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Gas and Liquid Injection Rates                                191


        (2007) found that this chart can be replaced by the following correlation
        with good accuracy:
                                   ðCN L Þ = 10 Y                   (9.29)
        where
                                                          2
                      Y = −2:69851 + 0:15841X 1 − 0:55100X
                                                          1
                                      3          4                  (9.30)
                           + 0:54785X − 0:12195X
                                     1           1
        and
                                 X 1 = logðN L Þ + 3                (9.31)

           Once the value of parameter (CN L ) is determined, it is used for calcu-
                                      0:1
        lating the value of the group  N vL p ðCN L Þ ,where p is the absolute pressure
                                   N 0:575 0:1  N D
                                       p
                                    vG  a
        at the location where the pressure gradient is to be calculated, and p a is
        the atmospheric pressure. The value of this group is then used as an entry
        in the second chart in Hagedorn and Brown’s model to determine param-
        eter ðy L /ψÞ. Guo and colleagues (2007) found that the second chart can
        be represented by the following correlation with good accuracy:

           y L                                                    2
           ψ   =−0:10307+0:61777½logðX 2 Þ+6Š−0:63295½logðX 2 Þ+6Š  (9.32)
                                     3                   4
                 +0:29598½logðX 2 Þ+6Š −0:0401½logðX 2 Þ+6Š
        where

                                         0:1
                                X 2 =  N vL p ðCN L Þ               (9.33)
                                      N  0:575 0:1
                                       vG  p N D
                                            a
        According to Hagedorn and Brown, the value of parameter ψ can be
                                                             0:38
                                                         N vG N
                                                             L
        determined from the third chart using a value of group  2:14 .
                                                           N
                                                            D
                                                 N vG N  0:38
           Guo and colleagues (2007) found that for  L  > 0:01 the third chart
                                                   N 2:14
                                                    D
        can be replaced by the following correlation with good accuracy:
                       ψ = 0:91163 − 4:82176X 3 + 1232:25X 2
                                                         3          (9.34)
                                      3            4
                           − 22253:6X + 116174:3X
                                      3            3
        where
                                             0:38
                                       N vG N
                                  X 3 =     L                       (9.35)
                                         N 2:14
                                           D
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