Russian Scientists to Make Oil Extraction More Efficient and Eco-friendly
'One of the major problems of modern oil production is that after pumping petroleum-containing fluid from wells and the first extraction of oil, very large amounts of polluted water remain,' Vyacheslav Eremenko, one of the developers, says. 'Then this water cannot be simply returned to the well, since first it must be purified to a certain extent. And then there are two problems at once. The first is that the resulting water should be rid of. It is also necessary to bring a new batch of clean water to continue oil production. Our technology makes the production cycle closed and allows to reuse water.'
According to Vyacheslav Eremenko, the most important feature of the development is the technology of so-called tangential filtration using ceramic filters. The filter is a tube into which polluted fluid is pumped. While passing through the tube, clean water streams down its outer walls, and polluted water flows inside. Such ceramic products have long been used in the nuclear industry and have proven proved to be very effective. The diameter of the holes in such filter varies from 1 μm to 1 nm. In the first case, there is a membrane with pores, each 1,000 times smaller than human hair in diameter. In some modifications they may be even smaller: up to 1 million less than the diameter of human hair (1 nm).
The device operates as follows: contaminated liquid is pumped into the tubular frame from the tank with ceramic filters. After passing through the chamber with filters, the polluted water goes through the frame again and after a certain number of cycles is sent into a separate container. On this stage the liquid is pretty much oil. Purified water is sent into another tank and can be put back into oil wells.
'The tangential filtration mode has several important distinctive features regarding dead-end filtration,' Alexander Cherepanov says. 'The key difference is that the flow of filtered liquid moves parallel to the filtering surface, while the flow of product water moves perpendicular to this surface. This makes it possible to significantly increase the time between the regeneration of the membrane with cleaning agents, since significantly less contaminants settle on the surface.'
Fine pored ceramic membranes used in filters are manufactured by sintering of metal-ceramic materials at superhigh temperatures. Titanium dioxide, aluminum oxide, zirconium dioxide and other ceramic and metal powders are used for this purpose in various combinations. The sintering process occurs at a temperature of more than 1 600℃. The use of ceramic membranes as a filter element provides several valuable advantages at once: the ability to manufacture a membrane with pores of very small sizes, high durability over a wide pH range, high thermal stability, resistance to abrasive particles, as well as high mechanical strength and easy cleaning.
The technology of tangential filtration with ceramic filters makes it possible to effectively separate the flows of the vast majority of liquid materials for their purification or extraction of useful substances for the purpose of their further use. The advantages described above make its use for the disposal of liquid waste of various enterprises extremely effective.
This technology is valuable for enterprises whose effluents contain pollutants in the form of suspended particles. Treatment of effluents using this method means completely ridding the liquid of undesirable impurities and decrease their concentration to meet the environmental standards and regulations. The use of ceramics makes it possible to work with a wide range of liquids of different acidity and temperature, from agricultural waste to oil companies and some melts.
'We conducted a series of experiments with curd whey at the enterprises of the Sverdlovsk region,' Alexander Cherepanov adds. 'Whey is considered a cottage cheese production waste. Filtration with tangential ceramic filters allows to extract residual protein from whey and reuse it in production process. This not only helps to reduce the toxicity of dairy plant wastewaters, but also increase production volumes, thus its profits.'
Provided by Ural Federal University