| 摘要 |
A well string member such as a drill collar includes an elongated tubular body (M) with an outer circumferential surface (12). First and second groove means (20, 21) each comprising a plurality of grooves (20a, 21a), are provided in the outer surface with the grooves (20a) of the first groove (20) means inclined in one direction and the grooves (21a) of the second groove means (21) inclined in the other whereby the first and second groove means (20, 21) intersect at a plurality of intervals along the surface to form opposed fluid flow paths to assist in positioning the well string in a well bore. <IMAGE> |
