Sensor apparatus

• US 20030101822A1
• Filed: 09/27/2002
• Published: 06/05/2003
• Est. Priority Date: 03/27/2000
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Atherton, Eric
• Granted Patent: US 7,299,678 B2
• Time in Patent Office: Days
• US Class Current: 73/649
• 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 each comprising a vibrating element, wherein the resonant frequency of each sensor shifts within a range dependent on at least the parameter sensed by the respective sensor, the ranges of each of the sensors being different.

3. Apparatus according to any one of the preceding claims in which the frequency ranges of the sensors are non-overlapping.

5. Apparatus according to claim 1 or claim 4 in which the sensors further comprise a means for exerting a physical force on the vibrating element dependent on the parameter.

6. Apparatus according to claim 5 in which the parameter of 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.

7. Apparatus according to claim 5 or claim 6 in which the parameter of 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 the relevant pressure and adapted to exert a force in response thereto.

8. Apparatus according to any one of claims 1 or 4 to 7 in which the vibrating element is driven by a transducer.

9. Apparatus according to claim 8 in which the transducer is driven by an oscillating signal.

10. Apparatus according to claim 9 in which the transducers produce an oscillating voltage in response to an oscillation of the vibrating element.

11. Apparatus according to claim 9 or claim 10 in which the oscillating signal is fed to all transducers via a single conductor.

12. Apparatus according to any one of claims 8 to 11 in which the transducer is a piezo element.

13. Apparatus according to any one of claims 8 to 12 in which the drive signal to the transducer is intermittent.

14. Apparatus according to claim 13 comprising a signal analyser to detect signals from the transducers.

2. A sensor apparatus comprising a plurality of resonant sensors each of whose operating frequency shifts within a range dependent on at least the parameter sensed by the respective sensor, the ranges of each of the sensors being different all of the sensors being supplied by a single signal conductor.

4. Apparatus according to claim 2 in which the sensors comprise a vibrating element whose resonant frequency depends on the parameter measured by that sensor.

15. Sensor apparatus for remote parameter measurement in boreholes comprising a measurement head, a cable leading from the measurement head to remote instrumentation, a conductor within the cable leading to transducers within the measurement head, each of which drive and are driven by a resonating element also within the measurement head and whose resonant frequency responds to the measured parameter.

16. Sensor apparatus substantially as herein described with reference to and/or as illustrated in the accompanying drawings.