I know the subject of Jars has been done to death, so I apologise for bringing up the subject once again....but;
Can anyone please point me in the direction of a good jar placement program?
It is nice to produce a BHA folder to include the engineering aspects.
Such things as hydraulics, tendency models, sag corrections, Non Mag requirements round the MWD etc.etc., are easily available. But to complete the study I would like to include a model to justify jar placement.
Because all jars have different hammer mass and different differential areas for every drilling program I ask the specific jar provider for the impact and impulse optimization. Best report was supplied by Weir Houston - now Sii/SLB. These reports even show when you would get the neutral point in the jar. Optimization is always not easy because amount of collars is limited, as well some rig operator always single in/ out the jar and never rack it back. Some jars come with latch, others with clamp. A clamp I would always rack back on bottom. SLB even spaced out the jar with DPs to get the jar in 45 degree. So for my understanding the DP would act like a spring and eat up all impact before it reaches the bit. But calculations showed different results. The NOV placement program is free - but should be used only for NOV jars. Apart from that these placement reports are free of charge (only once in Congo report came with a fee of 1000 USD). For your study the NOV software will help.