Solid expandable tubulars for constructing extended-reach wells

The torque and drag experienced when drilling an extended-reach well usually is the limiting factor in reaching the target. Drilling-fluid properties and the use of rotary-steerable drilling tools, among other technologies, mitigate these limits. Torque and drag are influenced primarily by geometric conditions such as dogleg severity (DLS) and casing or openhole size vs. drillstring size, surface effects (commonly grouped together as the friction factor), and drillstring dynamic conditions (such as axial and rotary motion that overcomes the friction). Solid expandables can provide favorable drillstring and casing geometry and can reduce the tendency for helical buckling or drillstring lockup. Another important effect is the ability to use larger drilling tubulars.