In the United States, CNOOC International has interests in a number of areas, both onshore and offshore. Our onshore assets are located in two major shale basins: the Eagle Ford (South Texas) and the Niobrara (Colorado and Wyoming). Our offshore assets are located in the Gulf of Mexico in the high-value Stampede and Appomattox fields.
CNOOC International has working interest in approximately 200,000 net acres in the Eagle Ford basin (South Texas), and 200,000 net acres in the Niobrara basin (Colorado and Wyoming). The assets consist mostly of unconventional shale oil with some unconventional shale wet gas, and the majority of our production is operated by Chesapeake Energy, our partner in a number of leases.
Our strategy onshore United States is to maximize value and optimize our shale and tight oil portfolio. As we continue to build our basin mastery, we will focus on working with our partners to develop our most economic and strategic resources.
In the Gulf of Mexico, CNOOC International works to strategically find, develop and produce deepwater oil and gas reserves. We deliver technical excellence within our partnerships, creating value and becoming a partner of choice in the Gulf of Mexico.
On May 22, 2019, production from the Appomattox platform safely commenced ahead of schedule and under budget. The Appomattox field is located approximately 128 kilometers southeast of Louisiana in the deepwater Gulf of Mexico, with water depth of approximately 2,255 meters. It is the first commercial discovery now brought into production in the Norphlet formation and has an expected peak production rate of 175,000 barrels of oil equivalent per day. CNOOC Petroleum Offshore U.S.A. Inc., a wholly owned subsidiary of CNOOC Limited, holds 21% interest in the Appomattox Field. Shell Offshore Inc. is the operator and holds 79% interest.
CNOOC International holds a 25% non-operated working interest in Stampede, which is located 258 kilometres (160 miles) off the coast of Louisiana in approximately 1,000 metres (3,500 feet) of water. First oil from the Stampede project was successfully and safely delivered in 2018 ahead of schedule and under budget.