A gamma-ray tomography system to determine wax deposition distribution in oil pipelines

Monitoring wax deposition in pipelines is of particular importance for oil extraction companies. In this work, a new gamma-ray tomography system based on using a rod CsI(Na) scintillator and 137Cs gamma source was developed to view the cross section of oil pipelines. The system can estimate the interaction position of gamma-rays by measuring light attenuation in the rod scintillator using two photomultiplier tubes coupled to its ends. Therefore, despite the simple structure of the employed detector, it can act as a position-sensitive instrument. In order to test the proposed tomography system, a selection of desired polyethylene round-bar pieces (as different wax thicknesses) was prepared to be placed in iron pipes, and their projections at different angles were acquired to construct cross-sectional images as well. The results showed that the designed system had the ability to scan the interior of the pipes and determine wax thickness with an error between 2.4% and 11.4%.