Drilling expenses has increased sharply in recent years. Average meters drilled per day significantly influences exploration costs. Hence it is important to understand the factors that determine meter per day. In this study we analyse the effect of drilling depth on meter per day. There are various physical and technical characteristics that enhance and decrease meter per day as drilling depth increases. Factors that reduce meter per day are present at depths way above depths of high pressure and high temperature. The counteracting effects on meter per day are described and analysed on a large number of exploration wells on the Norwegian continental shelf, and implications for drilling costs are discussed.