An initial investigation of the correlation between a number of drilling related quantities measured during down the hole drilling

Optimizing the performance for down the hole (DTH) drills is becoming increasingly important. This is due to that the industry is becoming highly competitive and therefore there is an ever-increasing demand for improving the efficiency of the drilling process. To do this, it is important to have a robust monitoring system in place that should be based on in-depth knowledge of the underlying physics of the drilling system and process. Such a system will assist drillers in improving the perfor-mance e.g. by providing recommendations concerning the settings of the drilling. To understand the performance of the system, it is very important to understand the information that can be extracted from different drilling related quantities. In this work, information obtained from the pressure signals from the feed/holdback line, impact pressure line and rotation line together with vibration signals measured with the aid of accelerometers mounted at specific locations on the drill rig are discussed. For instance, spectral properties of these quantities for good and bad drilling cases are investigated. The results indicate correlations, to some extent, between the spectral properties and the quality of the drilling