Acoustic transmitter for transmitting a signal through a downhole medium
AssigneeXACT Downhole Telemetry Inc.
InventorJohn Godfrey McRory
Life of this patent
Estimating the term…
Abstract
An acoustic transmitter for transmitting an acoustic signal through a downhole medium includes a voltage source; a composite load; and switching circuitry that applies voltage from the voltage source across the composite load in response to a drive signal. The composite load includes charge control circuitry, in the form of at least one inductor, connected electrically in series with a piezoelectric transducer that may be electrically modeled as a capacitor.
Claims30
A drilling tool comprising an acoustic transmitter for transmitting an acoustic signal through a drillstring, the transmitter comprising:
- (a) a voltage source;
- (b) a piezoelectric transducer and two metal shoulders constraining the piezoelectric transducer, the metal shoulders launching the acoustic signal into the drillstring when the piezoelectric transducer expands and contracts;
- (c) charge control circuitry comprising a pair of inductors, wherein the piezoelectric transducer is connected in series between the pair of inductors, the piezoelectric transducer and the charge control circuitry collectively comprising a composite load;
- and
- (d) switching circuitry comprising:
- (i) a control terminal for receiving a drive signal;
- (ii) a supply terminal connected to the voltage source;
- and
- (iii) a pair of output terminals across which the composite load is connected, wherein voltage from the voltage source is applied across the output terminals in response to the drive signal,
- wherein the composite load has a series resonant frequency that is at least four times the frequency of the acoustic signal.
An acoustic transmission system for transmitting an acoustic signal through a drillstring, the system comprising:
- (a) a transmitter located either within a downhole tool or on surface, the transmitter comprising:
- (i) a voltage source;
- (ii) a piezoelectric transducer and two metal shoulders constraining the piezoelectric transducer, the metal shoulders launching the acoustic signal into the drillstring when the piezoelectric transducer expands and contracts;
- (iii) charge control circuitry comprising a pair of inductors, wherein the piezoelectric transducer is connected in series between the pair of inductors, the piezoelectric transducer and the charge control circuitry collectively comprising a composite load;
- and
- (iv) switching circuitry comprising:
- (1) a control terminal for receiving a drive signal;
- (2) a supply terminal connected to the voltage source;
- and
- (3) a pair of output terminals across which the composite load is connected, wherein voltage from the voltage source is applied across the output terminals in response to the drive signal;
- (b) a receiver located within the downhole tool when the transmitter is on surface and located on surface when the transmitter is within the downhole tool, the receiver configured to receive the acoustic signal after propagating through the drillstring;
- and
- (c) a demodulator communicatively coupled to the receiver and configured to recover transmitted data from the received acoustic signal,
- wherein the composite load has a series resonant frequency that is at least four times the frequency of the acoustic signal.
A method for transmitting an acoustic signal through a drillstring, the method comprising applying a voltage across a composite load comprising a pair of inductors and a piezoelectric transducer connected in series between the pair of inductors in order to generate the acoustic signal, the piezoelectric transducer constrained by metal shoulders that launch the acoustic signal into the drillstring when the piezoelectric transducer expands and contracts in response to the voltage,
- wherein the composite load has a series resonant frequency that is at least four times the frequency of the acoustic signal.
A drilling tool comprising an acoustic transmitter for transmitting an acoustic signal through a drillstring, the transmitter comprising:
- (a) a voltage source;
- (b) a piezoelectric transducer and two metal shoulders constraining the piezoelectric transducer, the metal shoulders launching the acoustic signal into the drillstring when the piezoelectric transducer expands and contracts;
- (c) charge control circuitry comprising a pair of inductors, wherein the piezoelectric transducer is connected in series between the pair of inductors, the piezoelectric transducer and the charge control circuitry collectively comprising a composite load;
- and
- (d) switching circuitry comprising:
- (i) a control terminal for receiving a drive signal;
- (ii) a supply terminal connected to the voltage source;
- and
- (iii) a pair of output terminals across which the composite load is connected, wherein voltage from the voltage source is applied across the output terminals in response to the drive signal,
- wherein total inductance of the charge control circuitry connected in series with the piezoelectric transducer is
- L
- =
- V
- s
- V
- p
-
- T
- 2
-
-
- ω
-
-
- C
- wherein Vs is the magnitude of the voltage from the voltage source, Vp is a maximum voltage applied across the piezoelectric transducer, T is a period of the drive signal, C is a capacitance of the piezoelectric transducer, and ω is a radial frequency of the acoustic signal.
An acoustic transmission system for transmitting an acoustic signal through a drillstring, the system comprising:
- (a) a transmitter located either within a downhole tool or on surface, the transmitter comprising:
- (i) a voltage source;
- (ii) a piezoelectric transducer and two metal shoulders constraining the piezoelectric transducer, the metal shoulders launching the acoustic signal into the drillstring when the piezoelectric transducer expands and contracts;
- (iii) charge control circuitry comprising a pair of inductors, wherein the piezoelectric transducer is connected in series between the pair of inductors, the piezoelectric transducer and the charge control circuitry collectively comprising a composite load;
- and
- (iv) switching circuitry comprising:
- (1) a control terminal for receiving a drive signal;
- (2) a supply terminal connected to the voltage source;
- and
- (3) a pair of output terminals across which the composite load is connected, wherein voltage from the voltage source is applied across the output terminals in response to the drive signal;
- (b) a receiver located within the downhole tool when the transmitter is on surface and located on surface when the transmitter is within the downhole tool, the receiver configured to receive the acoustic signal after propagating through the drillstring;
- and
- (c) a demodulator communicatively coupled to the receiver and configured to recover transmitted data from the received acoustic signal,
- wherein total inductance of the charge control circuitry connected in series with the piezoelectric transducer is
- L
- =
- V
- s
- V
- p
-
- T
- 2
-
-
- ω
-
-
- C
- wherein Vs is the magnitude of the voltage from the voltage source, Vp is a maximum voltage applied across the piezoelectric transducer, T is a period of the drive signal, C is a capacitance of the piezoelectric transducer, and ω is a radial frequency of the acoustic signal.
A method for transmitting an acoustic signal through a drillstring, the method comprising applying a voltage across a composite load comprising a pair of inductors and a piezoelectric transducer connected in series between the pair of inductors in order to generate the acoustic signal, the piezoelectric transducer constrained by metal shoulders that launch the acoustic signal into the drillstring when the piezoelectric transducer expands and contracts in response to the voltage, wherein total inductance connected in series with the piezoelectric transducer is
- L
- =
- V
- s
- V
- p
-
- T
- 2
-
-
- ω
-
-
- C
- wherein Vs is the magnitude of the voltage from the voltage source, Vp is a maximum voltage applied across the piezoelectric transducer, T is a period of the drive signal, C is a capacitance of the piezoelectric transducer, and ω is a radial frequency of the acoustic signal.
Dependencies are inferred from the claim text.