Drillable bit is key to successful DwC operations

摘要

Drilling with casing (DwC) typically eliminates 20% to 30% of rig time by removing the need for a pilot hole. It virtually guarantees getting to the planned casing depth, minimizes hole stability problems associated with fluid loss while drilling. DwC mitigates fluid loss problems because of the "smear effect" - as the rotating casing rubs against the formation, it plasticizes the cuttings and creates an artificial filter cake that prevents fluid from getting into the formation. And because the annulus is smaller, fluid flows faster, cleaning the hole more effectively and allowing reduced pump rates.