Sensing strain in hydrocarbon wells

• US 6,555,807 B2
• Filed: 12/04/2000
• Issued: 04/29/2003
• Est. Priority Date: 10/06/2000
• Status: Expired due to Term

• Current Assignee: GE Oil & Gas UK Limited (Baker Hughes Company)
• Original Assignee: ABB Offshore Systems Limited (General Electric Company)
• Inventors: Clayton, Hugh R, Douglas, Neil I
• Primary Examiner(s): Dang, Hung Xuan
• Application Number:
  US09/729,633
• Publication Number:
  US 20020040963A1
• Time in Patent Office: 876 Days
• Field of Search: 250/231.1, 250/227.14, 250/227.18, 250/227.19, 250/227.16, 356/342, 356/32, 340/555, 340/556, 340/557, 340/626
• US Class Current: 250/227.16
• CPC Class Codes: E21B 47/007 Measuring stresses in a pipe string or casing for locating blocked portions of pipes E21B47/09
• CPC Class Codes: E21B 47/135 using light waves, e.g. infrared or ultraviolet waves
• CPC Class Codes: G01D 5/35364 using inelastic backscattering to detect the measured quantity, e.g. using Brillouin or Raman backscattering
• CPC Class Codes: G01M 11/085 the optical fiber being on or near the surface of the DUT

Abstract

An apparatus for sensing strain applied to a region of a hydrocarbon well comprises an optical fiber in communication with the region. The optical fiber is responsive to strain applied to the region and to a light signal transmitted through it, in order to produce a sensing light signal incorporating scattered light. A characteristic of the scattered light is indicative of the strain being applied to the region.

Claims

1. Apparatus for sensing strain applied to a region of a hydrocarbon well, comprising an optical fiber in communication with the region, the optical fiber being responsive to strain applied to the region and to a light signal transmitted through it, in order to produce a sensing light signal incorporating scattered light, wherein a characteristic of the scattered light is indicative of the strain being applied to the region.

2. Apparatus as claimed in claim 1, in which the characteristic of the scattered light is Brillouin scatter.

3. Apparatus as claimed in claim 1 further comprising a laser arranged to generate the light signal.

4. Apparatus as claimed in claim 3, in which a portion of light from the laser acts as a local reference.

5. Apparatus as claimed in claim 1 in which light is transmitted and sensed at the same end portion of the optical fiber.

6. A hydrocarbon well incorporating apparatus for sensing strain as claimed in claim 1.

7. A method of sensing strain in a hydrocarbon well, comprising transmitting a light signal in an optical fiber, detecting a light signal scattered in the fiber and deriving an indication of strain in dependence on a characteristic of the scattered light.

8. A method as claimed in claim 7, in which the indication of strain is derived from Brillouin scatter of the light signal.