Importance

Loading Importance Indicators...

Abstract

A downhole telemetry system having discrete multi-tone modulation and dynamic bandwidth allocation is disclosed herein. In one embodiment, the downhole telemetry system comprises a surface transceiver, a cable, and a downhole transceiver coupled to the surface transceiver via the cable. The downhole transceiver communicates to the surface transceiver using discrete multi-tone (DMT) modulation to transmit telemetry information over a set of frequency subchannels allocated for uplink communications. The surface transceiver may likewise communicate to the downhole transceiver using DMT modulation to transmit information over a set of frequency subchannels allocated for downlink communications. The number of uplink and downlink communications subchannels is preferably variable and preferably can be changed depending on the operating mode of the system. This allows additional subchannels to be allocated for downlink communications during programming and configuration of the downhole equipment, and additional subchannels to be allocated for uplink communications during normal logging operations. The set of uplink communications subchannels may be disjoint from the set of downlink communications subchannels, and the sets may be spaced apart in frequency or interleaved in frequency. The cable may be a single conductor or multi-conductor logging cable. In the case of the multi-conductor logging cable, one of several possible orthogonal transmission modes may be used to convey the information signals.

Loading the Abstract Image...

First Claim