Drillability and Mechanical Specific Energy analysis on the example of drilling in the Pomeranian Basin.
Rafał Wiśniowski, Dariusz Knez, Łukasz Hytroś
Vol. 32, no. 1 (2015), s. 201-209, 
The advancements in drilling have always depended on the cost of drilling of new wellbores, therefore mathematical models of the drilling process were elaborated to minimize the cost. The first simple models based on a few fundamental parameters, were then developed into complex, computer-based models employing many variables. Models made for cutter bits are used for PDC tools. They contain formulae accounting for drilling parameters and wearing of the bit. The paper addresses works which prove that in some particular situations the influence of the tools wear on the drop of rate of penetration can be neglected, thanks to which simple formulae are obtained, based on the fundamental parameters and which are easily applicable in the field conditions. The MSE is an amount of energy used for drilling a given volume of rock. This approach is useful and practicable because allows for detecting possible inefficiencies in a relatively short time (as compared to other parameters). Attempts are made to compare the drillability indications ZSP with MSE plots, thanks to which new conclusions and observations can be drawn as far as the analysis and interpretation of drillability plots is concerned.