US 4,285,407 A · Straight hole driller

Abstract

For use in a drilling string, the preferred and illustrated embodiment depicts a drill collar to be placed in the lower parts of the drill string for straightening the hole. The preferred embodiment utilizes a generally square drill collar with a thick or heavy wall. It is square in cross section along the greater portion of its length, the four corners being slightly rounded to a specified diameter on rotation, and the four lengthwise corners of the regular cross section are all reinforced with hardfacing material to a specified depth, typically tungsten carbide. The four edges abrade the bore hole as the drill string penetrates the earth. In addition, the lower end of the tubular body includes lengthwise flutes in the form known on a stabilizer to guide the hole straightening device into the hole to be reamed by operation of the device.

Claims8

Dependent claims

For use in a drill string positioned in a well which deviates, a hole straightening apparatus which comprises:

(a) an elongate, axially hollow, tubular member terminating in threaded connections enabling said tubular member to be connected in a drill string;
(b) said tubular member defining an intermediate section forming a plurality of substantially flat surfaces and a plurality of lengthwise straight ribs positioned between adjacent flat surfaces, said lengthwise ribs extending radially outwardly to a specified distance such that, on rotation of the drill string, each of said ribs contacts the deviated well bore to cut against the deviated hole and wherein said ribs each includes exposed hardfacing material thereon and wherein said ribs stand radially further than the adjacent portion of said external face;
and
(c) bottom located helical flute means being positioned beneath said ribs and at least partially encircling said tubular member and having a raised portion formed of hardfacing material on said external face to guide and advance said tubular member in a well bore.

1 more element

Dependencies are inferred from the claim text.

Straight hole driller

Life of this patent

Straight hole driller

Life of this patent

Abstract

Claims8