| 摘要 |
A retrievable center bit for use with a tubular including an inner bore and a drill shoe cutter mounted thereon. The retrievable center bit may include a body positionable in the bore of the tubular and including an upper end, a lower end and a side outer surface extending therebetween. A cutting surface may be supported on the lower end of the bit body. There may be a locking assembly on the body for releasably locking the bit axially and rotationally to the tubular. A longitudinal bore may extend from the upper end into the body and the body may include a fluid port extending from the bore to open on the cutting surface and a lateral fluid port extending from the bore opening on the side outer surface positionable adjacent the drill shoe cutter when the bit is locked to the tubular.
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