Harald G. Rønneberg | April 26, 2016
Currently the world financial situation is such that expensive exploration for new oil wells becomes less and less tempting. The successful oil business today is rather driven by the necessity to extract more oil out of any existing oil well, than previously considered desirable or indeed possible.
The various techniques to achieve this are called Enhanced Oil Recovery (EOR). Common for most EOR is some form of liquid or gaseous injection into the well under high pressure. The objective being to force more oil out of the reservoirs for collection.
Prolong the life of the well
There are enormous profits to be achieved by successful EOR. With small investments compared to new exploration, drilling and construction, the life of a well may be prolonged considerably. Even today, only an average of 40% of the oil is collected from each well in the North Sea. The majority of this important raw material is left in the ground forever. Better performed EOR would thus be very profitable.
Ineffective
The challenge, however, is huge. Contrary to popular belief, the oil is not resting in separate basins in the ground ready to be found. The oil is rather dispersed into an enormous network of porous rock. For the EOR to be efficient, many considerations must be taken, and they are likely to vary from well to well. The environment is harsh. It is hot, often with a pungent pH. The liquid to be injected must be stable under these conditions.
In the North Sea it has for years been usual to inject sea water or brine to press more oil out of the pores. Still one is not able to collect more than just above 40% of the oil, on average. After years of pressing brine into the same well, the method loses its effect because wider channels are eroded into the rock. The brine will follow these channels where the resistance is lower than in the pores containing oil.
Modify the brine
One line of research to improve EOR is to modify the injectable liquid so that it becomes more efficient, and to a lesser extent, creates large channels. The liquid must create stable dispersions, must be injectable and must be thermostable. Lately it has been suggested that a good quality MFC, in relatively low concentrations, may be able to modify the brine in a very positive manner.
- Dispersion stability
A good MFC in 2% suspension in water is a gel, like a thick and luscious hand cream! However diluted, it has a marvellous ability to keep dispersions stable. - Injectability
Even though suspensions of MFC in water are very thick at rest, the shear thinning effect of the fibril network makes it nearly free flowing under pressure. This will help an EOR medium to be very pumpable and to flow into even the finest of pores. - Thermostability
A good MFC does not lose its properties even at temperatures well over 140 °C, and it is active over a broad pH range. This suggests that it will last for a long time deep down in a harsh environment.
The Norwegian Paper and Fibre Research Institute are amongst the proponents for trying out MFC in EOR.
Exciting future
In short, it looks like the perfectly natural and renewable MFC offers properties that can enhance the EOR, even in very thin solutions. The future of this embryonic research will be very interesting to follow both in academia and industry.
