Nova Patents
USRE33751E

Untitled record

Claim Score by NHIP

Read claim 20, the broadest

Abstract

This record has no abstract on file.

Term

Term ended

Expired 23 May 2006, 20.3 years ago.

  1. Priority
  2. Filed
  3. Granted
  4. Expired
  5. Today

21 claims: 3 independent, 18 dependent

  1. 1.
    1. An improved system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly, comprising:PA1 a first, concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted between the drill bit and motor at a preselected distance from the bit around the output shaft of said downhole motor, said shaft being concentrically located therein;PA1 a .[.heat.]. .Iadd.bent .Iaddend.motor housing connected to the downhole end of said downhole motor that has a bend from its geometric center at a predetermined angle .alpha. at its downhole end, thereby offsetting the centerline of said first stabilizer and the centerline of the drill bit face from the borehole centerline by said angle .alpha.;PA1 a second concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from said first concentric stabilizer on the drillstring, said drillstring being concentrically located therein;and PA1 a third concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from said second concentric stabilizer on the drillstring, said drillstring being concentrically located therein;PA1 wherein the angle .alpha. of the bend in the motor housing, and the diameter and placement of the concentric stabilizers are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and both the drillstring and downhole motor housing are rotated.
  2. 19.
    19. A method for controlled directional and straight drilling of a borehole, according to a predetermined well plan, utilizing a bottomhole assembly connected to a drillstring comprising a drill bit connected for independent rotation from said drillstring to the output shaft of a downhole motor having its uphole side connected to the drillstring, comprising the steps of:PA1 1. selecting the placement and diameter of three concentric stabilizers on the drillstring as follows, the first concentric stabilizer being placed less than five feet from the face of the drill bit and having a slightly smaller diameter than the borehole, the second concentric stabilizer being placed a predetermined distance from the first stabilizer and having a slightly smaller diameter than the borehole, the third concentric stabilizer being placed a predetermined distance from the second stabilizer and having a slightly smaller diameter than the borehole;PA1 2. selecting a predetermined weight on bit;whereby the assembled concentrically stabilized drillstring with the selected weight on the bit exhibit a certain build angle or drop angle characteristic;PA1 3. selecting a bend angle under two degrees;PA1 4. placing the bend angle in the drillstring between the downhole motor and the drill bit on the uphole side of said first concentric stabilizer;whereby said first concentric stabilizer and said selected bend angle exhibit a certain build angle characteristic, the concentrically stabilized drillstring with the selected weight on bit and the selected bend angle combining to form an interacting bottomhole assembly having a certain build angle or drop angle characteristic uniquely suited to the well plan;and PA1 5. steering said unique downhole assembly by: PA1 (a) turning the drillstring to point the bend in the drillstring and the bit in the direction the borehole should follow;PA1 (b) activating the downhole motor while keeping the drillstring stationary when it is desired to drill along a curved path, as determined by the bend angle and first concentric stabilizing combination;PA1 (c) rotating the drillstring and downhole motor while activating the downhole motor to turn the drill bit when it is desired to drill along a straight path. .Iadd.
  3. 20.
    20. An improved steerable system for controlled directional and straight drilling of a borehole wherein the entire drillstring is rotatable from the surface, including a bottomhole assembly comprised of a drill bit connected to the output shaft of a downhole motor for independent rotation from the drillstring, said downhole motor connected at its uphole end to the drillstring, the improvement in the bottomhole assembly comprising:PA1 a concentric stabilizer, having a preselected diameter slightly smaller than the diameter of the borehole, mounted at a preselected distance from the drill bit, the output shaft of said downhole motor being concentrically located within the concentric stabilizer;and PA1 a bent housing connected above said concentric stabilizer and having a bend from its geometric center at a predetermined bend angle .alpha., thereby offsetting the centerline of said concentric stabilizer and the centerline of the drill bit face from the borehole centerline by said predetermined bend angle .alpha.;wherein the predetermined bend angle .alpha. of the bend in the bent housing, and the diameter and placement of the concentric stabilizer are determined by the desired path of the borehole to be drilled, said system drilling a curved borehole when only the downhole motor is activated, and drilling a straight borehole when the downhole motor is activated and the drillstring is rotated. .Iaddend. .Iadd.
Independent claims3