What is oil a short message. What is oil used for? Main oil and gas basins
Oil production is a complex and multi-stage process, so an integrated approach is required, including several stages of study, requiring huge investments and labor costs. Striving to maximize efficiency, reduce costs and eliminate negative consequences For environment pushes oil companies to innovate and thoroughly study the field long before work begins on it.
Is it worth it?
Geological exploration precedes production itself and requires huge investments, the use of the most modern technologies, deep and comprehensive expertise. Drilling the simplest shallow well costs millions of rubles; on the shelf, for example, in the North Sea, costs can reach 1.5 billion, and this is not the limit.
Against this background, the importance of all stages of geological exploration is difficult to overestimate, because every well that misses oil can cause huge losses. And for the long-term development of the company and the industry as a whole, it is necessary to constantly look for new oil locations. Even short breaks are fraught sharp decline production in the future.
In those days when hydrocarbons were practically not used in industry, and only their flammability and viscosity were valued, no one was chasing millions of barrels. Therefore, raw materials were often mined in the same place where they saw it on the surface of the soil, and no one could predict when it would end. As the industry developed in the early twentieth century, large volumes of raw materials were required, and it was this time that can be considered the starting point for geological exploration in the modern sense.
Where to look for oil?
One of the key properties of oil is that it is less dense than water. It’s very easy to check: pour into any container sunflower oil and add water. The water will be at the bottom, the oil will rise to the top. If there is still air in the container, which is a mixture of gases, then it will be located at the very top, forming the third layer. This is exactly how oil-bearing formations are formed: water at the bottom, oil in the middle, above - natural gas. Rocks that contain oil and allow the free movement and accumulation of liquids and gases are called reservoirs. Most often they are sedimentary. The porosity of reservoirs depends on the types of grains as well as the presence of cement. Permeability is determined by the size of the pores and their connectivity.
The main oil reservoirs are sands, sandstones, conglomerates, dolomites, limestones and others, highly permeable rocks. In this case, to form a reservoir, it is necessary that the porous layer be enclosed between impermeable layers, for example, clay and gypsum.
Oil lies in so-called “traps,” in which hydrocarbon-rich layers are sandwiched between impermeable layers. They are main prey oil workers. But it is useless to drill at random, because most deposits are located at a depth of more than a kilometer and the trap is not visible from the surface. To increase the chances of success, oil workers use aerial photography and seismic exploration.
Aerial photography and seismic exploration: what is this?
To increase the chances of success, humanity first learned to analyze the terrain, using indirect signs to determine where the oil was located. This direction was developed after the advent of aerial photography. Nowadays, the emphasis is on aeromagnetic and gravimetric surveys - with the help of such methods it is possible to identify structural features soil.
Moreover, today space technology is also helping oil workers: a constellation of Russian scientific satellites helps determine how the soil was formed and where raw materials may lie. Important role Expeditions are also playing, the purpose of which is to find out whether it is advisable to start drilling.
Today, seismic exploration on land is carried out using special mobile platforms and a network of thousands of high-precision sensors. Based on the data received, computers create a map on which not only the outlines are clearly visible, but also information about the composition of certain layers. The fact is that rocks of different types reflect sound differently, that is, salt “sings” differently than, for example, clay.
Sound waves can penetrate the earth 3 km deep or more. The soil conducts sound well.
How does it work in big water?
The specificity of working on the shelf is that you have to use pneumatics. First, a network of sensors is lowered to the bottom, and then the ship, using special sonic cannons, releasing compressed air, sends sound signals, which allow you to find out what is under seabed. These technologies are used only in conjunction with a whole range of measures to prevent the impact on marine fauna.
Verification work
Once a decision has been made about how deep and where exactly the oil trap is located, it is time to test wells. In fact, if we are talking about strategic geological exploration, then reference, parametric and structural wells can be drilled in early stages to determine which deposits the company can rely on in the future.
If we talk about the launch commercial use specific deposit, then it is important to understand what category of raw materials and in what volume are located underground, how easily they are extracted, and in general, from the point of view of monetization, is it worth starting full-scale production here?
It is interesting that the first target when drilling exploratory wells is not the oil itself, but a column of rock, the so-called core. A sample of a particular formation is raised to the surface cylindrical, which is then sent to detailed analysis to the laboratory. Having made conclusions about the prospects for oil production based on the structure of the core, the sample is sent to a special core storage facility, where it will always remain, even when the field itself is depleted.
In addition to physical samples, it is necessary to obtain Additional information. For example, about how the soil layer changes with distance from the well. A special geophysical probe can be lowered underground. It must be said that oil workers are not without humor. This method is called logging from the French "carotte" ("carrot"). This very high-tech probe looks like a carrot.
This is the kind of labor-intensive work that has to be done before full-scale oil production.
Petroleum is a fossil substance that is an oily flammable liquid. Oil deposits are found at depths from several tens of meters to 5-6 kilometers. Maximum amount The deposits are located at a depth of 2-3 kilometers. Oil remains the main fuel raw material in the world. Its share in the global energy balance is 46%.
Characteristics and types of oil
By chemical composition oil is a mixture of about 1000 substances. The main “ingredient” is hydrocarbons with different molecular weights. There are about 80-85% of them in oil. There are three types of hydrocarbons: paraffinic (methane), naphthenic and aromatic. The latter are the most toxic.
About 4-5% of oil is occupied by organic compounds - sulfur, nitrogen and oxygen. Other components: hydrocarbon gases, water, mineral salts, metals, mechanical impurities (sand, clay, limestone).
The color of oil varies from light yellow to dark brown. There is also black oil, and rich green and even colorless. The smell can also be different: from light and pleasant to heavy. It all depends on the content of sulfur, oxygen and nitrogen in oil.
Most important indicator The quality of oil is its density. The lighter it is, the higher it is valued. There are: light oil (800-870 kg/m³), medium (870-910 kg/m³) and heavy (over 910 kg/m³). The indicators depend on the composition of the oil, temperature, pressure and amount of gas content. Oil density is measured with a hydrometer.
Other parameters by which the quality of oil is determined: viscosity, crystallization, combustion and flash points, electrical conductivity and heat capacity.
Oilfield
Oil is a non-renewable resource. Deposits of this mineral are classified differently: depending on geographical location, on exploration and study, on the shape and size of deposits.
The richest country in oil is Saudi Arabia (36 billion tons). This is followed by Canada (28 billion tons), Iran (19 billion tons) and Libya (15 billion tons). Russia is in 8th place on this list (13 billion tons).
Super-giant oil fields, the reserves of which exceed 5 billion tons: Rumaila in Iraq, Cantarel in Mexico, Tengiz in Kazakhstan, Al-Ghawar in Saudi Arabia, Samotlor in Russia, Burgan in Kuwait and Daqing in China.
Work is constantly underway to develop new deposits. According to the BP Statistical review of world energy, Venezuela and Canada are very promising in this regard. Experts believe that at the current rate of industrial development, oil in these two countries alone will be enough for the entire world to last 110 years.
Oil production and refining
Oil production is very difficult process, consisting of many stages.
There are three methods of oil production:
Primary - the oil itself gushes out under the natural pressure of the upper layers. In order for oil to rise to the surface, submersible pumps and pumping machines are used. Up to 15% of the world's oil is produced this way.
Secondary method. When natural pressure is no longer enough, water is pumped into the formation to increase pressure. fresh water, carbon dioxide or air. The oil recovery factor in this case is 45%.
The tertiary method is used when the secondary one is no longer relevant. In this case, either water vapor is pumped in or the oil is liquefied by heating it to a certain temperature. In this way, another 15 percent of oil can be pumped out of the field.
Oil refining is a multi-stage cycle of operations that is carried out to obtain petroleum products from raw materials. First, oil is purified from gases, water, and various impurities, then transported to oil refineries, where complex operations receive industrial products.
Application of oil
People began to use oil long before our era. For example, asphalt and bitumen were used in the construction of the walls of Babylon. King Nebuchadnezzar heated a huge furnace with oil. And the ancient Greek historian Herodotus described the method of oil production used by the ancient Greeks. And in Ancient India Oil was widely used in construction.
Currently, the list of products derived from oil numbers in the thousands. Suffice it to mention that petroleum products are used in almost all types of industry: energy, heavy and light, chemical and food. Petroleum products have found application in the automotive industry, medicine, rocket science, agriculture and construction.
Oil is a mineral that is an oily liquid. It is a flammable substance, often black in color, although the color of petroleum is different areas vary. It can be brown, cherry, green, yellow, and even transparent. From a chemical point of view, oil is a complex mixture of hydrocarbons with an admixture of various compounds, for example, sulfur, nitrogen and others. Its smell can also be different, as it depends on the presence of aromatic hydrocarbons, sulfur compounds.
The hydrocarbons that make up oil are chemical compounds consisting of carbon (C) and hydrogen (H) atoms. IN general view hydrocarbon formula - CxHy. The simplest hydrocarbon, methane, has one carbon atom and four hydrogen atoms, its formula is CH4 (shown schematically on the right). Methane is a light hydrocarbon, always present in oil.
Depending on the quantitative ratio of the various hydrocarbons that make up oil, its properties also vary. Oil can be transparent and fluid like water. And it can be black and so viscous and inactive that it does not flow out of the vessel, even if it is turned over.
From a chemical point of view, ordinary (traditional) oil consists of the following elements:
Carbon – 84%
Hydrogen – 14%
Sulfur – 1-3% (in the form of sulfides, disulfides, hydrogen sulfide and sulfur itself)
Nitrogen – less than 1%
Oxygen – less than 1%
Metals – less than 1% (iron, nickel, vanadium, copper, chromium, cobalt, molybdenum, etc.)
Salts – less than 1% (calcium chloride, magnesium chloride, sodium chloride, etc.)
Oil (and its accompanying hydrocarbon gas) lies at depths from several tens of meters to 5-6 kilometers. At the same time, only gas is found at depths of 6 km and below, and only oil is found at depths of 1 km and above. Most reservoirs are found at depths between 1 and 6 km, where oil and gas occur in varying combinations.
Oil lies in rocks called reservoirs. A reservoir is a rock capable of containing fluids, i.e. mobile substances (this can be oil, gas, water). To put it simply, a reservoir can be thought of as a very hard and dense sponge, the pores of which contain oil.
ORIGIN OF OIL
Oil formation is a very, very long process. It goes through several stages and, according to some estimates, takes 50-350 million years.
The most proven and generally accepted theory today is organic origin oil or, as it is also called, the biogenic theory. According to this theory, oil was formed from the remains of microorganisms that lived millions of years ago in vast water pools(mainly in shallow waters). As these microorganisms died, they formed layers with a high content of organic matter at the bottom. The layers, gradually sinking deeper and deeper (let me remind you, the process takes millions of years), were influenced by the increasing pressure of the upper layers and rising temperatures. As a result of biochemical processes occurring without access to oxygen, organic matter converted to hydrocarbons.
Some of the resulting hydrocarbons were in a gaseous state (the lightest), some in a liquid state (heavier) and some in a solid state. Accordingly, a mobile mixture of hydrocarbons in gaseous and liquid states, under the influence of pressure, gradually moved through permeable rocks towards lower pressure (usually upward). The movement continued until they encountered a thick layer of impenetrable layers on their way and further movement was impossible. This is a so-called trap formed by a reservoir layer and an impermeable capstone layer covering it (picture on the right). In this trap, a mixture of hydrocarbons gradually accumulated, forming what we call an oil field. As you can see, the deposit is not actually a birthplace. It's more of a cluster. But, be that as it may, the practice of naming has already developed.
Since the density of oil is generally much less than the density of the water that is always present in it (evidence of its marine origin), the oil invariably moves upward and accumulates above the water. If gas is present, it will be at the very top, above the oil.
In some areas, oil and hydrocarbon gas, without encountering a trap on their way, reached the surface of the earth. Here they were exposed to various surface factors, as a result of which they were dispersed and destroyed.