Casing Drilling with Retrievable Drilling Assemblies

摘要

Retrievable Casing Drilling* tools have been used to drill morernthan 600,000 ft of hole in over 120 wells encompassing sixrncasing sizes ranging from 4-1/2” to 13-3/8” and reachingrninclinations of 90o. This drilling system is composed ofrndownhole and surface components that provide the ability tornuse normal oil field casing as the drill string so that the well isrnsimultaneously drilled and cased. The casing is rotated fromrnthe surface for all operations except slide drilling with a motorrnand bent housing assembly for oriented directional work.rnA retrievable drilling assembly is attached to the casingrninside a proprietary profile nipple located near the casing shoe.rnThe drilling assembly extending below the casing usuallyrnincludes an underreamer and a PDC or roller cone pilot bit.rnOther conventional drill-string components may be includedrnso that almost any normal drilling activity can be conducted.rnThese assemblies are retrieved with a wireline at the casingrnpoint or at any point in the drilling process when there is arnneed to change drilling tools.