| 摘要 |
A tubular body or mandrel incorporated into a string of tubular pipe, on which first and second swab cups and first and second metal brushes and a casing scraper are mounted, is run into a cased earth borehole to displace a first fluid in the borehole, usually a drilling fluid, with a second fluid, usually either a completion fluid or a workover fluid. In a first embodiment, reverse circulation, in which the second fluid is pumped into the borehole annulus above the swab cups and/or the metal brushes, and in which the first fluid is thereby pumped back towards the earth's surface through the interior of the string of tubular pipe, causes displacement of the first fluid merely by lowering the string of pipe while pumping the second fluid into the borehole annulus. In a second embodiment, using normal circulation, the first fluid is pumped from the earth's surface downwardly through the interior of the string of tubular pipe into the borehole annulus between the pair of swab cups, and/or between the metal brushes. The first fluid is then displaced from the preselected zone of the cased borehole by raising or lowering the string of tubular pipe. In an alternative embodiment, the tubular pipe, upon which the swab cups and the brushes and the casing scrapers are mounted, is pulled out of the riser or cased borehole to displace the undesired fluid in the riser or cased borehole. In yet another embodiment, a plurality of large swab cups are shearingly secured to the tubular body and a plurality of smaller swab cups are secured to the tubular body, which also includes one or more spring-loaded casing scrapers mounted below the smaller swab cups, thereby allowing the apparatus to be used in progressively smaller diameter casing during the same operation of the apparatus.
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