Technical Session: Drill Bits and Hole Openers

摘要

Underreaming with a rotary steer-able system (RSS) is becoming more commonplace simply because significant cost savings can be obtained by eliminating the need for designated hole-opening BHA runs. The risks associated with designated hole-opening runs, such as accidental sidetracks in soft unconsolidated formations, can also be reduced. However, ESS underreamer assemblies are often challenged with BHA instability, excessive vibration and stick slip problems when the two different cutting structures (a bit and underreamer) in the BHA interact with significantly different formations. This paper describes case histories of directional wells that have been drilled with both point-the-bit and push-the-bit RSS underreamer assemblies in the North Sea, Mediterranean Sea and Nile Delta. In particular, RSS underreamer assemblies opening from 13 in. to as large as 17 V4 in., using 12 Vi in. pilot holes will be discussed.