# US 2008/0184787 A1 · Temperature and pressure transducer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0184787 A1 - Document ID: US20080184787A1 - Status: Published application - Kind: A1 - Application number: 12/026,795 - Filed: 2008-02-06 - Published: 2008-08-07 - Earliest claimed: 2007-02-06 - Assignees: Chevron U.S.A. Inc. - Inventors: Don M. COATES - Web page: https://patentgrep.com/patent/US20080184787A1 ## CPC - E21B 47/06: Measuring temperature or pressure - G01K 5/48: the material being a solid - G01K 5/62: the solid body being formed of compounded strips or plates, e.g. bimetallic strip - G01K 7/34: using capacitative elements (capacitors per se H01G) - G01L 9/0072: {using variations in capacitance} - H01G 7/00: Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture - H01G 7/04: having a dielectric selected for the variation of its permittivity with applied temperature - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00) - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) - H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10) ## Abstract Methods for making and systems employing pressure and temperature sensors are described. Embodiments include a capacitive element including a first conductor plate and a second conductor plate. Each plate includes a conductor layer formed on a substrate. In a pressure sensor embodiment, seal is positioned at or near the edges of the conductor plates, and a gas retained in a gap defined between the plates. In a temperature sensor embodiment, the gap defined between the plates is in fluid communication with the external environment. ## Claims ### Claim 1 A system for sensing a characteristic in a subterranean environment, comprising: a signal generator, configured and arranged generate an electromagnetic signal; a sensor probe, locatable in a region of the subterranean environment, the sensor probe including a resonant circuit portion that includes a capacitive element, the resonant circuit portion being configured and arranged to receive energy from the electromagnetic signal and to generate a ringing signal in response to the electromagnetic signal, wherein the capacitive element of the sensor probe is responsive to a condition of the characteristic in the region of the subterranean environment to modulate the ringing signal in accordance therewith; the capacitive element comprising: a first conductor plate having a first conductive layer supported by a first substrate; and a second conductor plate having a second conductive layer supported by a second substrate, the first and second conductor plates together defining an adjustable gap therebetween, the adjustable gap being adjustable responsive to the condition to alter a capacitance of the capacitive element; a receiver, configured and arranged to receive the modulated ringing signal; and a processor, configured and arranged to process the modulated ringing signal to obtain a measurement of the condition. ### Claim 2 (depends on 1) A system in accordance with claim 1, wherein the characteristic is a pressure condition and further comprising: a seal between the first and second conductor plates, the seal constructed and arranged to retain a compressible material in an adjustable gap between the first and second conductor plates and wherein, the adjustable gap is adjustable responsive to the pressure condition to alter the capacitance of the capacitive element and wherein the first and second conductor plates are arranged and comprise materials selected such that a change in the adjustable gap due to a change in temperature is less than a change in the adjustable gap due to a change in pressure. ### Claim 3 (depends on 2) A system in accordance with claim 2, wherein a coefficient of thermal expansion of one or both of the first and second conductive layers is less than about 10·10−6 1/K. ### Claim 4 (depends on 3) A system in accordance with claim 3, wherein a coefficient of thermal expansion of one or both of the first and second substrates is less than about 5·10−6 1/K. ### Claim 5 (depends on 2) A system in accordance with claim 2, wherein a flexural response to pressure of the first conductive plate is greater than a flexural response to pressure of the second conductive plate. ### Claim 6 (depends on 4) A system in accordance with claim 4, wherein one or both of the first and second conductor plates comprises at least one of carbon fiber, 36FeNi or FeNi42. ### Claim 7 (depends on 2) A system in accordance with claim 2, wherein one or both of the first and second conductive layers comprises a plurality of layers, each layer comprising a material having a low coefficient of thermal expansion. ### Claim 8 (depends on 7) A system in accordance with claim 7, wherein each layer comprises a material having a coefficient of thermal expansion less than about 10·10−6 1/K. ### Claim 9 (depends on 8) A system in accordance with claim 8, wherein each layer comprises a material having a coefficient of thermal expansion less than about 5·10−6 1/K. ### Claim 10 (depends on 2) A system in accordance with claim 2, wherein the compressible material comprises an inert gas. ### Claim 11 (depends on 1) A system in accordance with claim 1, wherein the characteristic is a temperature condition and the first conductive layer has a higher coefficient of thermal expansion than does the first substrate, the second conductive layer has a higher coefficient of thermal expansion than does the second substrate, the first and second conductor plates being mutually arranged to define an adjustable gap therebetween, wherein the adjustable gap is adjustable responsive to the temperature condition to alter the capacitance of the capacitive element; and a volume between the first and second conductor plates comprising the adjustable gap being in fluid communication with the subterranean environment. ### Claim 12 (depends on 11) A system in accordance with claim 11, further comprising a member extending between the first and second conductor plates to define the volume and wherein the volume is in fluid communication with the subterranean environment via a vent formed in at least one of the first conductor plate and the second conductor plate. ### Claim 13 (depends on 12) A system in accordance with claim 12, wherein the member comprises a compressible member constructed and arranged to resiliently compress in response to flexing of the conductor plates. ### Claim 14 (depends on 11) A system in accordance with claim 11, wherein at least a portion of a periphery of the volume is open to allow the volume to be in fluid communication with the subterranean environment. ### Claim 15 (depends on 11) A system in accordance with claim 11, wherein the first conductive layer has a higher coefficient of thermal expansion than does the second conductive layer. ### Claim 16 (depends on 15) A system in accordance with claim 15, wherein the first substrate has a higher coefficient of thermal expansion than does the second substrate. ### Claim 17 (depends on 11) A system in accordance with claim 11, wherein one or both of the first conductive layer and the second conductive layer comprises a metal having a coefficient of thermal expansion greater than about 10·10−6 1/K. ### Claim 18 (depends on 17) A system in accordance with claim 17, wherein the metal comprises a metal selected from the group consisting of steel, copper, brass, and aluminum. ### Claim 19 (depends on 11) A system in accordance with claim 11, wherein one of the first and second conductor plates is inactive and the other is active. ### Claim 20 (depends on 19) A system in accordance with claim 19, wherein the inactive plate comprises at least one of carbon fiber, 36FeNi or FeNi42. ### Claim 21 A capacitive sensor comprising: a first conductor plate having a first conductive layer supported by a first substrate; a second conductor plate having a second conductive layer supported by a second substrate, the first and second conductor plates together defining an adjustable gap therebetween; and a seal between the first and second conductor plates, the seal constructed and arranged to retain a compressible material in an adjustable gap between the first and second conductor plates and wherein the adjustable gap is adjustable responsive to a pressure condition to alter the capacitance of the capacitive element and wherein the first and second conductor plates are arranged and comprise materials selected such that a change in the adjustable gap due to a change in temperature is less than a change in the adjustable gap due to a change in pressure. ### Claim 22 (depends on 21) A sensor in accordance with claim 21, wherein a coefficient of thermal expansion of one or both of the first and second conductive layers is less than about 10·10−6 1/K. ### Claim 23 (depends on 22) A sensor in accordance with claim 22, wherein a coefficient of thermal expansion of one or both of the first and second substrates is less than about 5·10−6 1/K. ### Claim 24 A capacitive sensor comprising: a first conductor plate having a first conductive layer supported by a first substrate, the first conductive layer having a higher coefficient of thermal expansion than does the first substrate; a second conductor plate having a second conductive layer supported by a second substrate, the second conductive layer having a higher coefficient of thermal expansion than does the second substrate, and the first and second conductor plates together defining an adjustable gap therebetween, wherein the adjustable gap is adjustable responsive to a temperature condition to alter an capacitance of the capacitive element; and a volume between the first and second conductor plates comprising the adjustable gap being in fluid communication with the subterranean environment. ### Claim 25 (depends on 24) A sensor in accordance with claim 24, further comprising a member extending between the first and second conductor plates to define the volume and wherein the volume is in fluid communication with the subterranean environment via a vent formed in at least one of the first conductor plate and the second conductor plate. ### Claim 26 (depends on 25) A sensor in accordance with claim 25, wherein the member comprises a compressible member constructed and arranged to resiliently compress in response to flexing of the conductor plates. ### Claim 27 (depends on 24) A sensor in accordance with claim 24, wherein at least a portion of a periphery of the volume is open to allow the volume to be in fluid communication with the subterranean environment. ### Claim 28 (depends on 24) A sensor in accordance with claim 24, wherein the first conductive layer has a higher coefficient of thermal expansion than does the second conductive layer. ### Claim 29 A method of measuring a characteristic in a subterranean environment, comprising: generating an electromagnetic signal; receiving energy from the electromagnetic signal and generating a ringing signal in response to the electromagnetic signal, using a capacitive element that is responsive to a condition of the characteristic in the region of the subterranean environment to modulate the ringing signal in accordance therewith; the capacitive element comprising: a first conductor plate having a first conductive layer supported by a first substrate; and a second conductor plate having a second conductive layer supported by a second substrate, the first and second conductor plates together defining an adjustable gap therebetween, the adjustable gap being adjustable responsive to the condition to alter a capacitance of the capacitive element; receiving the modulated ringing signal; and correlating the modulation with a measurement of the condition. ### Claim 30 (depends on 29) A method in accordance with claim 29, wherein the capacitive sensor further comprises a seal between the first and second conductor plates, the seal constructed and arranged to retain a compressible material in an adjustable gap between the first and second conductor plates and wherein the adjustable gap is adjustable responsive to a pressure condition to alter the capacitance of the capacitive element and wherein the first and second conductor plates are arranged and comprise materials selected such that a change in the adjustable gap due to a change in temperature is less than a change in the adjustable gap due to a change in pressure. ### Claim 31 (depends on 29) A method in accordance with claim 29, wherein the condition comprises a temperature, and a volume between the first and second conductor plates comprising the adjustable gap is in fluid communication with the subterranean environment such that a change in the adjustable gap due to a change in pressure is less than a change in the adjustable gap due to a change in temperature.