УДК 614.08

Oil spills and methods of their elimination in open water conditions, as well as in ice conditions

Зыкова Арина Александровна – студент факультета Кораблестроения и океанотехники Санкт-Петербургского морского технического университета.

Варламова Анастасия Витальевна – студент факультета Кораблестроения и океанотехники Санкт-Петербургского морского технического университета.

Научный руководитель Осипенко Елена Анатольевна – кандидат филологических наук, доцент кафедры Иностранных языков Санкт-Петербургского морского технического университета.

Abstract: The article is dedicated to the consideration of the stages of oil and petroleum product spill response, since oil spills cause serious material damage, and sometimes are difficult to take into account in terms of environmental consequences. The article provides statistics on the frequency of spills by year and formulates three main stages in the elimination of oil and petroleum products spills. At each stage, the characteristic features are identified, the main methods or methods of localization of spills, collection of oil and petroleum products, and oil utilization are systematized and disclosed. An assessment of the effectiveness of the three main stages of oil spill response is given.

Аннотация: Статья посвящена рассмотрению этапов ликвидации разливов нефти и нефтепродуктов, поскольку разливы нефти наносят серьезный материальный ущерб, а порой носят трудно учитываемый характер в аспекте экологических последствий. Именно поэтому целью данной статьи является рассмотрение этапов ликвидации разлива нефти и нефтепродуктов. В статье приведена статистика частоты разливов по годам, сформулированы три основные этапа при ликвидации разлива нефти и нефтепродуктов. В каждом этапе обозначены характерные особенности, систематизирована и раскрыты основные способы или методы локализации разливов, сбора нефти и нефтепродуктов, утилизации нефти. Дана оценка эффективности трах основных этапов ликвидации разлива нефти.

Keywords: oil, oil products, spill, liquidation, booms, sorbent, oil collectors.

Ключевые слова: нефть, нефтепродукты, разлив, ликвидация, боновые заграждения, сорбент, нефтесборщики.

Oil and oil products have occupied one of the most important positions in the fuel and energy sector for many decades. The use of oil determines the level of economic development and life of a modern person. However, the very process of extracting black gold, including exploration and disposal of its waste, can negatively affect the environment.

Currently, the environmental problem of oil spills is one of the most urgent. According to Greenpeace Russia, 8,126 oil spills were registered in Russia in 2018. WWF (World Wildlife Fund) also claims that about 4.5 million tons of oil are spilled in our country every year. And the main reason for this is worn–out oil pipelines. According to statistics, in the same year 2018, the vast majority of accidents (97%) occurred due to pipe corrosion.[1]

Of course, oil leaks are not only due to the operation of outdated equipment. Any facility of the enterprise can become a potential source of pollution: wells, oil storage facilities, offshore oil platforms, receiving points, etc.

The Russian Federation has unique reserves of hydrocarbons on the shelf, according to some data, approximately 41% of the region's oil and gas resources are located on the Arctic shelf. Insufficient control over the environmental safety of the region can lead to irreversible global consequences, including climate change, so it is necessary to pay due attention to environmental aspects in the development and operation of deposits.

The probability of oil spills depends on a wide range of natural and technological factors, and the consequences of their impact are quite difficult to predict. Oil production cannot be absolutely safe. As world experience shows, the number of oil accidents at production facilities, during transportation and processing operations occur quite often, which means that the amount of hydrocarbons entering the environment is also increasing.

According to world statistics (Fig.1), the volume of oil spilled from oil tankers around the world in 2021 amounted to about a thousand metric tons. However, in 2018, a total of 116 thousand metric tons of oil leaked as a result of incidents with oil tankers, which is the largest leak in 24 years. [2]

Figure 1. Global oil spill statistics.

When oil products are spilled over the water surface, three main stage are solved (Fig. 2):

Figure 2. Three stages of oil collection.

Let's briefly talk about each stage of oil spill response.

1 Stage. Localization of the spill

Localization is an enclosure of an oil spill in order to prevent its further spread over the water surface. The main means of localization of spills in the waters are slick bars.

Depending on the application, the slick bars are divided into three classes (Fig. 3):

Figure 3. Three classes of slick bars.

Slick bars are a structure consisting of such basic elements as (Fig.4) [3]:

• float designed to ensure buoyancy of the slick bar (7);
• the surface part prevents the oil film from overlapping through the slick bars (the float and the surface part are combined);
• underwater part (skirt), prevents the removal of oil under the slick bars (5);
• cargo (ballast), supports the vertical position of the slick bars relative to the surface of the water (in Fig. 4, the ballast is a chain);
• the element of longitudinal tension (traction cable), allows slick bars in the presence of wind, waves and currents to maintain the configuration and tow slick bars on the water (1);
• connecting nodes that ensure the assembly of slick bars from separate sections (4);
• devices for towing slick bars and attaching them to anchors and buoys.

Figure 4. The construction of the slick bar.

In the case of oil spills in the waters of rivers, where the localization of slick bars is difficult or impossible due to significant currents, it is recommended to restrain and change the direction of movement of the oil slick with the help of screen vessels, water jets from fire barrels of boats, tugs and ships standing in port.

2 Stage. Collection of oil and oil products

There are 4 main methods of oil collection:

Mechanical – is a conventional collection of spilled oil from the surface of the water. Its greatest efficiency is achieved in the first hours after the spill. This is due to the fact that the thickness of the oil layer is still quite large. The mechanical method uses oil collectors, garbage collectors and oil garbage collectors with various combinations of devices for collecting oil and garbage.

Oil collection devices, or skimmers, are designed to collect oil directly from the surface of the water. Depending on the type and quantity of spilled oil products and weather conditions, various types of skimmers are used, both in design and in principle of operation.

According to the method of movement or attachment, oil collecting devices are divided into self-propelled; stationary; towed and portable on various swimming facilities.

According to the principle of operation, skimmers are divided into:

• Threshold values. They are characterized by simplicity and operational reliability, based on the phenomenon of a surface layer of liquid flowing through an obstacle (threshold) into a container with a lower level.
• They differ in the insignificant amount of water collected together with oil, low sensitivity to the grade of oil and the ability to collect oil in shallow water, in ponds in the presence of dense algae, etc. The principle of operation of these skimmers is based on the ability of some materials to subject oil and oil products to adhesion.
• Vacuum ones. They are characterized by low weight and relatively small dimensions, so they are easy to transport to remote areas. However, they do not have pumping pumps in their composition and require onshore or marine vacuum installations to operate.
• They are based on the use of centrifugal forces to separate liquids of different densities - water and oil.
• It is based on burning out a layer of oil. It is used with a sufficient layer thickness and immediately after contamination (until an emulsion has formed). This method is dangerous, unecological and therefore rarely used at the moment.
• Physico-chemical. It is based on the use of dispersants and sorbents. It is considered effective in cases where mechanical oil collection is impossible, for example, with a small film thickness.

Dispersants are complex chemicals that accelerate the spreading of spilled oil products in the form of a thin film over the water surface, rupture and dispersion of it into small stable droplets in the water column. Their use is possible at a depth of more than 10 m, water temperature below 5 ° and outdoor air below 10 °.

In the case when the film thickness is significant, emulsifiers and surfactants are used, which turn oil into an emulsion and accelerate the processes of its biochemical destruction.

The use of dispersants in some cases can cause even greater harm to the environment than the components of oil and oil products, since the dispersants themselves have high permeability, thereby they can cause pathological changes in the organisms of marine animals and plants. [4]

A sorbent is a chemical substance capable of selectively interacting and absorbing the desired element from the external environment.

To date, there are more than 200 types of sorbents, of which it is customary to distinguish 3 main types:

• inorganic sorbents are one of the most inexpensive sorbents, but they are low in efficiency. This type includes clay, diatomite rocks, sand, pumice stone, etc.;
• organic or natural and organic mineral – the category with the highest oil capacity. An example is wood chips, modified peat, wool, wastepaper, etc.;
• synthetic – the most common and effective sorbents. This category includes polyurethane, polypropylene, spongy materials, etc. varieties of plastics.

Biological. The final method of oil spill response. It is used after "primary processing" — mechanical oil collection or launching sorbents or dispersants into the medium. In order for the method to work, it is necessary that the thickness of the oil layer does not exceed 0.1 mm. Suspensions with destructive bacteria are launched into the polluted environment, which contribute to the natural degradation of hydrocarbons. This method is absolutely harmless to the environment, while most biological purification technologies are cheap and not particularly time-consuming. To date, more than 1 thousand protozoa have been discovered that feed on various hydrocarbons. For example, Candida yeast feeds on petroleum paraffins. At a water temperature of t = 15-25 ° C and sufficient oxygen saturation, microorganisms can oxidize oil at a rate of up to 2 g/m²/day of the water surface.

At low temperatures, bacterial oxidation can last for 10 years. [5]

3 Stage. Disposal of oil

All oil products and oil-water mixture collected during the liquidation of the accident are collected either in a tanker or in a special container, which is subsequently sent for processing.

In addition to traditional methods of combating oil leaks, new solutions are constantly emerging in the world — scientists are developing many technologies for detecting and eliminating spills. [6]

For example, scientists at an American institute have made a giant membrane from nanofibers that absorbs exclusively spilled oil, leaving water unattended. After collecting oil products, the membrane is heated, as a result of which the oil is released.

The whole oil collector vessel was manufactured in Germany: the ship cleans oil-contaminated seawater using a filtration tank. Before starting work, a seemingly ordinary vessel opens its hull, forming a kind of triangle. Thanks to this solution, it can collect oil on a surface area of 40 m² per hour and a film thickness of up to 2 mm.

Chinese scientists have developed a biomimetic foam that separates oil from water. Due to the hollow tubular structure, the material has an absorbent and filtration ability: oil is retained, and water passes calmly through the foam.

And not so long ago, scientists from Russia discovered frost-resistant microorganisms capable of absorbing hydrocarbons in harsh weather conditions.

Another unique technology, Aeroshoop, was developed at the Biological Institute of TSU. The essence of the innovation is as follows: a hose is lowered to the bottom of the reservoir, with which a powerful jet of high-pressure air is supplied to the spill site. The oil rises to the surface, where it is collected by special receivers.

The preservation of a favorable environment and the further development of the oil industry are two of the most important tasks of modern society, the solution of which depends on how well the industries can coexist and take into account each other's problems.

References

1. Oil spill response [Electronic resource]. – Access mode: https://dprom.online/oilngas/likvidatsiya-razlivov-nefti.
2. [Electronic resource]. – Access mode: https://translated.turbopages.org/proxy_u/en-ru.ru.b8d6547b-63270bdf-2eb54bc3-74722d776562/https/www.statista.com/statistics/268557/quantity-of-oil-spilt-from-tanker-incidents-since-1970.
3. Emergency oil spills: means of localization and methods of liquidation [Electronic resource]. – Access mode: http://secuteck.ru/articles2/prom_sec/avariynie_razlivi.
4. Classification of methods for collecting oil products from the water surface [Electronic resource]. – Access mode: https://lektsii.org/3-96188.html.
5. Liquidation of emergency oil spills of LARN [Electronic resource]. – Access mode: https://neftegaz.ru/tech-library/ekologiya-pozharnaya-bezopasnost-tekhnika-bezopasnosti/141808-likvidatsiya-avariynykh-razlivov-nefti-larn.
6. Oil spill response [Electronic resource]. – Access mode: https://dprom.online/oilngas/likvidatsiya-razlivov-nefti.