Investigation of a drift velocity model for predicting superficial velocities of oil and water in incline oil-in-water pipe flows with a centre body

摘要

In this paper it is shown that a drift velocity model of the kind described by Hasan and Kabir can be used to accurately describe the behaviour of inclined oil-in-water flows with a centre body. It is shown, however, that values for the distribution parameter C_(0θ) and single-droplet terminal rise velocity υ_(tθ) (which are both required by the drift velocity model) that have been suggested by Hasan and Kabir may be inappropriate for certain flow conditions. In particular, it is shown that the presence of a centre body, of the type used during production logging operations, can have a marked effect on the values of C_(0θ) and υ_(tθ). Finally the authors show that, for oil-in-water flows inclined at angles of up to 60° from the vertical, the drift velocity model can be used in conjunction with values of C_(0θ) and υ_(tθ) obtained by calibration experiments to make reasonably accurate predictions of the superficial velocities of oil and water. For the range of flow conditions investigated in the present study it was found that the average percentage error in the predicted oil superficial velocity was equal to 0.4%, the standard deviation of the percentage error in the predicted oil superficial velocity was equal to 6.9% and the average absolute percentage error in the predicted oil superficial velocity was equal to 5.5%. The average percentage error in the predicted water superficial velocity was equal to -0.22%, the standard deviation of the percentage error in the predicted water superficial velocity was equal to 5.6% and the average absolute percentage error in the predicted water superficial velocity was equal to 3.59%. The results presented in this paper will allow better estimates of the volumetric flow rates of oil and water at a given location in the well to be made from measurements of the homogeneous velocity and the oil volume fraction obtained at this location during production logging operations.