| 摘要 |
Method and apparatus for cementing a casing in a borehole in two distinct stages by connecting the tool of the invention in series relationship respective to the casing and running the entire tool string downhole into the borehole. The tool which connects the upper and lower casing strings together includes a coupling member actuated by relative movement between the upper and lower strings. The tool always captures the upper and lower casing strings to one another and when the tool is unlatched and the upper casing string lifted, a lateral flow passageway is opened which enables cement to be pumped downhole to the tool and laterally directly into the borehole annulus. The tool therefore enables cement to be pumped along an isolated flow path to the bottom of the borehole, and thereafter pumped down the upper casing string and laterally from the tool directly into a mid-portion of the borehole annulus causing the cement to flow uphole towards the surface of the ground, and thereafter the upper string is again moved respective to the lower string, thereby closing the lateral flow passageway, whereupon the tool becomes a permanent part of the casing string.
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