Two phase flow of waxy crude oil-water in horizontal pipes

Abstract

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 many engineering applications, such as design and operation of flow lines and wells, separation systems, logs interpretations, and determination of the amount of free water in contact with the wall of the pipes that could render erosion or corrosion problems. Presently, there is no two phase flow study done on the Malaysian waxy crude oil-water. Therefore, a research work was conducted at the UTM-MPRC Institute for Oil and Gas, Universiti Teknologi Malaysia, to study the flow pattern, pressure drop, and water holdup of the Malaysian waxy crude oil-water flowing in a closed-loop system at an 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, flow pattern observation using a video camera camcorder, pressure drop, and liquid holdup measurement. 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 investigations proved that pressure drop was greatly influenced by flow pattern and mixture velocity. It was also found that the water holdup decreased slightly at higher water cuts due to the presence of emulsion in the crude oil – a great challenge when using a waxy crude oil in a two phase flow system. The experimental results could be used as a platform to understand better a more complex case of gas, oil, and water concurrent flow in a pipeline.