Burst QAM downhole telemetry system
US6348876B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 22, 2000 |
| Grant date | Feb 19, 2002 |
| Priority date | — |
| Expiry date | Jun 22, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V11/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A downhole telemetry system that transmits a burst-QAM uplink signal to the surface of the well is disclosed. In a preferred embodiment, the well includes composite tubing having circumferentially-spaced electrical conductors helically wound within the walls of the tubing. A downhole instrument coupled to a pair of adjacent conductors transmits a burst-QAM uplink signal to a surface system similarly coupled to the pair of adjacent conductors. The burst-QAM signal preferably comprises a series of data frames carrying telemetry data. Each data frame is preferably preceded by a quiet interval (when no signal is present), a timing synchronization sequence, and a training sequence. The timing synchronization sequence is designed for easy timing recovery at the surface, and the training sequence is designed to aid the adaptation of the equalizer. The data frame itself preferably includes a synchronization field, a data count, and a checksum in addition to the data. Direct digital synthesis is preferably employed to modulate the uplink signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.