Gas hydrates

In each article of the Ecowatt portal, we try to present to your attention the most interesting and relevant information about the development of the oil and gas complex. Today, the topic of alternative energy sources is increasingly being raised in the press. This is not surprising, because in the foreseeable future humanity will exhaust all natural gas deposits that allow its extraction using traditional methods. Then there will be two borderline options: switching to alternative fuels and searching for alternative sources.

gas hydrate, gas hydrates, methane hydrates, biofuel

Until a type of fuel has yet been invented that can become a worthy replacement for the traditional one, the main direction of this search is the development of new methods for extracting traditional fuel. Their list is still relatively short: water-dissolved gases of the underground hydrosphere, methane of coal-bearing strata and natural gas hydrates. In this article we will talk about one of the most promising energy sources for Russia today, the so-called “methane hydrates”.

First, a little about what these mysterious gas hydrates what they are and why calling them “methane hydrates” is not entirely correct. As you probably already guessed, gas hydrates are bottom accumulations of gas (most often, but not necessarily, methane). These clusters form under conditions of low temperature and high pressure. Their state of aggregation can most easily be represented as a cluster of crystals (loose ice).

The beauty of gas hydrates is that one cubic meter of these crystals can contain 0.87 cubic meters of water and 164 cubic meters of methane in the gaseous state. However, there is also a certain content of other substances. Unfortunately, to date, the full potential of such reserves has not yet been identified. No. 6 of the journal “Foreign Information” for 2000 provided data according to which, according to preliminary estimates, there are 14 × 10 12 -34 × 10 15 cubic meters of methane in gas hydrates in the water area, and 3.1 × 10 15 - 7.6 × 10 18 cubic meters of methane in the water area. Even if only a small fraction (10%) of these reserves were considered recoverable, they would be twice the world's current reserves of conventional natural gas.

The idea of ​​producing methane from gas hydrates is not so new. Initially, humanity encountered gas hydrates as part of the organization of underwater gas pipelines. When moisture got into the pipes it led to their formation and clogging of the pipelines. Then American scientists had to develop special technologies for additional sealing and drying of pipes. However, it was Russian scientists who were the first to consider gas hydrate accumulations as an additional source of fuel. More precisely, even Soviet ones.

The Messoyakha deposit was put into commercial development back in 1970. Initially, its reserves were about 30 billion cubic meters of methane, of which more than half has already been produced to date. According to data published in No. 7 of the Gas Industry magazine for 2001, domestic reserves of natural gas in hydrates of the continental and shelf parts of Russia are estimated at 100-1000 trillion cubic meters. And according to the latest assessment by VNIIGAZ in Russia, about 30% of the territory is favorable for hydrate accumulation.

At the same time, global reserves are extremely heterogeneous. This is primarily due to serious differences in hydrate-forming conditions. In different bodies of water, the temperature and chemical composition of water are not uniform. Soviet scientists devoted a lot of time to studying the nature of gas hydrate deposits and compiling their detailed map for the spaces of the former USSR. But, as you understand, Russia is not the only lucky owner of such gas industry potential.

Most of the resources are located in the waters of the world's oceans (off the coasts of North, Central and South America, Japan, Norway and Africa, and only about 2% are in the polar parts of the continents. In the USA, the resources of deposits on land and shelf were estimated by the Geological Survey at 6000 trillion cubic meters, and the program for their production has received, along with space and nuclear ones, a priority. According to preliminary estimates, reserves of gas in a crystallized state in Alaska reach 66.8 trillion cubic meters, and another 1.03 trillion cubic meters of methane in the form of gas hydrates have been identified in the Gulf of Mexico. In 2001, the US Senate allocated about $42 million for methane production.

In general, it would not be superfluous to note that in the last decade, interest in this underwater fuel source has become extremely acute. In 1998, in the Mackenesie River delta (Canada), an experimental well, Malik, was drilled, which revealed the presence of a powerful field of gas hydrate accumulations. India is not lagging behind, which, according to one of its development programs, should begin the industrial development of its gas hydrate fields by 2010.

In 2003, Gazprom created a special expert group for exploration and preparation for industrial development of domestic gas hydrate deposits. As a result, this will allow the company to nominally increase its natural gas reserves by 50 times (by 1,400 trillion cubic meters) and bring it to first place in terms of reserves among the world's leading producers. However, technologies for industrial production of gas hydrate deposits since Soviet research remain undeveloped.

Japanese geologists have achieved the greatest success in this field so far. In the Land of the Rising Sun, the development of new high-precision geophysical logging methods and new technologies for gas production from hydrate deposits has been underway for several years now: by heating formations, reducing pressure or chemical injections. But Norwegian researchers proposed using the process of gas hydrate formation to simplify its transportation and storage. In addition, technology is being developed for using gas hydrates as chemical raw materials for desalination of seawater and separation of gas mixtures.

In other words, the study of gas hydrates has opened up a lot of new interesting opportunities for humanity, in some places not even related to the work of the oil and gas complex. But, as you probably already guessed, there are also a number of serious obstacles to such a blissful turn of events. First of all, this is, of course, the lack of high-quality extraction and processing technologies. Moreover, the development of gas hydrate fields will inevitably lead to an increase in the volume of natural gas released into the atmosphere and, as a result, to an increase in the greenhouse effect.

The second stumbling block for miners is the very unpleasant property of gas hydrates to “detonate” with the slightest shocks. In this case, the crystals quickly undergo a phase of transformation into a gaseous state, and acquire a volume several tens of times greater than the original one. This is what led at one time to the destruction of mining platforms in the Caspian Sea. Thus, the risk of accidents is unnecessarily high, and consequently a sharp decrease in the profitability of developing hydrate deposits. However, so far everything is going to the point that time and the situation on the world market will force companies to take a deliberate risk and join a new source of hydrocarbons.

That is why the research and production of gas hydrates is considered today the most promising technological direction in the oil and gas industry. Observing the development of the situation with the search for new sources of fuel, one involuntarily recalls the fairy tale about a kolobok, molded by the owners from what was found in the waste. We will find out how high Gazprom’s culinary abilities are and whether the methane bun will “leave” from it in the not very distant future.

For now, we can only follow with interest the development of this once fabulous plot..

gas hydrate, gas hydrates, methane hydrates, biofuel

Russia's oil and gas prospects in the 21st century are associated with the development of the shelf of its Arctic seas, where, according to various experts, over 100 billion tons of hydrocarbons in oil equivalent lie.

According to specialists from OJSC NK Rosneft, up to 80% of all potential hydrocarbon resources in Russia are concentrated on the Arctic shelf. At the same time, the most studied area is the Western Arctic - the shelves of the Barents, Pechora and Kara seas. Thus, according to the Ministry of Natural Resources of the Russian Federation, the initial recoverable hydrocarbon resources in this region amount to 62 billion tons. It should be noted that most of the 13 hydrocarbon fields discovered in the western part of the Arctic are large, and some are even unique objects. The rest of the Russian North is still little studied geologically. Nevertheless, it was established that the initial recoverable hydrocarbon resources of the Laptev Sea amount to 3.7 billion tons of equivalent. t. (tons of standard fuel), East Siberian Sea - 5.6 billion tons. tons and the Chukchi Sea - 3.3 billion tons. etc. But there are also unconventional, and also non-conventional, that is, not subject to mandatory agreement with other countries during their development, hydrocarbons - gas hydrates. According to various expert estimates, gas hydrate deposits contain approximately 20,000–21,000 trillion m3 of methane. Search, assessment and research work on aquatic gas hydrate topics is currently being carried out by Russia, Norway, the USA, Canada, Germany, the Netherlands, Japan, China, India and even South Korea.

Arctic gas hydrates - a giant hydrocarbon resource in Russia

Gas hydrates are the only source of natural gas on Earth that has not yet been developed on an industrial scale, but is a very promising source of natural gas. They can be a real competitor to traditional hydrocarbons: due to the presence of enormous resources, wide distribution on the planet, shallow occurrence and very concentrated state (1 m3 of natural methane hydrate contains about 164 m3 of methane in the gas phase and 0.87 m3 of water).
Thus, South Korea is already planning to begin drilling for pilot production of methane from shelf gas hydrate deposits in the Sea of ​​Japan. The Koreans discovered their first gas hydrate deposit in the Sea of ​​Japan (with a gas-bearing layer thickness of 130 m) 135 km northeast of the South Korean port of Pohang.
Most natural gases (CH4, C2H6, C3H8, CO2, N2, H2S, isobutane, etc.) form hydrates or clathrates - crystalline structures in which the gas is surrounded by water molecules (Fig. 1), held together by low temperature and high pressure of the surrounding water environment.

Deposits of aquatic methane hydrates are formed within the upper 1.5 km of seabed sediments (the depth level of 200–800 meters below the seabed is considered the most promising for their industrial development).
The thickness of aquatic gas hydrate deposits depends on the depth of the water area and the temperature of its bottom waters and ranges from 100 m to 300-350 m (in the northern seas at shelf depths of about 1000 m).
The Arctic shelf of the Arctic Ocean occupies a special place among other water areas of the Earth due to the presence of a fairly extensive submarine permafrost zone, which is associated with the formation of numerous gas hydrate deposits. The presented fragment of the map clearly shows that the zones of possible gas hydrate content of the Russian shelf are very extensive and, apparently, can be considered as very important sources of hydrocarbons in the future (Fig. 3).
Thermobaric conditions for the existence of aquatic gas hydrates are characteristic of most of the bottom of the World Ocean with depths of more than 300–400 m. On the Arctic shelf, the zone of stability of gas hydrates is associated with the presence of a submarine cryolithozone and therefore can exist at a slightly shallower depth (if the base of the cryolithozone is located at a depth of more than 260 m from sea level). In particular, low-temperature, potentially hydrate-bearing sediments occupy the central, north- and south-eastern parts of the Barents Sea, adjacent to Novaya Zemlya (Fig. 3).
In the course of numerous expeditionary studies conducted by Russia, quantitative data and indicators were obtained characterizing the zone of stability of gas hydrate deposits at the bottom of the Arctic Ocean (table).
The results of such studies, together with their scientific interpolation and expert estimates, made it possible to calculate the volumes of potential methane resources in the existing gas hydrate deposits of the main geomorphological structures of the Arctic Ocean bottom.
The given figures are not final, since work is currently underway to clarify the shelf areas (the issue of the modern division of the Arctic shelf is being considered by the UN Commission on the Limits of the Continental Shelf based on the provisions of the UN Convention on the Law of the Sea) and Russia lays claim to the Arctic territory with a total area of ​​1.2 million km2, which may lead to a further increase in potential volumes of gas hydrates.

Geoecological risks and economic aspects of gas hydrate development

The development of gas hydrates on the shelf entails an environmental threat associated with global warming. In particular, permafrost in Western Siberia is already thawing by 4 cm per year, and in the next 20 years its border will shift north by about 80 km. The situation is similar with the melting of ice in the Arctic. Thus, if in 1979 the area of ​​Arctic ice was 7.2 million km2, then already in 2007 it decreased to 4.3 million km2. In addition, the thickness of the ice cover here has approximately halved during this period. The water of the seas and oceans is also noticeably warming (even at depths of up to 2000 m). And gas hydrates are stable only at low temperatures and elevated pressures (Fig. 5).
As a result, firstly, we may lose such a valuable hydrocarbon natural resource, and secondly, during the decomposition of aquatic gas hydrates due to an increase in temperature even by a few degrees, the released methane will enter the Earth’s atmosphere, where its concentration will double and significantly enhance the greenhouse effect.
It should also be noted that the rapid destruction of gas hydrate deposits can lead to the formation of tsunami waves that can cause serious damage to coastal areas. Giant craters in the Yamalo-Nenets Autonomous Okrug in 2012 and 2013 were formed due to the release of gas hydrates caused by heating of the earth's surface.
The development (development) of significant volumes of natural gas hydrates and aquatic deposits that have been identified to date, containing about 15,000 × 1012 m3 of CH4, is hampered by their rather unstable state, causing possible rapid (explosive) destruction of their massifs. During such self-destruction of gas hydrates, the volume of resulting gas increases 160–180 times, which significantly complicates and even prevents the use of known industrial technologies for their development.
The cost of gas production from gas hydrate deposits depends on a number of factors: primarily on geological conditions and the technology used. It should be immediately noted that the limited number of both implemented projects for methane production from gas hydrate deposits and economic calculations of such projects makes it difficult to develop a reasonable estimate of their average cost.
Thus, an assessment of methane production from the Mallick gas hydrate deposit in the Canadian Arctic, carried out in 2008, showed that the total capital and operating costs of such development vary between 195–230 dollars/thousand. m3 for gas hydrates located above free gas, and in the range of 250–365 dollars/thousand. m3 - for gas hydrates located above the seabed. The need to have appropriate infrastructure for transporting produced gas was especially noted.
Japanese developers estimate the cost of methane production from subbottom gas hydrates at $540/thousand. m3, while according to estimates from ERI RAS and the Analytical Center, this technology becomes competitive only at methane production costs of less than $390/thousand. m3. According to IEA calculations, the estimated cost of industrial development of gas hydrate deposits could be $175–350/thousand. m3, which still makes them the most expensive known method of natural gas production.

Spherical nanoparticles as agents for activating gas hydrates

Currently, a significant reduction in the cost of manufactured products is possible primarily on the basis of
the use of advances in the field of nanotechnology, which is explained by the presence of fundamentally new properties and characteristics of nano-level substances. It was experimentally established that the main structural element of gas hydrates are crystalline cells - nanosized elements consisting of water molecules, inside of which gas molecules are located. In this case, the structure of hydrates is similar to the structure of ice, but differs from the latter in that the gas molecules are located inside the crystal lattices, and not between them.
Obviously, to destroy such a gas hydrate cell in order to release methane, it is more effective to use various nanoparticles commensurate with the cell.
It should be noted that the bond lengths in the crystal lattices of gas hydrates and the angles between them are almost the same and equal to 2.76° and 109.5°.
In accordance with the developments of Professor A.E. Vorobyov initially intended to supply and use nanoparticles of almost any shape. In this case, the main factor was their scale proportionality with the destructible cells of clathrates - gas hydrates.
Subsequently, a clear dependence of the efficiency of destruction of gas hydrates on the shape of nanoparticles was established: in particular, on the presence of various spikes on spherical nanoparticles (Fig. 6), distributed evenly over their entire surface.
To effectively ensure the process of destruction of a clathrate cell with a methane molecule included in it, the optimal parameters (length, distance between them, etc.) and shape (straight, curved, thickened, etc.) of the spikes of a spherical nanoparticle are also important.
Such nanostructures, which look like natural biological objects - sea urchins (Fig. 8), are quite easily formed by the electrochemical method. Currently, the main material for their construction is polystyrene.
The polystyrene microsphere provides a base on which zinc oxide forms a three-dimensional surface. The result is hollow, spherical nanostructures with spikes sticking out in all directions. Currently, the cost of producing 10 kg of such nanoparticles is $50.
During development, gradual destruction of the upper layer of gas hydrate accumulations is ensured by a hydrodynamic jet of sea water, previously saturated with spherical nanoparticles. When a spherical particle moves along the surface of a crystalline cell of gas hydrates, it is destroyed and a methane molecule is released (Fig. 7). In this way, a solution of methane and its homologues is formed, the extraction of which to the surface is carried out first by force, and then due to the gas lift effect.
However, during the processing of aquatic gas hydrate deposits, such particles can fly away in different directions and subsequently be lost. For collection, they are made magnetic, that is, they are made entirely of magnetic materials, which significantly increases their cost, or magnetic materials are placed in them.
In addition, the supply of “magnetized” water into the pipes is also carried out using submersible equipment. The resulting water-gas mixture is collected using a bell (Fig. 9). The resulting water-gas mixture of gas hydrates is pumped out through a system of pipes connected to a storage tank installed on the coastal surface, floating platform or vessel.
To do this, water saturated with spherical nanoparticles is supplied evenly over the surface of the gas hydrate deposit through hydrant nozzles. As a result, fragments of gas hydrates, gas and a solution of methane in water are formed in the internal space of the bell.
Through a system of pumping pipes, the resulting water-gas mixture flows upward independently (airlift effect) and is sent to a special storage tank, from where it flows through a pipeline to its destination. Magnetic nanoparticles are collected via an electromagnet (not shown in the diagram) and used again.

Prospects for the use of rare earth metals in nanotechnologies for the development of gas hydrate deposits

Nanocomposites that contain a mixture of neodymium nanoparticles with iron nanoparticles have a great future in gas hydrate development technologies. The result of the interaction of such nanostructured magnet fragments is an increase in its magnetic properties compared to conventional magnetic alloys.
The improvement in magnetic properties in these nanocomposites is due to a property called exchange coupling (synergistic interaction). Simplifying a complex physical process, we can say that the connection between individual nanoparticles in the resulting composite leads to the appearance of magnetic properties stronger than the sum of the properties of its individual components.
In addition, in the course of our research, several quite significant aspects were established that determine the effectiveness of the industrial application of such nanotechnologies in the development of gas hydrate deposits.
Firstly, the potential energy of the working tool - nanoparticles - obtained as part of a hydrodynamic jet ensures its movement along the surface of gas hydrates only over a very short distance, since its rebound is often observed, with the loss of potential energy for the destruction of clathrate bonds and a change in the trajectory of movement, from the surface of the gas hydrate deposits. And, therefore, almost each of them destroys a fairly small number of cells - clathrates, a chaotic sequence.
Therefore, in addition to spherical nanoparticles, it is more advisable to use various molecular gears (Fig. 11) and wheels connected by an axle as a working tool for destroying hydrate deposits. Models of such nanodevices were proposed by K.E. Drexler and R. Merkle from IMM (Institute for Molecular Manufacturing, Palo Alto).
The shafts of the “gears” in such a “gearbox” are carbon nanotubes, and the “teeth” are benzene molecules. In this case, the characteristic rotation speeds of the gears are several tens of gigahertz.
The mechanism of formation of such nanowheels has already been substantiated in detail (Fig. 12). Thus, a group of researchers led by Achim Müller from the University of Bielefeld (Germany) discovered that mixing sodium molybdate, water and a reducing agent at low pH leads to the spontaneous formation of donut-like nanowheels consisting of molybdenum oxide. The diameter of the emerging molybdenum-containing wheels is about 4 nm.
It should be noted that not only the energy of a hydrodynamic flow can be used to destroy gas hydrate cells with nanoparticles. In particular, one of the important and promising areas of application of nanotechnology in the oil and gas industry is the creation of special miniature devices equipped with microprocessors and capable of performing targeted operations with nanometer-scale objects, called “nanorobots.”
Nanorobots (in English literature the terms “nanobots”, “nanoids”, “nanites” are also used) are nanomachines created from various nanomaterials and comparable in size to a molecule. They must have the functions of movement, processing and transmission of information, as well as the execution of special programs. The dimensions of nanorobots do not exceed several nanometers.
According to modern theories, nanorobots should be able to carry out two-way communication - respond to various signals and be able to be recharged or reprogrammed externally through sound or electrical vibrations. Also important are their replication functions - self-assembly of new nanites and programmed self-destruction, for example, at the end of work. In this case, robots should be broken down into environmentally friendly and quickly dismantled components.
At the same time, there are various approaches to the development of nanorobots: one of them is the creation of self-propelled micro- and nano-sized actuators (nanomotors). A nanomotor is a molecular device capable of converting various types of energy into motion. Typically it can produce a force on the order of one piconewton.
The energy of movement of nanomotors can be various chemical reactions, energy of light, sound (mechanical vibrations), electromagnetic field and electric current.
Thus, laboratory experiments were carried out at the University of California on the movement of nanotubes through dielectrophoresis in aqueous solutions. In this case, the gap between the nanotube electrodes was 10 nm, and the voltage applied to them was 1 V. As a result, a rather strong inhomogeneous electrostatic field was formed at the ends of such electrodes, attracting such particles.
Nanotube electrodes form the stator, and the nanoparticles in the center form the rotor. If an alternating voltage is applied to the electrodes, the nanoparticle will rotate, and its position directly depends on the voltage applied to the electrodes.
In addition, M.P. Hughes from the School of Engineering, University of Surrey proposed a model of an asynchronous electrodynamic nanomotor that produces torque due to a rotating electromagnetic field.
Such an interaction “rotating field - electric dipole (rotor)” significantly stabilizes the position of the rotor. The electric field is generated due to rectangular pulses sent to the stator, which makes it possible to directly control such a nanomotor by computer. Precision control of the rotation speed of such a rotor is also possible. The developed nanomotor consists of a rotor 1 μm long and 100 nm in diameter. Such a nanomotor develops a torque of 10–15 N/m.
Such nanotechnologies ensure effective and consistent development of the entire surface of an aquatic gas hydrate deposit with the required rate of their destruction and production of the planned volumes of methane.
In the future, new technologies for producing combustible natural gas from gas hydrates will increase global demand for certain types of rare and rare earth metals (REM). Due to the reserves and resources of rare earth metals available in Russia, the possible economical production of such metals will strengthen the position of Russia and its producers in the world market. In particular, holmium is an ideal paramagnet. And most rare earth elements exhibit similar magnetic properties. Magnetic properties put gadolinium on par with iron, cobalt and nickel. While lanthanum and other lanthanides are paramagnetic, gadolinium is ferromagnetic, even stronger than nickel and cobalt.
The resource potential of rare earth metals in Russia is sufficient to meet both the internal needs of industrial development in the future for 2020–2030 and beyond, and the organization of their export in the form of final chemical and metallurgical products and products. The matter is the technological realization of this potential through the technical modernization of OJSC Lovozersky Mining and Processing Plant and the Solikamsk Metallurgical Plant, the industrial development of the Tomtorskoye deposit as a global iron ore-aluminophosphate-rare metal supergiant, enriched in yttrium landanide and scandium, and, finally, organizing the development of the most popular various sources of yttrium-earth minerals. lanthanides of the medium-heavy group and yttrium (eudialyte and other ores). From these positions, the above material focuses on the organization of research and development on the use of rare earth metals in various technological areas of development of mineral resources of the Arctic coast and shelf, including nanotechnology in relation to gas hydrate resources. Here, our country has obvious prospects for outpacing not only the “state of mind”, but also high-tech solutions. Academician N.P. Laverov considers the exploration of the Arctic more difficult than space exploration. Consequently, solving the technological problems of its development requires combining the capabilities of academic, university and industrial science, subject to the necessary support for targeted scientific research from the state and business.
New challenges are facing Russian scientific organizations and technical universities. Thus, the famous specialist in rare earth metals L.P. Rikhvanov, professor of the Department of Geoecology and Geochemistry of TPU (Tomsk), believes that “special preparation of master’s programs with a narrow focus is needed. Since rare earths and uranium deposits differ in geochemistry, the experience of uranium specialists alone will not be enough.” This point of view is supported, in particular, by the capital’s MGRI-RGGRU, which is the oldest university in Russia training geologists, geophysicists and mining engineers. With a population of about five thousand people, this university currently has 120 graduate students. Among the scientific schools of MGRI-RGGRU are uranium and rare earth. For many years, MGRI worked on instructions from the USSR Ministry of Medium Machine Building. In accordance with the assignment of the Ministry of Education and Science of the Russian Federation No. 26.2510.2014 K dated July 17, 2014, MGRI-RGGRU began work on a three-year research project “Development of recommendations for the development of the mineral resource and production base of rare earth minerals in Russia, taking into account global trends.” Project manager - E.A. Kozlovsky, Doctor of Technical Sciences, Professor, Vice-President of the Russian Academy of Natural Sciences, former Minister of Geology of the USSR.
From the stated positions, the timeliness of the organization and development of prospecting and research work for gas hydrates in Russia, despite the provision of oil and gas reserves and resources for decades, acquires promising strategic importance. Moreover, in addition to the coastal zone of the Arctic seas, certain prospects for identifying large gas hydrate deposits in Russia are associated in the south with the Black Sea (30–50 trillion tons) and in the Far East with the Okhotsk Sea (>17 trillion tons). Gas resources in hydrates on the continental and shelf parts of Russia are estimated at 100–1000 trillion m3. Consequently, the prospect of obtaining natural gas from unconventional gas hydrate deposits, as well as from shale hydrocarbon raw materials, must be qualified as a “breakthrough innovative technology” in the development of the subsoil of the Arctic and other regions by the Russian gas industry.

Vorobyov Alexander Egorovich
Doctor of Technical Sciences, Professor, Head of the Department of Petroleum Geology, Mining and Oil and Gas Engineering at Peoples' Friendship University of Russia, Director of the Research Center "Innovations in the Mining and Oil and Gas Complex" at RUDN University and the Research Center for "National Mineral Resources Security of the Countries of Central Asia" (KRSU, Bishkek, Kyrgyzstan ), professor of the Grozny State Petroleum Institute, director of the RUDN graduate school in the direction of “Geology, exploration and development of mineral resources”

A.E. VOROBYEV, V.I. LISOV, G.B. MELENTYEV
Peoples' Friendship University of Russia

National Mineral Resources University Mining

Scientific supervisor: Yuri Vladimirovich Gulkov, Candidate of Technical Sciences, National Mineral Resources Mining University

Annotation:

This article discusses the chemical and physical properties of gas hydrates, the history of their study and research. In addition, the main problems that impede the organization of commercial production of gas hydrates are considered.

In this article we describe the chemical and physical characteristics of gas hydrates, the history of their study and research. In addition, the basic problems hindering the organization of commercial production of gas hydrates are considered.

Keywords:

gas hydrates; energy; commercial mining; Problems.

gas hydrates; power engineering; commercial extraction; problems.

UDC 622.324

Introduction

Initially, man used his own strength as a source of energy. After some time, the energy of wood and organic matter came to the rescue. About a century ago, coal became the main energy resource; 30 years later, its primacy was shared by oil. Today, the world's energy sector is based on the gas-oil-coal triad. However, in 2013, this balance was shifted towards gas by Japanese energy workers. Japan is the world leader in gas imports. The State Oil, Gas and Metals Corporation (JOGMEC) (Japan Oil, Gas & Metals National Corp.) was the first in the world to obtain gas from methane hydrate at the bottom of the Pacific Ocean from a depth of 1.3 kilometers. The trial production lasted only 6 weeks, despite the fact that the plan considered two-week production, 120 thousand cubic meters of natural gas were produced. This discovery will allow the country to become independent from imports and fundamentally change its economy. What is gas hydrate and how can it affect global energy?

The purpose of this article is to consider problems in the development of gas hydrates.

To achieve this, the following tasks were set:

• Explore the history of gas hydrate research
• Study chemical and physical properties
• Consider the main problems of development

Relevance

Traditional resources are not evenly distributed across the Earth, and they are also limited. According to modern estimates, oil reserves by today's consumption standards will last for 40 years, natural gas energy resources for 60-100. World shale gas reserves are estimated at approximately 2,500-20,000 trillion. cube m. This is the energy reserve of humanity for more than a thousand years. Commercial extraction of hydrates would raise the world energy sector to a qualitatively new level. In other words, the study of gas hydrates has opened up an alternative source of energy for humanity. But there are also a number of serious obstacles to their study and commercial production.

Historical reference

The possibility of the existence of gas hydrates was predicted by I.N. Strizhov, but he spoke about the inexpediency of their extraction. Villar first obtained methane hydrate in the laboratory in 1888, along with hydrates of other light hydrocarbons. Initial encounters with gas hydrates were seen as problems and obstacles to energy production. In the first half of the 20th century, it was established that gas hydrates cause plugging in gas pipelines located in Arctic regions (at temperatures above 0 °C). In 1961 the discovery of Vasiliev V.G., Makagon Yu.F., Trebin F.A., Trofimuk A.A., Chersky N.V. was registered. “The property of natural gases to be in a solid state in the earth’s crust,” which announced a new natural source of hydrocarbons - gas hydrate. After this, they started talking about the exhaustibility of traditional resources more loudly, and already 10 years later the first gas hydrate deposit was discovered in January 1970 in the Arctic, on the border of Western Siberia, it is called Messoyakha. Further, large expeditions of scientists from both the USSR and many other countries were carried out.

Word of chemistry and physics

Gas hydrates are gas molecules stuck around water molecules, like “gas in a cage.” This is called an aqueous clathrate framework. Imagine that in the summer you caught a butterfly in your palm, the butterfly is a gas, your palms are water molecules. Because you protect the butterfly from external influences, but it will retain its beauty and individuality. This is how the gas behaves in the clathrate framework.

Depending on the conditions of formation and the state of the hydrate former, hydrates appear externally as clearly defined transparent crystals of various shapes or as an amorphous mass of densely compressed “snow.”

Hydrates occur under certain thermobaric conditions - phase equilibrium. At atmospheric pressure, gas hydrates of natural gases exist down to 20-25 °C. Due to its structure, a unit volume of gas hydrate can contain up to 160-180 volumes of pure gas. The density of methane hydrate is about 900 kg/m³, which is lower than the density of water and ice. When phase equilibrium is disturbed: an increase in temperature and/or a decrease in pressure, the hydrate decomposes into gas and water with the absorption of a large amount of heat. Crystalline hydrates have high electrical resistance, conduct sound well, are practically impenetrable to free water and gas molecules, and have low thermal conductivity.

Development

Gas hydrates are difficult to access because... To date, it has been established that about 98% of gas hydrate deposits are concentrated on the shelf and continental slope of the ocean, at water depths of more than 200 - 700 m, and only 2% - in the subpolar parts of the continents. Therefore, problems in developing commercial production of gas hydrates are encountered already at the stage of developing their deposits.

Today, there are several methods for detecting gas hydrate deposits: seismic sounding, gravimetric method, measuring heat and diffuse flows over the deposit, studying the dynamics of the electromagnetic field in the region under study, etc.

Seismic sounding uses two-dimensional (2-D) seismic data; in the presence of free gas under a hydrate-saturated formation, the lower position of hydrate-saturated rocks is determined. But seismic exploration cannot detect the quality of the deposit or the degree of hydrate saturation of the rocks. In addition, seismic exploration is not applicable on complex terrain. But it is most beneficial from the economic side, however, it is better to use it in addition to other methods.

For example, the gaps can be filled by using electromagnetic exploration in addition to seismic exploration. It will make it possible to more accurately characterize the rock, thanks to the individual resistances at the points where gas hydrates occur. The US Department of Energy plans to conduct it starting in 2015. The seismoelectromagnetic method was used to develop the Black Sea fields.

It is also cost-effective to develop a saturated deposit using a combined development method, when the process of hydrate decomposition is accompanied by a decrease in pressure with simultaneous thermal effects. Reducing the pressure will save thermal energy spent on the dissociation of hydrates, and heating the pore medium will prevent the re-formation of gas hydrates in the near-wellbore zone of the formation.

Production

The next stumbling block is the actual extraction of hydrates. Hydrates occur in solid form, which causes difficulties. Since gas hydrate occurs under certain thermobaric conditions, if one of them is violated, it will decompose into gas and water; in accordance with this, the following hydrate extraction technologies have been developed.

1. Depressurization:

When the hydrate leaves phase equilibrium it will decompose into gas and water. This technology is famous for its triviality and economic feasibility, in addition, the success of the first Japanese production in 2013 rests on its shoulders. But not everything is so rosy: the resulting water at low temperatures can clog equipment. In addition, the technology is really effective, because... During a test production of methane at the Mallick field, 13,000 cubic meters were produced in 5.5 days. m of gas, which is many times higher than production at the same field using heating technology - 470 cubic meters. m of gas in 5 days. (see table)

2. Heating:

Again, you need to decompose the hydrate into gas and water, but this time using heat. Heat supply can be carried out in different ways: coolant injection, hot water circulation, steam heating, electrical heating. I would like to dwell on the interesting technology invented by researchers from the University of Dortmund. The project involves laying a pipeline to gas hydrate deposits on the seabed. Its peculiarity is that the pipe has double walls. Sea water, heated to 30-40˚C, the phase transition temperature, is supplied to the field through the inner pipe, and bubbles of methane gas along with the water rise upward through the outer pipe. There, methane is separated from the water, sent to tanks or into the main pipeline, and warm water returns down to the gas hydrate deposits. However, this extraction method requires high costs and a constant increase in the amount of heat supplied. In this case, the gas hydrate decomposes more slowly.

3. Introduction of inhibitor:

I also use the injection of an inhibitor to decompose the hydrate. At the Institute of Physics and Technology of the University of Bergen, carbon dioxide was considered as an inhibitor. Using this technology, it is possible to obtain methane without directly extracting the hydrates themselves. This method is already being tested by the Japan National Oil, Gas and Metals Corporation (JOGMEC) with the support of the US Department of Energy. But this technology is fraught with environmental hazards and requires high costs. The reaction proceeds more slowly.

Project name	date	Participating countries	Companies	Technology
Mallik, Canada		Japan, USA Channel, Germany, India	JOGMEC, BP, Chevron Texaco	Heater (coolant - water)
North Slope of Alaska, USA		USA, Japan	Conoco Phillips, JOGMEC	Carbon dioxide injection, inhibitor injection
Alaska, USA			BP, Schlumberger	Drilling to study the properties of gas hydrate
Mallik, Canada		Japan, Canada	JOGMEC as part of a private public consortium	Depressurization
Fire in Ice (IgnikSikumi), Alaska, USA		USA, Japan, Norway	Conoco Phillips, JOGMEC, University of Bergen (Norway)	Carbon dioxide injection
A joint project (JointIndustryProject) Gulf of Mexico, USA			Chevron as consortium leader	Drilling to study the geology of gas hydrates
Near Atsumi Peninsula, Japan			JOGMEC, JAPEX, Japan Drilling	Depressurization

Source - analytical center based on open source materials

Technologies

Another reason for the undeveloped commercial production of hydrates is the lack of technology for their profitable extraction, which provokes large capital investments. Depending on the technology, there are different barriers: the operation of special equipment for the introduction of chemical elements and/or local heating to avoid the re-formation of gas hydrates and plugging of wells; application of technologies that prevent sand mining.

For example, in 2008, preliminary estimates for the Mallick field in the Canadian Arctic indicated that development costs ranged from $195-230/thousand. cube m for gas hydrates located above free gas, and in the range of 250-365 dollars/thousand. cube m for gas hydrates located above free water.

To solve this problem, it is necessary to popularize the commercial production of hydrates among scientific personnel. Organize more scientific conferences, competitions to improve old or create new equipment, which could provide lower costs.

Environmental hazard

Moreover, the development of gas hydrate fields will inevitably lead to an increase in the volume of natural gas released into the atmosphere and, as a result, to an increase in the greenhouse effect. Methane is a powerful greenhouse gas and, despite the fact that its lifetime in the atmosphere is shorter than CO₂, the warming caused by the release of large quantities of methane into the atmosphere will be tens of times faster than the warming caused by carbon dioxide. In addition, if global warming, the greenhouse effect, or other reasons cause the collapse of at least one gas hydrate deposit, this will cause a colossal release of methane into the atmosphere. And, like an avalanche, from one occurrence to another, this will lead to global climate change on Earth, and the consequences of these changes cannot be even approximately predicted.

To avoid this, it is necessary to integrate data from complex exploration analyzes and predict the possible behavior of deposits.

Detonation

Another unsolved problem for miners is the very unpleasant property of gas hydrates to “detonate” with the slightest shocks. In this case, the crystals quickly undergo a phase of transformation into a gaseous state, and acquire a volume several tens of times greater than the original one. Therefore, reports from Japanese geologists very carefully talk about the prospect of developing methane hydrates - after all, the disaster of the Deepwater Horizon drilling platform, according to a number of scientists, including UC Berkeley professor Robert Bee, was the result of the explosion of a giant methane bubble that formed from bottom hydrate deposits disturbed by drillers.

Mining of oil and gas

Gas hydrates are considered not only from the energy resource side; they are more often encountered during oil production. Once again we turn to the death of the Deepwater Horizon platform in the Gulf of Mexico. Then, to control the escaping oil, a special box was built, which they planned to place above the emergency wellhead. But the oil turned out to be very carbonated, and methane began to form entire ice deposits of gas hydrates on the walls of the box. They are about 10% lighter than water, and when the amount of gas hydrates became large enough, they simply began to lift the box, which, in general, was predicted in advance by experts.

The same problem was encountered in the production of traditional gas. In addition to “natural” gas hydrates, the formation of gas hydrates is a big problem in gas pipelines located in temperate and cold climates, since gas hydrates can clog the gas pipeline and reduce its throughput. To prevent this from happening, a small amount of an inhibitor is added to natural gas or heating is simply used.

These problems are solved in the same ways as during production: by lowering the pressure, heating, introducing an inhibitor.

Conclusion

This article examined the barriers to commercial production of gas hydrates. They occur already at the stage of development of gas fields, directly during production itself. In addition, gas hydrates are currently a problem in oil and gas production. Today, impressive gas hydrate reserves and economic profitability require accumulation of information and clarification. Experts are still searching for optimal solutions for developing gas hydrate fields. But with the development of technology, the cost of developing deposits should decrease.

Bibliography:

1. Vasiliev A., Dimitrov L. Assessment of the spatial distribution and reserves of gas hydrates in the Black Sea // Geology and Geophysics. 2002. No. 7. v. 43.
2. Dyadin Yu. A., Gushchin A.L. Gas hydrates. // Soros educational journal, No. 3, 1998, p. 55–64
3. Makogon Yu.F. Natural gas hydrates: distribution, formation models, resources. – 70 s.
4. Trofimuk A. A., Makogon Yu. F., Tolkachev M. V., Chersky N. V. Features of detection of exploration and development of gas hydrate deposits - 2013 [Electronic resource] http://vimpelneft.com/fotogalereya/ 6-komanda-vymlnefti/detail/32-komanda-vympelnefti
5. Chemistry and Life, 2006, No. 6, p. 8.
6. The Day The Earth Nearly Died – 5. 12. 2002 [electronic resource] http://www.bbc.co.uk/science/horizon/2002/dayearthdied.shtml

Reviews:

12/1/2015, 12:12 Mordashev Vladimir Mikhailovich
Review: The article is devoted to a wide range of problems related to the urgent task of developing gas hydrates - a promising energy resource. Solving these problems will require, among other things, the analysis and synthesis of heterogeneous data from scientific and technological research, which is often disordered and chaotic in nature. Therefore, the reviewer recommends that in their future work the authors pay attention to the article “Empiricism for Chaos”, website, No. 24, 2015, p. 124-128. The article “Problems of Gas Hydrate Development” is of undoubted interest to a wide range of specialists and should be published.

12/18/2015 2:02 Reply to the author’s review Polina Robertovna Kurikova:
I have read the article and will use these recommendations when further developing the topic and solving the problems covered. Thank you.

Gas hydrates or natural gas hydrates are crystalline formations of gas, such as methane, and water. Outwardly, they look like ice and are a white solid mass. One volume of gas hydrate can contain from 160 to 180 volumes of pure natural gas.

The formation of gas hydrates is possible only when certain thermobaric conditions are created: low temperatures or high pressure. It is possible to obtain gas hydrates even at zero degrees Celsius; for this you only need to maintain a pressure of 25 atmospheres. Most often, favorable conditions for the formation of gas hydrates are found in areas with a cold climate.

These gas-water compounds are also called "burning ice" due to their ability to burn and explode when heated. Such methane and water compounds are considered one of the potential energy sources against traditional minerals.

Gas hydrate deposits

Gas hydrates can be found almost throughout the entire world ocean - in 90% of the territories. On land they are found in 23% of territories.

Experts agree that the natural gas contained in the lithosphere is mostly found there in the form of natural gas hydrates. The total volume of gas contained in the hydrates is estimated at 2 - 5 quadrillion cubic meters. Moreover, most of them are located in polar latitudes: permafrost creates a favorable background for their formation. The content of gas hydrates in the polar latitudes of Russia, according to various expert estimates, can be about 1 quadrillion cubic meters.

In addition, optimal conditions for the appearance of gas hydrates occur at a depth of 300 to 1200 meters in the seas or oceans. The depth of formation depends on the temperature and climate conditions of the area. In the same Arctic, cold ocean waters allow gas hydrates to form already at a depth of 250 - 300 meters.

When gas hydrate rises to the surface, it decomposes into methane and water. This is due to an increase in temperature and a decrease in the applied pressure.

Gas hydrate production

In May 2017, it was reported that China had successfully extracted methane from gas hydrates in the South China Sea. The gas production process was carried out in the northern part of the sea in the territory of Shenhu. The depth of the sea at the mining site reached 1266 meters. At the same time, the Chinese had to sink even lower than the seabed and drill a well 200 meters deep. It was reported that gas production, consisting of 99.5% methane, reached 16 thousand cubic meters per day. According to Chinese authorities, this test mining was a turning point.

The first discoveries of gas hydrates in the South China Sea date back to 2007. The entire process of extracting gas from hydrates was carried out on a floating platform.

Earlier in the same year, Japan announced the successful production of gas from gas hydrates located in the Pacific Ocean. The first successful experimental production was carried out by Japanese specialists back in 2013. According to experts, commercial gas production in this manner should begin in Japan as early as 2023. The successful development of this area can make Japan an energy independent country. According to various estimates, natural gas resources from hydrates can solve the problem of the country's energy dependence in the next hundred years.

The International Energy Agency estimates the industrial development of gas hydrate deposits at $175-350 per thousand cubic meters. Today, such gas production is the most expensive method.

In addition to China and Japan, Canada and the USA are accelerating work on similar production. Projects for the exploration and development of gas hydrate deposits are carried out by such companies as BP, Chevron, ConocoPhillips, and Schlumberger.

In Russia, gas hydrate production was carried out in the 70s at the Messoyakha field. About 36% of the gas produced was obtained from hydrates. In the 1980s, Russia also searched for gas hydrates in the Sea of ​​Okhotsk on the Pacific coast. However, the research did not lead to the start of industrial development.

The difficulty of extracting gas hydrates is determined by the difficulties in lifting them to the surface, as well as in transporting and storing them due to changes in external conditions. The Japanese technology for transporting and storing gas hydrates consists of creating dense blocks of frozen hydrate using specialized mechanisms. After freezing, they are loaded into tanks with a cooling system, and then the containers are delivered to the gasification site. There, gas hydrates decompose by partially heating the containers and release the required volume of gas. After the gas has been completely used up, the remaining water and containers are delivered back.

Dangers of Gas Hydrate Mining

The main environmental risks associated with the extraction of gas hydrates relate to the likelihood of large methane emissions, which can lead to changes in the earth's biosphere. Methane is one of the gases that causes the greenhouse effect.

Uncontrolled methane emissions, which are likely to occur when working with deep-sea fields, can negatively affect the surrounding environmental situation.

In addition, underwater mining can disrupt the seabed and change its topography. And this in turn can cause the formation of a tsunami

Gases of gas-oil and oil-and-gas deposits. Gas-oil and oil-gas deposits are two-phase. Free gas occurs in them together with oil. Wherein Voil and gas deposits gas occupies the main volume of the trap and is located above the oil part of the deposit, called oil rim. IN gas and oil deposits gas occupies less volume of the trap. The gas part of such a deposit is called gas cap, and the produced gases are called incidental.

Associated gases are a mixture of free gas from the gas cap and gas dissolved in oil - oil gas. Their composition differs from the gases of gas deposits and depends on the composition, density of the oil and the solubility of individual gas components in oil.

In gas caps, methane is usually found in smaller quantities compared to deposits of dry and gas condensate gases. Gases from gas caps are also distinguished by an increased content of TUHC and liquid hydrocarbon vapors, heavier than hexane C 6 H 14 . Sometimes their total content exceeds the methane content. In most cases, propane C 3 H 8 predominates from TUVG.

Often high concentrations of non-hydrocarbon gases are found in the gases of gas caps: nitrogen, carbon dioxide or hydrogen sulfide. In this case, nitrogen and carbon dioxide can sharply predominate.

Chemical composition of gases dissolved in oil. Gases dissolved in oil are called petroleum or associated petroleum. Petroleum gas is a mixture of gaseous and vaporous hydrocarbon and non-hydrocarbon components released from reservoir oil during its degassing in gas separators as a result of changes in pressure and temperature.

The qualitative composition of associated petroleum gases does not differ from natural free gases: methane, its homologues, nitrogen, carbon dioxide, hydrogen sulfide, helium, argon and other components. However, the quantitative difference is often quite significant. The methane content does not exceed 20–30%, but its homologues, including higher hydrocarbons, are much larger. Petroleum gases are fatty (among hydrocarbons they often predominate propane and butane) .

The composition of the hydrocarbon part of petroleum gases is closely related to the composition of oil. Light methane oils are accompanied by rich gases consisting of 20–80% methane homologues. Heavy Oils, on the contrary, contain predominantly methane. Of the non-hydrocarbon gases, carbon dioxide, hydrogen sulfide and especially nitrogen, which can be the predominant component, are of significant importance.

Gas hydrates

All gases, with the exception of hydrogen, helium, neon and n-butane, as well as highly volatile organic liquids, the molecules of which have dimensions not exceeding 0.69 nm, at appropriate pressures and temperatures form solid solutions with water, called gas hydrates, gas hydrates, or clathrates. The appearance of gas hydrates (GH) resembles snow or firn (loose ice).

When GG is formed, the cavities of the crystal lattice formed by water molecules with the help of strong hydrogen bonds (Fig. 8) are filled with molecules of only one specific gas. In this case, one volume of water binds from 70 to 300 volumes of gas, so the density of gas hydrates varies in a wide range, from 0.8 to 1.8 g/cm 3 . The general ideal formula for gas hydrates is M∙nH 2 O, where M is 1 mole of a specific gas. The values ​​of n vary from 5.75 to 17, depending on the gas composition and conditions of hydrate formation. The conditions for the formation of gas hydrates are determined by the gas composition, temperature, pressure and water salinity. Typically, gas hydrates are formed at temperatures below 30°C and elevated pressure. For example, at 0ºС methane hydrate is formed at a pressure of 3 MPa, and at a temperature of 25ºС already at a pressure of 40 MPa. Thus, the higher the temperature, the higher the pressure required for the formation of GG.

Figure - 8. Crystal lattice of gas hydrate (according to Yu.F. Makagon; 1985)

Unit cells of hydrate: a – structure I, formed by light components of hydrocarbon gases; b – structure II, formed by heavy components of hydrocarbon gases.

In addition, the equilibrium conditions for the formation of gas hydrates are greatly influenced by influence of water salinity: the larger it is, the lower temperatures or higher pressures are necessary for the formation of hydrates. Since only fresh water passes into the hydrate, during their formation the mineralization of the remaining formation water increases.

GGs are not formed directly in water because the concentration of dissolved gas there does not reach the required values. They are formed in water-saturated sediments and at rock-water interfaces, since there is a layer of adsorbed gas molecules on the surface of mineral particles. GGs are also formed from free gas at the gas–water interface. The formation of gas hydrates can occur in the formation during the development of a gas deposit, in a wellbore or in a gas pipeline, so before the gas is supplied to consumers, it is dried.

The conditions for the formation of GG in nature correspond to permafrost zones, as well as marine and lake sediments lying at a sufficient depth. Seasonal fluctuations in water temperature in the World Ocean cover only the upper layer about 100 m thick. Then the fluctuations are smoothed out and at depths below 1500–2000 m the temperature becomes constant within the range of 2 to 3ºС and only in the Arctic drops to -0.7 and even to - 1.4 ºС. Therefore, the formation of hydrates occurs in deep waters, regardless of latitude. It has now been established that up to 23% of the area of ​​the continents, especially Eurasia, and 90% of the area of ​​the World Ocean correspond to the conditions for hydrate formation. Hydration resources tens of thousands of times exceed world natural gas reserves. In Russia, gas hydrates can occupy about half of the land area, which freezes to a depth of 500 to 1000 m. They are also found in the bottom sediments of the Baltic, Black and Caspian seas, and Lake Baikal.

Hydrated gas resources in water areas are associated with both biochemical gases and deep-seated gases, including catagenetic gases.

LITHOGENESIS AND FORMATION OF OIL AND GAS

According to the organic theory, the process of oil and gas formation develops periodically, in stages, over a long period of time and continuously, has a regional character and is directly related to tectogenesis and lithogenesis.

The formation of deposits occurs during the following two stages: oil and gas formation and oil and gas accumulation.

The oil and gas formation stage is divided into three stages: sedimentogenesis of OM, diagenesis of OM and catagenesis of O B. Carbon is the main biogenic element, or the basis of living matter and OM in sedimentary rocks. In addition, carbon in large quantities, both in oxidized (CO, CO 2) and reduced (CH 4, etc.) forms, enters the sedimentary shell and biosphere from the Earth's mantle.