Method and apparatus for reaming well bore surfaces nearer the center of drift

摘要

The present invention provides a method and apparatus for increasing the drift diameter and improving the well path of the well bore, accomplished in one embodiment by cutting away material primarily forming surfaces nearer the center of the drift, thereby reducing applied power, applied torque and resulting drag compared to conventional reamers that cut into all surfaces of the well bore.

主权项

1. An apparatus for use on a drill string for increasing the drift diameter of a well bore during drilling:
a first reamer comprising at least a portion that is substantially cylindrical, the substantially cylindrical portion of the first reamer having a longitudinal axis; a second reamer comprising at least a portion that is substantially cylindrical, the substantially cylindrical portion of the second reamer having a longitudinal axis, the second reamer configured to be coupled to a drill string; a coupling member extending between the first and second reamers for rotating the first and second reamers synchronously, the coupling member having an axis of rotation aligned with a drill string to which the second reamer is coupled; each reamer having a plurality of cutting blades extending a distance radially outwardly from the outer surface of the reamer, wherein, in an order counter to the direction of rotation, a first cutting blade extends a first distance and each additional cutting blade extends an equal or greater distance than the preceding cutting blade, the plurality of blades defining a curved cutting area extending approximately 50% of the circumference of each reamer; wherein the longitudinal axis of the first reamer is displaced from the axis of rotation of the coupling member toward at least one of the one or more first reamer cutting blades; wherein the longitudinal axis of the second reamer is displaced from the axis of rotation of the coupling member; and wherein the longitudinal axis of the second reamer is angularly displaced from the longitudinal axis of the first reamer about the axis of rotation of the coupling member, such that engagement of the second reamer with the well bore urges at least one of the one or more first reamer cutting blades into engagement with the surface of the well bore at an angular displacement from the engagement of the second reamer with the well bore equal to the angular displacement of the longitudinal axis of the first and second reamers.