Bottom hole assembly for directional drilling
US5857531A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 1997 |
| Grant date | Jan 12, 1999 |
| Priority date | — |
| Expiry date | Apr 18, 2017 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/20
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
The bottom hole assembly of the present invention includes a drill bit driven by a positive displacement drilling motor, the motor being constructed of tubular housings, one of said housings having a bend so as to cause the bit to drill directionally, another housing containing a rotor and stator to generate power, and a flexible section between the power generation housing and the bend. A stabilizer is disposed on one end of the flexible section for engaging the wall of the borehole and the housing with the bend includes a wear pad for engaging the lower side of the borehole. The bottom hole assembly contacts the borehole at three contact points, namely at the stabilizer, the wear pad, and the drill bit, for producing the necessary build-up rate, along with the bend, and thus the curvature of the borehole being drilled. The flexible section has a stiffness which is less than the stiffness of the housing of the stator and has a stiffness which is on the order of 33% or less of that of the power generation housing. The stiffness is determined by the selection of the material, wall thickness and length of the flexible section such that the desired flexibility is achieved, but the nec…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.