Patent ID: 9689224
Date: 2017-06-27
CPC Classifications: E21B

Claim:
1. A cable-operated jar comprising a releasable coupling arranged for connection to a piece of downhole equipment, in which a mandrel, which is connected to a cable, comprises a hammer section which is arranged to strike, on the release of a mandrel coupling, against a shoulder section in a housing accommodating the mandrel, and the mandrel is pre-tensioned in a releasable position with a spring arrangement including an adjusting mechanism operated by alternately tensioning and relieving the cable, wherein the mandrel has an upper section configured to be releasably connected to a lower mandrel section by the mandrel coupling which is movable into and out of engagement with an engagement portion fixed inside the housing; the housing includes a bottom portion and a further shoulder section fixed to the housing between the mandrel coupling and the bottom portion; and the adjusting mechanism is configured for adjustment from within the housing, and includes an adjusting sleeve which is axially slidable along an inner surface of the housing, and also includes a guide device engaged for axial movement between a change-over abutment in which the spring arrangement is disengaged from the further shoulder section and the adjusting sleeve rests on the bottom portion of the housing, and a number of different work abutments formed in a guiding groove which extends continuously with respect to the inner surface of the housing, wherein the work abutments have different axial positions which provide a desired distance between the adjusting mechanism and the further shoulder section to enable contact of the spring arrangement with the further shoulder section and cause compression of the spring arrangement upon axial movement of the mandrel until the mandrel coupling engages the engagement portion thereby releasing the upper mandrel section from the lower mandrel section, and causing the hammer section to strike the shoulder section and transmit an impact force to the downhole equipment.