEO John Hess said in a separate release. “Redtail is the ninth discovery in the southeast area of the block which we expect will underpin future development.”

Word of the additional resources follows news of the Uaru discovery announced in January and Yellowtail-1 in July. It also comes as the consortium continues to advance other developments on the block. These include the Liza Phase 2 project due to begin production in 2022, producing up to 220,000 bbl/d. The development will utilize the Liza Unity FPSO, construction of which is underway in Singapore, Exxon said.

However, “a third production vessel for the Payara development, with production capacity of 220,000 barrels a day, is on hold pending government approval,” the company said.

The consortium’s first development on the block—Liza Phase 1—achieved first production in December. With an estimated breakeven price of about $35/bbl Brent, Liza Phase 1 was moving toward full capacity of 120,000 bbl/d in August.

Exxon and partner Hess have said resources discovered on the block are enough for at least five FPSOs. Planning for the fourth and fifth are already underway, partners have said.

Speaking on Hess’ second-quarter earnings call in July, Hess COO Greg Hill the Yellowtail and Redtail wells will form the basis of another FPSO development.

The partners are deciding which of the remaining developments will become part of Phase 4 or Phase 5. Given its higher quality oil and value, Yellowtail could move ahead of Hammerhead in the development queue, according to Hill.