WO2009017728A1 - System and method for sensing pressure using an inductive element - Google Patents

System and method for sensing pressure using an inductive element Download PDF

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Publication number
WO2009017728A1
WO2009017728A1 PCT/US2008/009161 US2008009161W WO2009017728A1 WO 2009017728 A1 WO2009017728 A1 WO 2009017728A1 US 2008009161 W US2008009161 W US 2008009161W WO 2009017728 A1 WO2009017728 A1 WO 2009017728A1
Authority
WO
WIPO (PCT)
Prior art keywords
electromagnetic energy
pressure
shaped elastomer
transducer
inductive element
Prior art date
Application number
PCT/US2008/009161
Other languages
French (fr)
Inventor
M. Clark Thompson
David W. Beck
Don M. Coates
Original Assignee
Chevron U.S.A. Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Chevron U.S.A. Inc. filed Critical Chevron U.S.A. Inc.
Priority to EP08780331.8A priority Critical patent/EP2185793A4/en
Priority to CA2693629A priority patent/CA2693629C/en
Priority to AU2008282816A priority patent/AU2008282816B2/en
Priority to BRPI0814156-8A2A priority patent/BRPI0814156A2/en
Priority to CN200880100875.1A priority patent/CN101765698B/en
Priority to EA201070203A priority patent/EA019220B1/en
Publication of WO2009017728A1 publication Critical patent/WO2009017728A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0089—Transmitting or indicating the displacement of pistons by electrical, electromechanical, magnetic or electromagnetic means
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B47/00—Survey of boreholes or wells
    • E21B47/06—Measuring temperature or pressure
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/12—Measuring force or stress, in general by measuring variations in the magnetic properties of materials resulting from the application of stress
    • G01L1/127—Measuring force or stress, in general by measuring variations in the magnetic properties of materials resulting from the application of stress by using inductive means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
    • G01L19/08—Means for indicating or recording, e.g. for remote indication
    • G01L19/086—Means for indicating or recording, e.g. for remote indication for remote indication
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/0001—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means
    • G01L9/0004—Transmitting or indicating the displacement of elastically deformable gauges by electric, electro-mechanical, magnetic or electro-magnetic means using variations in inductance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
    • G01L9/10—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of variations in inductance, i.e. electric circuits therefor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F21/00—Variable inductances or transformers of the signal type
    • H01F21/02—Variable inductances or transformers of the signal type continuously variable, e.g. variometers
    • H01F21/08—Variable inductances or transformers of the signal type continuously variable, e.g. variometers by varying the permeability of the core, e.g. by varying magnetic bias
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F17/00—Fixed inductances of the signal type 
    • H01F17/04—Fixed inductances of the signal type  with magnetic core
    • H01F17/06—Fixed inductances of the signal type  with magnetic core with core substantially closed in itself, e.g. toroid
    • H01F17/062—Toroidal core with turns of coil around it
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F17/00—Fixed inductances of the signal type 
    • H01F17/04—Fixed inductances of the signal type  with magnetic core
    • H01F2017/048—Fixed inductances of the signal type  with magnetic core with encapsulating core, e.g. made of resin and magnetic powder
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/08—Cores, Yokes, or armatures made from powder

Definitions

  • Pressure transducers are disclosed, such as transducers that shift the frequency of a reflected signal based on a response to pressure.
  • Devices have been used for monitoring downhole conditions of a drilled well, where environmental conditions can be relatively harsh. These downhole conditions include temperature and pressure, among others.
  • the sensing device includes a shaped elastomer and ferromagnetic material embedded as discrete particles within the shaped elastomer, wherein a percentage by weight of the ferromagnetic particles is selected such that an inductance of the shaped elastomer will vary a predetermined amount for a given compression of the shaped elastomer.
  • the system comprises means for generating electromagnetic energy, and means for modulating the electromagnetic energy.
  • the modulating means includes an inductive element comprising a shaped elastomer and ferromagnetic material embedded as discrete particles within the shaped elastomer, wherein a percentage by weight of the ferromagnetic particles is selected such that an inductance of the shaped elastomer will vary a predetermined amount for a given compression of the shaped elastomer.
  • An exemplary method of sensing pressure uses a transducer that includes a compressible inductive element.
  • the method comprises supplying electromagnetic energy to a transducer which is configured to reflect the electromagnetic energy at a ring frequency determined by an inductance of the transducer, wherein the inductance changes in response to compression of the inductive element.
  • the ring frequency of electromagnetic energy reflected by the transducer is correlated to a pressure value.
  • Figure 1 shows an exemplary inductive sensor for sensing pressure
  • Figure 2 is a flowchart illustrating an exemplary process of manufacturing the exemplary inductive sensor of Figure 1;
  • Figure 3 shows an exemplary system for sensing pressure in a well
  • Figure 4 is a flowchart illustrating an exemplary process of sensing pressure in a well
  • Figure 5 is a flowchart illustrating a system for sensing pressure in a compressible vessel; and [0012] Figure 6 shows an exemplary inductive sensor and housing for sensing pressure.
  • Figure 1 shows an exemplary inductive sensor for sensing pressure.
  • the inductive sensor 100 can be configured as a ferrite core in the form of a shaped elastomer that includes ferromagnetic material such that an inductance of the inductive element varies as a function, of compression of the shaped elastomer due to a pressure of the surrounding environment.
  • the ferrite core can be formed in. the shape of a ring for coupling to production tubing within a drilling well or any other shape suitable for achieving the desired response or performance.
  • the inductive sensor 100 can be formed of ferromagnetic material that is potted using an elastomeric potting agent, e.g. silicone rubber or any other suitable elastomeric material as desired.
  • the inductive sensor 100 can include a ferromagnetic blend of various ferromagnetic materials (or particles), such as iron oxides, iron powder, or any other suitable materials as desired.
  • the composition by weight of each magnetic material in the ferromagnetic blend determines various parameters of the inductive sensor 100, which can include but are not limited to an impedance value, core loss, frequency response, temperature response, quality (Q) factor, power handling, and any other controllable parameters or characteristics.
  • FIG. 1 illustrates an exemplary method for manufacturing the inductive sensor 100 of Figure 1.
  • ferromagnetic materials can be mixed with a liquid elastomeric material to form a ferromagnetic material-elastomer mixture.
  • the ferromagnetic materials can include a blend of various ferromagnetic-based magnetic materials. The materials can be added in various compositions by weight to establish a desired hardness composition of the rubber matrix, and which determine various parameters and characteristics of the inductive sensor 100, such as an inductance value, for example.
  • the liquid elastomeric material can include any of a number of known elastomers, such as amorphous polymers or other silicone-based materials as desired.
  • a step 202 the ferromagnetic material-elastomer mixture is transferred to a mold, such as a ring, cylinder, or any other suitable shape mold as desired.
  • step 204 the ferromagnetic material-elastomer mixture in the mold is cured at any suitable temperature (e.g., room temperature or greater), to form an inductive structure.
  • the curing temperature is determined by the material composition of ferromagnetic material-elastomer mixture.
  • the curing temperature can be determined by whether the elastomer is a saturated or unsaturated material.
  • saturated elastomers such as silicones, fluoroelastomers (e.g., Viton®), and perfluoroelastomers (e.g., Kalrez®) can be cured at room temperature absent a catalyst or curing agent for vulcanization.
  • Unsaturated materials such as polyisoprene (e.g., butyl rubber) and polybutadiene (e.g., nitrile), for example, can require the introduction of a curing agent such as sulfur to promote vulcanization.
  • the inductive sensor 100 can be made compatible with temperatures up to 400° F, or greater.
  • the inductive structure can be deaerated to remove bubbles. Deaerating enables the expansion of the inductive mold to be controlled and reproducible. One of ordinary skill in the art will recognize that any known deaerating technique or process can be used.
  • the inductive sensor 100 If the inductive sensor 100 is to be used in an environment in which contamination may be present, then the inductive sensor 100 can be configured to include a protective coating and/or mounted in a protective casing.
  • the inductive mold can be encapsulated with a protective material such as Teflon®, for example, and/or encapsulated in a vessel, formed as a cylinder, or any other suitable encapsulating means as desired.
  • a protective material such as Teflon®
  • Figure 3 shows an exemplary system 300 for sensing pressure in a well using the exemplary inductive sensor.
  • the exemplary system 300 can be a telemetry system as described in United States Patent Application Serial No., 11/394,186 filed March 31 , 2006, and additional details regarding such a telemetry system can be found in that application, the contents of which are hereby incorporated in their entirety by reference.
  • the telemetry system 300 includes means, such as a signal generator 302, for generating electromagnetic (EM) energy and applying the EM energy to a transmission means (not shown), such as a borehole casing or production tubing.
  • the signal generator 302 can generate the EM energy as a pulse (e.g., a sequence or series of pulses or chirps), or as a continuous wave.
  • the EM energy can be generated in a range defined between a desired low resolution (e.g., 1 pulse/sec) and a desired high resolution (e.g., 20 kHz or greater) signals.
  • Modulating means such as one or more downhole transducers 304, are coupled to the production tubing for interacting with and modulating at least some of the EM energy of the pulse at a "ring frequency.”
  • Receiving means such as a receiver 306 located at or near the surface, receives the EM energy that is reflected by the transducer 304 at the ring frequency. The receiver 306 samples the EM energy at a rate much higher than either of the ring frequency or the frequency of the EM energy so that the original signal can be reproduced.
  • an EM pulse generator is used.
  • Non-nuclear means for generating EM pulses are well- known to those in the nuclear-weapons community.
  • Such EM pulse generators are typically used to test electronic devices by simulating EM pulses associated with nuclear blasts. See, e.g., U.S. Patent Nos. 3,562,741 (McEvoy et al.); 4,430,577 (Bouquet); 4,845,378 (Garbe et al.); and 5,150,067 (McMillan).
  • the one or more transducers 304 can include an inductive element 308, such as the inductive sensor 100, and a capacitive element 310.
  • the inductive sensor 100 can be configured to sense a characteristic, e.g. pressure, of the well through an observed range of compression, and modulate the frequency of the EM energy based on the compression.
  • the capacitive element 310 is coupled to the inductive element 308 to form a tank circuit.
  • the capacitive element 310 can be configured to be less sensitive to temperature and pressure than the inductive element 308.
  • each transducer 304 can be configured to operate at a different "ring" frequency.
  • each transducer 304 can include an inductive element 308 having different formulations (i.e. composition by weight, percentage weight) of ferromagnetic material, which result in varying sensitivities to pressure across the multiple transducers 304.
  • the receiver 306 can include processing means, such as a processor 312. Those of ordinary skill in the art will appreciate that the processor 312 can be implemented as a computer or other suitable hardware and/or software processing means as desired.
  • the modulating (ring) frequency of the transducer 304 can be calibrated using a graphical user interface (GUI) associated with the processor 312.
  • GUI graphical user interface
  • the processor 312 can be configured to store information (e.g., look-up tables, files, and/or databases) that correlate various ring frequency values to observed compression ranges of the inductive element 308.
  • FIG. 4 is a flowchart illustrating an exemplary process of sensing pressure using a transducer including the exemplary inductive element 100 in connection with the telemetry system 300.
  • the pulse generator 302 generates EM energy and supplies the EM energy to the transducer 304 via the production tubing.
  • the transducer 304 being coupled to the production tubing, interacts with the EM energy and reflects the EM energy at a ring frequency determined by the inductive element 308 of the transducer 304.
  • the inductance of the inductive element 308 can vary based on a degree to which the inductive element is compressed by the observed pressure in the borehole.
  • the receiver 306 receives the reflected EM energy.
  • the processor 312 of the receiver 306 uses means, such as a look-up table, for correlating the ring frequency of the received EM energy to a pressure value (step 404). For example, the processor 312 determines an inductance value of the inductive element 308 based on the ring frequency of the transducer 304. The processor 312 correlates the inductance value of the inductive element 308 to a degree of compression of the inductive element 308. The processor 312 then associates the compression of the inductive element 308 to the pressure in the well.
  • Figure 5 shows an exemplary device 500 having an inductive sensor 502 mounted in a housing. As shown in Figure 5, the inductive sensor 502 is encapsulated within a vessel 504.
  • the inductive sensor 500 can be configured to include the physical properties and characteristics as described with respect to the inductive sensor 100 of Figure 1.
  • the inductive sensor 500 can also be configured in any shape determined by the vessel 500 and/or a shape suitable to achieving the desired response within the vessel 504.
  • the vessel 504 also includes a load-bearing element 506, such as a piston, and a port 508 for applying a load or force to the load- bearing element 506.
  • a processor 510 can be connected to the vessel to compute the pressure in the vessel based on the inductance of the inductive sensor 502.
  • FIG. 6 is a flowchart illustrating a method for sensing pressure using the inductive sensor 502 of Figure 5.
  • a step 600 pressure is applied to a load-bearing element 506, e.g. piston, of the vessel so that the inductive element 502 is compressed.
  • the processor 510 monitors and records a measurement of an inductance of the inductive sensor 502.
  • the processor 510 determines an observed degree of compression of the inductive sensor 502 based on the measured inductance of the inductive sensor 502. The processor 510 correlates the determined compression to the pressure in the vessel 500 (step 506).

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Abstract

Exemplary systems and method are directed to a sensing device, and to a pressure sensing system and method. An exemplary method includes supplying electromagnetic energy to a transducer which is configured to reflect the electromagnetic energy at a ring frequency determined by an inductance of the transducer, wherein the inductance changes in response to compression of the inductive element. The ring frequency of electromagnetic energy reflected by the transducer is correlated to a pressure value.

Description

SYSTEM AND METHOD FOR SENSING PRESSURE USING AN
INDUCTIVE ELEMENT
BACKGROUND
FIELD
[0001] Pressure transducers are disclosed, such as transducers that shift the frequency of a reflected signal based on a response to pressure.
BACKGROUND INFORMATION
[0002] Devices have been used for monitoring downhole conditions of a drilled well, where environmental conditions can be relatively harsh. These downhole conditions include temperature and pressure, among others.
SUMMARY
[0003] An exemplary sensing device is disclosed. The sensing device includes a shaped elastomer and ferromagnetic material embedded as discrete particles within the shaped elastomer, wherein a percentage by weight of the ferromagnetic particles is selected such that an inductance of the shaped elastomer will vary a predetermined amount for a given compression of the shaped elastomer.
[0004] An exemplary system for sensing pressure in a borehole is also disclosed.
The system comprises means for generating electromagnetic energy, and means for modulating the electromagnetic energy. The modulating means includes an inductive element comprising a shaped elastomer and ferromagnetic material embedded as discrete particles within the shaped elastomer, wherein a percentage by weight of the ferromagnetic particles is selected such that an inductance of the shaped elastomer will vary a predetermined amount for a given compression of the shaped elastomer.
[0005] An exemplary method of sensing pressure uses a transducer that includes a compressible inductive element. The method comprises supplying electromagnetic energy to a transducer which is configured to reflect the electromagnetic energy at a ring frequency determined by an inductance of the transducer, wherein the inductance changes in response to compression of the inductive element. The ring frequency of electromagnetic energy reflected by the transducer is correlated to a pressure value.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Other advantages and features described herein will be more readily apparent to those skilled in the art when reading the following detailed description in connection with the accompanying drawings, wherein: [0007] Figure 1 shows an exemplary inductive sensor for sensing pressure;
[0008] Figure 2 is a flowchart illustrating an exemplary process of manufacturing the exemplary inductive sensor of Figure 1;
[0009] Figure 3 shows an exemplary system for sensing pressure in a well;
[0010] Figure 4 is a flowchart illustrating an exemplary process of sensing pressure in a well;
[0011] Figure 5 is a flowchart illustrating a system for sensing pressure in a compressible vessel; and [0012] Figure 6 shows an exemplary inductive sensor and housing for sensing pressure.
DETAILED DESCRIPTION
[0013] Figure 1 shows an exemplary inductive sensor for sensing pressure. As shown in Figure 1, the inductive sensor 100 can be configured as a ferrite core in the form of a shaped elastomer that includes ferromagnetic material such that an inductance of the inductive element varies as a function, of compression of the shaped elastomer due to a pressure of the surrounding environment. The ferrite core can be formed in. the shape of a ring for coupling to production tubing within a drilling well or any other shape suitable for achieving the desired response or performance.
[0014] The inductive sensor 100 can be formed of ferromagnetic material that is potted using an elastomeric potting agent, e.g. silicone rubber or any other suitable elastomeric material as desired. The inductive sensor 100 can include a ferromagnetic blend of various ferromagnetic materials (or particles), such as iron oxides, iron powder, or any other suitable materials as desired. The composition by weight of each magnetic material in the ferromagnetic blend determines various parameters of the inductive sensor 100, which can include but are not limited to an impedance value, core loss, frequency response, temperature response, quality (Q) factor, power handling, and any other controllable parameters or characteristics. Due to the physical properties of the ferromagnetic blend, the inductive sensor 100 can be compressed by an external force, e.g., pressure, such that an inductive value of the sensor 100 will vary in response to the external force. Those of skill in the art will recognize that a ferromagnetic material does not have to comprise iron compounds, but can be comprised of other metal-based ceramics. [0015] Figure 2 illustrates an exemplary method for manufacturing the inductive sensor 100 of Figure 1. [0016] In a step 200, ferromagnetic materials can be mixed with a liquid elastomeric material to form a ferromagnetic material-elastomer mixture. The ferromagnetic materials can include a blend of various ferromagnetic-based magnetic materials. The materials can be added in various compositions by weight to establish a desired hardness composition of the rubber matrix, and which determine various parameters and characteristics of the inductive sensor 100, such as an inductance value, for example.
[0017] The liquid elastomeric material can include any of a number of known elastomers, such as amorphous polymers or other silicone-based materials as desired. [0018] In a step 202, the ferromagnetic material-elastomer mixture is transferred to a mold, such as a ring, cylinder, or any other suitable shape mold as desired. In step 204, the ferromagnetic material-elastomer mixture in the mold is cured at any suitable temperature (e.g., room temperature or greater), to form an inductive structure. The curing temperature is determined by the material composition of ferromagnetic material-elastomer mixture. The curing temperature can be determined by whether the elastomer is a saturated or unsaturated material. For example, saturated elastomers, such as silicones, fluoroelastomers (e.g., Viton®), and perfluoroelastomers (e.g., Kalrez®) can be cured at room temperature absent a catalyst or curing agent for vulcanization. Unsaturated materials, such as polyisoprene (e.g., butyl rubber) and polybutadiene (e.g., nitrile), for example, can require the introduction of a curing agent such as sulfur to promote vulcanization. Based on the material composition of the elastomeric materials, the inductive sensor 100 can be made compatible with temperatures up to 400° F, or greater. [0019] In a step 206, the inductive structure can be deaerated to remove bubbles. Deaerating enables the expansion of the inductive mold to be controlled and reproducible. One of ordinary skill in the art will recognize that any known deaerating technique or process can be used. [0020] If the inductive sensor 100 is to be used in an environment in which contamination may be present, then the inductive sensor 100 can be configured to include a protective coating and/or mounted in a protective casing. In a step 208, the inductive mold can be encapsulated with a protective material such as Teflon®, for example, and/or encapsulated in a vessel, formed as a cylinder, or any other suitable encapsulating means as desired. One of ordinary skill will appreciate that the disclosed method can be performed by a machine.
[0021] Figure 3 shows an exemplary system 300 for sensing pressure in a well using the exemplary inductive sensor. The exemplary system 300 can be a telemetry system as described in United States Patent Application Serial No., 11/394,186 filed March 31 , 2006, and additional details regarding such a telemetry system can be found in that application, the contents of which are hereby incorporated in their entirety by reference.
[0022] The telemetry system 300 includes means, such as a signal generator 302, for generating electromagnetic (EM) energy and applying the EM energy to a transmission means (not shown), such as a borehole casing or production tubing. The signal generator 302 can generate the EM energy as a pulse (e.g., a sequence or series of pulses or chirps), or as a continuous wave. The EM energy can be generated in a range defined between a desired low resolution (e.g., 1 pulse/sec) and a desired high resolution (e.g., 20 kHz or greater) signals. Modulating means, such as one or more downhole transducers 304, are coupled to the production tubing for interacting with and modulating at least some of the EM energy of the pulse at a "ring frequency." Receiving means, such as a receiver 306 located at or near the surface, receives the EM energy that is reflected by the transducer 304 at the ring frequency. The receiver 306 samples the EM energy at a rate much higher than either of the ring frequency or the frequency of the EM energy so that the original signal can be reproduced.
[0023] In embodiments wherein the EM energy is in the form of an EM pulse, an EM pulse generator is used. Non-nuclear means for generating EM pulses are well- known to those in the nuclear-weapons community. Such EM pulse generators are typically used to test electronic devices by simulating EM pulses associated with nuclear blasts. See, e.g., U.S. Patent Nos. 3,562,741 (McEvoy et al.); 4,430,577 (Bouquet); 4,845,378 (Garbe et al.); and 5,150,067 (McMillan). As shown in Figure 3, the one or more transducers 304 can include an inductive element 308, such as the inductive sensor 100, and a capacitive element 310. The inductive sensor 100 can be configured to sense a characteristic, e.g. pressure, of the well through an observed range of compression, and modulate the frequency of the EM energy based on the compression. The capacitive element 310 is coupled to the inductive element 308 to form a tank circuit. The capacitive element 310 can be configured to be less sensitive to temperature and pressure than the inductive element 308.
[0024] When the telemetry system 300 is configured to include multiple transducers 304, each transducer 304 can be configured to operate at a different "ring" frequency. For example, each transducer 304 can include an inductive element 308 having different formulations (i.e. composition by weight, percentage weight) of ferromagnetic material, which result in varying sensitivities to pressure across the multiple transducers 304. [0025] The receiver 306 can include processing means, such as a processor 312. Those of ordinary skill in the art will appreciate that the processor 312 can be implemented as a computer or other suitable hardware and/or software processing means as desired. Prior to placing the transducer 304 into the well, the modulating (ring) frequency of the transducer 304 can be calibrated using a graphical user interface (GUI) associated with the processor 312. As a result, the processor 312 can be configured to store information (e.g., look-up tables, files, and/or databases) that correlate various ring frequency values to observed compression ranges of the inductive element 308.
[0026] Figure 4 is a flowchart illustrating an exemplary process of sensing pressure using a transducer including the exemplary inductive element 100 in connection with the telemetry system 300. In a step 400, the pulse generator 302 generates EM energy and supplies the EM energy to the transducer 304 via the production tubing. The transducer 304, being coupled to the production tubing, interacts with the EM energy and reflects the EM energy at a ring frequency determined by the inductive element 308 of the transducer 304. [0027] The inductance of the inductive element 308 can vary based on a degree to which the inductive element is compressed by the observed pressure in the borehole. In a step 402, the receiver 306 receives the reflected EM energy. Based on the prior calibration, the processor 312 of the receiver 306 uses means, such as a look-up table, for correlating the ring frequency of the received EM energy to a pressure value (step 404). For example, the processor 312 determines an inductance value of the inductive element 308 based on the ring frequency of the transducer 304. The processor 312 correlates the inductance value of the inductive element 308 to a degree of compression of the inductive element 308. The processor 312 then associates the compression of the inductive element 308 to the pressure in the well. [0028] Figure 5 shows an exemplary device 500 having an inductive sensor 502 mounted in a housing. As shown in Figure 5, the inductive sensor 502 is encapsulated within a vessel 504. The inductive sensor 500 can be configured to include the physical properties and characteristics as described with respect to the inductive sensor 100 of Figure 1. The inductive sensor 500 can also be configured in any shape determined by the vessel 500 and/or a shape suitable to achieving the desired response within the vessel 504. The vessel 504 also includes a load-bearing element 506, such as a piston, and a port 508 for applying a load or force to the load- bearing element 506. A processor 510 can be connected to the vessel to compute the pressure in the vessel based on the inductance of the inductive sensor 502.
[0029] Figure 6 is a flowchart illustrating a method for sensing pressure using the inductive sensor 502 of Figure 5. In a step 600, pressure is applied to a load-bearing element 506, e.g. piston, of the vessel so that the inductive element 502 is compressed. In a step 602, the processor 510 monitors and records a measurement of an inductance of the inductive sensor 502. In a step 604, the processor 510 determines an observed degree of compression of the inductive sensor 502 based on the measured inductance of the inductive sensor 502. The processor 510 correlates the determined compression to the pressure in the vessel 500 (step 506). [0030] While the invention has been described with reference to specific embodiments, this description is merely representative of the invention by way of example only and is not to be construed as limiting the invention, as numerous variations will exist. Various modifications and applications may occur to those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:
1. A sensing device, comprising: a shaped elastomer; and ferromagnetic material embedded as discrete particles within the shaped elastomer, wherein a percentage by weight of the ferromagnetic particles is selected such that an inductance of the shaped elastomer will vary a predetermined amount for a given compression of the shaped elastomer.
2. The sensing device of claim 1, further comprising: a capacitive element coupled to the shaped elastomer.
3. The sensing device of claim 2, wherein the capacitive element is less sensitive to temperature and pressure than the shaped elastomer.
4. The device of claim 2, wherein the shaped elastomer and capacitive element are mounted in a vessel.
5. A system for sensing pressure in a borehole, comprising: means for generating electromagnetic energy; and means for modulating the electromagnetic energy, wherein the modulating means includes an inductive element which comprises: a shaped elastomer; and ferromagnetic material embedded as discrete particles within the shaped elastomer, wherein a percentage by weight of the ferromagnetic particles is selected such that an inductance of the shaped elastomer will vary a predetermined amount for a given compression of the shaped elastomer.
6. The system of claim 5, further comprising: means for receiving the modulated electromagnetic energy; and means for processing the modulated electromagnetic energy to determine pressure.
7. The system of claim 5, wherein the means for generating electromagnetic energy comprises an electromagnetic pulse generator.
8. The system of claim 5, wherein the modulating means comprises: a capacitive element coupled to the inductive element.
9. The system of claim 8, wherein the capacitive element is less sensitive to temperature and pressure than the inductive element.
10. The system of claim 6, wherein the means for receiving the modulated electromagnetic energy comprises a surface RF receiver.
11. The system of claim 6, wherein the means for processing the modulated electromagnetic energy to determine pressure involves use of a lookup table of known pressure-modulation correlations.
12. A method of sensing pressure using a transducer having a compressible inductive element, the method comprising: supplying electromagnetic energy to a transducer which is configured to reflect the electromagnetic energy at a ring frequency determined by an inductance of the transducer, wherein the inductance changes in response to compression of the inductive element; and correlating the ring frequency of electromagnetic energy reflected by the transducer to a pressure value.
13. The method of claim 12, wherein the electromagnetic energy is emited as a continuous wave.
14. The method of claim 12, wherein the electromagnetic energy is emitted as a pulse.
15. The method of claim 12, wherein the ring frequency is correlated to the pressure value using a look-up table.
PCT/US2008/009161 2007-07-30 2008-07-30 System and method for sensing pressure using an inductive element WO2009017728A1 (en)

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EP08780331.8A EP2185793A4 (en) 2007-07-30 2008-07-30 System and method for sensing pressure using an inductive element
CA2693629A CA2693629C (en) 2007-07-30 2008-07-30 System and method for sensing pressure using an inductive element
AU2008282816A AU2008282816B2 (en) 2007-07-30 2008-07-30 System and method for sensing pressure using an inductive element
BRPI0814156-8A2A BRPI0814156A2 (en) 2007-07-30 2008-07-30 SENSOR DEVICE, PRESSURE DETECTING SYSTEM IN A PROBING HOLE AND PRESSURE DETECTING METHOD
CN200880100875.1A CN101765698B (en) 2007-07-30 2008-07-30 System and method for sensing pressure using an inductive element
EA201070203A EA019220B1 (en) 2007-07-30 2008-07-30 System and method for sensing pressure using an inductive element

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CA2693629A1 (en) 2009-02-05
CA2693629C (en) 2016-03-29
CN101765698A (en) 2010-06-30
EA019220B1 (en) 2014-02-28
BRPI0814156A2 (en) 2015-01-06
EA201070203A1 (en) 2010-08-30
AU2008282816A1 (en) 2009-02-05
US20090031796A1 (en) 2009-02-05
EP2185793A1 (en) 2010-05-19
EA021214B1 (en) 2015-04-30
US7841234B2 (en) 2010-11-30
EP2185793A4 (en) 2014-07-30
CN101765698B (en) 2014-01-22

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