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Expandable tubulars
The challenge of drilling ever longer wells comes down to how a well is ‘put together’. Traditionally, a section of the well is drilled and a casing or liner is inserted in that section. Once the next section is drilled, a second casing must be put in place. But to get there, the second section has to come through the first. As such, each casing section gets progressively smaller until the well is too narrow to be drilled any further. Inspired by a netting used to protect bottles, a Shell engineer solved the problem with the invention of expandable tubulars.
These tubulars are metal casings that can literally be stretched once they are placed in the well by forcing an expansion cone through it. This means that while the tubular can be small enough to pass through the previous section of casing, it can then be expanded to the total diameter of the well ready for the next section. As such no tapering occurs and wells can now be longer than ever – reaching out to tap in to far away oil and gas that may have been left behind as too expensive or difficult to recover.
The concept of expandable tubulars has been transferred to a range of well products that enable longer wells, reduced use of materials and lower costs and are now deployed in some 23 countries around the world.
