Mud Pulse Telemetry Noise Reduction Method
AssigneeSchlumberger Technology Corporation
InventorAndrew G. Brooks
Life of this patent
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Abstract
A method for reducing noise in downhole fluid communications includes processing first and second received signals in combination with a strobe signal from an active pump to obtain pump signatures at first and second spaced measurement locations. The pump signatures are used to compute a transfer function of the fluid channel between the two measurement locations. The transfer function may then be used to estimate the telemetry signal traveling in the uphole direction.
Claims19
A method for communicating a signal through a fluid in a borehole between a first downhole location and a second uphole location, the method comprising:
- (a) receiving signals in the fluid at at least first and second spaced uphole positions, the received signals including at least a telemetry signal, a reflected telemetry signal, and a pump noise signal;
- (b) receiving a strobe signal from an active pump, the pump being in fluid communication with the first and second positions;
- (c) causing a processor to process the signals received in (a) and the strobe signal received in (b) to obtain pump signatures and clean signals at each of the first and second positions, the pump signatures including the pump noise signal and the clean signals including the telemetry signal and the reflected telemetry signal;
- (d) causing the processor to compute a transfer function between the first and second positions from the pump signatures obtained in (c);
- and
- (e) causing the processor to remove the reflected telemetry signal from at least one of the clean signals via processing the transfer function computed in (d) and the clean signals obtained in (c) so as to obtain the telemetry signal.
A system for communicating a signal through a fluid in a borehole between a first downhole location and a second uphole location, the system comprising:
- a transmission device deployed at the downhole location;
- first and second sensors deployed at first and second spaced apart positions at the uphole location;
- and
- a controller configured to:
- (i) receiving signals from the first and second sensors, the received signals including at least a telemetry signal, a reflected telemetry signal, and a pump noise signal;
- (ii) receive a strobe signal from an active pump, the pump being in fluid communication with the first and second positions;
- (iii) process the received signals and the strobe signal to obtain pump signatures and clean signals at each of the first and second positions, the pump signatures including the pump noise signal and the clean signals including the telemetry signal and the reflected telemetry signal;
- (iv) compute a transfer function between the first and second positions from the pump signatures;
- and (v) remove the reflected telemetry signal from at least one of the clean signals via processing the transfer function and the clean signals so as to obtain the telemetry signal.
Dependencies are inferred from the claim text.