Optical Magnetic Field Sensor Units for a Downhole Environment

• US 20170082770A1
• Filed: 05/19/2014
• Published: 03/23/2017
• Est. Priority Date: 05/19/2014
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: MANDVIWALA, Tasneem A., Wilson, Glenn A., FOUDA, Ahmed, Donderici, Burkay, Samson, Etienne
• Granted Patent: US 10,598,810 B2
• Time in Patent Office: Days
• CPC Class Codes: E21B 47/017 Protecting measuring instruments
• CPC Class Codes: E21B 47/092 by detecting magnetic anomalies
• CPC Class Codes: E21B 47/10 Locating fluid leaks, intrusions or movements
• 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: E21B 49/00 Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
• CPC Class Codes: G01R 33/032 using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
• CPC Class Codes: G01V 3/18 specially adapted for well-logging
• CPC Class Codes: G01V 3/26 operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device with electromagnetic waves G01V3/30

Abstract

A magnetic field sensor unit for a downhole environment includes an optical fiber, a magnetic field sensor, and an optical transducer. The sensor unit also includes a sealed housing that encloses the magnetic field sensor and the optical transducer. The optical transducer is configured to generate a light beam or to modulate a source light beam in the optical fiber in response to a magnetic field sensed by the magnetic field sensor. Related magnetic field measurement methods and systems deploy one or more of such magnetic field sensor units in a downhole environment to obtain magnetic field measurements due to an emitted electromagnetic field.

Claims

1. A magnetic field sensor unit for a downhole environment, the sensor unit comprising:

an optical fiber;

a magnetic field sensor;

an optical transducer; and

a sealed housing that encloses the magnetic field sensor and the optical transducer,

wherein the optical transducer is configured to generate a light beam or to modulate a source light beam in the optical fiber in response to a magnetic field sensed by the magnetic field sensor.

2. The sensor unit of claim 1, wherein the housing is filled with a fluid that is non-magnetic, electrically insulating, and chemically inert.

3. The sensor unit of claim 1, wherein the housing is filled with a fluid that is non-compressible.

4. The sensor unit of claim 1, wherein the housing is filled with a fluid that enhances magnetic flux density inside the housing in presence of a magnetic field.

5. The sensor unit of claim 1, wherein the housing includes connectors at opposite ends of the housing for coupling the sensor to a fiber optic cable.

6. The sensor unit of claim 1, further comprising a plurality of magnetic field sensors and corresponding optical transducers having different orientations within the housing.

7. The sensor unit of claim 1, wherein the housing is configured to withstand operating temperatures greater than 175°

C. and operating pressures greater than 35,000 psi.

8. The sensor unit of claim 1, wherein the housing resists corrosion from cementation, steam injection, acidization, and hydraulic fracturing.

9. The sensor unit of claim 1, wherein the housing has a maximum width of less than 1 inch.

10. The sensor unit of claim 1, wherein the housing is made from an Inconel material or an Incoloy material.

11. A magnetic field measurement system for a downhole environment, the system comprising:

an electromagnetic source to emit an electromagnetic field;

an optical fiber and an optical magnetic field sensor unit positioned in the downhole environment, wherein the optical magnetic field sensor unit comprises a sealed housing that encloses a magnetic field sensor and an optical transducer; and

a remote interrogation or monitoring unit coupled to the optical fiber to obtain a magnetic field measurement from the optical magnetic field unit due to the emitted electromagnetic field.

12. The system of claim 11, further comprising a logging-while-drilling (LWD) tool or wireline tool string associated with the optical magnetic field sensor unit to adjust a position of the optical magnetic field sensor unit in the downhole environment.

13. The system of claim 11, further comprising a permanent well casing associated with the optical magnetic field sensor unit to maintain a permanent position of the optical magnetic field sensor unit in the downhole environment.

14. The system of claim 11, further comprising a plurality of optical magnetic field sensor units, each sensor unit having a housing that encloses a magnetic field sensor and an optical transducer, wherein the plurality of optical magnetic field sensor units are distributed in a single well or in multiple wells.

15. The system of claim 11, further comprising a computer that receives and processes measurements corresponding to one or more optical magnetic field sensor units to generate a log for display.

16. The system of claim 11, wherein the interrogation or monitoring unit emits a source light beam along the optical fiber and monitors phase changes in the light beam caused by one or more optical magnetic field sensor units distributed along the optical fiber.

17. The system of claim 11, wherein the housing has a maximum width of less than 1 inch and is configured to withstand operating temperatures greater than 175°

C. and operating pressures greater than 35,000 psi.

18. A magnetic field measurement method for a downhole environment, the method comprising:

positioning an optical fiber and an optical magnetic field sensor unit in the downhole environment, wherein the optical magnetic field sensor unit comprises a sealed housing that encloses a magnetic field sensor and an optical transducer;

emitting an electromagnetic field; and

interrogating or monitoring an output of the optical magnetic field sensor unit to obtain a magnetic field measurement due to the emitted electromagnetic field.

19. The method of claim 18, wherein said positioning comprises temporarily positioning the optical magnetic field sensor unit using a logging-while-drilling (LWD) string or wireline tool string.

20. The method of claim 18, wherein said positioning comprises permanently positioning the optical magnetic field sensor unit as part of a permanent well installation.

21. The method of claim 18, wherein the housing has a maximum width of less than 1 inch and is made from at least one of an Inconel material and an Incoloy material.