Method of operating a steerable rotary drilling system
US5685379A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 21, 1996 |
| Grant date | Nov 11, 1997 |
| Priority date | — |
| Expiry date | Feb 21, 2016 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B7/068
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A steerable rotary drilling system comprises a bottom hole assembly which includes, in addition to a drill bit, a modulated bias unit and a control unit including an instrument carrier which is rotatable relative to the bias unit. The bias unit comprises a number of hydraulic actuators spaced apart around the periphery of the unit, each having a movable thrust member which is displaceable outwardly for engagement with the formation. Each actuator can be connected, through a rotatable control valve, to a source of drilling fluid under pressure, the control valve comprising a first part, rotatable with the instrument carrier, which cooperates with a second part which is rotatable with the bias unit. Means are provided to roll stabilize the instrument carrier so that relative rotation between the bias unit and instrument carrier, as the bias unit rotates, causes the valve to operate the actuators in synchronism with rotation of the bias unit so as to apply a lateral bias thereto. In order to neutralize or reduce the net bias applied to the bias unit the instrument carrier may be rotated in various modes instead of being roll stabilized, e.g., it may be rotated at a constant slow speed…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.