Enabling non-disruptive production conditions - slug flow with surfactants

usual, and separators and process equipment can be overwhelmed by the varying supply of oil and gas. This can in turn cause equipment damage, temporary downtime of the process and increased use of excess gas burning. Existing models of slug flow are largely based on experiments under idealized conditions and simple fluids, such as water and air systems in short pipes. In this project a more realistic fluid systems will be investigated which includes the effects of fluid chemistry, especially in terms of surface tension. Surface tension is a force that determine the shape and strength of the surface between different fluids and gases, and which therefore regulate how gas and liquids mix and separate and form bubbles and foam. Slug flow with a large proportion of mixed gas is one of the main focus areas for this project. In addition to rarely being studied in previous research, we believe that this type of slug flow leads to particularly long and irregular oil slugs which in turn leads to particularly demanding operating conditions and loads on equipment. The experiments in the project will be carried out at SINTEF's multi-phase flow laboratory at Tiller in Norway. Here, complex fluid systems can be tested and the details of the slug flow phenomenon can be quantified by advanced measurement systems.

Slug flow regimes will become more frequent in the NCS in the future as it is most commonly observed when flow rates decrease. Slug growth is also promoted by the current field developments involving long tie-ins, e.g. in the arctic regions. Properly controlling and handling slugs can reduce the need for gas flaring which reduces the environmental impact and the CO2 emissions. The structural stability of the sub-sea components due to fatigue is a major concern for the oil companies. Operation under slug flow regime is considered as the worst case scenario from a structural and an operational point of view. Further, unforeseen long slugs can cause damage and flooding of separators. And finally, slug frequency has a direct impact on corrosion. The existing slug flow models are weak because they are (a) largely based on experiments in short pipes, and (b) do not sufficiently consider realistic fluid chemistry e.g. the presence of surfactants and therefore significant gas buildup within the liquid slugs. This project will work towards reliable predictions of slug flow based on representative experiments. Our goal is to enable non-disruptive production conditions in relation to slug flow with realistic fluid chemistry through pragmatic model developments. We will concentrate our research on gas entrainment and surface chemistry effects, since our hypotheses leads us to believe that these factors are critical to accurately characterize slug flow in real applications with regards to slug length and frequency. The experimental part of the research will be carried out in a series of experiments at the low pressure flow loop at SINTEFs Multiphase flow laboratory at Tiller (Trondheim). SINTEF Petroleum will be the project owner and will work in close cooperation with SINTEF Materials and Chemistry, NTNU and the international research partner HZDR (Germany). One PhD candidate will be educated as part of the project.