| 摘要 |
A centralizer (101) comprises two annular bands (102, 103) which are spaced apart by a plurality of hollow members (104, 105, 106) extending therebetween. The hollow members (104, 105, 106) overlie openings (110-115; 116-121) in the annular bands (102, 103) respectively. In use, fluid can enter and leave the hollow member via inter alia the openings. This flow helps maintain a film of fluid between the annular bands (102, 103) and the tubular on which the centralizer is mounted and thus facilitates rotation of the tubular with respect to the centralizer.
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