The correlations shown in Fig. 14, Fig. 15, Fig. 16 and Fig. 17 are based on data obtained from Yabase oil field. From these curves shown in these charts, the relationship expressed in Eq. (1) was also found between apparent friction factor f and apparent density of gas-oil mixtures p. Apparent friction factor increases rapidly with increasing apparent density of the mixtures, but the rate of increase becomes slowly after reaching a constant value corresponding the rate of liquid flow (see Fig. 12). The upper limit of apparent friction factor may be obtained from Fig. 4 of Poettomann and Carpenter. The corresponding values of f and Dvp were plotted as shown in Fig. 13. The chart shows the relation within the range of oil production below 5kl/day. By using these charts we can calculate the bottom hole pressure of oil well. An example is worked out in Table 4.