Method and apparatus for multi-channel downhole electromagnetic telemetry
AssigneeEvolution Engineering Inc.
InventorsMingdong Xu, Jili Liu, David A. Switzer, Aaron W. Logan
Life of this patent
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Abstract
An electromagnetic (EM) telemetry method comprises encoding downhole data into a single data stream; separating the single data stream into a plurality of separate data streams; converting each separate data stream into a corresponding separate waveform using a selected digital modulation technique wherein at least one of the frequency and phase of each waveform is assigned a unique value or unique non-overlapping range of values; combining each separate waveform into a combined waveform; and transmitting from a downhole location, an electromagnetic (EM) telemetry carrier wave comprising the combined waveform.
Claims22
A electromagnetic (EM) telemetry method comprising
- (a) encoding downhole data into a single data stream;
- (b) separating the single data stream into a plurality of separate data streams;
- (c) converting each separate data stream into a corresponding separate waveform using a selected digital modulation technique wherein at least one of the frequency and phase of each waveform is assigned a unique value or unique non-overlapping range of values;
- (d) combining each separate waveform into a combined waveform;
- and
- (e) transmitting from a downhole location, an electromagnetic (EM) telemetry carrier wave comprising the combined waveform.
An electromagnetic (EM) telemetry system comprising:
- a downhole telemetry tool comprising:
- (a) a gap sub assembly;
- (b) an EM carrier frequency signal generator for generating an EM carrier wave across an electrically isolated gap of the gap sub assembly;
- (c) an electronics subassembly communicative with the signal generator and comprising a downhole processor and a memory containing an encoder program code executable by the downhole processor to perform a method comprising:
- (i) encoding downhole data into a single data stream;
- (ii) separating the single data stream into a plurality of separate data streams;
- (iii) converting each separate data stream into a corresponding separate waveform using a selected digital modulation technique wherein at least one of the frequency and phase of each waveform is assigned a unique value or unique non-overlapping range of values;
- (iv) combining each separate waveform into a combined waveform;
- and
- (v) sending control signal to the signal generator to transmit an EM telemetry carrier wave comprising the combined waveform.
Dependencies are inferred from the claim text.