Much of the equipment used for air-rotary coring is basically the same type of equipment as that used for hydraulic-rotary coring. Drill pipe used for coring by both methods are interchangeable and wire-line coring or conventional coring can be accomplished using either air-rotary or hydraulic-rotary drilling method. Air-rotary coring bits and core barrels are constructed with discharge ports and air passageways larger than those used for hydraulic- rotary coring; otherwise, they are quite similarly constructed. The outside diameters of the diamond or carbide cutting matrices on air-rotary bits and core-barrel reaming shells are also slightly oversized as compared to the outside diameters of hydraulic rotary or conventional-type drilling-mud circulating bits and reaming shells. Hydraulic-rotary core barrels and coring bits can be modified for use in air coring; however, modifications must be fairly extensive (Teasdale and Pemberton, 1984).
Was this article helpful?