AGH UST researchers want to give a new lease of life to oil and gas wells by recovering lithium from formation water

Contrary to appearance, hydrocarbons are not the main product that is extracted the most from oil and natural gas reservoirs. Rough estimates say that for 1 m3 of petroleum comes up to 3 m3 of brine. As the extraction process progresses, the ratio of water used to produce oil or gas increases steadily to the point where it is practically the only product. At best, this brine is pumped back to the well, where it is used to displace oil or gas to the surface. However, as mentioned previously, this process cannot continue forever, and the hydrocarbon extraction business, sooner or later, ceases to be profitable. At the same time, the produced water itself can be a source of industrially valuable elements if only we can manage it properly. Taking into account the fact that the world is turning away from fossil fuels in favour of low-emission energy sources, this might, in fact, give the old wells a new lease of life. This is exactly the goal on which the engineers from the AGH UST Faculty of Drilling, Oil, and Gas have been focusing. They have been involved in a project titled CompLithium – a comprehensive lithium and wastewater recovery technology from formation water. Their initiative received funding (PLN 1.5 million) from the National Centre for Research and Development (NCBR) – the LIDER programme.

Lithium extraction and its applications

Lithium is a precious metal that finds numerous applications in industry, for example, to produce grease, glass, and ceramics, and as an alloy component used in aviation and space technology. It is also widely used in lithium-ion batteries, which our laptops, smartphones, and other portable electronic devices cannot do without. Moreover, lithium-ion batteries have been used increasingly in electric and hybrid cars, as well as other vehicles powered by electricity. Therefore, with the growing demand for environmentally friendly means of transport, we should probably assume that the demand for this valuable element will also grow.

Lithium does not occur naturally in an elemental form, but in the form of lithium salts. The largest world producers of this element, including Argentina and Chile – where underground deposits contain very high concentrations of lithium – use a very simple technology to extract it. The brine, after being pressure-pumped to the surface, creates large pools and concentrates as a result of solar evaporation. From this concentrated brine, using various precipitation techniques, lithium salts are extracted. The disadvantage of this solution is the fact that maintaining steady production is possible only in a warm climate. Furthermore, lithium salts are not the only solid product of this process. As a result, the extraction site becomes a salt desert, which is environmentally unacceptable in countries such as Poland. Therefore, other lithium extraction methods have been used worldwide, namely nanofiltration membranes and sorbents, which, in a major simplification, can be compared with sponges that selectively absorb this particular element. The development of such an innovative sorbent based on aluminium and titanium that could capture lithium from post-extraction wastewater is one of the chief objectives of the CompLithium project.

Innovative sorbent prepared with the use of 3D printing

Ewa Kanpik, DSc, the project leader, explains: ‘Sorbents described in the literature to date occur in the form of powders that are difficult to use on large scales for operational reasons. Our sorbents will be prepared using 3D printing so that we can create high-porosity spatial mouldings. They could be placed regularly in adsorption columns through which the brine passes continuously. What is extremely important here is the selectivity because lithium ions are small and difficult to separate from other ions, especially given the similar size of magnesium ions. Which is why we have to use intercalation. Sorbents are characterised by a layered structure, where lithium ions can fit tightly into the gaps in their crystal lattice. Then, lithium is eluted with a special solution’.

Equipment for lithium and water recovery from brine

What the scientists have in mind is that the adsorption columns will become an element of a novel, comprehensive apparatus that could be installed in oil and natural gas production sites. Simultaneously, during one procedure, the machinery would recover both lithium and sweet water from brine. The recovered water could then be used, for example, to irrigate neighbouring crops or to produce steam in the very same production plant. To desalinate brine, AGH UST scientists intend to use crown-ether-modified nanofiltration membranes, which will allow them to capture residual lithium that had not previously been recovered in adsorption columns. The installations currently used around the world can recover either lithium or sweet water from brine, but they cannot perform these two functions simultaneously. Therefore, merging them into one process will constitute a novelty and innovation.

‘In the first phase, the installation will perform the initial treatment, that is, coagulation and filtration’, explains Dr Knapik. ‘The brine extracted from the reservoir contains petroleum derivatives, particulates, and dissolved gases. All contaminants must be removed so that they do not damage our adsorption module or the membranes. The second stage is the adsorption columns that are directly intended for lithium recovery. These columns work always in a dual system, because when one captures lithium, the other regenerates – this means that the element is being eluted from it. The next phase is desalination using membranes. As a result, we always get two streams: sweet water and concentrated brine. The latter will be pumped back into the reservoir using our technology. A huge advantage of the proposed technology is that it is wasteless.’

AGH UST researchers plan to study the materials produced in a laboratory, where they will recreate highly similar natural conditions. ‘Using process engineering tools, we will perform the appropriate process flow calculations for the installation working under real-life conditions. There’s an entire theory of process and equipment scale expansion. If tests are successful for a column that is one metre high, we’re able to calculate the results for a five-metre column. It’s important to maintain a proper operational regimen, which means, among other things, providing the appropriate raw material, the operational pressure corresponding to the actual installation, and the appropriate flow rate (which affects the time of contact with the sorbent, that is, the efficiency of adsorption). In terms of sorbent regeneration, the right composition of the eluting solution must be selected’, explains Dr Knapik.

How much lithium is there in the Polish formation waters?

For the installation of the apparatus to make economic sense, formation waters must contain adequately high concentrations of the element. According to estimates from the Polish Institute of Geology, economically prospective brines are those that contain at least 10 mg of lithium per 1 litre of water. Therefore, another important goal of the CompLithium project, in addition to the development of lithium recovery technology, is to examine Polish underground pools in search of this element, which is to complement the current gaps in our knowledge in this field.

‘We will collect samples from various reservoirs to find the answer to the question of how much lithium they contain. We’ve received first signals that there are a few prospective loci where the concentration of lithium is heightened. Many of such reservoirs are in the Polish Plain, where the waters show high mineralisation. If they contain many different salts, there is a chance that lithium salts are among them. Germany has similar geological formations, where higher concentrations of this element have been reported. There’s even a start-up company that wants to recover lithium from geothermal waters’, says the leader of the CompLithium project.

In addition to data collection, AGH UST scientists want to create a useful application that will allow its users, using objective criteria, to determine whether lithium recovery in a given area is profitable for a prospective investor. Apart from showing the concentration of the element itself, the app will take into account aspects, such as the quantity of extracted water, the pressure in a particular reservoir, or the presence of other ions. ‘The tool will be offered as a commercial product that, after a few modifications, will later be used to choose the most magnesium- or potassium-rich brines’, claims Dr Knapik.

Interdisciplinary nature of the project

The aim of the project that launched in January 2022 is to find the answer to the question of whether it is possible to recover lithium from underground reservoirs in Poland and how to technologically achieve the recovery of this element and sweet water. The project is carried out in laboratories of the Department of Petroleum Engineering, which have unique equipment, including high-pressure (up to 500 bars) batch and continuous reactors and systems used to analyse liquid and gaseous samples.

The engineering work will be complemented by environmental risk and profitability analyses of the proposed solution, which will facilitate its future implementation. AGH UST engineers have given themselves three years to achieve the set goals.