Method and apparatus for mud pulse telemetry in underbalanced drilling systems
US6097310A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 8, 1999 |
| Grant date | Aug 1, 2000 |
| Priority date | — |
| Expiry date | Jan 8, 2019 |
Classification
- Technology area (CPC E)Fixed Constructions
- CPC primaryE21B21/16
- WIPO fieldCivil engineering
- WIPO sectorOther fields
Abstract
A mud pulse telemetry system uses a downhole pulser to produce sequences of positive and/or negative pulses according to a selected pattern. Positive pulses, negative pulses, and combinations thereof may be produced. A flow rate sensor at the surface measures changes in the flow rate at the top of the wellbore instead of or in addition to changes in the pressure. The flow rate changes are detectable even though the pressure pulses themselves may have a poor signal to noise ratio. This enables the invention to function effectively in underbalanced drilling wherein the use of light muds with a high gas content is required. One embodiment of the invention uses a conventional downhole pulser with the main valve closed and the pilot valve operating in a direct pulse mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.