Importance

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Abstract

After the drilling of an oil well bore there is normally carried out testing using a test tool string. Following completion of the test, the test tools must be shut down, and the test string removed. It is an advantage if the string incorporate some means of isolating the upper portion of the its tubing, and of subsequently providing a communication route between this tubing and the annulus, so that tubing-contained well liquid above the test string can be circulated out of the tubing before it is raised to the surface. Previous apparatus suggested for this purpose performs quite satisfactorily, but commonly is a 'one-off' system; once activated, the several operations resulting therefrom are irreversible, and the tool cannot easily be put back into the initial state. The present invention proposes a solution to this problem, by providing a novel valve arrangement that enables the opening and closing of the test string circulation valve, and--when that valve is closed--the opening and closing of the tubing isolating valve, as many times as desired, a complete cycle of operations also being repeatable at will. To attain this end the invention employs a number of inventive arrangements and systems. The invention proposes the use of a J-slot indexer to control the operation of a tool, the slot being in the form of a closed loop track, and there is a second closed loop track part of which is in common with the first track, the two tracks controlling two different tool mode operations.

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First Claim