Bi-center bit with oppositely disposed cutting surfaces
AssigneeDiamond Products International, Inc.
InventorsRoger Silva, Brad Weston, Henry Rebollido, Coy M. Fielder
Life of this patent
Estimating the term…
Abstract
An improved bi-center bit with improved directional stability and wear resistance is disclosed, which bit optimally utilizing a plurality of shaped PDC cutting elements selectively situated about the cutting surfaces of the pilot and the reamer to produce a minimal force imbalance, where further the pilot bit and the reamer are force balanced to further reduce imbalance in the operation of the tool.
Claims21
A bi-center bit having enhanced stability comprising:
- a body defining a proximal end adapted for connection to a drill string and a distal end, where said distal end defines a pilot bit and an intermediate reamer section, where both the pilot bit and the reamer section possess one or more cutting surfaces, said reamer section defining a leading cutting surface and one or more trailing surfaces;
- a plurality of cutter assemblies being radially disposed about the cutting surfaces of the pilot bit and the reamer section;
- and
- said leading and trailing surfaces of said reamer section defining a midpoint therebetween where at least one first cutting surface on said pilot bit is disposed within ten degrees of a line taken through said midpoint and normal to a line connecting said leading and trailing surfaces and opposite said reamer section.
A method for enhancing the stability of a drill bit assembly when drilling in a borehole through a formation, where said bit comprises a body having a proximal end which is operatively engageable to a drill string and a distal end which defines a pilot bit, where further one side of said body intermediate the distal and the proximal ends defines a reamer section, where both said pilot and reamer sections define a series of cutting surfaces, said method comprising the steps of:
- radially mounting a plurality of cutter assemblies about the cutting surfaces of the pilot bit and reamer section, where the cutting surfaces on said reamer section define a leading and a trailing surface;
- and
- positioning the cutting surface of said pilot bit within ten degrees of a line taken normal to a line connecting said leading and trailing surfaces of and opposite to said reamer section.
The method of clam 16 where said reamer includes a leading upset and follow-on upsets, where the cutter assemblies disposed on said leading upset are provided with a reduced angle of attack vis-a-vis the formation when compared to other cutter assemblies on said bit.
Dependencies are inferred from the claim text.