System for determining and imaging wax deposition and corrosion in pipelines

Abstract

The system for determining and imaging wax deposition and corrosion in pipelines relate to systems for determining wax deposition and corrosion by one or both of two techniques. In both techniques, a source of neutron radiation is directed at the pipeline. In one technique, a neutron detector surrounded by an absorption shield defining a collimation window counts neutrons reflected back to the detector by back diffusion or backscatter radiation. In the other technique, a gamma ray detector measures gamma rays emitted when the emitted neutrons are absorbed in the pipeline. A neutron moderator-reflector is placed around three sides of the pipeline to increase the likelihood of neutron capture. A gamma detector surrounded by a gamma absorption shield defining a collimation window counts neutron capture gamma rays. An energy window can be taken for selection of Fe and H gamma rays for high precision imaging.

I claim: 
     
         1 . A system for determination of wax deposition and corrosion in a pipeline, comprising:
 a neutron radiation source for emitting neutrons towards a pipeline;   a slow neutron detector;   an absorption shield having a high slow neutron absorption cross section surrounding the slow neutron detector, the absorption shield defining a collimation window for collimating neutrons diffusing back to the detector from the pipeline; and   means for counting neutrons diffusing back to the slow neutron detector, the amount of wax deposition and corrosion in the pipeline being positively correlated with the count of neutrons as provided by the counting means.   
     
     
         2 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , further comprising means for calibrating the system before the system is used to determine wax deposition and corrosion in the pipeline. 
     
     
         3 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein composition of the absorption shield surrounding the slow neutron detector is selected from the group consisting of a thick layer of boron powder, cadmium, and boric acid. 
     
     
         4 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein the absorption shield surrounding the slow neutron detector comprises a 2.5 cm thick layer of boron powder. 
     
     
         5 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein the counting means provides a proportional count of the neutrons detected at the slow neutron detector. 
     
     
         6 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein the collimation window aimed at the pipeline is 1 cm wide. 
     
     
         7 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein the collimation window is adjustable in height. 
     
     
         8 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein said detector is vertically oriented. 
     
     
         9 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein the neutron radiation source is selected from the group consisting of  241 Am—Be and  252 Cf. 
     
     
         10 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 1 , wherein said detector is oriented horizontally. 
     
     
         11 . The system for determination of wax deposition and corrosion in a pipeline according to  claim 10 , wherein said absorption shield is cylindrical, collimation being adjustable by adjusting distance between said detector and the pipeline and by retracting said detector a selectable distance within said cylindrical absorption shield. 
     
     
         12 . A system for simultaneous determination of wax deposition and corrosion in pipelines by neutron capture gamma rays, comprising:
 a neutron radiation source for emitting neutrons towards a pipeline;   a germanium gamma ray detector configured to detect gamma rays emitted by absorption of the emitted neutrons in the pipeline;   a gamma shield separating the neutron radiation source from the germanium gamma ray detector;   a neutron moderator-reflector configured for surrounding the pipeline on three sides to increase the likelihood of neutron capture in the pipeline; and   means for counting gamma rays impinging upon the germanium gamma ray detector.   
     
     
         13 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 12 , further comprising means for calibrating the system before the system is used to determine wax deposition and corrosion in the pipeline. 
     
     
         14 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 12 , wherein the gamma shield separating the neutron radiation source from the germanium gamma ray detector is selected from the group consisting of lead and tungsten. 
     
     
         15 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 12 , further comprising a neutron moderator surrounding the neutron radiation source. 
     
     
         16 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 15 , wherein the neutron moderator surrounding the neutron radiation source comprises a layer of paraffin. 
     
     
         17 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 15 , wherein the neutron moderator surrounding the neutron radiation source comprises a layer of polyethylene. 
     
     
         18 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 12 , wherein the neutron radiation source is selected from the group consisting of  241  Am—Be and  252 Cf 
     
     
         19 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 12 , wherein said neutron moderator-reflector comprises a vessel containing water. 
     
     
         20 . A system for simultaneous determination of wax deposition and corrosion in pipelines by neutron capture gamma rays, comprising:
 a neutron radiation source for emitting neutrons towards a pipeline;   a gamma ray detector configured to detect gamma rays emitted by absorption of the emitted neutrons in the pipeline;   a gamma shield separating the neutron radiation source from the germanium gamma ray detector;   a gamma collimator disposed in front of the gamma ray detector, the emitted gamma rays being collimated; and   means for counting gamma rays impinging upon the gamma ray detector.   
     
     
         21 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 20 , further comprising means for rotating the gamma ray detector around a circumference of the pipeline wherein only a small region of the pipeline and scale is inspected at a time. 
     
     
         22 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 21 , further comprising means for taking energy windows across an Fe primary energy level, an Fe single escape energy level, and an Fe double escape energy level thereby determining corrosion in the pipeline. 
     
     
         23 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 22 , further comprising means for taking the Fe energy windows in coincidence to produce a high precision single image of the corrosion in the pipeline. 
     
     
         24 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 21 , further comprising means for taking energy windows across an H primary energy level, an H single escape energy level, and an H double escape energy level thereby determining scale in the pipeline. 
     
     
         25 . The system for simultaneous determination of wax deposition and corrosion in a pipeline according to  claim 24 , further comprising means for taking the H energy windows in coincidence to produce a high precision single image of the scale in the pipeline.