Study on the Penetration Rate at Tsuchizaki-oki Oil Field and Kumoide Gas Field

The auther has stunied on the penetration rates at Tsuchizaki-oki Oil Field and Kumoide Gas Field, especially on the effect of the bit weight and the rotary speed. Resnlts obtained are as follows: 1. At shallower formations the penetration rate per revolution is affected by the bit weight linearly (Figs. 2 and 7).2. At medium depth the penetration rate per revolution is affected both by the bit weight and the rotary speed. Higher penetration rate per ravolution is obtained at lower rotary speed. At higher rotary speed than a certain limit, the penatration rate dots not incrase with the rncrease of ratary speed (Fig. 8).3. At deeper formetions the penetration rate is affected only by the bit weight and not by the rotary speed (Figs. 3, 5 and 9).