Summary
Flow-rate prediction of oil production wells is of prime importance to
effectively confront high-water-cut and separator problems. (Semi-) empirical
multiphase-flow correlations are proved quite useful for this purpose. This
work presents new generalized multiphase flow choke correlation, derived on the
basis of actual production data from horizontal and vertical wells from an oil
field in Iran. The newly established correlation predicts liquid flow rates as
a function of flowing wellhead pressure, gas/liquid ratio, surface wellhead
choke size, and the newly incorporated parameters: basic sediment and water
(BS&W) and temperature. To evaluate the influence of these two new
parameters, a parameter-sensitivity analysis was performed and the results are
shown. This proposed correlation exhibited an average error of roughly 2.89%,
which is superior to those previous correlations in the literature that did not
use these two newly incorporated parameters (BS&W and temperature). These
new parameters can be added to the previous correlations when the water cut and
temperature become important in the production history of the wells.
Introduction
The phenomenon of multiphase flow (liquid and gas) happens in the wellhead
of the majority of the producing wells. As the regulation of the flow rate
becomes important during the production period in the producing wells, chokes
are used for isolating the underground reservoir from pressure variations in
the surface equipment, and also they are used for preventing or reducing the
water production. Larger amounts of produced water from oil recovery result in
increasing of operating costs and are a major environmental concern for oil
production (Jin and Wojtanowicz 2010).
Although numerous multiphase-flow correlations are included in the
literature (Al-Attar 2010), almost all of them are limited to a special
operational condition in which the correlations are driven. As a result, the
strength of those correlations for predicting the actual flow rate is
restricted.
Gilbert (1954) developed the most popular multiphase flow surface choke
correlation, but this correlation is valid for the critical flow condition when
the upstream pressure of the choke is 70% or more higher than the downstream
pressure (Ghareeb and Shedid 2007).
Flow through the wellhead chokes is mainly divided into two critical and
subcritical conditions. Within this manuscript, the critical-flow condition
refers to the state at which the flow rate reaches a maximum amount independent
of the downstream and upstream pressure difference of the choke. Empirical
correlations are mainly used for critical-flow condition.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
15 August 2011
- Revised manuscript received:
4 November 2011
- Manuscript approved:
16 January 2012
- Published online:
31 August 2012
- Version of record:
13 November 2012
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