III. fundamentals of oil and gas geology. Federal Budgetary State Educational Institution of Higher Professional Education
Oil and natural gas
Topic study plan
- 1. Oil, its elemental composition.
- 2. a brief description of physical properties of oil.
- 3. Hydrocarbon gas.
- 4. Component composition and a brief description of the physical properties of the gas.
- 5. The concept of gas condensate.
- 6. Origin of oil and gas.
- 7. Oil as a source of environmental pollution.
Oil and natural gas are valuable minerals. I.M. Gubkin noted that the clue to the origin of oil is not only of scientific and technical interest, but also of paramount practical importance, because. it provides reliable indications of where to look for oil and how it is most expedient to organize its exploration.
The origin of oil is one of the most complex and still unresolved problems of natural science. The existing hypotheses are based on ideas about the organic and inorganic origin of oil and gas.
Oil is a mixture of hydrocarbons containing oxygen, sulfur and nitrogen compounds. Depending on the predominance of a number of hydrocarbons, oils can be: methane, naphthenic, aromatic.
Commercial quality of oil depends on the content of paraffin. Oils are distinguished: low paraffinic no more than 1%, slightly paraffinic - from 1% to 2; highly paraffinic over 2%.
The main physical properties of oil are characterized by density, volumetric coefficient, viscosity, compressibility, surface tension and saturation pressure.
Hydrocarbon gas is found in the bowels of the Earth in the form of independent accumulations, forming purely gas deposits or gas caps, as well as in dissolved water. Combustible gas is a mixture of saturated hydrocarbons methane, ethane, propane and butane, often in the composition of the gas there are heavier hydrocarbons pentane, hexane, heptane. Hydrocarbon gases usually contain carbon dioxide, nitrogen, hydrogen sulfide and small amounts of rare gases (helium, argon, neon).
Natural hydrocarbon gases have the following physical properties, density, viscosity, gas compressibility factor, gas solubility in liquid.
What is oil, natural gas?
What are the main properties of oil and gas?
What are the theories of the origin of oil?
What oils are called paraffinic?
What properties do oils have?
Main:
Additional: p.93-99
Conditions for the occurrence of oil, natural gas and formation water in the earth's crust
Topic study plan
- 1. The concept of rocks - collectors. Groups of breeds - collectors.
- 2. Pore spaces in rocks, their types, shape and size.
- 3. Reservoir properties of rocks.
- 4. Granulometric composition.
- 5. Porosity, fracturing.
- 6. Permeability.
- 7. Carbonate.
- 8. Methods for studying reservoir properties.
- 9. Oil and gas saturation of reservoir rocks.
- 10. Breeds - tires. The concept of natural reservoirs and traps. Water-oil gas-oil contacts. Contours of oil and gas potential.
- 11. The concept of deposits and deposits of oil and gas.
- 12. Destruction of deposits.
- 13. Formation waters, their commercial classification. Mobile and bound water.
- 14. General information on pressure and temperature in oil and gas reservoirs. Isobar maps, their purpose.
Brief summary of theoretical issues.
Natural reservoir - a natural receptacle for oil, gas and water, within which they can circulate and the shape of which is determined by the ratio of the reservoir to the enclosing (reservoir) poorly permeable rocks. There are three main types of natural reservoirs: reservoir, massive, lithologically limited from all sides.
Rocks that have the ability to contain oil, gas and water and release them in industrial quantities during development are called reservoirs. Collectors are characterized by capacitive and filtration properties.
Tires are called poorly permeable rocks that cover and shield the accumulation of oil and gas. The presence of tires is the most important condition for the preservation of oil and gas accumulations.
A trap is a part of a natural reservoir in which, due to a structural threshold, stratigraphic screening, and lithological limitation, oil and gas accumulations can form. Any trap is a three-dimensional three-dimensional form in which hydrocarbons are accumulated and stored due to capacitive, filtration and screening properties.
The migration of oil and gas refers to the various movements of these fluids in the rock mass. Distinguish between primary and secondary migration.
Oil and gas deposits are understood as local industrial accumulations of these minerals in permeable reservoirs - traps of various types. A spatially limited subsoil area containing a deposit or several deposits of oil and gas located in the same area is called a field.
Questions for self-control on the topic:
What are the types of natural reservoirs?
The main properties of rocks - reservoirs?
What is a trap?
Types of oil and gas traps?
Types of oil and gas migration?
Types of oil and gas fields?
Oil and gas provinces
Topic study plan
- 1. Zoning of the oil and gas bearing territories of Russia, the prospects for their development;
- 2. The concept of oil and gas provinces, regions and districts, zones of oil and gas accumulation.
- 3. The main oil and gas provinces and regions of Russia.
- 4. The largest and unique oil and oil and gas fields in Russia.
- 5. Characteristics of oil and gas provinces with a developed oil industry (West Siberian, Volga-Ural, Timan-Pechora, North Caucasian, East Siberian).
- 6. Main features geological structure and oil and gas potential.
Brief summary of theoretical issues.
In the east of the European part of the Russian Federation, there are vast Volga-Ural and Caspian oil and gas provinces.
The Volga-Ural oil and gas province has firmly entered the history of the country's oil and gas industry under the name of the Second Baku.
The West Siberian oil and gas province corresponds to the Epipaleozoic platform, occupies a significant part of the territory of the vast West Siberian Lowland.
Caspian oil and gas province, located in the southeast of the European part of the Russian Federation
It is necessary to consider their main features of the geological structure, oil and gas content, oil and gas fields.
Questions for self-control on the topic:
- 1. General characteristics of the Volga - Ural oil and gas province?
- 2. General characteristics of the West Siberian oil and gas province?
- 3. General characteristics of the Caspian oil and gas province?
- 4. The main features of the geological structure of the provinces?
Main and additional sources on the topic
Basic: pp. 92 -110; 119 - 132; 215 - 225
Additional: p.105-122
Regimes of oil and gas deposits
Topic study plan
- 1. Energy sources in reservoirs, a brief description of the operating modes of oil and gas deposits
- 2. Natural regimes of oil and gas deposits, geological factors of their formation and manifestation.
- 3. Saturation pressure and its influence on the operation mode of deposits.
- 4. Brief description of water pressure, elastic water pressure, gas pressure (gas cap regime), dissolved gas and gravitational regimes.
- 5. Characteristics of the natural regimes of gas and gas condensate deposits.
- 6. Determination of operating modes of deposits in the process of pilot operation.
Brief summary of theoretical issues.
Reservoir energy in oil and gas deposits can be as follows: marginal water pressure; elastic forces of oil, gas and water; expansion of gas dissolved in oil; compressed gas pressure; gravity. The manifestation of reservoir energy is determined by the nature of the underground reservoir, the type of reservoir and the shape of the deposit; reservoir properties of the formation inside and outside the reservoir, the composition and ratio of fluids in the reservoir, remoteness from the formation water supply area and development conditions.
The reservoir regime is the nature of the manifestation of reservoir energy that moves oil and gas along the reservoir to the well bottoms and depends on natural conditions and measures to influence the reservoir.
Depending on the source of reservoir energy, which ensures the movement of oil from the reservoir to the well, there are the following modes of oil deposits: water-driven, elastic-water-driven modes; dissolved gas regime; gas pressure and gravity modes. With the simultaneous manifestation of several types of energy, it is customary to speak of a mixed or combined mode.
In the development of gas fields, water-pressure, gas, mixed modes are also used. Water pressure is extremely rare.
The technology of opening productive horizons causes an increase in well productivity, improves the flow of oil and gas from low-permeable interlayers, which ultimately contributes to an increase in oil recovery.
Reservoir opening methods depending on the reservoir pressure and the degree of saturation of the reservoir with oil, the degree of drainage, the position of the gas-oil contact and the depth of the reservoir and other factors.
The design of well bottoms is chosen taking into account the lithological and physical properties and the location of wells in the reservoir, therefore, well bottoms can be open or cased holes.
Questions for self-control
Origin of oil
There are 4 stages in the development of views on the origin of oil:
1) pre-scientific period;
2) a period of scientific conjecture;
3) formation period scientific hypotheses;
4) modern period.
Bright pre-scientific ideas are the views of the Polish naturalist of the XVIII century. Canon K. Klyuk. He believed that oil was formed in paradise, and is the remnant of the fertile soil on which the Gardens of Eden bloomed.
An example of the views of the period of scientific conjectures is the idea expressed by M.V. Lomonosov that oil was formed from coal under the influence of high temperatures.
With the beginning of the development of the oil industry, the question of the origin of oil has become of great practical importance. This gave a powerful impetus to the emergence of various scientific hypotheses.
Among the numerous hypotheses of the origin of oil, the most important are: organic and inorganic.
First hypothesis organic origin expressed in 1759 by the great Russian scientist M.V. Lomonosov. Subsequently, the hypothesis was developed by Academician I.M. Gubkin. The scientist believed that the organic matter of sea silts, consisting of plant and animal organisms, is the starting material for the formation of oil. The old layers are quickly overlapped by younger ones, which protects the organic matter from oxidation. The initial decomposition of plant and animal residues occurs without access to oxygen under the action of anaerobic bacteria. Further, the layer formed on the seabed sinks as a result of the general bowing of the earth's crust, which is characteristic of marine basins. As sedimentary rocks sink, their pressure and temperature increase. This results in the conversion of dispersed organic matter into diffusely dispersed oil. The most favorable pressures for oil formation are 15…45 MPa and temperatures 60…150°С, which exist at depths of 1.5…6 km. Further, under the influence of increasing pressure, oil is displaced into permeable rocks, along which it migrates to the place of formation of deposits.
Author inorganic hypothesis considered D.I.Mendeleev. He noticed an amazing pattern: the oil fields of Pennsylvania (US state) and the Caucasus, as a rule, are located near large faults in the earth's crust. Knowing that the average density of the Earth exceeds the density of the earth's crust, he concluded that metals are mainly found in the bowels of our planet. In his opinion, it must be iron. During mountain-building processes, water penetrates deep into the earth's crust along cracks-faults that cut through the earth's crust. Encountering iron carbides on its way, it reacts with them, as a result of which iron oxides and hydrocarbons are formed. Then the latter rise along the same faults into the upper layers of the earth's crust and form oil fields.
In addition to these two hypotheses, it is worth noting "space" hypothesis. It was put forward in 1892 by the professor of the Moscow State University V.D. Sokolov. In his opinion, hydrocarbons were originally present in the gas and dust cloud from which the Earth was formed. Subsequently, they began to stand out from the magma and rise in a gaseous state through cracks in the upper layers of the earth's crust, where they condensed, forming oil deposits.
The hypotheses of the modern period include " magmatic" hypothesis Leningrad oil geologist, professor N.A. Kudryavtsev. In his opinion, at great depths at very high temperatures, carbon and hydrogen form carbon radicals CH, CH 2 and CH 3 . Then, along deep faults, they rise up, closer to earth's surface. Due to a decrease in temperature, in the upper layers of the Earth, these radicals combine with each other and with hydrogen, resulting in the formation of various petroleum hydrocarbons.
N. A. Kudryavtsev and his supporters believe that the breakthrough of petroleum hydrocarbons closer to the surface occurs along faults in the mantle and the earth's crust. The reality of the existence of such channels is proved by the wide distribution of classical and mud channels on Earth, as well as kimberlite pipes explosion. Traces of vertical migration of hydrocarbons from the crystalline basement into the layers of sedimentary rocks were found in all wells drilled to great depths - on the Kola Peninsula, in the Volga-Ural oil province, in Central Sweden, in the state of Illinois (USA). Usually these are inclusions and veinlets of bitumen filling cracks in igneous rocks; liquid oil was also found in two wells.
Until recently, the generally accepted hypothesis organic oil(this was facilitated by the fact that most of the discovered oil fields are confined to sedimentary rocks), according to which " black gold» lies at a depth of 1.5...6 km. There are almost no white spots in the bowels of the Earth at these depths. Therefore, the theory of organic origin does not offer practically any prospects for the exploration of new large oil fields.
There are, of course, the facts of the discovery of large oil fields not in sedimentary rocks (for example, a giant field " white tiger”, discovered on the shelf of Vietnam, where oil occurs in granites), this fact is explained by hypothesis of inorganic origin of oil. In addition, in the bowels of our planet there is a sufficient amount of source material for the formation of hydrocarbons. The sources of carbon and hydrogen are water and carbon dioxide. Their content in 1 m 3 of the substance of the Earth's upper mantle is 180 and 15 kg, respectively. A favorable chemical environment for the reaction is provided by the presence of ferrous compounds of metals, the content of which in volcanic rocks reaches 20%. Oil formation will continue as long as there is water, carbon dioxide and reducing agents (mainly ferrous oxide) in the bowels of the Earth. In addition, the practice of developing the Romashkinskoye field (on the territory of Tatarstan) works on the hypothesis of the inorganic origin of oil. It was discovered 60 years ago and was considered to be 80% depleted. According to the state adviser to the President of Tatarstan R. Muslimov, every year oil reserves at the field are replenished by 1.5-2 million tons and, according to new calculations, oil can be produced up to 2200g . Thus, the theory of the inorganic origin of oil not only explains the facts that baffle the “organics”, but also gives us hope that the oil reserves on Earth are much larger than those explored today, and most importantly, they continue to replenish.
In general, we can conclude that the two main theories of the origin of oil quite convincingly explain this process, mutually complementing each other. And the truth lies somewhere in the middle.
Origin of gas
Methane is widely distributed in nature. It is always included in the reservoir oil. A lot of methane is dissolved in formation waters at a depth of 1.5...5 km. Gaseous methane forms deposits in porous and fractured sedimentary rocks. In small concentrations, it is present in the waters of rivers, lakes and oceans, in the soil air and even in the atmosphere. The main mass of methane is dispersed in sedimentary and igneous rocks. Recall also that the presence of methane is recorded on a number of planets of the solar system and in deep space.
The wide distribution of methane in nature suggests that it was formed in various ways.
Today, several processes leading to the formation of methane are known:
Biochemical;
Thermal catalytic;
Radiation-chemical;
Mechanochemical;
metamorphic;
Cosmogenic.
biochemical process methane formation occurs in silts, soil, sedimentary rocks and hydrosphere. More than a dozen bacteria are known, as a result of which methane is formed from organic compounds (proteins, cellulose, fatty acids). Even oil at great depths, under the action of bacteria contained in formation water, is destroyed to methane, nitrogen and carbon dioxide.
Thermal catalytic process the formation of methane is to transform into a gas organic matter sedimentary rocks under the influence of elevated temperature and pressure in the presence of clay minerals that play the role of a catalyst. This process is similar to the formation of oil. Initially, organic matter that accumulates at the bottom of water bodies and on land undergoes biochemical decomposition. Bacteria at the same time destroy the simplest compounds. As organic matter sinks deeper into the Earth and the temperature rises accordingly, the activity of bacteria fades and completely stops at a temperature of 100°C. However, another mechanism has already turned on - the destruction of complex organic compounds (remains of living matter) into simpler hydrocarbons and, in particular, into methane, under the influence of increasing temperature and pressure. Important role natural catalysts play in this process - aluminosilicates, which are part of various, especially clay rocks, as well as trace elements and their compounds.
What is the difference between the formation of methane and the formation of oil in this case?
Firstly, oil is formed from organic matter of the sapropel type - sediments of the seas and the ocean shelf, formed from phyto- and zooplankton enriched with fatty substances. The source for the formation of methane is organic matter of the humus type, consisting of the remains of plant organisms. This substance during thermal catalysis forms mainly methane.
Secondly, the main zone of oil formation corresponds to the temperatures of rocks from 60 to 150°C, which occur at a depth of 1.5...6 km. In the main zone of oil formation, along with oil, methane is also formed (in relatively small quantities), as well as its heavier homologues. A powerful zone of intense gas formation corresponds to temperatures of 150...200°C and more, it is located below the main zone of oil formation. In the main zone of gas formation in hard temperature conditions there is a deep thermal destruction of not only dispersed organic matter, but also hydrocarbons of combustible shale and oil. This produces a large amount of methane.
Radiation chemical process methane formation occurs when exposed to radioactive radiation on various carbonaceous compounds.
It has been noted that black finely dispersed clayey sediments with a high concentration of organic matter are, as a rule, also enriched in uranium. This is due to the fact that the accumulation of organic matter in sediments favors the precipitation of uranium salts. Under the influence of radioactive radiation, organic matter decomposes with the formation of methane, hydrogen and carbon monoxide. The latter itself decomposes into carbon and oxygen, after which carbon combines with hydrogen, also forming methane.
Mechanochemical process methane formation is the formation of hydrocarbons from organic matter (coals) under the influence of constant and variable mechanical loads. In this case, at the contacts of grains of mineral rocks, high voltages, whose energy is involved in the transformation of organic matter.
Metamorphic process The formation of methane is associated with the conversion of coal under the influence of high temperatures into carbon. This process is part of the general process of transformation of substances at temperatures above 500 °C. Under such conditions, clays turn into crystalline schists and granite, limestone into marble, etc.
Cosmogenic process the formation of methane is described by the "cosmic" hypothesis of oil formation by V. D. Sokolov.
What is the place of each of these processes in the general process of methane formation? It is believed that the bulk of methane in most gas fields in the world is of thermal catalytic origin. It is formed at a depth of 1 to 10 km. A large proportion of methane is of biochemical origin. Its main quantity is formed at depths up to 1...2 km.
The internal structure of the Earth
To date, general ideas about the structure of the Earth have been formed, since the most deep wells on Earth, only the earth's crust was opened. More details about ultra-deep drilling will be discussed in the section on well drilling.
In the solid body of the Earth, three shells are distinguished: the central one - the core, the intermediate one - the mantle and the outer one - the earth's crust. The distribution of internal geospheres by depth is presented in Table 16.
Table 16 Internal geospheres of the Earth
Currently, there are various ideas about the internal structure and composition of the Earth (V.Goldshmidt, G.Washington, A.E. Fersman, etc.). The Gutenberg-Bullen model is recognized as the most perfect model of the structure of the Earth.
Core – it is the most dense shell of the Earth. According to modern data, a distinction is made between the inner core (which is considered to be in a solid state) and the outer core (which is considered to be in a liquid state). It is believed that the core mainly consists of iron with an admixture of oxygen, sulfur, carbon and hydrogen, and the inner core has an iron-nickel composition, which fully corresponds to the composition of a number of meteorites.
Next is mantle. The mantle is divided into upper and lower. It is believed that the upper mantle consists of magnesian-ferruginous silicate minerals such as olivine and pyroxene. The lower mantle is characterized by a homogeneous composition and consists of a substance rich in iron and magnesium oxides. At present, the mantle is estimated as a source of seismic and volcanic phenomena, mountain-building processes, as well as a zone of magmatism realization.
Above the mantle is Earth's crust. The boundary between the earth's crust and mantle is established by a sharp change in seismic wave velocities, it is called the Mohorovich section, in honor of the Yugoslav scientist A. Mohorovich, who first established it. The thickness of the earth's crust changes dramatically on the continents and in the oceans and is divided into two main parts - continental and oceanic and two intermediate - subcontinental and suboceanic.
This nature of the planetary relief is associated with the different structure and composition of the earth's crust. Under the continents, the thickness of the lithosphere reaches 70 km (average 35 km), and under the oceans 10-15 km (average 5-10 km).
The continental crust consists of three layers of sedimentary, granite-gneiss and basalt. The oceanic crust has a two-layer structure: under a thin loose sedimentary layer there is a basalt layer, which in turn is replaced by a layer composed of gabbro with subordinate ultrabasic rocks.
The subcontinental crust is confined to island arcs and is thicker. The suboceanic crust is located under large ocean trenches, in the inland and marginal seas (Okhotsk, Japanese, Mediterranean, Black, etc.) and, unlike the oceanic, it has a significant thickness of the sedimentary layer.
The structure of the earth's crust
The earth's crust is the most studied of all the shells. It is made up of rocks. Rocks are mineral compounds of constant mineralogical and chemical composition, forming independent geological bodies that make up the earth's crust. Rocks are divided into three groups according to their origin: igneous, sedimentary and metamorphic.
Igneous rocks formed as a result of solidification and crystallization of magma on the surface of the Earth in the depths of the earth's surface or in its bowels. These rocks are mostly crystalline. They contain no animal or plant remains. Typical representatives of igneous rocks are basalts and granites.
Sedimentary rocks formed as a result of sedimentation of organic and inorganic substances on the bottom water basins and continental surfaces. They are divided into clastic rocks, as well as rocks of chemical, organic and mixed origin.
clastic rocks formed as a result of the deposition of small pieces of destroyed rocks. Typical representatives: boulders, pebbles, gravel, sands, sandstones, clays.
breeds chemical origin formed as a result of precipitation of salts from aqueous solutions or as a result of chemical reactions in the earth's crust. Such rocks are gypsum, rock salt, brown iron ore, siliceous tuffs.
Breeds of organic origin are the fossilized remains of animals and plants. These include limestone, chalk.
Breeds of mixed origin composed of materials of detrital, chemical, organic origin. Representatives of these rocks are marls, clayey and sandy limestones.
metamorphic rocks formed from igneous and sedimentary rocks under the influence of high temperatures and pressures in the thickness of the earth's crust. These include shale, marble, jasper.
The bedrocks of Udmurtia come out from under soils and Quaternary deposits along the banks of rivers and streams, in ravines, as well as in various workings: quarries, pits, etc. Terrigenous rocks absolutely predominate. These include such varieties as siltstones, sandstones and much less - conglomerates, gravelstones, clays. Rare carbonate rocks include limestones and marls. All these rocks, like any others, consist of minerals, i.e. natural chemical compounds. So, limestones consist of calcite - a compound of CaCO 3 composition. Grains of calcite in limestones are very small and are distinguishable only under a microscope.
Marls and clays, in addition to calcite, contain a large amount of microscopically small clay minerals. For this reason, after exposure to marl with hydrochloric acid, clarified or darker spots form at the reaction site - the result of the concentration of clay particles. In limestones and marls, nests and veins of crystalline calcite are sometimes found. Sometimes you can also see druses of calcite - intergrowths of crystals of this mineral, grown at one end to the rock.
Terrigenous rocks are divided into detrital and clayey. Most of The bedrock surface of the republic is composed of clastic rocks. These include the already mentioned siltstones, sandstones, as well as rarer gravelstones and conglomerates.
Siltstones consist of detrital grains of minerals such as quartz (SiO 2), feldspars (KAlSi 3 O 8; NaAlSi 3 O 8 ∙CaAl 2 Si 2 O 8), other silty particles with a diameter of not more than 0.05 mm. As a rule, siltstones are weakly cemented, lumpy and appearance reminiscent of clay. They differ from clays in greater petrification and less plasticity.
Sandstones are the second most common bedrock in Udmurtia. They consist of detrital particles (grains of sand) of various composition - grains of quartz, feldspars, fragments of siliceous and effusive (basalt) rocks, as a result of which these sandstones are called polymictic or polymineral. The size of sand particles ranges from 0.05 mm to 1 - 2 mm. As a rule, sandstones are weakly cemented, easily loosened, and therefore are used for construction purposes like ordinary (modern river) sands. Loose sandstones often contain interbeds, lenses, and concretions of calcareous sandstones, the detrital material of which is cemented by calcite. Unlike siltstones, sandstones are characterized by both horizontal and oblique bedding. Sandstones occasionally contain small calcareous shells of freshwater bivalves. All taken together (oblique bedding, rare fossil mollusks) testify to the fluvial, or alluvial, origin of polymictic sandstones. The cementation of sandstones with calcite is associated with the decomposition of calcium bicarbonate in groundwater circulating through the pores of the sands. In this case, calcite was isolated as an insoluble reaction product as a result of carbon dioxide volatilization.
Less commonly, terrigenous rocks are represented by gravelstones and conglomerates. These are strong rocks, consisting of rounded (round, oval) or smoothed fragments of brown marls cemented with calcite. Mergeli - local origin. As an admixture in the clastic material, there are dark cherts and effusives (ancient basalts) introduced Permian rivers from the Urals. The size of gravelstone fragments ranges from 1 (2) mm to 10 mm, respectively, in conglomerates from 10 mm to 100 mm and more.
Basically, oil deposits are confined to sedimentary rocks, although there are oil deposits confined to either metamorphic (Morocco, Venezuela, USA) or igneous rocks (Vietnam, Kazakhstan).
13. Reservoirs. Porosity and permeability.
Collector a rock is called a rock that has such geological and physical properties that provide the physical mobility of oil or gas in its void space. The reservoir rock can be saturated with both oil or gas, and water.
Rocks with such geological and physical properties, in which the movement of oil or gas in them is physically impossible, are called non-collectors.
FEDERAL BUDGET STATE EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION
"KUBAN STATE TECHNOLOGICAL UNIVERSITY"
Faculty of full-time education of the Institute of Oil and Gasand energy.
Department of Oil and Gas Field
LECTURE NOTES
By discipline:
« Geology of oil and gas»
for students of all forms of education specialties:
130501 Design, construction and operation of oil and gas pipelines and oil and gas storage facilities;
130503 Development and operation
130504 Drilling of oil and gas wells.
bachelors in the direction 131000 "Oil and gas business"
Compiled by: Senior Lecturer
Shostak A.V.
KRASNODAR 2012
LECTURE 3-
FEATURES OF ACCUMULATION AND TRANSFORMATION OF ORGANIC COMPOUNDS DURING LITHOGENESIS………………………………….19
LECTURE 4 -
COMPOSITION AND PHYSICO-CHEMICAL PROPERTIES OF OIL AND GAS….2
5
LECTURE 5 -
CHANGES IN THE COMPOSITION AND PHYSICO-CHEMICAL PROPERTIES OF OIL AND GAS DEPENDING ON THE INFLUENCE OF DIFFERENT NATURAL FACTORS……………………………………………………………………….. 4
5
LECTURE 6 -
PROBLEMS OF THE ORIGIN OF OIL AND GAS……………………….56
LECTURE 7 -
MIGRATION OF HYDROCARBONS…………………………………………………62
LECTURE 8 -
FORMATION OF DEPOSITS……………………………………………………75
LECTURE 9 -
ZONING OF OIL FORMATION PROCESSES………………….81
LECTURE #10
LECTURE 11 - OIL AND GAS FIELDS AND THEIR MAIN CLASSIFICATION FEATURES………………………………………………………….108
BIBLIOGRAPHY……………………………………………………………………….112
LECTURE 1
INTRODUCTION
Among the most important types of industrial products, one of the main places is occupied by oil, gas and products of their processing.
Until the beginning of the XVIII century. oil was mainly extracted from diggers, which were planted with wattle. As oil accumulated, it was scooped out and exported to consumers in leather bags.
The wells were fastened with a wooden frame, the final diameter of the cased well was usually from 0.6 to 0.9 m with some increase downwards to improve the flow of oil to its bottomhole.
The rise of oil from the well was carried out with the help of a manual gate (later a horse drive) and a rope, to which a wineskin (leather bucket) was tied.
By the 70s of the XIX century. the main part of oil in Russia and in the world is extracted from oil wells. So, in 1878 there were 301 of them in Baku, the debit of which is many times greater than the debit from wells. Oil was extracted from wells with a bailer - a metal vessel (pipe) up to 6 m high, in the bottom of which a check valve is mounted, which opens when the bailer is immersed in liquid and closes when it moves up. The hoisting of the bailer (bagging) was carried out manually, then horse-drawn (early 70s of the 19th century) and using a steam engine (80s).
The first deep-well pumps were used in Baku in 1876, and the first deep-well pump in Grozny in 1895. However, the tethering method remained the main one for a long time. For example, in 1913 in Russia 95% of oil was produced by gelation.
Geology of oil and gas- a branch of geology that studies the conditions for the formation, placement and migration of oil and gas in the lithosphere. The formation of oil and gas geology as a science took place at the beginning of the 20th century. Its founder is Gubkin Ivan Mikhailovich.
1.1. Short story development of oil and gas production
Modern methods of extracting oil were preceded by primitive methods:
collection of oil from the surface of reservoirs;
processing sandstone or limestone impregnated with oil;
extraction of oil from pits and wells.
Processing of sandstone or limestone impregnated with oil, with the aim of extracting it, were first described by the Italian scientist F. Ariosto in the 15th century: near Modena in Italy, oil-containing soils were crushed and heated in boilers; then they were placed in bags and pressed with a press. In 1819, in France, oil-bearing limestone and sandstone layers were developed by the mine method. The mined rock was placed in a vat filled with hot water. With stirring, oil floated to the surface of the water, which was collected with a scoop. In 1833-1845. oil-soaked sand was mined on the shores of the Sea of Azov. Then it was placed in pits with a sloping bottom and poured with water. The oil washed out of the sand was collected from the surface of the water with bunches of grass.
Extraction of oil from pits and wells also known from ancient times. In Kissia - an ancient region between Assyria and Media in the 5th century. BC. oil was extracted using leather buckets of wineskins.
In Ukraine, the first mention of oil production dates back to the beginning of the 15th century. To do this, they dug digging holes 1.5-2 m deep, where oil leaked along with water. Then the mixture was collected in barrels, closed from the bottom with stoppers. When the lighter oil floated, the plugs were removed and the settled water was drained. By 1840, the depth of the digging holes reached 6 m, and later oil was extracted from wells with a depth of about 30 m.
Since ancient times, on the Kerch and Taman peninsulas, oil has been extracted using a pole, to which a felt or a bundle made from the hair of a horse's tail was tied. They were lowered into the well, and then the oil was squeezed into prepared dishes.
On the Absheron Peninsula, oil extraction from wells has been known since the 13th century. AD During their construction, a hole was first torn off like an inverted (inverted) cone to the very oil reservoir. Then ledges were made on the sides of the pit: with an average cone immersion depth of 9.5 m, at least seven. The average amount of earth taken out when digging such a well was about 3100 m 3, then the walls of the wells from the very bottom to the surface were fastened with a wooden frame or boards. Holes were made in the lower crowns for the flow of oil. It was scooped from wells with wineskins, which were lifted with a manual collar or with the help of a horse.
In his report on a trip to the Apsheron Peninsula in 1735, Dr. I. Lerkhe wrote: “... In Balakhani there were 52 oil wells 20 fathoms deep (1 fathom - 2.1m), 500 batmans of oil...” (1 batman 8.5 kg). According to Academician S.G. Amelina (1771), the depth of oil wells in Balakhany reached 40-50 m, and the diameter or side of the square of the well section was 0.7-1 m.
In 1803, the Baku merchant Kasymbek built two oil wells in the sea at a distance of 18 and 30 m from the shore of Bibi-Heybat. The wells were protected from water by a box of tightly knocked together boards. Oil has been extracted from them for many years. In 1825, during a storm, the wells were broken and flooded with the waters of the Caspian Sea.
With the well method, the technique of oil extraction has not changed over the centuries. But already in 1835, an official of the mining department, Fallendorf on Taman, first used a pump to pump oil through a lowered wooden pipe. A number of technical improvements are associated with the name of the mining engineer N.I. Voskoboinikov. To reduce the amount of excavation, he proposed to build oil wells in the form of a shaft, and in 1836-1837. carried out the reconstruction of the entire system of storage and distribution of oil in Baku and Balakhani. But one of the main deeds of his life was the drilling of the world's first oil well in 1848.
For a long time, oil production through drilling in our country was treated with prejudice. It was believed that since the well cross-section is smaller than that of an oil well, then the oil inflow to the wells is significantly less. At the same time, it was not taken into account that the depth of the wells is much greater, and the complexity of their construction is less.
During the operation of wells, oil producers sought to transfer them to the flowing mode, because. it was the most easy way mining. The first powerful oil gusher in Balakhany struck in 1873 at the Khalafi site. In 1887, 42% of the oil in Baku was produced by the fountain method.
Forced extraction of oil from wells led to the rapid depletion of the oil-bearing layers adjacent to their wellbore, and the rest (most) of it remained in the bowels. In addition, due to the lack of a sufficient number of storage facilities, significant oil losses occurred already on the surface of the earth. So, in 1887, 1088 thousand tons of oil were thrown out by fountains, and only 608 thousand tons were collected. Extensive oil lakes formed on the areas around the fountains, where the most valuable fractions were lost as a result of evaporation. The weathered oil itself became unsuitable for processing, and it was burned out. Stagnant oil lakes burned for many days in a row.
Oil production from wells, the pressure in which was insufficient for flowing, was carried out using cylindrical buckets up to 6 m long. A valve was arranged in their bottom, which opens when the bucket moves down and closes under the weight of the extracted fluid when the bucket pressure goes up. The method of extracting oil by means of bailers was called tartan,in In 1913, 95% of all oil was produced with its help.
However, engineering thought did not stand still. In the 70s of the 19th century. V.G. Shukhov suggested compressor method of oil extraction by supplying compressed air to the well (airlift). This technology was tested in Baku only in 1897. Another method of oil production, gas lift, was proposed by M.M. Tikhvinsky in 1914
Natural gas outlets from natural sources have been used by man since time immemorial. Later found the use of natural gas obtained from wells and wells. In 1902, the first well was drilled in Surakhani near Baku, which produced industrial gas from a depth of 207 m.
In the development of the oil industry There are five main stages:
Stage I (until 1917) - pre-revolutionary period;
Stage II (from 1917 to 1941) the period before the Great Patriotic War;
Stage III (from 1941 to 1945) - the period of the Great Patriotic War;
Stage IV (from 1945 to 1991) - the period before the collapse of the USSR;
Stage V (since 1991) - the modern period.
pre-revolutionary period. Oil has been known in Russia for a long time. Back in the 16th century. Russian merchants traded Baku oil. Under Boris Godunov (XVI century), the first oil produced on the Ukhta River was delivered to Moscow. Since the word "oil" entered the Russian language only at the end of the 18th century, it was then called "thick burning water."
In 1813, the Baku and Derbent khanates with their richest oil resources were annexed to Russia. This event had a great influence on the development of the Russian oil industry in the next 150 years.
Another major oil-producing region in pre-revolutionary Russia was Turkmenistan. It has been established that black gold was mined in the Nebit-Dag region already about 800 years ago. In 1765 on about. Cheleken, there were 20 oil wells with a total annual production of about 64 tons per year. According to the Russian explorer of the Caspian Sea N. Muravyov, in 1821 the Turkmens sent about 640 tons of oil to Persia by boat. In 1835, she was taken from about. There are more Cheleken than from Baku, although it was the Absheron Peninsula that was the object of increased attention of the oil owners.
The beginning of the development of the oil industry in Russia is 1848,
In 1957, the Russian Federation accounted for more than 70% of the oil produced, and Tataria came out on top in the country in terms of oil production.
main event given period was the discovery and the beginning of the development of the richest oil fields in Western Siberia. Back in 1932, Academician I.M. Gubkin expressed the idea of the need to start a systematic search for oil on the eastern slope of the Urals. First, information was collected on observations of natural oil seeps (the rivers Bolshoi Yugan, Belaya, etc.). In 1935 Geological exploration parties began to work here, which confirmed the presence of outcrops of oil-like substances. However, there was no "big oil". Exploration work continued until 1943, and then was resumed in 1948. Only in 1960 was the Shaimskoye oil field discovered, followed by the Megionskoye, Ust-Balykskoye, Surgutskoye, Samotlorskoye, Varyeganskoye, Lyantorskoye, Kholmogorskoye and others. the beginning industrial production oil in Western Siberia is considered to be 1965, when it was produced about 1 million tons. Already in 1970, oil production here amounted to 28 million tons, and in 1981 329.2 million tons. Western Siberia became the main oil-producing region of the country, and the USSR came out on top in the world in oil production.
In 1961, the first oil fountains were obtained at the Uzen and Zhetybay fields in Western Kazakhstan (the Mangyshlak Peninsula). Their industrial development began in 1965. The recoverable oil reserves from these two fields alone amounted to several hundred million tons. The problem was that Mangyshlak oils were highly paraffinic and had a pour point of +30...33 °C. Nevertheless, in 1970, oil production on the peninsula was increased to several million tons.
The systematic growth of oil production in the country continued until 1984. In 1984-85. there was a drop in oil production. In 1986-87. it rose again, reaching a maximum. However, starting from 1989, oil production began to fall.
modern period. After the collapse of the USSR, the decline in oil production in Russia continued. In 1992 it amounted to 399 million tons, in 1993 354 million tons, in 1994 317 million tons, in 1995 307 million tons.
The continued decline in oil production is due to the fact that the influence of a number of objective and subjective negative factors has not been eliminated.
First, worsened raw material base industries. The degree of involvement in the development and depletion of deposits in the regions is very high. In the North Caucasus, 91.0% of the explored oil reserves are involved in the development, and the depletion of the fields is 81.5%. In the Ural-Volga region, these figures are 88.0% and 69.1%, respectively, in the Komi Republic 69.0% and 48.6%, in Western Siberia 76.8% and 33.6%.
Secondly, the increase in oil reserves decreased due to newly discovered fields. Due to a sharp decrease in funding, exploration organizations have reduced the scope of geophysical work and exploration drilling. This led to a decrease in the number of newly discovered deposits. So, if in 1986-90. oil reserves in newly discovered fields amounted to 10.8 million tons, then in 1991-95. only 3.8 million tons
Thirdly, the water cut of the produced oil is high.. This means that with the same costs and production volumes of the reservoir fluid, the oil itself is produced less and less.
Fourth, the costs of restructuring. As a result of the breakdown of the old economic mechanism, the strict centralized management of the industry was eliminated, and a new one is still being created. The resulting imbalance in prices for oil, on the one hand, and for equipment and materials, on the other, made it difficult to equip the fields. But this is necessary right now, when most of the equipment has worked out its life, and many fields require a transition from the flowing method of production to pumping.
Finally, there are numerous miscalculations made in past years. Thus, in the 1970s, it was believed that the oil reserves in our country were inexhaustible. In accordance with this, the emphasis was not on the development of their own species industrial production, and for the purchase of finished industrial goods abroad for the currency received from the sale of oil. Enormous funds were spent on maintaining the appearance of prosperity in Soviet society. The oil industry was financed to a minimum.
On the Sakhalin shelf back in the 70-80s. were opened large deposits which have not yet been put into operation. Meanwhile, they are guaranteed a huge sales market in the countries of the Asia-Pacific region.
What are the future prospects for the development of the domestic oil industry?
There is no unambiguous assessment of oil reserves in Russia. Various experts give figures for the volume of recoverable reserves from 7 to 27 billion tons, which is from 5 to 20% of the world. The distribution of oil reserves across Russia is as follows: Western Siberia 72.2%; Ural-Volga region 15.2%; Timan-Pechora province 7.2%; The Republic of Sakha (Yakutia), Krasnoyarsk region, Irkutsk region, shelf of the Sea of Okhotsk about 3.5%.
In 1992, the restructuring of the Russian oil industry began: following the example Western countries began to create vertically integrated oil companies that control the extraction and processing of oil, as well as the distribution of oil products obtained from it.
1.2. Goals and objectives of oil and gas field geology
For a long time, natural oil and gas outlets fully satisfied the needs of mankind. However, development economic activity man demanded more and more sources of energy. In an effort to increase the amount of oil consumed, people began to dig wells in places of surface oil manifestations, and then drill wells. First, they were laid where oil came to the surface of the earth. But the number of such places is limited. At the end of the last century, a new promising search method was developed. Drilling began to be carried out on a straight line connecting two wells already producing oil.
In new areas, the search for oil and gas deposits was carried out almost blindly, shying from side to side. Curious memories of laying the well were left by the English geologist K. Craig.
Drilling managers and field managers came together to select a location and jointly determined the area within which the well should be laid. However, with the usual caution in such cases, no one dared to indicate the point where drilling should begin. Then one of those present, who was distinguished by great courage, said, pointing to a crow circling above them: “Gentlemen, if you don’t care, let’s start drilling where the crow sits ...”. The offer was accepted. The well turned out to be extremely successful. But if the crow had flown a hundred yards further to the east, there would have been no hope of meeting oil ... It is clear that this could not go on for long, because drilling each well costs hundreds of thousands of dollars. Therefore, the question arose of where to drill wells in order to accurately find oil and gas.
This required an explanation of the origin of oil and gas, gave a powerful impetus to the development of geology - the science of the composition and structure of the Earth, as well as methods for prospecting and exploration of oil and gas fields.
Oil and gas field geology is a branch of geology that deals with a detailed study of oil and gas fields and deposits in their initial (natural) state and in the process of development in order to determine their national economic significance and rational use of the subsoil. From this definition it can be seen that oil and gas field geology approaches the study of deposits and deposits of hydrocarbons (HC) from two points of view.
First of all, hydrocarbon deposits should be considered in a static state as natural geological objects for development design based on the calculation of reserves and the assessment of the productivity of wells and reservoirs /natural geological conditions/.
Secondly, hydrocarbon deposits should be considered in a dynamic state, since in them, when put into operation, the processes of movement of oil, gas and water to the bottomholes of production wells and from the bottomholes of injection wells begin. At the same time, it is obvious that the features of the object dynamics are characterized not only by the natural geological properties of the deposit (ie properties in a static state), but also by the characteristics of the technical system (ie the development system). In other words, an oil or gas deposit put into development is an inseparable whole, already consisting of two components: geological (the deposit itself) and technical (technical system designed for the exploitation of the deposit). We will call this whole a geological and technical complex (GTC).
Feature of oil and gas field geology, consisting therein, what she wide uses theoretical concepts and factual data obtained by methods of other sciences, and in its conclusions and generalizations very often relies on patterns established in other sciences.
Goals oil and gas geology are in the geological substantiation of the most effective ways of organizing oil and gas production, ensuring the rational use and protection of subsoil and the environment. This main goal is achieved by studying the internal structure of the oil and gas deposit and the patterns of its change in the development process.
The main goal is broken down into a number of components, acting as private goals of oil and gas field geology, which include:
field geological modeling of deposits
reserve calculation oil, gas and condensate;
geological substantiation of the development system oil and gas fields;
geological substantiation of measures to improve the efficiency of development and oil, gas or condensate recovery;
substantiation of the complex of observations in the exploration and development process.
subsoil protection oil and gas fields;
geological service of the drilling process wells;
improvement of own methodology and methodological base.
Among this set can be distinguished three types of tasks:
specific scientific tasks oil and gas geology, aimed at the object of knowledge;
methodical tasks;
methodological tasks.
1. Study of the composition and properties of rocks composing productive deposits, both containing and not containing oil and gas; study of the composition and properties of oil, gas and water, geological and thermodynamic conditions of their occurrence. Particular attention should be paid to the variability of the composition, properties and conditions of occurrence of rocks and fluids saturating them, as well as to the laws that this variability is subject to.
2. Selection tasks(based on the solution of problems of the first group) of natural geological bodies, determining their shape, size, position in space, etc. In this case, layers, layers, horizons, reservoir replacement zones, etc. are distinguished. In general, this group combines tasks aimed at identifying the primary structure of a deposit or deposit.
3. Dismemberment tasks natural geological bodies into conditional ones, taking into account the requirements and capabilities of the equipment, technology and economics of the oil and gas industry. The most important here will be the tasks of establishing the conditions and other boundary values of natural geological bodies (for example, for separating high-, medium-, and low-productive rocks).
4. Tasks related to the construction of the classification of the State Customs Committee according to a variety of features, and primarily by the types of internal structures of deposits and deposits.
5. Tasks related to the study of the nature, features, patterns of the relationship between the structure and function of the SCC, i.e. the influence of the structure and properties of the reservoir on the indicators of the development process and the characteristics of the structure and parameters of the technical component, as well as on the performance indicators of the GTC as a whole (stability of oil and gas extraction, development rates, production cost, ultimate oil recovery, etc.).
Methodical tasks development of methodological equipment for oil and gas field geology, i.e. improvement of old and creation of new methods for solving concrete-scientific field-geological problems.
The need for a solution methodological tasks arises due to the fact that from epoch to epoch, from period to period, the norms of knowledge, methods of organizing knowledge, methods of scientific work. In our time, the development of science is extremely fast. In such conditions, in order to keep up with the general pace of development of science, it is necessary to have an idea of what science is based on, how scientific knowledge is built and rebuilt. Getting answers to these questions is the essence of the methodology . Methodology is a way of understanding the structure of science and the methods of its work. Distinguish between the methodology of general scientific and private scientific.
LECTURE 2
NATURAL FUEL RESOURCES
Oil is a combustible, oily liquid, with a specific odor, consisting of a mixture of hydrocarbons, containing no more than 35% of asphaltene-resin substances and located in reservoir rocks in a free state. Oil contains 8287% carbon, 1114% hydrogen (by weight), oxygen, nitrogen, carbon dioxide, sulfur, and small amounts of chlorine, iodine, phosphorus, arsenic, etc.
Hydrocarbons isolated from various oils belong to three main series: methane, naphthenic and aromatic:
methane (paraffin) with the general formula C n H 2 n +2;
naphthenic - C n H 2 n;
aromatic - C n H 2 n -6.
Hydrocarbons of the methane series predominate (methane CH 4, ethane C 2 H 6, propane C 3 H 8 and butane C 4 H 10), which are at atmospheric pressure and normal temperature in a gaseous state.
Pentane C 5 H 12, hexane C 6 H 14 and heptane C 7 H 16 are unstable, they easily pass from a gaseous state to a liquid and vice versa. Hydrocarbons from C 8 H 18 to C 17 H 36 are liquid substances.
Hydrocarbons containing more than 17 carbon atoms (C 17 H 36 -C 37 H 72) are solids (paraffins, resins, asphaltenes).
Oil classification
Depending on the content of light, heavy and solid hydrocarbons, as well as various impurities, oil is divided into classes and subclasses. This takes into account the content of sulfur, resins and paraffin.
By sulfur content oils are divided into:
low sulfur (0 ≤S≤0.5%);
medium sulfur (0.5
sulphurous (1
sour (S>3%).
Petroleum wax-it is a mixture of solid hydrocarbons two groups that differ sharply from each other in properties - paraffinsC 17 H 36 -WITH 35 H 72 and ceresin C 36 H 74 - C 55 H 112 . The melting point of the first 27-71°C, second- 65-88°С. At the same melting temperature, ceresins have a higher density and viscosity. The content of paraffin in oil sometimes reaches 13-14% or more.
World units of oil
1 barrel depending on the density of approximately 0.136 tons of oil
1 ton of oil is approximately 7.3 barrels
1 barrel = 158.987 liters = 0.158 m3
1 cubic meter about 6.29 barrels
Physical properties oil
Density(volumetric mass) - the ratio of the mass of a substance to its volume. The density of reservoir oil is the mass of oil extracted to the surface from the bowels with the preservation of reservoir conditions, per unit volume. The SI unit of density is expressed in kg/m 3 . ρ n \u003d m / V
According to the density of oil, they are divided into 3 groups:
light oils (with a density of 760 to 870 kg / m 3)
medium oils (871970 kg / m 3)
heavy (over 970 kg / m 3).
The density of oil in reservoir conditions is less than the density of degassed oil (due to an increase in the gas content in oil and temperature).
The density is measured with a hydrometer. Hydrometer - a device for determining the density of a liquid by the depth of the float (a tube with divisions and a weight at the bottom). On the scale of the hydrometer, divisions are plotted showing the density of the studied oil.
Viscosity- the property of a liquid or gas to resist the movement of some of its particles relative to others.
Dynamic viscosity coefficient ( ). is the friction force per unit area of the contacting liquid layers at a velocity gradient equal to 1. / Pa s, 1P (poise) = 0.1 Pa s.
The reciprocal of dynamic viscosity called fluidity.
The viscosity of a liquid is also characterized coefficient of kinematic viscosity , i.e. the ratio of dynamic viscosity to the density of a liquid. In this case, m 2 / s is taken as a unit. Stokes (St) \u003d cm 2 / s \u003d 10 -4 m 2 / s.
In practice, the term is sometimes used conditional (relative) viscosity, which is the ratio of the outflow time of a certain volume of liquid to the outflow time of the same volume of distilled water at a temperature of 20 0 C.
Reservoir oil viscosity is a property of oil that determines the degree of its mobility in reservoir conditions and significantly affects the productivity and efficiency of reservoir development.
The viscosity of reservoir oil of different deposits varies from 0.2 to 2000 mPa s or more. The most common values are 0.8-50 mPa s.
Viscosity decreases with increasing temperature, increasing the amount of dissolved hydrocarbon gases.
According to the viscosity, oils are distinguished
low viscosity - n
low viscosity - 1
with increased viscosity-5
high-viscosity - n > 25 mPa s.
Viscosity depends on the chemical and fractional composition of oil and tar content (the content of asphaltene-resinous substances in it).
Saturation pressure (onset of vaporization) of reservoir oil is the pressure at which the release of the first bubbles of dissolved gas from it begins. Reservoir oil is called saturated if it is at a reservoir pressure equal to the saturation pressure of undersaturated - if the reservoir pressure is higher than saturation pressure. The value of saturation pressure depends on the amount of gas dissolved in oil, on its composition and reservoir temperature.
The saturation pressure is determined by the results of the study of deep oil samples and experimental graphs.
G\u003d Vg / V b.s.
The gas content is usually expressed in m 3 /m 3 or m 3 /t.
Field gas factor G is the amount of gas produced in m3 per 1 m3 (t) of degassed oil. It is determined based on data on oil and associated gas production for a certain period of time. There are gas factors: initial, determined for the first month of well operation, current - for any period of time and average for the period from the beginning of development to any arbitrary date.
Surface tension - this is the force acting per unit length of the interface contour and tending to reduce this surface to a minimum. It is due to the forces of attraction between molecules (with SI J/m 2 ; N/m or dyn/cm) for oil 0.03 J/m 2 , N/m (30 dyne/cm); for water 0.07 J / m 2, N / m (73 dynes / cm). The greater the surface tension, the greater the capillary rise of the liquid. The surface tension of water is almost 3 times greater than that of oil, which determines different speeds their movement through the capillaries. This property affects the peculiarity of the development of deposits.
Capillarity- the ability of a liquid to rise or fall in small diameter tubes under the action of surface tension.
Р = 2σ/ r
P is the uplift pressure; σ - surface tension; r –
capillary radius .
h= 2σ/ rρ
g
h - lifting height; ρ – liquid density; g - acceleration of gravity.
Oil color varies from light brown to dark brown and black.
Another main property of oil is evaporation. Oil loses light fractions, so it must be stored in sealed vessels.
Oil compressibility factor β n is the change in the volume of reservoir oil with a pressure change of 0.1 MPa.
It characterizes the elasticity of oil and is determined from the ratio
where V 0 - the initial volume of oil; ΔV- change in the volume of oil with a change in pressure by Δр;
Dimension β n -Pa -1 .
The oil compressibility coefficient increases with an increase in the content of light oil fractions and the amount of dissolved gas, an increase in temperature, and a decrease in pressure and has the values (6-140) 10 -6 MPa -1 . For most reservoir oils, its value is (6-18) 10 -6 MPa -1 .
Degassed oils are characterized by a relatively low compressibility factor β n =(4-7) 10 -10 MPa -1 .
Coefficient thermal expansion n is the degree of expansion of oil with a change in temperature by 1 °C
n = (1/ Vo) (V/t).
Dimension - 1/°С. For most oils, the values of the coefficient of thermal expansion range from (1-20) *10 -4 1/°C.
The coefficient of thermal expansion of oil must be taken into account when developing a deposit in a non-stationary thermohydrodynamic regime when the reservoir is exposed to various cold or hot agents.
Reservoir oil volume factorb shows how much volume occupies in reservoir conditions 1 m
3
degassed oil:
b n = V pl.n / V deg \u003d n./ pl.n
Where V sq.n - volume of oil in reservoir conditions; Vdeg is the volume of the same amount of oil after degassing at atmospheric pressure and t=20°C; pl.p - density of oil in reservoir conditions; -density of oil under standard conditions.
Using the volume factor, it is possible to determine the "shrinkage" of oil, i.e., to establish a decrease in the volume of reservoir oil when it is extracted to the surface. Oil shrinkage U
U=(bn-1)/bn*100
When calculating oil reserves by the volumetric method, the change in the volume of reservoir oil during the transition from reservoir conditions to surface conditions is taken into account using the so-called conversion factor.
conversion factor is the reciprocal of the reservoir oil volume factor. 
=1/b=Vdeg/Vb.s.=b.s./n
BASICS OF PRODUCTION GEOLOGY AND DEVELOPMENT OF OIL AND GAS FIELDS 1 page
Oil and gas field geology (NGPG) is a branch of geology that deals with a detailed study of oil and gas fields and deposits in their initial (natural) state and in the process of development in order to determine their national economic significance and rational use of the subsoil.
The main objectives of the NGPG are as follows:
Field-geological modeling of deposits;
Structuring of oil, gas and condensate reserves;
Geological substantiation of the system for the development of oil and gas fields;
Geological substantiation of measures to improve the efficiency of development and oil, gas or condensate recovery.
The tasks of the NGPG are to solve various issues related to: obtaining information about the object of research; with the search for patterns that combine the observed disparate facts about the structure and functioning of the deposit into a single whole; in creating methods for processing, summarizing and analyzing the results of observations and research; in evaluating the effectiveness of these methods in various geological conditions, etc.
This methodological guide offers 11 laboratory works, the implementation of which allows you to master a number of methods for collecting and processing geological and field information, understand many key concepts of field geology, such as: oil and gas reservoir, deposit boundaries, heterogeneity of productive strata, conditional limits of reservoirs, imperfection of wells, reservoir pressure, filtration characteristics of the reservoir (permeability, hydraulic conductivity,
piezoconductivity), indicator diagram, pressure recovery curve (PRC), development dynamics, oil recovery factor.
Laboratory work No. 1 Determining the position of the boundaries of an oil reservoir from data
well drilling
Revealing the internal structure of the reservoir according to measurements, observations and definitions is the task of building a model of the reservoir structure. An important step in solving this problem is the drawing of geological boundaries. The form and type of the deposit depends on the nature of the geological boundaries limiting it.
Geological boundaries include surfaces: structural,
associated with the contact of rocks of different age and lithology; stratigraphic unconformities; tectonic disturbances; as well as surfaces separating reservoir rocks (RC) by the nature of their saturation, that is, water-oil, gas-oil and gas-water contacts (WOC, GOC, GWC). Most oil and gas deposits are associated with tectonic structures(folds, uplifts, domes, etc.), the shape of which determines the shape of the deposit.
Structural forms, including the form of structural surfaces (roofs and bottoms of deposits) are examined using structural maps.
The initial data for constructing a structural map are the well location plan and the absolute elevations of the mapped surface in each well. The absolute elevation is the vertical distance from sea level to the mapped surface:
H=(A+Al)-L, (1.1)
where A is the wellhead altitude, L is the depth of the mapped surface in the well, D1 is the well elongation due to curvature.
The triangle method is the traditional way of constructing structural maps.
The boundaries of the deposits associated with the heterogeneity of the reservoirs are drawn along the lines along which the permeable PK of the productive formation, as a result of facies variability, lose their reservoir properties and become impermeable, or the formation has been wedged out or washed out. With a small number of wells, the position of the reservoir replacement line, wedging or erosion lines is conventionally drawn at half the distance between pairs of wells, in one of which the reservoir is composed of rock, and in the other - impermeable rocks or the reservoir was not deposited or eroded here.
A more correct position of the facies transition line of reservoirs is determined on maps of changes in reservoir parameters: porosity,
permeability, spontaneous polarization potential amplitude
(SP), etc., for which the standard limit is set, i.e. the value of the parameter at which the reservoir loses its reservoir properties.
The position of the WOC in the deposit is substantiated by constructing special scheme. Wells are considered first. carrying information about the position of the VNK. These are wells located in the oil-water zone, in which the WOC can be determined from well logging data. Wells from purely oil and water zones are also used, in which, respectively, the bottom and top of the formation are in close proximity to the OWC.
Columns of selected wells are applied to the scheme, indicating the nature of reservoir saturation (oil, gas or water) according to logging data, perforation intervals and well testing results. Based on this information, a line is selected and drawn that most fully corresponds to the position of the OWC.
On the plan (map), the boundaries of the deposit are the contours of the oil and gas content. There are external and internal contours of oil and gas content. The outer contour is the line of intersection of the WOC (GWC, GOC) with the top of the reservoir, and the inner contour is the line of intersection of the WOC (GWC, GOC) with the bottom of the reservoir. The outer contour is found on the structural map along the top of the formation, and the inner contour is found on the structural map along the bottom of the formation. Within the inner contour there is an oil or gas part of the reservoir, and between the inner and outer contours there is a water-oil or water-gas part.
With horizontal WOC (GOC, GWC), the position of the oil and gas contour lines is found on structural maps near
the corresponding isohypse corresponding to the accepted
hypsometric contact position. When the contact is horizontal, the contour lines do not cross the isohypses.
If the productive horizon consists of many layers, characterized by discontinuous lithologically uneven
structure, then the position of the oil-bearing contours as a whole for the horizon is determined by combining the structural maps along the top of each layer (these maps also show the reservoir replacement boundaries and the oil-bearing contour for this layer).
On the combined map, a deposit boundary of a complex shape is obtained, passing in some areas along the replacement lines of reservoirs, and in others - along the line of the external contour within different layers.
The initial data for the proposed work are: a table with information about the wellhead altitudes, elongations, depths of the formation roof, formation thicknesses, OWC depth; well layout.
1. Determine the absolute elevations of the roof and bottom of the formation.
2. Calculate the absolute marks of water-oil contact in wells and justify the position of water-oil contact for the deposit as a whole.
E. Determine the boundaries of the distribution of reservoirs on the well location plan.
4. Build structural maps for the top and bottom of the formation and analyze them.
5. Show the position of the external and internal contours of oil content on the specified structural maps.
6. Describe the type of oil deposit and justify its position in modern classifications of oil and gas deposits.
EXAMPLE. Determine the boundaries of the deposit on a given well layout according to drilling and geophysical survey data (Table 1.1), the depths of the OWC.
Table 1.1
| Kskv | Altitude, m | Elongation, m | Roof depth, m | Thickness, m | Abs. roof elevation, m | Abs. sole mark, m |
| 125.7 | 0.4 | 2115.1 | -1989 | -1992 | ||
| 121.5 | 0.8 | 2120.3 | -1998 | -2002 | ||
| 120.5 | 2106.9 | 8.2 | -1983.4 | -1991.6 | ||
| 123.5 | 1.2 | 2129.7 | 11.8 | -2005 | -2016.8 | |
| 122.3 | 0.2 | 2121.5 | -1999 | -2002 | ||
| 121.9 | 1.6 | 2110.5 | 12.6 | -1987 | -1999.6 | |
| 125.5 | 0.6 | 2120.1 | 14.4 | -1994 | -2008.4 | |
| 125.9 | 0.2 | 2129.7 | 15.4 | -2003.6 | -2019 | |
| 124.3 | 0.8 | 2124.7 | -1999.6 | -2016.6 | ||
| 126.7 | 1.4 | 2142.1 | 18.8 | -2014 | -2032.8 | |
| 0.5 | 3.5 | -1994.5 | -1998 | |||
| 120.2 | 0.7 | -1986.1 | -1991.1 | |||
| 0.5 | -1993.5 | -1999.5 | ||||
| 121.5 | 0.6 | 4.5 | -1995.9 | -2000.4 | ||
| 0.7 | 4.3 | -1991.3 | -1995.6 | |||
| 0.8 | 5.1 | -1996.2 | -2001.3 | |||
| 0.9 | 5.5 | -1996.1 | -2001.6 | |||
| 1.5 | 4.1 | -2000.5 | -2004.6 |
The depth of WOC pick-off by logging was determined in three wells: well 2 (2120.3m), well 7 (2124.4m) and well 6 (2121.5m).
Job progress:
According to the formula (1.1), the absolute marks of the top of the formation are determined (calculation results are given in Table 1.1). The same formula is applicable to determine the absolute mark of the water contact, which is minus 1998m in all three wells.
Assuming that the surface of the OWC is flat and horizontal, then the data from three wells is sufficient to delineate the reservoir, since the plane is defined by three points.
Absolute marks of the bottom of the formation in this case it is easier to determine using data on the thickness of the reservoir (calculation results are shown in Table 1.1). Structural maps along the top and bottom of the formation are built according to the absolute marks of the indicated surfaces (Fig. 1.1 and 1.2).
The maps reveal an anticlinal structure elongated in the sublatitudinal direction, complicated by two domes. The structure is a hydrocarbon trap in the presence of other favorable conditions.
The outer contour of the oil content is drawn on the structural map along the top of the reservoir, and the inner contour of the oil content is drawn on the structural map along the bottom of the reservoir along the isoline -1998m.
The contours of the deposit are not closed. According to the studied part of the deposit, it can be characterized as a reservoir arch, since it is confined to the arch of the structure, PCs have a uniform structure and a small thickness.
The oil zone is limited by the inner contour of oil-bearing capacity, and the water-oil zone is limited by the inner and outer contours of oil-bearing capacity.
Laboratory work No. 2 Determination of macro-heterogeneity of the productive horizon
The purpose of this work is to introduce the concept of geological heterogeneity using the example of macroheterogeneity, which is taken into account when identifying production facilities and choosing a development system. The development of methods for studying geological heterogeneity and taking it into account when calculating reserves and developing deposits is the most important task of commercial geology.
Under the geological heterogeneity understand the variability natural characteristics oil and gas saturated rocks within the deposit. Geological heterogeneity has a huge impact on the choice of development systems and on the efficiency of oil extraction from the subsoil, on the degree of involvement of the reservoir volume in the drainage process.
There are two main types of geological heterogeneity: macroheterogeneity and microheterogeneity.
Macroheterogeneity reflects the morphology of the occurrence of reservoir rocks in the reservoir volume, i.e. characterizes the distribution of collectors and non-collectors in it.
To study macroheterogeneity, logging data for all drilled wells are used. A reliable assessment of macroheterogeneity can only be obtained if there is a qualified detailed correlation of the productive part of the well sections.
Macro-heterogeneity is studied vertically (along the thickness of the horizon) and along the strike of the layers (along the area).
In terms of thickness, macroheterogeneity is manifested in the dismemberment of the productive horizon into separate layers and interlayers.
Along the strike, macroheterogeneity manifests itself in the variability of the thicknesses of reservoir rocks up to zero, i.e. the presence of zones of absence of reservoirs (lithological replacement or wedging out). In this case, the nature of the distribution zones of collectors is of great importance.
Macro-heterogeneity is displayed by graphical constructions and quantitative indicators.
Graphically, vertical macroheterogeneity (along the thickness of the object) is displayed using geological profiles (Fig. 2.1.) and detailed correlation schemes. By area, it is displayed using maps of the distribution of reservoirs of each layer (Fig. 2.2.), which show the boundaries of the areas of distribution of the reservoir and non-reservoir, as well as the confluence areas of neighboring layers.
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Fig.2.2. A fragment of a map of the distribution of reservoir rocks of one of the horizon layers: 1 - rows of wells (H - injection; D - producing), 2 - boundaries of the distribution of reservoir rocks, 3 - boundaries of confluence zones, sections 4 - distribution of reservoir rocks, 5 - absence reservoir rocks, 6 - coalescence of the reservoir with the overlying reservoir, 7 - coalescence of the reservoir with the underlying reservoir.
There are the following quantitative indicators characterizing macroheterogeneity:
1. The coefficient of compartmentalization, showing the average number of layers
(interlayers) of reservoirs within the deposit, Kp = (X Shch) / N (2.1), where n -
number of reservoir layers in i-th well; N - number of wells.
2. Net-to-gross ratio, showing the proportion of reservoir volume (or formation thickness) in the total volume (thickness) of the productive horizon:
Kpesch = [ X (Kf^ bsht)]i/ N (2.2), where h^ is the effective thickness of the reservoir in
well; N - number of wells. The net-to-gross ratio is a good carrier of information for the following reasons: it is related by correlations with many other geological and physical parameters and characteristics of production facilities: compartmentalization, discontinuity of formations over the area, their lithological connectivity along the section, etc.
As an indicator of macroheterogeneity, which takes into account both dissection and grit, a complex indicator is used -
Coefficient of macroheterogeneity: K m = (X n i )/(X h i ) (2.3), where n -
i=1 i =1
number of permeable layers; h is the thickness of the permeable layers penetrated by the well. The coefficient of macroheterogeneity characterizes the dissection of the development object per unit of thickness.
3. Coefficient of lithological connectivity - coefficient of confluence, evaluating the degree of confluence of reservoirs of two layers, K sl = S^/S^ where S CT - total area of confluence areas; sj. - the area of distribution of collectors within the deposit. The greater the coefficient of lithological connectivity, the higher the degree of hydrodynamic connectivity of adjacent layers.
4. Coefficient of distribution of reservoirs on the deposit area, which characterizes the degree of discontinuity of their occurrence over the area (replacement of reservoirs with impermeable rocks),
K disp = SA where S is the total area of the zones of distribution of reservoir reservoirs;
5. The coefficient of complexity of the boundaries of the distribution of reservoir reservoirs, necessary for studying and evaluating the complexity of the structure of discontinuous, facially variable reservoirs, K sl = L^/n, where is the total length of the boundaries of areas with the distribution of reservoirs; P - the perimeter of the deposit (the length of the outer contour of the oil-bearing capacity). It has been established that in heterogeneous, discontinuous formations, as the well grid is compacted, the complexity factor is constantly decreasing. This indicates that even with a dense grid of producing wells, all the details of reservoir variability are still unknown.
6. Three coefficients characterizing reservoir distribution zones in terms of oil displacement conditions:
Kspl \u003d Yasil / Yak; Kpl \u003d S ^ S * Cl \u003d S ^ S *
where K cpl, Kpl, K l - respectively, the coefficients of continuous propagation of collectors, half lenses and lenses; I spl is the area of zones of continuous distribution, i.e. zones receiving the effect of a displacing agent from at least two sides; S ra is the area of the half lenses, i.e. zones receiving unilateral impact; - the area of the lenses that are not affected; K cpl + K pl + K p \u003d 1.
The study of macroheterogeneity makes it possible to solve the following problems when calculating reserves and designing a development: modeling the shape of a complex geological body serving as a reservoir of oil or gas; identify areas of increased reservoir thickness resulting from the merging of interlayers (layers), and, accordingly, possible places for oil and gas flow between layers during the development of the deposit; determine the feasibility of combining layers into a single operational facility; justify the effective location of production and injection wells; predict and evaluate the degree of coverage of the deposit by development; select deposits similar in terms of macroheterogeneity in order to transfer the experience of developing previously developed objects.
The initial data when performing the task are a table with data on the thickness of the horizon and the reservoir rocks from which it is composed, the layout of wells, information about the reservoir (deposit depth, reservoir lithological type, reservoir permeability, oil viscosity, reservoir regime, reservoir size) .
1. Build isopach maps for each layer and horizon as a whole, indicate the boundaries of the distribution of reservoirs on them and analyze them.
3. Determine the coefficients characterizing the macroheterogeneity of the horizon.
EXAMPLE. Determine the coefficients of net-to-gross ratio, dissection, macroheterogeneity for a multilayer horizon.
Data in table 2.1.
| Table 2.1
|
Estimated data are presented in table 2.2
| Table 2.2
|
According to formulas 2.1, 2.2, 2.3, we determine that the dismemberment coefficient Кр=32/14=2.29; net-to-gross ratio Kpesch=280/362=0.773;
coefficient of macroheterogeneity Km= 32/280=0.114.
The combined use of Kp, Kpesch, Km allows you to get an idea of the macroheterogeneity of the section: the more Kp, Km and the smaller Kpesch, the higher the macroheterogeneity. Comparatively homogeneous are layers (horizons) with Кpesch > 0.75 and Кр< 2,1. К неоднородным соответственно относятся пласты (горизонты) с Кпесч < 0,75 и Кр >2.1. According to these criteria, the horizon considered in the example can be characterized as weakly heterogeneous (Кpesch=0.773, Кр=2.29)
Laboratory work No. 3 Determining the conditional limits of reservoir parameters
The correct calculation of oil and gas reserves involves the disclosure of the internal structure of the estimated object, knowledge of which is necessary for organizing the effective development of deposits, in particular, for choosing a development system. To identify the internal structure of the deposit, it is also necessary to know the position in terms of the boundaries between reservoirs and non-reservoirs, drawn according to the values of porosity-permeability (or any other) properties of rocks, called conditional.
The conditional limits of the parameters of productive formations are the boundary values of the parameters by which the rocks of the productive formation are divided into reservoirs and non-reservoirs, as well as reservoirs with different field characteristics in order to more reliably distinguish in the total volume of the deposit its effective volume as a whole and volumes of different productivity, t .e. determination of reservoir conditions means the definition of criteria for selection in the context of reservoirs and their classification according to lithology, productivity, etc.
Reserve conditions are a set of requirements for the geological, physical, technical, economic and mining parameters of the deposit, ensuring the achievement of model oil recovery with the profitability of the development process in compliance with the laws on labor protection, subsoil and the environment. Determination of reserve conditions is used to assess the commercial potential of a deposit and classify geological reserves according to their commercial significance.
Reservoir conditions are determined by a large group of factors that determine the reservoir properties of rocks (RP). The main parameters affecting reservoir properties are porosity, permeability, oil, gas, bitumen saturation, supplemented by parameters of carbonate content, clay content, residual water, the nature of oil, gas, bitumen saturation, particle size distribution, material genetic typing, well logging parameters (GIS ) - saturation parameter, porosity parameter, etc., as well as field indicators - productivity or specific production rate. The method of substantiating the conditions is the correlation analysis between the specified properties of the rocks according to the data of the laboratory study of the core, according to the data of well logging and hydrodynamic studies.
Conditions for reserves depend on social needs for hydrocarbon raw materials and on the level of technical and technological development of oil, gas, bitumen production. Reserve conditions are justified taking into account specific reserves, initial and final well flow rates, displacement efficiency, oil recovery factor (ORF), development system, marginal cost. The method of substantiating the conditions is technical and economic calculations for the options for the development of the object.
Separation of collectors.
A natural reservoir containing hydrocarbons includes at least two classes of rocks: reservoirs and non-reservoirs. These classes differ in the structure of the pore space, the values of petrophysical parameters, and the nature of their distribution.
The class boundaries are the boundaries of the qualitative and quantitative transition from one property to another, independent of the applied reservoir development technologies. However, it should be taken into account that when applying methods of intensive stimulation of the reservoir, which significantly affect the structure of the pore space (expansion of filtration channels, dissolution of carbonates during physical and chemical stimulation, creation of cracks, etc.), it is possible to transfer reservoirs to higher classes, and when applying methods calmotations - to the lower ones.
It has already been noted above that the main parameters characterizing reservoirs are porosity Kp, permeability Kp, residual water content Kow, for a reservoir containing hydrocarbons - oil, gas, bitumen saturation Kn(g, b).
Relationships between geological and field parameters are statistical, complex, including components that characterize certain classes of rocks or reservoirs. When processing such dependencies, the least squares method is used. Practice has shown that these dependencies are approximated by the parabola Y=a*X b .
The change in the nature of the dependence is controlled by the change in the coefficients of the parabola for different sections of the correlation field, and the intersection points of the parabolas indicate the position of the class boundaries.
To find these boundaries, a correlation field is often built in logarithmic coordinates (linearization method), where the parabola is converted into a straight line: LgY=Lga+b*LgX. The points of intersection of the lines indicate the boundaries of the classes.
The argument and function should be chosen according to the physical meaning, for example, in a pair Kp-Kb: Kp is an argument, and Kb is a function, in a pair Kp-Kpr: Kp is an argument, Kpr is a function.
As a basis for determining the boundaries of classes, the correlation field Kpr \u003d f (Kp) is recommended.
There are two conditional limits. The first limit is the limit above which a breed can contain a.w. The second limit is the limit above which the breed is able to give s.v. The first limit is the lower boundary of the reservoir, the second limit is the boundary of the productive reservoir. The first limit is set according to the data of lithological and petrographic studies of the core and the petrophysical properties of the rocks. The second limit is set according to the results of studies of displacement characteristics on core samples, according to phase permeability curves, according to the dependence of residual water on porosity and permeability. The second limit must be confirmed by the results of well testing - a comparison of permeability with productivity. The dependence of productivity (or specific production rate) on permeability, taking into account the minimum production rate, below which the development is not profitable, allows us to determine the third limit - the technological one.
GIS are the most widespread type of research. According to well logging data, the main parameters of the reservoirs are determined and their classification is carried out.
There are two ways to substantiate the conditions according to field geophysics data.