Methods and systems for extending the range for fiber optic distributed temperature (DTS) systems

• US 8,333,505 B2
• Filed: 01/17/2009
• Issued: 12/18/2012
• Est. Priority Date: 01/18/2008
• Status: Expired due to Fees

• Current Assignee: Sensortran Incorporated (Halliburton Company)
• Original Assignee: Sensortran Incorporated (Halliburton Company)
• Inventors: Lee, Chung, Kalar, Kent, Ajgaonkar, Mahesh, Sanders, Michael
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): WILLIAMS, JAMEL E
• Application Number:
  US12/735,356
• Publication Number:
  US 20110280277A1
• Time in Patent Office: 1,431 Days
• Field of Search: 374/137
• US Class Current: 374/137
• CPC Class Codes: G01K 11/32 using changes in transmittance, scattering or luminescence in optical fibres

Abstract

Systems and methods for extending the range of a fiber optic DTS system are provided. In one respect, a method may provide steps for transmitting, in a first time period, an optical signal at a first energy level through an optical fiber, collecting backscatter signals as a result of the first transmission, adjusting the first energy level to a second energy level, transmitting, in an additional time period, the adjusted optical signal through the optical fiber, collecting backscatter signals as a result of the adjusted transmissions, and using a portion of the collected backscatter as a result of the first transmission and a portion of the collected backscatter as a result of the additional transmissions, determining one or more parameter profiles, such as a temperature profile.

Claims

1. A method for extending the distance range of a fiber optic distributed temperature system using a single optical source comprising the steps of:

a. transmitting, in a first time period, a first optical signal, at a first energy level and at a first wavelength through an optical fiber;

b. collecting backscatter Raman Stokes and anti-Stokes signals as a result of said first transmission of said optical signal from a first length of the optical fiber;

c. transmitting, in at least one additional time period, an additional optical signal at higher energy level and at the first wavelength through said optical fiber;

d. collecting backscatter Raman Stokes and anti-Stokes signals as a result of said additional transmission from an additional length of the optical fiber;

wherein said backscatter Raman Stokes and anti-Stokes signals are those resulting from the spontaneous scattering of the additional optical signal at the first wavelength;

e. using the collected Raman Stokes and anti-Stokes backscatter as a result of said first transmission to calculate a temperature profile of said first length of optical fiber and the collected Raman Stokes and anti-Stokes backscatter as a result of said additional transmissions to calculate a temperature profile of said additional length of optical fiber, and adding the temperature profiles to display a temperature response of the whole sensing fiber.

2. The method for extending the distance range of a fiber optic distributed temperature system using a single optical source of claim 1, wherein transmitting an additional optical signal at a higher energy level comprises adjusting a variable optical attenuator.

3. The method for extending the distance range of a fiber optic distributed temperature system using a single optical source of claim 1, wherein transmitting an additional optical signal at a higher energy level comprises adjusting the optical source'"'"'s transmitting energy by changing the operating condition of the optical source.