Expandable tubular technology
Expandable tubular technology is a system for increasing the diameter of the casing or liner of an oil well by up to 30% after it has been run down-hole. == Telescoping well design == During the planning stages, one of the primary considerations that the well engineer takes into account is the density (or "weight") of the drilling fluid.
Source: Wikipedia — Expandable tubular technology (CC BY-SA 4.0)