More than 40% of oil reserves in Russia are hard to recover. Scientists from MEPhI have proposed a new method of increasing the production of such fields which is effective and do not harm the environment. Heating of a casing pipe by high-frequency electric current leads to melting of accumulated in it paraffin-resinous deposits.

Usually extraction of difficult hydrocarbons requires to influence on the layer by means of chemical reagents, heated steam, acoustic waves, etc. Specialists of MEPhI proposed a non-standard solution. A spiral coil of copper wire is placed into a casing pipe inside the well. After that, a high-frequency current is passed through the coil, the alternating magnetic field of which excites a strong current in the pipe, which heats its small section to a temperature of 120-150 degrees Celsius. Herewith the deposits on the internal walls fall off. Pumps evacuate it together with oil. Then the coil moves 15 cm higher or lower, heats another area, etc.

“Productive capacity of wells with high viscosity of oil can be increased without the use of expensive and environmentally hazardous methods,” believes the co-author of the development, professor of the Department of laser and plasma technologies at MEPhI Alexey Ponomarenko.

According to him, the method to increase the productive capacity of a field, popular today among oilmen, (partial dismantle of a well and dropping of the equipment for heating the reservoir to its full thickness) is connected with huge energy costs. Another way is to use a special reagent to cause a chemical reaction with the release of a large amount of heat. Here energy consumption is lower, but the environmental consequences are very unpleasant. The third option is to clean off scurfs from the inner surface of the pipe using remotely controlled scrapers; it is associated with huge labor costs. In addition, in this case, there are still deposits inside the perforation holes (oil from the reservoir is "pressed" into the casing pipe through them). These hardened heavy oil components complicate production.

“The advantage of our method is that the heat treatment of a pipe occurs without interrupting the work of a well. Promptly removing sediments, we do not allow their accumulation and consequently reduce the bandwidth of the perforations,” said Alexey Ponomarenko.

According to the scientist, the use of the technology will allow domestic oil industry to save millions of rubles.

“If today the oil well is clogged, its operation is often suspended "until better time,” said professor.

Tests of a model of ahigh-frequency generator with an induction heater were held in the laboratory of MEPhI. Today, scientists are developing a high-strength body for it and optimize the generator circuit. The hydrostatic pressure in the well casing at a depth of 2 km can be up to 200 atmospheres. Therefore, a shell of an immersion apparatus should be comparable with the hull of a submarine in strength.

Natalia Skibitskaya, the Head of the Laboratory of hard-to-recover hydrocarbons reserves at the Institute of oil and gas problems of RAS, believes that the technology developed in MEPhI is more effective than the use of scrapers.

“Indeed, there is a problem. During the extraction of heavy oil, asphalt-resin paraffins clog perforation holes and pipes, reduce the debit of the well. From time to time it is needed to stop production and clean the bore with a scraper or solvent. The proposed method is, of course, not a revolution, but an innovation,” said Natalia Skibitskaya.

An associate professor of the Department of development and operation of oil fields at the Gubkin Russian State University of oil and gas Alexey Dengaev fears that the installation of new equipment inside a well can increase an accident rate. It is not clear how the additional power supply will affect the existing instrumentation, the expert believes.

The technology was developed according to the grant of the Russian Science Foundation.

“Today, RSF is funding over ten projects, the themes of which are linked to oil and oil production,” said representatives of the Fund.

The results of the work were positively evaluated by the expert council of the RSF, as evidenced by the recent decision to continue research on the grant.