Sensor apparatus

• US 7,299,678 B2
• Filed: 03/27/2001
• Issued: 11/27/2007
• Est. Priority Date: 03/27/2000
• Status: Expired due to Fees

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Atherton, Eric
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): Miller; Rose M
• Application Number:
  US10/240,134
• Publication Number:
  US 20030101822A1
• Time in Patent Office: 2,436 Days
• Field of Search: 735/79, 736/10, 736/44, 73D/IG.1, 374/117
• US Class Current: 73/24.06
• CPC Class Codes: E21B 47/06 Measuring temperature or pressure
• CPC Class Codes: E21B 47/07 Temperature
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• CPC Class Codes: G01L 9/0022 of a piezoelectric element
• CPC Class Codes: Y10S 73/01 Vibration

Abstract

A measurement head particularly for borehole use can measure multiple parameters with no electronics in the head and only a single conductor cable. Double-ended tuning forks (26, 28 and 38, 40) in the head are arranged to respond to different parameters such as temperature and pressure by adjusting their resonant frequencies. A drive signal on the conductor (50) is applied to transducers (30, 32, 42, 44) on all the tuning forks and those whose instantaneous resonant frequency is close will resonate. The signal is removed and the transducers return a decaying signal at the resonant frequency along the conductor. Other drive frequencies are tried, to locate the other sensors whose frequency ranges are separate.

Claims

1. A sensor apparatus comprising a plurality of resonant sensors connected to a common electrical conductor that provides drive signals to each such sensor, wherein each sensor further comprises a vibrating element, and wherein the resonant frequency of each sensor shifts within a range dependent on at least a parameter sensed by the respective sensor, and wherein the ranges of the sensors being different and non-overlapping.

2. The apparatus according to claim 1 in which the vibrating element is driven by a transducer.

3. The apparatus according to claim 2, wherein transducer is driven by an oscillating signal.

4. The apparatus according to claim 3, wherein the transducers produces an oscillating voltage in response to an oscillation of the vibrating element.

5. The apparatus according to claim 3 or claim 4, wherein the oscillating signal is fed to all transducers via the single electrical conductor.

6. The apparatus according to any one of the claims 2 to 4 in which the transducer is a piezo element.

7. The apparatus according to any one of the claims 2 to 4 in which the drive signal to the transducer is intermittent.

8. The apparatus according to claim 7, further comprising a signal analyzer to detect signals from each of the transducers.

9. The apparatus of claim 1, wherein the plurality of resonant sensors includes at least two sensors, each such sensor sensing a different parameter.

10. A sensor apparatus comprising a plurality of resonant sensors each of whose operating frequency shifts within a range dependent on at least a parameter sensed by the respective sensor, the ranges of the sensors being different and non-overlapping, and all of the sensors being supplied drive signals by a single electrical conductor.

11. The apparatus according to claim 10, wherein each of the sensors comprises a vibrating element whose resonant frequency depends on the parameter sensed by that sensor.

12. An apparatus comprising a plurality of resonant sensors connected to a common electrical conductor that provides drive signals to each such sensor, wherein each sensor further comprises a vibrating element, and wherein the resonant frequency of each sensor shifts within a range dependent on at least a parameter sensed by the respective sensor, the ranges of sensors being different, and wherein the sensors comprise a device for exerting a physical force on the vibrating elements dependent on the parameter sensed.

13. The apparatus according to claim 12, wherein the parameter sensed by at least one sensor is temperature and the vibrating element of that sensor is held by a member of a material with a different coefficient of thermal expansion than that of the vibrating element.

14. The apparatus according to claim 12 or claim 13, wherein the parameter sensed by at least one sensor is pressure and the vibrating element of that sensor is held at one end by a member which is exposed to pressure that exerts a force on the vibrating element in response thereto.

15. A sensor for remote parameter measurement in a borehole comprising a measurement head, a cable leading from the measurement head to a remote instrumentation, a single electrical conductor within the cable leading to transducers within the measurement head, each of which drives and is driven by a resonating element within the measurement head and whose resonant frequency responds to a measured parameter.

16. An apparatus, comprising:

a plurality of resonant sensors connected to a common electrical conductor that provides drive signals to each such sensor, wherein each sensor includes a double-ended tuning fork that comprises a vibrating element, and wherein the resonant frequency of each sensor shifts within a range dependent on at least a parameter sensed by the respective sensor, the ranges of each of the sensor being different.