<P> In 1938, Humble Oil built a mile - long wooden trestle with railway tracks into the sea at McFadden Beach on the Gulf of Mexico, placing a derrick at its end - this was later destroyed by a hurricane . </P> <P> In 1945, concern for American control of its offshore oil reserves caused President Harry Truman to issue an Executive Order unilaterally extending American territory to the edge of its continental shelf, an act that effectively ended the 3 - mile limit "freedom of the seas" regime . </P> <P> In 1946, Magnolia Petroleum (now ExxonMobil) drilled at a site 18 miles (29 km) off the coast, erecting a platform in 18 feet (5.5 m) of water off St. Mary Parish, Louisiana . </P> <P> In early 1947, Superior Oil erected a drilling and production platform in 20 feet (6.1 m) of water some 18 miles (29 km) off Vermilion Parish, La . But it was Kerr - McGee Oil Industries (now Anadarko Petroleum), as operator for partners Phillips Petroleum (ConocoPhillips) and Stanolind Oil & Gas (BP) that completed its historic Ship Shoal Block 32 well in October 1947, months before Superior actually drilled a discovery from their Vermilion platform farther offshore . In any case, that made Kerr - McGee's well the first oil discovery drilled out of sight of land . </P>

Offshore oil and gas operations & ocean environment