Platform rig:
An immobile offshore structure from which development wells are drilled and produced.Platform rigs may be built of steel or concrete and may be either rigid or compliant.
Rigid platform rigs, which rest on the seafloor, are the caisson-type platform, the concrete gravity platform, and the steel-jacket platform.
Compliant platform rigs, which are used in deeper waters and yield to water and wind movements are the guyed-tower platform and the tension-leg platform.