Material Technology

Kjeller MEG Loop II (KML-II)

Kjeller MEG Loop II (KML-II) is a joint industry project started in 2011. It is a continuation of KML-I carried out in the period 2005-2010. Both the previous and the present project are supported by the Research Council of Norway. Both projects deal with formation of scale and particles in Mono Ethylene Glycol systems used for long-distance tie-ins of unprocessed gas directly from subsea wells.
Contact

Seiersten, Marion

Deputy Head of Department / Chief Scientist

 

Summary

Glycol, usually monoethylene glycol (MEG), combined with corrosion inhibiting chemicals is often the preferred solution for hydrate inhibition and corrosion mitigation for long distance gas condensate pipelines transporting unprocessed well stream. The glycol usually circulates in a closed loop with integrated regeneration.

Objectives

The project shall result in more efficient use of thermodynamic hydrate inhibitors in long gas-condensate pipelines to avoid hydrate and scale formation. New predictive models shall form a basis for improved system design and operation of gas-condensate systems using mono- ethylene glycol (MEG) as hydrate inhibitor.

Sub goals

  1. Generate new experimental data for the nucleation and growth of calcium and iron carbonate in MEG systems and use the data to develop predictive models for such nucleation and growth
  2. Develop software for accurate simulation of mass transport and solids precipitation kinetics for the total MEG loop processing cycle (pipeline, process system and MEG regeneration).

 

Sponsors

Aker Solutions, BG-Group, Cameron, Chevron, Petrobras, Petronas, Shell, Statoil, Total and Woodside.

Research tasks

The project has two main tasks:

  • Data generation, analyses and development of local models that describe degassing, precipitation, dissolution and   chemicals behaviour.
  • Develop a system simulator with models for simulation of the full MEG loop.

Task 1: Data generation, analyses and development of local models

The main challenge in the project is to be able to predict the actual formation of scale and particles by understanding the kinetic of dissolution and precipitation reactions in glycol systems where salt and added inhibitors have accumulated. This requires:

  • Dedicated equipment and experiments that reveal kinetic parameters.
  • Dedicated experiments to study particle assisted foaming, clogging and emulsions.
  • Sampling and testing in existing systems and model units.
  • Systematisation of existing and acquired knowledge.
  • Extension and development of kinetic models.

Task 1 focuses on the generation of fundamental data on the kinetics of precipitation, the systematisation of the data and the development of models describing seed formation, crystal growth rates and agglomeration rates for the most important precipitates; i.e. CaCO3, FeCO3, NaCl, KCl, sulphates and sulphides.

One PhD study and one post doc position are included in this task. They are carried out at NTNU with associate professor Jens-Petter Andreassen as supervisor. The studies address the morphology, particle nucleation and growth mechanisms and growth on surfaces for the most relevant salts that are expected to precipitate throughout the MEG-loop:

  • Determination of crystal growth and agglomeration rates through population balance modelling for chlorides and carbonates in different compositions of the MEG/water mixture. Development of adequate techniques for particle size distribution measurements within these systems.
  • Gas/liquid equalisation and CaCO3 and FeCO3 precipitation at conditions relevant for the MEG injection point.
  • Growth of FeCO3/CaCO3 on hot surfaces.
  • Equilibrium reactions in high temperature highly concentrated MEG solutions.

Task 2: System model

MEG loop II - System model

The simulator developed in the KML project is operational and it is already a useful tool for process design and problem solution. It includes major process components and pipelines relevant for the study of the use and recycling of MEG.  Tasks during this phase are to improve the simulator by developments within the following areas:

  • Thermodynamics and kinetics; including more species and adding all new kinetic models.
  • General simulator functionality improvement to allow control loops and time series, speed up simulation and simplify variable selection for trending and display.
  • Development of new unit models and development of existing models to account for growth on surfaces and enhanced treatment of solids.
  • Validation of thermodynamics, kinetics and global simulator behaviour including documentation, sponsor company assistance, advice, functionality improvements and error correction.

2012-01-16 Marion Seiersten