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Application of Tomographic NDT Techniques in Oil Industry

The advent of computerized tomography (CT) has revolutionized the way engineers approach nondestructive testing and evaluation exercises these days. There has been a recent laboratory study (at Leibniz University Hannover) that uses a similar X-ray CT scanner for a three-phase flow system having industrial equivalent in the oil exploration industry. This study has applied “KT-1 signature” approach for such applications. It is based on Sobolev space analysis and utilizes different Hamming filters (for a given Fourier cut-off frequency) for tomographic reconstructions from Fourier transform based techniques. This work relates the point wise theoretical error in reconstruction of objects that belong to certain Sobolev space. The present work extends this concept to characterize types of flow pattern that may be encountered in oil industry applications and “KT-2 signature” approach is adopted. This analysis is also based on Sobolev spaces and it utilizes different Fourier cut-off frequencies for a fixed Hamming filter. This approach is global in nature and it guarantees the order of error in tomographic reconstructions. These signatures give a linear relationship between inherent error and Fourier cut-off frequency. The slope of this linear behaviour is used to characterize the flow images. Such a technique provides very useful input for three-phase flow pumping phenomenon that is relevant to oil exploration industry. A three-phase bubble column reactor is investigated in this study. Three phases in this bubble column were: air, water and polyvinyl chloride (PVC). The composition of PVC was made 5% of the total volume of bubble column. Water was injected with velocity of 0.07 m/s and four different air velocities used were 0.06 m/s, 0.08 m/s, 0.12 m/s and 0.14 m/s. This bubble column was scanned at two different heights of 1.7 m and 3.2 m from the inlet.

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