| 摘要 |
<p>A centralizer for a downhole system, such as but not limited to a casing system. In some embodiments, the centralizer has a tubular body and a plurality of roller ball assemblies circumferentially spaced about the tubular body. Each roller ball assembly includes a plurality of rotatable balls adapted to engage a surface radially offset from the centralizer and rotate relative to the surface in any direction.</p> |
