A numerical study on two-phase core-annular flows of waxy crude oil/water in inclined pipes

Abstract Although the problem of wax deposition in multiphase transportation pipelines have been addressed and some related wax deposition models have been developed in recent years, the complex wax deposition paths derived from the potential variety of flow regimes in multiphase flow have not been well understood. This study presented a method for characterizing wax crystals aggregation behavior and developed a model for describing wax deposition path in oil/water two-phase flows. The impact of the emulsified water droplets on wax crystals aggregation in shearing flows was quantified using polarized light microscopy and image analysis method. The role of the emulsified water droplets in the wax deposition path reaching the upper side and lower side of pipeline wall was discussed by solving the developed model which involves the possible inclination angle of multiphase transportation pipeline. The availability of the mechanistic model was validated by the data and knowledge in the existing literature. The results indicated that wax crystals morphologies and structures tended to be regular with the enhancement of shearing effect, and their aggregation behavior were restrained. The circular degree and particle size of wax crystals showed a characteristic that it firstly increased and then decreased with the accumulation of emulsified water droplets in shearing flow, and this transition appeared to the phase inversion point of the oil/water two-phase. The velocity for wax crystals depositing to pipeline wall decreased and the time for wax crystals depositing to pipeline wall extended with the existence of emulsified water droplets. The wax deposition path became more complex in multiphase transportation, and such effect became remarkable when the dispersity of oil/water two-phase enhanced. Accordingly, the intractable wax deposition of waxy crude oil in cold environment transportation would be mitigated to some extent. This study contributes to comprehending the distinction of wax deposition mechanism in single-phase and multiphase transportation of waxy crude oil, and the proposed method and model are valuable for further predicting wax deposition in waxy crude oil emulsions pipelines. The findings in this study also point out an approach to conducting cost-effective flow assurance operations in crude oil production and transportation.

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Flow Pattern Map of Malaysian Crude Oil and Water Two-Phase Flow in a Pipe System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.931-932.1243 ◽

2014 ◽

Vol 931-932 ◽

pp. 1243-1247 ◽

Cited By ~ 1

Author(s):

Issham Ismail ◽

Shahir Misnan ◽

Ahmad Shamsul Izwan Ismail ◽

Rahmat Mohsin

Keyword(s):

Crude Oil ◽

Flow Pattern ◽

Water Flow ◽

Phase Flow ◽

Waxy Crude Oil ◽

Two Phase ◽

Dispersed Flow ◽

Oil Film ◽

Waxy Crude ◽

Oil Water

Water produced along with the crude oil during production and transported together in a pipeline is a common occurrence in a petroleum production system. Understanding the behavior of crude oil-water flow in a pipe is crucial to engineering applications such as design and operation of flow lines and wells, and separation systems. Presently, there was no two phase flow study done on the Malaysian waxy crude oil-water. Therefore, a research work was conducted at the Malaysia Petroleum Resources Corporation Institute for Oil and Gas, Universiti Teknologi Malaysia to study the flow pattern of the Malaysian waxy crude oil-water flowing in a closed-loop system at the ambient condition through a 5.08 cm ID stainless steel horizontal pipeline. The research works comprised fluid characterization and flow pattern observation using a video camera camcorder. Five flow patterns have been identified, namely stratified wavy flow, stratified wavy with semi dispersed flow at interface and oil film, dispersion of water in oil and oil continuous with emulsion, dispersion of oil in water with water continuous, and the newly found semi dispersed flow with semi emulsion at interface and thin oil film. The experimental results could be used as a platform to understand better a more complex case of gas, oil, and water flow in a pipeline, which is of utmost importance in designing optimum surface facilities.

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Pressure Drop and Water Holdup of Malaysian Crude Oil and Water Two-Phase Flow in Pipes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.931-932.1248 ◽

2014 ◽

Vol 931-932 ◽

pp. 1248-1252 ◽

Cited By ~ 1

Author(s):

Issham Ismail ◽

Shahir Misnan ◽

Ahmad Shamsul Izwan Ismail ◽

Rahmat Mohsin

Keyword(s):

Pressure Drop ◽

Crude Oil ◽

Two Phase Flow ◽

Research Work ◽

Complex Case ◽

Phase Flow ◽

Waxy Crude Oil ◽

Two Phase ◽

Waxy Crude ◽

Oil Water

Understanding the pressure drop and water holdup of crude oil-water flow in a pipe is crucial to many engineering applications. Free water in contact with the pipes wall can cause erosion or corrosion problems. An experimental research was conducted at the Malaysia Petroleum Resources Corporation Institute for Oil and Gas, Universiti Teknologi Malaysia to study the pressure drop and water holdup of the Malaysian waxy crude oil-water flowing in a closed-loop system at ambient condition through a 5.08 cm ID stainless steel horizontal pipeline. In the research work, water cuts were varied from 0 - 90% with mixture velocities ranging from 0.1 0.8 m/s. The research works comprised fluid characterization, pressure drop, and liquid holdup measurement.The investigations proved that pressure drop increased with flow rates, while the water holdup was found to have decreased slightly at higher water cuts due to the presence of emulsion in the crude oil a challenge when using a waxy crude oil in a two phase flow system. The experimental results can be used as a platform to understand better a more complex case of liquid-liquid two phase flow.

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