How did offshore drilling structures develop from shallow-water barges into floating drilling ships?

Following World War II, the offshore oil industry emerged as a new field of engineering, requiring expertise from oceanographers and marine engineers to address challenges like wave forces that were unfamiliar to land-based petroleum engineers.1

The evolution of drilling structures progressed through several stages to reach deeper waters:

• Shallow-water barges: Initially, drilling equipment was mounted on barges that could be floated into position and rested on the seafloor. These were generally restricted to depths of 15 metres (50 feet) or less.2
• Mobile platforms and jack-up rigs: As technology advanced, these barges evolved into mobile platforms. The jack-up rig became a popular fixed-platform solution, featuring legs that could be lowered to the seafloor to raise the platform above the water's surface.31
• Floating drilling ships and semisubmersibles: To reach deep and ultradeep waters, engineers developed floating structures. Drill ships are oceangoing vessels used primarily for exploration, while semisubmersible platforms provide greater stability by keeping their buoyant hulls entirely underwater, minimizing the impact of wave action.31