Page 105 - Petroleum and Gas Field Processing

the simultaneous flow of oil, gas, and water (multiphase flow),
which makes the pressure drop dependent on many variables,
some of which are interdependent. There is no analytical solution
to this problem. Instead, empirical correlations and mechanistic
models have been developed and used for predicting the pressure
drop in multiphase flow. Computer programs based on such
correlations and models are now available for the determination
of pressure drops in vertical, inclined, and horizontal pipes.
3. Sizing tubing and flow line: Determination of the tubing and
flow line sizes is a complex process involving the determination
and prediction of future well productivity, analysis of multi-
phase flow under varying production conditions, and economic
analysis. However, a simplified approach is summarized in the
following steps and illustrated in Figure 18:
(i) Determine (predict) the present and future IPR. Plot the
results as P wf versus q.
(ii) Selecting tubing and flow line diameters and starting with a
specified value for the surface separator pressure, determine
the flowing bottom-hole pressure for a specified production
rate, water cut (W.C.) and gas–oil ratio (GOR), using
available multiphase flow correlations or models.
Determine the diameter and seam-to-seam length of a horizontal separator
for the following operating conditions. Determine the actual gas and oil
capacity of the designed separator.
Gas rate: 15 MMSCFD
Gas specific gravity: 0.6
Oil rate: 3,000 bbl/day

Oil gravity: 35 API
Operating pressure: 985 psi

Operating temperature: 60 F
Retention time: 3 min

Solution
From Example 1, we have
m g ¼ 0.013 cP
g ¼ 3.708 lb/ft 3
o ¼ 53.03 lb/ft 3
Z ¼ 0.84
c d ¼ 1.1709

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.