Royal Dutch Shell plc said Thursday it has struck its sixth oil and natural gas find in the Norphlet play in the deepwater U.S. Gulf of Mexico (GOM) after encountering more than 800 net feet of pay at the Dover discovery.

The discovery, 100% owned, is about 13 miles from the the producer’s Appomattox host and considered an attractive potential tieback, according to Houston-based Shell Offshore Inc. The Appomattox host, now on location, is expected to begin operations before the end of 2019.

“Dover showcases our expertise in discovering new, commercial resources in a heartland helping deliver our deep water growth priority,” said Upstream Director Andy Brown. “By focusing on near-field exploration opportunities in the Norphlet, we are adding to our resource base in a prolific basin that will be anchored by the Appomattox development.”

Dover was drilled in Mississippi Canyon Block 612, about 170 miles southeast of New Orleans, in waters about 7,500 feet deep. Total vertical drilling depth was 29,000 feet of measured depth.

The Appomattox host, sanctioned three years ago, was Shell’s eighth and largest floating platform in the U.S. offshore. Appomattox initially is to produce from the Appomattox and Vicksburg fields, with average peak production estimated to reach 175,000 boe/d. The two fields, 80 miles offshore Louisiana, are in 7,200 feet of water.

The Appomattox host is owned by Shell (79%) and CNOOC Ltd.’s Nexen Petroleum Offshore U.S.A. Inc. (21%).

Shell, one of the largest and most active U.S. offshore operators, is forecasting its global, deepwater production will exceed 900,000 boe/d by 2020 from already discovered, established area.

In January Shell touted the Whale discovery in Alaminos Canyon of the deepwater GOM, which is considered one of the largest discoveries in a decade. The deepwater well, about 200 miles southwest of Houston in 8,000 feet of water, encountered more than 1,400 net feet of oil bearing pay. Evaluation of the discovery is ongoing, and appraisal drilling is underway to further delineate the discovery and define development options.

Whale is operated by Shell (60%) and co-owned by Chevron U.S.A. Inc. (40%). The discovery is adjacent to the Shell-operated Silvertip field and about 10 miles from the Shell-operated Perdido platform.

In addition to Appomattox, Shell has four deepwater projects in the GOM now under construction, including Kaikias and Coulomb Phase 2 and the newly sanctioned Vito, which was given the green light in April.

Management estimated that Vito has a forward-looking, breakeven price of less than $35/bbl. The final investment decision set in motion construction and fabrication of a “new, simplified host design and subsea infrastructure.”

Vito is expected to reach peak production of 100,000 boe/d; the development in Mississippi Canyon has an estimated, recoverable resource of 300 million boe.