초록 ▼

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 coup

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.

대표청구항 ▼

1. A well comprising:composite tubing having a telemetry conduit; a surface system coupled to the telemetry conduit; and a downhole instrument coupled to the surface system via the telemetry conduit, wherein the downhole instrument is configured to transmit telemetry information to the surface syste

1. A well comprising:composite tubing having a telemetry conduit; a surface system coupled to the telemetry conduit; and a downhole instrument coupled to the surface system via the telemetry conduit, wherein the downhole instrument is configured to transmit telemetry information to the surface system using burst quadrature amplitude modulation (burst-QAM).