| 摘要 |
A method and apparatus for flushing a well involves the use of a tool which enables a certain jarring displacement to cause a flush valve to be opened. Rotary oscillation of a stem in a given direction may be converted by a ratchet mechanism into rotation of a sleeve in the same direction. The stem may oscillate in either of two rotary directions but rotation in only one direction is transferred to the sleeve. In addition, the ratchet mechanism may be arranged so that rotation of the stem by a given amount results in rotation of the sleeve by a lesser amount. The rotation of the sleeve may be converted into a reciprocating motion of a valve portion through a cam-like engagement between the sleeve and the valve portion. The valve portion includes a port which is capable of communicating with a port in the barrel in response to a predetermined extent of displacement along the longitudinal axis of a drill string. Thus, the ratchet mechanism may be arranged so that a given number of rotary movements of the stem are required in order to achieve communication between the ports in the barrel and the valve portion. The stem may be connected to a jar mechanism, advantageously a rotary mechanical jar, so that jarring and flushing actuations may be interrelated. The arrangement of the flush valve and its operating structure enables continuous communication through the region of the drill string bore proximate to the flush valve and the ratchet mechanism, regardless of the state of the valve.
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