Modulated bias unit for rotary drilling
US5520255A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 1995 |
| Grant date | May 28, 1996 |
| Priority date | — |
| Expiry date | May 31, 2015 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B17/1014
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A modulated bias unit, for controlling the direction of drilling of a rotary drill bit when drilling boreholes in subsurface formations, comprises a number of hydraulic actuators spaced apart around the periphery of the unit, each having a movable thrust member which is hydraulically displaceable outwardly for engagement with the formation of the borehole being drilled. A selector control valve modulates the fluid pressure supplied to each actuator in synchronism with rotation of the drill bit so that, as the drill bit rotates, each movable thrust member is displaced outwardly at the same selected rotational position so as to bias the drill bit laterally and thus control the direction of drilling. The control valve is a disc valve comprising two relatively rotating elements having contiguous surfaces formed of polycrystalline diamond. The elements are maintained in coaxial relation by a polycrystalline diamond bearing pin which extends axially from one element and engages in a central axial bearing aperture in the other element.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.