Effects of Mono-Ethylene Glycol on Three-Phase Low Liquid Loading Flow Characteristics in Near-Horizontal Pipelines
Mono-ethylene glycol (MEG) is commonly used in deep water gas production systems as a hydrate inhibitor. However, MEG mixing in multiphase flow and its effects on flow parameters are not well understood. This paper provides with comprehensive data for three-phase stratified flow in a 6-in ID pipe, with MEG in the aqueous phase. In addition, the prediction performances of the commonly used predictive tools in the industry are provided.
The experimental study is conducted using a 6-in ID facility to investigate the effects of the presence of MEG on three-phase stratified wavy flow in horizontal pipelines under low liquid loading conditions, commonly observed in wet gas pipelines. The analyzed flow characteristics include wave pattern, liquid holdup, aqueous phase fraction, pressure gradient, and wetted wall fraction.
The experimental range covers superficial gas velocity, vSg, values of 8-23 m/s, superficial liquid velocity, vSL, values of 1-2 cm/s, and inlet liquid stream aqueous phase fraction, WCMEG, values of 0-100%. Experiments are conducted with 50 wt% of MEG in the aqueous phase, and the results are compared to the case with no MEG, presented by Karami et al. (2015). Differential pressure transmitters, a quick closing valve and pigging system, and a high speed camera are used for data acquisition. The trends in the resulting data with respect to input parameters are investigated. The performances of commonly used models and predictive tools are compared to liquid holdup, pressure gradient and aqueous phase fraction experimental results.
The observed wave patterns include stratified smooth and stratified wavy with 2-D waves, 3-D waves, roll waves, and atomization flow, with transition boundaries varying with the liquid phase composition. The trends of pressure gradient, liquid holdup, and aqueous phase fraction with respect to vSg, vSL, WCMEG, and MEG wt% are observed, and physical justifications are provided. The predictions of a commercial multiphase flow simulator (OLGA 7.1), an in-house software (TUFFP unified model v. 2012), Beggs and Brill (1973) correlation, and Taitel and Dukler (1976) and Xiao et al. (1990) models are compared with the acquired experimental data. The liquid holdup experimental data are under-predicted by all the models, especially for higher WCMEG values. However, the results from OLGA 7.1 and Xiao et al. (1990) model are in better agreement with experimental data. The three-phase aqueous phase fraction trends are not predicted well. The complex nature of liquid-liquid interactions in three-phase low liquid loading flow causes higher uncertainties in predictions.
Beggs, D. H., & Brill, J. P. (1973). A study of two-phase flow in inclined pipes. Journal of Petroleum technology, 25(05), 607-617.
Karami, H., Torres, C., Pereyra, & E., Sarica, C.: “Experimental investigation of Three-Phase Low Liquid Loading Flow”, SPE-174926-MS, presented at 2015 SPE ATCE, Houston, TX, 28-30 September, 2015.
Taitel, Y., & Dukler, A. E. (1976). A model for predicting flow regime transitions in horizontal and near horizontal gas‐liquid flow. AIChE Journal, 22(1), 47-55.
Xiao, J. J., Shoham, O., & Brill, J. P. (1990, January). A comprehensive mechanistic model for two-phase flow in pipelines. In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers.
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