drilling platform

noun

a structure, either fixed to the sea bed or mobile, which supports the machinery and equipment (the drilling rig), together with the stores, required for digging an offshore oil well

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012