The current work presents a fully compositional tool for modeling systems
exhibiting two-phase (gas/water) flow. The tool couples complex hydrodynamic
and thermodynamic models to describe the behavior of fluids flowing in a pipe.
The model described herein focuses on gas transmission with low-liquid loading
conditions (hl /d < 0.3).
Results show the model is capable of predicting the hydrodynamic behavior as
well as the compositional profiles of gas and water flowing in a pipe. This is
important in the light of compositional dependence of hydrate or acid
formation. Compositional changes in the aqueous phase may create the conditions
for forming hydrates or acids.
The model was benchmarked using several published works, details of which
can be found in the work of Zaghloul (2006). In this paper, model performance
is illustrated using a case study. The case study compares model calculations
with an experimental data set obtained from Eaton et al. (1967). Model
calculations predicted the observed flow pattern, pressure and liquid holdup
profiles reported in the case study. Calculated pressures are within 2% of
experimental values, while liquid holdup (approx 4%) is in agreement with the
value predicted by Eaton’s correlation ( Eaton et al. 1967).
The model is capable of predicting the initial water condensation point in
the pipeline and the concentration of different substances in the aqueous
mixture. The tool gives production engineers important information on how much
hydrate/corrosion inhibitors to inject and where, thus saving in the design,
operation, and maintenance of pipeline systems.
Several flow assurance issues can be more effectively handled either through
appropriate design or operational protocols if compositional profiles of the
traveling coexisting phases are known. The model presented herein provides
engineers with a tool for predicting compositional profiles in two-phase
(gas/water) flow in pipes. This will help flow assurance engineers make better
assessments on the actions required to prevent hydrate or acids.
© 2009. Society of Petroleum Engineers
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- Original manuscript received:
15 August 2007
- Meeting paper published:
17 October 2007
- Revised manuscript received:
1 August 2008
- Manuscript approved:
24 August 2008
- Published online:
6 August 2009
- Version of record:
22 December 2009