How Bacteria And Waste Help Make Oil Production Greener
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Waste from industrial enterprises, ash from waste incineration, and anaerobic bacteria are actively used in the fuel and energy complex to optimize and increase oil and gas production. We tell you exactly how
At first glance, it seems that oil production and “green” technologies are at different poles. We will try to debunk this myth and talk about modern environmentally friendly methods that scientists (chemists, geologists) offer and are already used by oilmen.
The use of waste from industrial enterprises to increase oil production
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One of the “green” modern methods that allow for increasing oil production is the injection of various chemicals – including waste from industrial enterprises – into the reservoirs through injection or stopped production wells. In this case, oil production increases due to chemical processes resulting from the interaction of injected chemistry with rock and reservoir fluids (oil, water, and sometimes gas). Before pumping chemicals into the reservoir, laboratory tests are carried out to understand what maximum effect can be obtained.
Injection into reservoirs implies the presence of large volumes of chemicals, which cost the customer a large amount. Therefore, various cheap chemicals are being searched and researched. One of the solutions is the use of waste from industrial enterprises and thermal power plants.
Of course, not all waste can give a positive effect. In addition, part of the injected chemistry can be brought to the surface mixed with the extracted oil and water, which complicates the process of oil treatment and separates this chemistry from it. Therefore, this process is also studied in laboratory conditions. As a result, such wastes are selected that are most optimal for increasing oil production.
Successful examples include injection of ammonia water from chemical plants, or injection of alkaline water from thermal power plants. The discharge of such waters into rivers, of course, has a detrimental effect on the environment, and a fine is provided for this. But the amount of the fine is much lower than the cost of water treatment or disposal. And many companies often dumped this waste into rivers. Laboratory studies have shown the effectiveness in washing oil from the surface of the core pores with such waters. Thus, ammonia and alkaline water can be successfully used to increase oil production.
Use Of Petroleum Gas To Generate Electricity
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In the oil under the pressure of the overlying rocks, a gas is dissolved, which is called oil or associated. This is mainly methane, ethane, propane and other hydrocarbon gases: carbon dioxide, nitrogen. As oil rises to the surface, the pressure exerted on the oil in the well decreases, which leads to the release of dissolved gas. This gas, together with the liquid, reaches the oil treatment plants, where it is finally separated (separated from the oil). It turns out that petroleum gas is a by-product of oil production.
The question arises: what to do with it? It seems to be a valuable product, especially considering the recently increased gas price. But, oddly enough, the cheapest way to burn this gas is simply to burn it. This has been done for almost a hundred years. Particularly sad in this regard was, and partially still remains, the situation in Western Siberia, where there are a huge number of deposits and large uninhabited territories.
People flying in an airplane over this region at night say that the whole of Western Siberia is strewn with spotlights. Each such point is a torch on which petroleum gas is burned. For domestic purposes, such crude gas cannot be used because of the content (albeit a small amount) of hydrogen sulfide in it.
Since 2012, a law has been in force, according to which companies can burn no more than 5% of petroleum gas, the rest must be disposed of, that is, used for any needs or processed. Large companies that have the necessary infrastructure have set up gas processing plants. In remote places, gas is used either for own needs (for example, heating) or is still burned.
One of the ways to utilize associated gas is also to re-inject gas into oil reservoirs to increase reservoir pressure – as a method of increasing oil recovery. The implementation of such a project requires investments, technical capabilities and corresponding volumes of gas, so the technology is rarely used.
Another area that is gaining popularity is the use of petroleum gas to generate electricity. In this case, much less investment is required, and the efficiency is obvious. Depending on the volume of gas, gas generators are able to supply not only lighting and heating to industrial facilities, but also provide electricity to pumps in wells.
How does incineration ash increase oil production?
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Nanoparticles make it possible, due to chemical-physical processes, to better wash oil from the surface of the formation pores. Nanoparticles are understood to mean particles ranging in size from units to hundreds of nanometers (nm). Such particles are smaller than the pore channels in the reservoir: as a result, they can freely pass deep into the reservoir when they are injected. That is, when pumping water, to which nanoparticles are added, the volume of oil from production wells increases.
The only disadvantage of nanoparticles is their high cost. Therefore, various oil and gas and service companies are conducting a lot of research to find cheap nanoparticles. One solution is to use ashes from waste incineration. Ash particles during complete combustion have an average size of 50-250 nm, which is much smaller than the size of the pore channels, which average 500-1500 nm for traditional collectors.
I participated in the creation of this technology. Initially, we conducted research on wood ash. Moreover, I put forward the idea of using ashes when I heard from my grandmother that earlier in the villages there was no shampoo and people washed their hair with water infused with wood ash.
Such water successfully laundered dirt and grease. The same mechanism is in the reservoir: when water with ash washes oil from the surface of the rock pores. In laboratory conditions, we conducted core studies and compared how much oil can be recovered by injecting formation water and water with nanoparticles. It turned out that in the second case, about 25% more.
However, no one will burn the forest for the sake of extracting oil – this is not efficient, environmentally friendly, and costly. Therefore, we conducted studies on the ash remaining after coal mining in thermal power plants. The volumes of such ash are quite large and are a waste of production. Studies have shown a slightly lower efficiency – about 20%, but nevertheless still quite high.
How do bacteria help extract oil and produce gas from coal?
“Green” technologies also include the use of bacteria in oil and gas production, since the hydrocarbons obtained in this way have passed through their vital activity. Bacteria living in the water, which is located in the pores of the formation rock, are anaerobic, that is, they do not need oxygen. The most common variant of their application is to increase oil recovery.
To do this, nutrients (feed) are pumped into the reservoir for the “reservoir” bacteria that feed on them. The waste products are mainly biological surfactants (essentially “washing powder”) that help wash oil from the pore surface of the rock, resulting in increased oil production. In addition, colonies of such bacteria grow, which helps to block the zones washed by injected or formation water and allows for reducing the water cut of the wells.
Modern reservoir engineering technologies also include biotechnology. Cores and fluids taken from the reservoir generally always contain water, in which anaerobic bacteria live. Under surface conditions, they do not survive, but their DNA remains. In each layer, over thousands of years, bacteria form with their own set of DNA, which differs from the neighboring layer, if these layers are not interconnected.
The study of bacterial DNA on the samples of cores and/or fluids from different wells makes it possible to determine whether the reservoirs are connected to each other, from which specific reservoirs oil is being produced, in what percentage is the production from one or another reservoir distributed.
The latest technology using bacteria is the production of gas from coal. Coal seams can occur at depths of several kilometers. Building a mine of such depth is not always profitable. It is easier to drill wells and act on these formations. Of course, coal cannot be produced at the same time, but it is quite possible to extract another valuable product – methane.
To do this, the bacteria that live in coal seams, which feed on coal, are first studied in the laboratory and additional nutrients are selected for them. Then, nutrient solutions are pumped through the wells, which leads to the rapid growth of bacterial colonies, which, in addition to nutrients, also eat coal, producing methane. The resulting methane is taken from the wells.
Thus, the “green” technologies used in the fuel and energy complex make it possible to dispose of industrial waste and create closed-loop production, when the by-products of oil and gas production are reused and used to increase well production, as well as conduct important research for oil and gas development.
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