| 摘要 |
<p>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 employed: 1) the use of a J-slot indexer to control the operation of a tool, the slot being in the form of two closed loop tracks (one laying within the other, with a common part), the two tracks controlling two different tool mode operations; 2) the operation of a multimode tool by a succession of annulus pressure pulses, wherein an initial operation is effected by pressure changes 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 (from the preceding pulse), the mode of the tool is altered and a third pulse thereafter 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 operation, one J-slot indexer controlling the movement of a first operating member connected to and driving a second operating member the movement of which is controlled by the other J-slot indexer.</p> |
