To surmount these obstacles, petroleum companies have invested billions into the development of offshore drilling and offshore oil platforms . The first of these platforms was constructed in 1897 at the end of a wharf in California . In the years to follow, oil prospectors pushed out into the ocean, first on piers and then on artificial islands. In 1928, a Texan oilman unveiled the first mobile oil platform for drilling in wetlands. The structure was little more than a barge with a drilling outfit mounted on top, but it set the example for decades of advancements to come.