Heavy pulling and jarring shall be carried out using the top drive/ kelly on the string. On those rare occasions where this is not possible, the elevator latch shall be secured by means of a rope or chain. Remove the kelly spinner (if possible) before any jarring with the kelly is done, to avoid damage.
When sustained jarring is done, the block-line shall be slipped at regular intervals to avoid permanent damage to the line at the cross-over points. The time interval between slipping depends on the intensity of the jarring.
If applicable consider closing a kelly cock in the string to prevent unwanted U-tubing, i.e.:
- to prevent back-flow as a result of spotting a pill in the annulus.
- to prevent losing to the annulus, a pill that is being purposely retained in the drill pipe.
Regularly check the derrick and lifting equipment for loose bolts etc. Ensure that the block-line cannot jump a sheave in the crown block.
Prior to jarring always mark the string position at the rotary table and simultaneously note the reading on the heave/tide indicator.
When jarring is carried out with a circulating sub in the string, check afterwards that the pin(s) of the sleeve have not sheared due to the jarring action. Avoid jarring with an overshot, as screwing back in is preferred. In the latter case, use one single drill collar below the standard fishing assembly; the proper jarring method is to allow the jar to trip first with the required overpull before further overpull is applied.