Switch actuator and flow restrictor pilot valve assembly for measurement while drilling tools
US5660238A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 16, 1996 |
| Grant date | Aug 26, 1997 |
| Priority date | — |
| Expiry date | Jan 16, 2016 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B47/18
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
An apparatus for selectively activating a downhole Measurement While Drilling (MWD) tool, so as to prolong the life of the MWD battery and improve function of the MWD flow restrictor pilot valve assembly, includes a switch actuator responsive to pressure differential disposed incorporated within a fluid sealed pressure chamber which also incorporates a pilot valve assembly for activating the flow restrictor for causing mud pulse signals. The switch actuator comprises upstream and downstream bellows sealing a fluid filled reservoir, with a push-action switch within the upstream bellows, isolated from the drilling fluid. Ports expose the upstream and downstream bellows to longitudinally spaced points in the flowstream, the upstream ports providing flow-through cleaning of the upstream bellows. During drilling fluid flow, a friction pressure loss occurs between the ports, and with flow within desired rates, the resulting pressure differential on the upstream bellows actuates the switch and activates the MWD tool. The flow restrictor pilot valve assembly is partly within the reservoir and comprises a dual dashpot, controlling valve stem movement, with a volume compensating means that p…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.