| 摘要 |
The present invention provides a novel valve arrangement that enables the opening and closing of the test string circulation valve, and - when the valve is closed - the opening and closing of the tubing isolating valve, as many times as desired. To attain this end a number of arrangement are em- ployed: 1) the use of a 3-slot indexer to control the operation of a tool, t he slot being in the form of two closed loop tracks (one laying within the othe r, with a common part), the two tracks controlling two different tool mode op- erations; 2) the operation of a multimode tool by a succession of annulus pressure pulses, wherein an initial operation is effected by pressure change s of a first pulse, and the operation following the subsequent pressure change is effected slowly so that, if a second pulse occurs within a given time (fr om the preceding pulse), the mode of the tool is altered and a third pulse thereof- ter causes a different operation to be initiated; 3) the use of two separate J- slot indexers, each in the form of a closed loop track, to control tool oper a- tion, one J-slot indexer controlling the movement of a first operating membe r connected to and driving a second operating member the movement of which is controlled by the other J-slot indexer.
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