Apparatus for inductively coupling signals between a downhole sensor and the surface
First Claim
1. An apparatus for transmitting signals between surface equipment and downhole equipment, including:
- a set of inductive coupling coils, including a first downhole coil and a second downhole coil separated by a pressure barrier from the first downhole coil, for inductively coupling an AC drive signal from the surface equipment to the downhole equipment;
wherein the downhole equipment includes;
a sensor, for generating a data signal having a frequency indicative of a measured quantity;
a rectifier for receiving the AC drive signal from the first downhole coil and generating a rectified signal from the received AC signal; and
a modulator connected between the first downhole coil and the sensor, for receiving the data signal and impressing on the first downhole coil a modulation indicative of the data signal frequency.
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0 Petitions
Accused Products
Abstract
An apparatus employing a set of inductive coils to transmit AC data and power signals between a downhole apparatus (which may include a sensor and a safety valve) and apparatus at the surface of the earth. In a preferred embodiment, the invention inductively couples a low frequency (less than 3 KHz) AC power signal from an outer wellhead coupler coil to an inner wellhead coupler coil wound around a tubing string. The AC signal propagates down a wireline conductor along the tubing string to a first downhole coupler coil (also wound around the tubing string) and is inductively coupled from the first downhole coupler coil to a second downhole coupler coil within the tubing. The power signal is preferably rectified, and then employed to power various items of downhole equipment. Data from a downhole sensor (whose frequency is preferably in the range from about 1.0 KHz to about 1.5 KHz) is impressed on the second downhole coil to modulate the AC power signal. The modulated AC signal is inductively coupled from the second downhole coil to the first downhole coil, and from the inner wellhead coil to the outer wellhead coil, and is demodulated by phase locked loop circuitry at the wellhead to extract the sensor data.
220 Citations
33 Claims
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1. An apparatus for transmitting signals between surface equipment and downhole equipment, including:
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a set of inductive coupling coils, including a first downhole coil and a second downhole coil separated by a pressure barrier from the first downhole coil, for inductively coupling an AC drive signal from the surface equipment to the downhole equipment;
wherein the downhole equipment includes;a sensor, for generating a data signal having a frequency indicative of a measured quantity; a rectifier for receiving the AC drive signal from the first downhole coil and generating a rectified signal from the received AC signal; and a modulator connected between the first downhole coil and the sensor, for receiving the data signal and impressing on the first downhole coil a modulation indicative of the data signal frequency. - View Dependent Claims (2, 7, 8)
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3. An apparatus for transmitting signals between surface equipment and downhole equipment, including:
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a set of inductive coupling coils, including a first downhole coil and a second downhole coil separated by a pressure barrier from the first downhole coil, for inductively coupling an AC drive signal from the surface equipment to the downhole equipment;
wherein the downhole equipment includes;a sensor, for generating a data signal having a frequency indictive of a measured quantity, wherein the sensor generates a first data signal having a first frequency indictive of a first measured quantity and a second data signal having a second frequency indicative of a second measured quantity; a rectifier for receiving the AC drive signal from the first downhole coil and generating a rectified signal from the received AC signal; and a modulator connected between the first downhole coil and the sensor, for receiving the data signal and impressing on the first downhole coil a modulation indicative of the data signal frequency, wherein the modulator includes means for alternately impressing on the first downhole coil a first modulation indicative of the first frequency and a second modulation indicative of the second frequency. - View Dependent Claims (4)
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5. An apparatus for transmitting signals between surface equipment and downhole equipment, including:
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a set of inductive coupling coils, including a first downhole coil and a second downhole coil separated by a pressure barrier from the first downhole coil, for inductively coupling an AC drive signal from the surface equipment to the downhole equipment;
wherein the downhole equipment includes;a sensor, for generating a data signal having a frequency indicative of a measured quantity, wherein the sensor generates a first data signal having a first frequency indicative of a first measured quantity and a second data signal having a second frequency indicative of a second measured quantity, and wherein the first data signal and the second data signal are time division multiplexed; a rectifier for receiving the AC drive signal from the first downhole coil and generating a rectified signal from the received AC signal; and a modulator connected between the first downhole coil and the sensor, for receiving the data signal and impressing on the first downhole coil a modulation indicative of the data signal frequency.
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6. An apparatus for transmitting signals between surface equipment and downhole equipment, including:
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a set of inductive coupling coils, including a first downhole coil and a second downhole coil separated by a pressure barrier from the first downhole coil, for inductively coupling an AC drive signal from the surface equipment to the downhole equipment;
wherein the downhole equipment includes;a sensor, for generating a data signal having a frequency indicative of a measured quantity, wherein the sensor generates a first data signal having a first frequency indicative of temperature and a second data signal having a second frequency indicative of pressure; a rectifier for receiving the AC drive signal from the first downhole coil and generating a rectified signal from the received AC signal; and a modulator connected between the first downhole coil and the sensor, for receiving the data signal and impressing on the first downhole coil a modulation indicative of the data signal frequency.
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9. An apparatus for transmitting signals between surface equipment and downhole equipment, including:
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a set of inductive coupling coils, including a first downhole coil and a second downhole coil separated by a pressure barrier from the first downhole coil, for inductively coupling an AC drive signal from the surface equipment to the downhole equipment;
wherein the downhole equipment includes;a sensor, for generating a data signal having a frequency indicative of a measured quantity, wherein the sensor includes power terminals; voltage limiting diode means connected across said power terminals; a rectifier for receiving the AC drive signal from the first downhole coil and generating a rectified signal from the received AC signal, wherein the rectified signal is supplied to the sensor to power said sensor; and a modulator connected between the first downhole coil and the sensor, for receiving the data signal and impressing on the first downhole coil a modulation indicative of the data signal frequency.
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10. A surface apparatus for communicating with downhole equipment, including:
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drive means for generating an AC signal; a pair of inductive coupling coils coupled to the drive means, for receiving the AC signal and a modulated data signal having modulations indicative of a downhole sensor frequency; a phase locked loop connected to a first of the coils, for receiving the current signal at said first coil and generating therefrom a demodulated signal indicative of the downhole sensor frequency, and including a means for closing the phase locked loop only when the current signal has a value above a predetermined threshold. - View Dependent Claims (11, 12, 13, 14)
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15. An apparatus for communicating with surface equipment, including:
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a first coil and a second coil separated by a pressure barrier from the first coil, wherein the second coil will inductively couple to the first coil an AC drive signal received from the surface equipment, and wherein the AC drive signal has a primary frequency component; a sensor for generating a data signal having a frequency indicative of a measured quantity; a rectifier for receiving the AC drive signal from the first coil and generating a rectified signal from the received AC signal; and a modulator connected between the first coil and the sensor, for receiving the data signal and impressing on the first coil a modulation indicative of the data signal frequency. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. A surface apparatus for detecting a data signal from a downhole sensor, wherein the data signal has a data signal frequency within a sensor frequency range, and wherein the data signal frequency is indicative of a measured quantity, including:
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an AC power driver for generating an AC signal having a primary frequency component with a primary frequency outside the sensor frequency range; a first coil connected to the driver, for receiving the AC signal, wherein the first coil has a current; a second coil separated from the first coil by a pressure barrier, for receiving the data signal and inductively coupling the data signal to the first coil; a band pass filter connected to the first coil, for passing frequency components of the first coil current within the sensor frequency range, but not passing frequency components of the first coil current having the primary frequency; detection means connected to the first coil and the band pass filter, for receiving the first coil current and the filtered signal passed by the band pass filter, measuring a first signal indicative of the frequency of the filtered signal during each half cycle of the primary frequency component, and determining the data signal frequency from the first signal. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. A surface apparatus for communicating with downhole equipment, including:
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drive means for generating an AC signal; a pair of inductive coils coupled to the drive means, for receiving the AC signal and a modulated data signal having modulations indicative of a downhole sensor frequency; a demodulator connected to a first of the coils, for receiving the current signal at said first coil and generating therefrom a demodulated signal indicative of the downhole sensor frequency, and including a means for enabling the demodulator only when the current signal has a value above a predetermined threshold. - View Dependent Claims (33)
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Specification