The walnut and the crude oil

When a walnut and crude oil meet, they bond. This property is exploited in the production of crude oil, where walnut shells are used as a filter when treating the water.

Our colleagues love walnuts. Especially Peter Piller and Johann Lechner. But not (just) for eating. In fact, it’s the shell of the nut that interests them—after all, it plays an important role in producing crude oil. “Every time crude oil is produced, water is extracted alongside crude oil and natural gas—and a lot of water at that. More than 90% of oil production is water”, explains Peter Piller, who was responsible for the construction of the new water treatment plant in Weinviertel, Lower Austria. The water that is extracted is not just a side product, it is critically important. After all, the water is pumped back into the stores in order to maintain and increase the pressure. This cycle only works with water that has been very well cleaned. “After the production station in which oil, gas and water are separated, the water still has an oil content of 300 ppm—that’s 300 parts oil to a million parts water. This oil is then filtered from the water and this is where water treatment plants come into play. And this is also where walnut shells are our magic bullet”, says Johann Lechner, manager of the new plant.

Walnut shells are ideally suited as a natural filter for water treatment. When they are finely crushed, they separate the crude oil from the water, which we can then reuse for producing crude oil
Johann Lechner, Head of Assets, OMV Austria Exploration & Production GmbH

The nut in action

Nutshells have a powerful affinity to residual oil particles. Crushed to the coarseness level of sand grains, the nuts absorb the residual oil and bind its. The nutshells can be used for a long time since they can be cleaned very easily with the formation water and then reused. After this process the water has an oil content of just 2ppm—2 parts of oil for every million parts of water. This faciliates the production of around 54 barrels a day, which corresponds to the average production of an oil well, not a bad rate for a “side product”.

In the following video you can see the detailed water cycle:

Fact box water treament:

The new water treatment plant in Schönkirchen (Lower Austria) came on stream in the summer of 2016, taking over from the earlier plant that had been in service for 56 years. You can see the construction in time lapse in this video.

The new construction of the water treatment plant was realized in two and a half years and 450,000 work hours.

The water extracted is not groundwater or drinking water; it’s far too deep in the earth for that. We’re talking about formation water, formed millions of years ago by the enclosure of seawater.

1,200 m³ of water per hour runs through the plant, equivalent to 28,800 m³ per day.