Designing the drilling jar placement for better jarring performance

The sticking of drilling string happens occasionally during drilling operation, it is necessary to place drilling jars in proper placement of the drilling string. The jar placement in the bottom hole assembly (BHA) will affect the jarring operation very severely. According to the jarring principle, this paper builds the designing model about optimum drilling jar placement. The model considers the influence of the weight of BHA, the drillstring drag, and the different BHA. An example of calculation shows that the model achieves better agreement with the reality, and it can be used to design the drilling jar placement in directional well, horizontal well and extend reach well.