Now, new Danish research may have come up with an explanation as to where and how North Sea oil clings to underground rocks. This explanation could turn out to be the first step on the way to developing improved oil production techniques with the intent of increasing oil production from Danish oil fields.
A research group at the Nano-Science Center, part of the Institute of Chemistry at University of Copenhagen has investigated drill cores collected from North Sea oil fields using an atomic force microscope. Their investigations show that the spaces which contain oil have totally different surface qualities than expected from our knowledge of the minerals which make up the rock. The rocks which contain oil in the Danish part of the North Sea are primarily chalk the same type of rock that the cliffs of Stevns and Mns in Denmark are made of. Assistant Professor Tue Hassenkam lead the research, whose preliminary results were published in the respected scientific publication PNAS (Proceedings of the National Academy of Sciences) this week. He says that this is the first time that investigations of this type have been carried out on chalk from an oil field in the North Sea.
"Previous investigations were carried out on the surface properties of pure mineral crystals. But our investigation has shown that this chalk has a different and more complex structure" says Tue Hassenkam.
The oil bearing layers in the subsurface are reminiscent of a sponge. The oil "hides" in tiny pores and gaps and only some of the oil can be pressed out of the chalk and into the borehole by injecting water into the chalk layer. The rest is left behind as small droplets of oil surrounded by water either in small gaps in the rock or stuck to the walls of the pores. The chalk particles ought to repel oil if they act like particles of the mineral calcite, which chalk is almost 100% made up of. However the new investigations, carried out with a particularly power
|Contact: Tue Hassenkam|
University of Copenhagen