Drill stem element and corresponding drill pipe

A drill stem element for drilling a well with flow of a drilling fluid around an element and in a direction extending from a drilling well bottom towards a surface, comprising:

• a member;
• a coupling mounted to rotate about the member, wherein the coupling comprises at least two abutment zones to abut against a wall of the well during drilling, each abutment zone externally including at least one abutment portion having an outer diameter greater than a diameter of other portions of the element, each abutment zone having a convex rounded shape generated by revolution, each abutment zone being axially remote from at least one other abutment zone;
• and
• an activation zone which comprises a plurality of grooves which are generally of helical shape around an axis of the element,
• the coupling further comprising an intermediate zone provided between the two abutment zones,
• an opening being provided between the coupling and the member for the flow of drilling fluid between the coupling and the member forming a fluid bearing, and
• an activation zone is provided on in an annular locking ring that comprises an internal surface in contact with and radially locking segments which form an abutment ring for the coupling.

A drill stem element for drilling a well with flow of a drilling fluid around an element and in a direction extending from a drilling well bottom towards a surface, comprising:

• a member;
• and
• a coupling mounted to rotate about the member, wherein the coupling comprises at least two abutment zones to abut against a wall of the well during drilling, each abutment zone externally including at least one abutment portion having an outer diameter greater than a diameter of other portions of the element, each abutment zone having a convex rounded shape generated by revolution, each abutment zone being axially remote from at least one other abutment zone;
• the coupling further comprising an intermediate zone provided between the two abutment zones,
• an opening being provided between the coupling and the member for the flow of drilling fluid between the coupling and the member forming a fluid bearing, and
• the member comprises at least one zone in contact with an internal surface of the coupling, a hardness of the zone being greater than a hardness of the internal surface of the coupling.