Method for drilling and completing oil wells with small intermediate diameters

A method for drilling and completing an oil well of small intermediate diameter in a sea bed in ultra deep water, comprising:

• a first stage of drilling and running at least two casings into the seabed, a first said casing extending from a surface of the seabed to a first depth in the seabed, a second said casing extending from said surface of said seabed to a second depth in said seabed, said second depth being greater than said first depth, said second casing having a diameter less than a diameter of said first casing;
• and
• a second stage of drilling and running following said first stage, said second stage of drilling and running including drilling and running at least two suspended liners, a first end of a first said liner being fixed to a lower end of a last of said casings from said first stage of drilling and running, and a first end of a second said liner being fixed to a lower, second end of said first liner, said first liner being of larger diameter than said second liner, wherein said first stage consists essentially of drilling and running solely first and second casings whereby said first stage of drilling and running casings comprises the following steps:
• drilling and running the first casing;
• and
• drilling and running the second casing;
• wherein said first liner is fixed to the lower end of said second casing;
• and
• wherein said first casing has an outside diameter of about 30 inches (76.2 cm) and said second casing has an outside diameter of about 13⅜ inches (33.97 cm).