Reverse circulation bit assembly

摘要

A drill bit assembly for boring including a drill bit and a bit sub. A front bit end has a plurality cutting elements at a forward face of the front bit end and a first fluid return passage extending through the drill bit to a rear bit end. The bit sub couples to the rear bit end. The bit sub includes a bore disposed at a front sub end sized and shaped to receive the rear bit end of the drill bit. A plurality of legs extends from a mid-sub region toward the front sub end between pairs of cutting elements. The plurality of legs has a fluid delivery passage disposed therein with the fluid delivery passage extending from the plurality of legs to a rear sub bit end. The bit sub has a second fluid return passage connecting the first fluid return passage to the rear sub bit end.

主权项

1. A drill bit assembly for earth boring, the drill bit assembly comprising:
a drill bit having a front bit end and a rear bit end, the front bit end having a plurality of cutting elements at a forward face of the drill bit, and a first fluid return passage extending through the drill bit from the front bit end to the rear bit end; a bit sub disposed about the rear bit end and coupled to the rear bit end, the bit sub comprising:
a nut component having a first end with a bore sized and shaped to receive the rear bit end of the drill bit in a threaded connection, a second end adapted to connect to an adjacent downhole component, and a second fluid return passage connecting the first fluid return passage to the second end; anda skirt component disposed between the nut component and the drill bit, the skirt component having a central bore sized and shaped to fit over a portion of the rear bit end and a plurality of legs extending from the skirt component toward the front bit end between pairs of cutting elements.