Due to the depletion of conventional crude oils, the production is currently shifting to unconventional crude oils (acidic, heavy, and extra heavy) also to crude oils present in extreme and harsh environment. The Barents Sea in the Artic area is such an example. The transportation of the future oil produced in this area will be challenging owing to low temperatures and ice coverage over the ocean surface. At low temperatures, compounds like waxes and gas hydrate could crystallize and prevent the transportation of oil by plugging pipeline.
Gas hydrates are solids that are formed of water and gas molecules such methane that co-crystallize under pressure and at temperatures higher than 0 ° C. The gas hydrates are generally formed as particles that can stick together and plug pipeline.
Waxes are long molecules formed only of carbon and hydrogen atoms. They can crystallize and induce oil transportation problem when the crude oil is cooled down below a critical temperature.
Since the Barents Sea is shared by Russia and Norway, this program aims to develop collaboration between research groups from the two countries in the field of transportation of crude oil. The research groups are:
-The Ugelstad Laboratory (UL) / NTNU in Trondheim, Norway.
-The Chemistry Department / Murmansk State Technical University (MSU), Russia
In the program three Master and PhD students from MSU had come to Trondheim multiple times to be trained onto modern instrumentation in colloid chemistry and perform research works under the supervision of Ugelstad Laboratory researchers.
In their visit periods, MSU students have studied the crystallization of droplets of water dispersed in crude oil (water-in-oil emulsions) to understand the properties of gas hydrates. Their work involves preparation and characterization of crude oil and model emulsions with variable parameters, such as water phase concentration, emulsification conditions, salinity and composition of the water phase. The influence of these parameters on the droplet size distributions (DSD) is evaluated by means of Nuclear-Magnetic Resonance Spectroscopy (NMR) and Digital Video Microscopy (DVM). The DSD profiles and average droplet sizes are correlated to the crystallization behaviour of the water droplets and is measured by Differential Scanning Calorimetry (DSC). The technique also allows evaluation of emulsion stability during crystallisation.
DSC has also been implemented to determine how fast the droplets are crystallized as a function of different compositions. The results has made it possible to propose a mathematical model of the process, which approximates the experimental data sufficiently accurately. In conclusion, this study has allowed to develop a model calculating how much water in droplets is crystallized as a function of time.
After analysing model gas hydrates, the next step of the study has consisted to study the stability of gas hydrate under realistic conditions. For this purpose, MSU PhD student Daria Kolotova has performed a visiting period at the facilities of NalcoChampion in Aberdeen, UK to performed experiments on specialized pressurized instrumentation. During the visit Mrs Kolotova has studied the mechanism of actions of chemicals, which prevent the agglomeration of gas hydrate particles (anti-agglomerant-AA). She determined that the addition of AA leads to a decrease in the rate of hydrate formation in comparison with systems that do not contain AA. Addition of AA prevents blockage of cells by hydrates (reduced viscosity). It was also shown that water-in-crude oil emulsions lose their stability after hydrate dissociation in presence of AA. Finally, a mechanism of AA action has been proposed.
Finally, the influence of wax crystals on crude oil emulsion stability has consequently been studied. The results show that the wax crystal can increase the stability of crude oil emulsion especially if they are present during the emulsification process. An increase of the wax content would, however, induce some destabilization.
The project has allowed to develop collaboration between Ugelstad Laboratory/NTNU in Norway and Department of Chemistry/Murmansk State Technical University in Russia thanks to the visit of Russian students in Trondheim. 3 students (2 MS and 1 PhD) have been trained by the researchers at UL.
The research works performed by Russian students at UL have dealt with properties of gas hydrates and waxes. These compounds are responsible in issues in crude oil transportation under low temperature conditions.
The project has allowed to gain knowledge on the mechanism of formation of gas hydrates, and their properties. The influence of waxes on the stability of water-in-crude oil emulsions was also determined. The knowledge gained in the project will allow to develop better strategy to mitigate issues associated to the formation of gas hydrates and waxes during the crude oil transportation, especially in artic area.
This program will establish Murmansk State Technical University (MSTU) as a leading academic center for flow assurance R&D by cooperating with Ugelstad Laboratory on development of new flow assurance technology for Arctic conditions. Two PhD students will be based at MSTU and one post-doc will be based at Ugelstad Laboratory. The PhD students will receive training and regular exchange periods at Ugelstad Laboratory, which will serve to elevate competence in colloid and surface science, while the majority of the research work will be performed at MSTU. The post-doc will work to ensure a high level of competence transfer to MSTU, while overseeing advanced research activities related to petroleum production. The joint research and education program for the PhD students will entail regular courses, student colloquia, research meetings, internal/external presentations, and high level one-on-one research discussions.
The joint research project will map phase stability and rheological stability of ice-in-oil dispersions stabilized by asphaltene-modified wax solids, resin-stabilized asphaltene nanoaggregates, indigenous surfactants, and synthetic emulsifiers. Ice-in-oil dispersions will serve as a justified analogy to hydrate dispersions in oil. A new comprehensive predictive model for ice-in-oil dispersion stability will provide a scientific basis for a new Arctic flow assurance technology in which precipitated particles, surface active agents, and qualified emulsification serves to eliminate a free water phase in the transport medium, circumventing production problems with gas hydrates, corrosion and scaling.
An important facet of the program will be to hold open academic courses on flow assurance and rheology in Murmansk, promoting use of innovative research methodologies in development of flow assurance technologies. The courses will elevate strategic competence in a key industrial sub-discipline, while strengthening ties between researchers in Norway and Russia.