Field development system and their qualifications. The essence of the development of oil and gas wells, systems and stages of the process. Types of in-circuit flooding
Oil field development systems with reservoir pressure maintenance
Maintaining reservoir pressure by injecting water, in addition to increasing oil recovery, ensures intensification of the development process. This is due to the approach of the high-pressure zone created by pumping water into water injection wells to the production wells.
To make a decision on maintaining reservoir pressure by injecting water into a specific oil deposit, the following issues are sequentially considered:
determine the location of water injection wells;
determine the total volume of injected water;
calculate the number of water injection wells;
establish basic requirements for injected water.
Location of water injection wells is determined mainly by the features of the geological structure of the oil deposit. The task comes down to selecting an arrangement of water injection wells that ensures the most effective connection between the water injection zones and the extraction zones with uniform displacement of oil by water.
Depending on the location of water injection wells, the following waterflooding systems are currently used in oil field development practice.
Contour flooding used to develop deposits with small oil reserves. The wells are located in the aquifer-bearing part of the formation (Fig. 1). The use of a contour development system is possible when the oil-water contact can move under achievable pressure drops. The practice of developing oil fields has revealed cases where, directly at the surface, an oil deposit is “sealed” by oil oxidation products (asphaltenes, resins, paraffin and others) or bacterial waste products. In addition, the design and implementation of this system requires a detailed study of the boundary part of the reservoir. Sometimes the characteristics of the boundary part of the formation, in terms of porosity, permeability, and sand content, differ significantly from the characteristics of the central part of the formation.Edge flooding used when the hydrodynamic connection of the oil zone of the reservoir with the boundary area is difficult. A number of injection wells in this case are located in the oil-water zone or near the internal oil-bearing contour.
In-circuit flooding They are mainly used in the development of oil deposits with very large area sizes. In-circuit flooding does not negate peripheral flooding, and in necessary cases, intra-circuit flooding is combined with peripheral flooding. For large oil deposits, edge flooding is not effective enough, since with it, 3-4 rows of oil production wells located closer to the water injection wells work most efficiently.Dividing the oil-bearing area into several areas using intra-circuit flooding makes it possible to bring the entire oil-bearing area into effective development simultaneously. To fully cut the oil-bearing area, injection wells are arranged in rows. When water is pumped into them along the lines of rows of injection wells, a zone of high pressure is formed, which prevents the flow of oil from one area to another. As injection progresses, the pockets of water formed around each injection well increase in size and finally merge, forming a single front of water, the progress of which can be regulated in the same way as during peripheral flooding. In order to accelerate the formation of a single water front along the line of a number of injection wells, the development of wells for injection in a row is carried out “every other”. In the intervals, design water injection wells are put into operation as oil production wells, with forced extraction carried out in them. As injected water appears in the “intermediate” wells, they are transferred to water injection.
Production wells are located in rows parallel to the rows of water injection wells. The distance between rows of oil producing wells and between wells in a row is selected based on hydrodynamic calculations, taking into account the features of the geological structure and physical characteristics of reservoirs in a given development area.
Rice. 3. Schematic diagram of reservoir development using block systems.
For symbols, see Fig. 1.
The development of each area can be carried out according to its own system for placing production wells with maximum consideration of the geological characteristics of the area.
The great advantage of the described system is the ability to start development from any area and, in particular, to bring into development, first of all, areas with the best geological and operational characteristics, the highest density of reserves with high well flow rates.
In Fig. Figure 2 shows a diagram of the development of the Romashkinskoye field, Tatar Autonomous Soviet Socialist Republic, with in-circuit flooding.
According to the initial development project drawn up by the All-Russian Scientific Research Institute, the Romashkinskoye field was cut into 23 independent development areas by rows of water injection wells. Subsequently, individual areas were further cut into smaller sections.
A type of in-circuit flooding system is block development systems.
Block systems developments are used in elongated fields with rows of water injection wells located more often in the transverse direction. The fundamental difference between block development systems and intra-circuit flooding systems is that block systems require the abandonment of peripheral flooding. In Fig. 3 shown circuit diagram development of formation A4 of the Kulishovskoye oil field (Kuibyshev region). As can be seen from the diagram, rows of water injection wells cut a single deposit into separate sections (blocks) of development.
The advantage of block systems is as follows.
1. Refusal to locate water injection wells in the boundary zone eliminates the risk of drilling wells in a part of the reservoir that is poorly studied at the stage of exploration of the field.
2. The manifestation of the natural forces of the hydrodynamic region of the boundary part of the reservoir is used more fully.
3. The area to be equipped with reservoir pressure maintenance facilities is significantly reduced.
4. Maintenance of the reservoir pressure maintenance system (wells, clusters) is simplified pumping stations etc.).
5. The compact, close location of production and water injection wells makes it possible to quickly resolve issues of development regulation by redistributing water injection among rows and wells and fluid withdrawal in oil producing wells.
Block systems have become widespread at the fields of the Kuibyshev region and Western Siberia.
Block development systems involve the location of water injection wells in a direction perpendicular to the strike line of the fold. At the same time, for quiet, gently sloping anticlinal folds, it is advisable to locate water injection wells along the axis of the fold. In this case, it becomes possible to have one instead of several injection lines.
Flooding of formations when water injection wells are located near the axis of the fold is called axial flooding.
All the advantages of block development systems are also characteristic of axial flooding.
Area flooding used in the development of formations with very low permeability.
With this system, production and injection wells are placed according to regular patterns of four-, five-, seven- and nine-point systems.
In Fig. Figure 4 shows the main schemes of areal flooding. The schemes differ not only in the location of the wells, but also in the ratio between the number of production and injection wells.
| Rice. 4. Basic schemes of area flooding: a - four-point; b - five-point; c - seven-point; g - nine-point; 1 – production wells; 2 - injection wells. |
Thus, in a four-point system (see Fig. 4) the ratio between oil production and injection wells is 2:1, with a five-point system - 1:1, with a seven-point system - 1:2, with a nine-point system - 1:3. Thus, the most intense among those considered are the seven- and nine-point systems.
The efficiency of area flooding is greatly influenced by the homogeneity of the formation and the amount of oil reserves per well, as well as the depth of the development object.
In conditions of a heterogeneous formation, both in section and area, premature water breakthroughs to production wells occur in the more permeable part of the formation, which greatly reduces oil production during the dry period and increases the oil-water factor, therefore it is advisable to use area flooding when developing more homogeneous formations.
Local flooding- this is an addition to the already implemented system of peripheral or intracircuit flooding. With this waterflooding system, groups of injection wells are located in areas of the reservoir that are lagging behind in terms of the intensity of use of oil reserves. In some cases, with a well-studied geological structure of the productive formation, focal flooding can be used as an independent field development system.
DEVELOPMENT SYSTEMS
Development is a scientifically based process (set of works) of controlling the movement of fluid in oil, gas or condensate deposits due to:
Selecting a development object;
Placement of wells or choice of well pattern density;
Determination of optimal bottomhole pressure;
The choice of the natural mode of operation of the deposit or the need to use a method of artificial influence on the deposit;
Method and agent PPD;
Use of certain development technologies;
Definitions of pressure gradient;
A set of measures to control and regulate the development process.
A field development system is understood as a set of technological and technical measures that ensure the extraction of oil, gas, condensate and associated components from formations and the management of this process.
Depending on the number, thickness, types and filtration characteristics of reservoirs, the depth of each of the productive formations, the degree of their hydrodynamic connectivity, etc. The field development system may provide for the identification of one, two or more development objects (operational objects) in its geological section.
When selectedat the field two or more objects each of them has its own justification rational development system . Being tied up between themselves , development systems for individual operational facilities constitute rational system of field development as a whole .
A development system that provides:
The country's needs for oil (gas);
More complete extraction of oil, gas, condensate and useful associated components from reservoirs is possible at the lowest cost.
Until the mid-40s. the development of oil fields was carried out only using the natural energy of the deposits.
From the mid-40s. As a result of the discovery of new oil and gas bearing areas, the development of the oil industry is associated mainly with the development of platform-type fields, which are characterized by large oil-bearing areas, significant depths of the main productive formations and, in most cases, an ineffective natural regime - elastic water pressure, quickly turning into a dissolved gas regime.
Scientists and production workers in a relatively short period of time theoretically substantiated and proved in practice the need and possibility of using fundamentally new development systems with the artificial introduction of additional energy into productive oil reservoirs by injecting water into them. The widespread use of the waterflooding method began in the mid-40s. Initially, it was introduced in new oil fields of Bashkiria and Tataria - Tuymazinsky, Romashkinsky, Shkapovsky, Bavlinsky, etc., then it was distributed in all oil-producing regions of the country in new fields with insufficiently effective natural regimes.
The use of waterflooding made it possible to develop oil deposits at a fairly high rate with a significantly smaller number of wells, accelerate the ramp-up of production facilities to high production levels, and double oil recovery on average compared to development under low-efficiency modes.
Development systems with waterflooding provide the greatest effect when developing low-viscosity oil deposits confined to productive formations with moderate heterogeneity and increased permeability. When developing deposits with deteriorated geological characteristics (increased viscosity of reservoir oil, reduced permeability of reservoir rocks), waterflooding also achieves an increase in the oil recovery factor by almost 2 times compared to its value when developed in natural conditions, but the absolute values of this coefficient are not in all cases are quite high.
For each of these points, decisions must be made that most fully correspond to the geological characteristics of the operational facility. At the same time, on some points, recommendations can be given unambiguously based on the data of field geological studies, on others, two or three similar recommendations can be offered. On this basis, specialists in the field of field development technology perform hydrodynamic calculations of several options for the development system. The options differ in the combination of recommendations based on geological data. From these, the optimal option is selected that meets the requirements for a rational development system. Choice optimal option performed on the basis comparison of the dynamics of annual technological and economic indicators development of the considered options.
Studies to generalize the experience of developing oil fields when oil is displaced by water, carried out in different years and on different scales, indicate that main influence influences the dynamics of technical and economic development indicators geological field characteristics objects. At the same time, the use of a development system that corresponds to geological and physical conditions makes it possible to significantly mitigate the unfavorable geological and production features of production facilities.
Justification for the allocation of operational facilities and optimal options development systems for each of them is based on the one formed at the beginning of design work geological model each of the deposits and the field as a whole.
Geological model of the deposit.
The rationale for identifying production facilities and optimal options for development systems for each of them is based on the geological model of each of the deposits and the field as a whole formed at the beginning of design work.
The geological model is:
A set of commercial geological graphic maps and diagrams;
Digital data;
Curves characterizing the relationships between various parameters of deposits,
As well as a verbal description of the characteristics of the deposits (text part).
Among the graphic cards and circuits required:
Consolidated lithological and stratigraphic section of the deposit;
Detailed correlation schemes;
Structural maps reflecting the tectonic structure of the operational facility;
Maps of object reservoir surfaces with initial contours of oil and gas content;
Geological profiles for the production facility reflecting the conditions of oil and gas occurrence;
Reservoir distribution maps (for each formation separately);
Maps of total, effective, effective oil-saturated and gas-saturated capacity for the entire facility and for individual layers.
In case of specific features of the deposit, the necessary additional maps and diagrams are provided (scheme for justifying the position of the OWC and GWK, maps of the distribution of reservoirs different types, temperature map, light absorption coefficient map, permeability map, etc.).
Digital data is characterized by:
Porosity,
Permeability,
Initial oil (gas) saturation of reservoir rocks;
Full, effective, effective oil (gas) saturated power;
Thickness of permeable sections between layers;
Physicochemical characteristics reservoir oil, gas, condensate, water.
In this case, for each parameter the following is indicated: the number of determinations by different methods and the number of studied wells; value intervals; assessment of heterogeneity at all hierarchical levels; the average value for the object as a whole and for its parts.
The group of digital data also includes;
Statistical series of permeability distribution; micro- and macroheterogeneity of formations (ratio of volumes of reservoirs of different types, coefficients of sandiness, dissection, discontinuity, merger, etc.); thermobaric conditions; results of physical and hydrodynamic studies conducted in laboratory conditions on the displacement of oil (gas) by agents, the use of which is expected in the development of the facility.
The most important digital data characterizing the geological model of the field includes:
Balance and recoverable reserves of oil, gas, condensate, valuable associated components;
Dimensions of oil bearing area;
Width, length and height of the deposit;
Dimensions of parts of the deposit - pure oil, oil-water, oil and gas, oil-gas-water, gas-water zones.
Among the curves characterizing the dependencies between parameters are:
Dependency curves physical properties oil and gas from pressure and temperature,
Characteristics of phase permeabilities,
Dependence of displacement coefficient on permeability.
The text part of the geological model of the deposit describes its natural regime and, based on all the above-mentioned materials, outlines the main geological and physical features of the deposit, which determine the choice of technological solutions and the development system as a whole, and also affect the expected development indicators.
Oil reservoir development systems
Under natural conditions.
Oil deposits with effective natural regimes include deposits with water-pressure and active elastic-water-pressure regimes.
The most common method of influence - waterflooding - does not bring the desired results when the oil viscosity in reservoir conditions is more than 30-40 mPa×s, since this does not create a stable front for displacing oil with water in the reservoir: the latter quickly moves through the thinnest most permeable layers of the reservoir, leaving it undeveloped the main volume of the deposit. Waterflooding cannot be
A system for developing an oil reservoir using the pressure of regional waters. The system is used for reservoir-type oil deposits with natural water pressure or active elastic water pressure regime. It involves drilling out the deposit with production wells, locating them mainly in the purely oil part of the deposit in closed (“circular”) rows parallel to the internal oil-bearing contour. If possible, the staggered order of well placement is observed. To extend the water-free period of well operation, the distances between rows of wells can be set somewhat larger than between wells in rows. For the same purpose, in the wells of the outer row, the lower part of the oil-saturated thickness of the formation is usually not perforated. In the wells of the internal rows, the oil-saturated formation is perforated throughout its entire thickness. During the development process, the oil-bearing contours “contract” and the size of the deposit decreases. Accordingly, the wells of the outer ring row are gradually watered and decommissioned, then, through certain stages, the wells of subsequent rows are decommissioned.
Development system using bottom water pressure. The system is used for massive oil deposits (usually the entire or almost entire area of the deposit is underlain by water), which have a water-pressure or active elastic-water-pressure regime. When developing such deposits, the displacement of oil by water is accompanied by a widespread rise in water-oil contact, i.e. deposit intervals located at approximately the same hypsometric marks are sequentially watered; the size of the deposit decreases.
When the height of the deposit is measured in tens of meters, the wells are spaced evenly and the formation in them is perforated from the roof to a certain conventionally accepted boundary, several meters away from the OWC. When the reservoir height is 200-300 m or more (which is typical for some massive deposits in carbonate reservoirs), it is preferable to place wells along a grid condensing towards the center of the reservoir, maintaining the principle of equality of oil reserves per well. At the same time, the approach to opening the productive part of the section in wells depends on the filtration characteristics of the deposit. With low oil viscosity - up to 1-2 mPa×s, high permeability and a relatively uniform structure of the productive strata, it is possible to open the upper part of the oil-saturated capacity in wells, since under such conditions oil from the lower part can be displaced to the opened intervals. With low oil viscosity and heterogeneous structure of reservoir rocks or with increased oil viscosity, sequential opening of oil-saturated capacity can be realized.
Development system using the energy of gas released from oil. The system is used in dissolved gas mode and involves drilling out a production facility, usually along a uniform grid with perforation in all wells of the entire oil-saturated capacity.
Development system with joint use of formation water pressure and gas cap gas. The system for developing the oil part of a gas-oil deposit involves the use of a mixed regime of the deposit and the displacement of oil by contour water and gas from the gas cap. With this system, wells are placed along a uniform grid and only part of the oil-saturated capacity is perforated into them with a significant deviation from the contacts.
Since water has better washing ability compared to gas, the system is preferable to use for deposits with relatively small gas caps.
With a significant volume of the oil part of the deposit compared to the gas cap, a more effective effect of water pressure and a decrease in the influence of the gas cap appear at large angles of dip of the formations and a significant height of the oil part of the deposit, high reservoir pressure, increased values of permeability and hydraulic conductivity of reservoir rocks. Under the conditions under consideration, reservoir development becomes significantly more complicated due to the formation of gas and water cones. This must be taken into account when justifying perforation intervals and well flow rates.
A system using the pressure of formation water with a stationary hydrocarbon condensate. The system provides for ensuring the extraction of oil from an oil and gas deposit (with a potentially mixed natural regime) only through the introduction of formation water with a constant volume of the gas cap. Stabilization of the gas oil reservoir in its initial position is ensured by regulating the pressure in the gas cap by selecting strictly justified volumes of gas from it through special wells, corresponding to the rate of pressure reduction in the oil part of the deposit. With such a development system, the perforation interval in the wells can be located somewhat closer to the gas-condensing oil pipeline compared to its position when water and gas pressure are used together. However, here too, when choosing a perforation interval, one should take into account the possibility of the formation of gas and water cones and the need to extend the period of water-free operation of wells in conditions of rising OWC.
Related information.
Annotation: Development of mineral deposits is a system of organizational and technical measures for the extraction of minerals from the subsoil.
Development of mineral deposits is a system of organizational and technical measures for the extraction of minerals from the subsoil. The development of oil and gas fields is carried out using boreholes. Sometimes mine oil production is used (Yarega oil field, Komi Republic).
The system of development of oil fields and deposits is understood as a form of organizing the movement of oil in layers to production wells.
The oil field development system is determined by:
- the procedure for bringing operational facilities of a multi-layer field into development;
- grids for placing wells at sites, the pace and order of their commissioning;
- ways to regulate the balance and use of reservoir energy.
It is necessary to distinguish between development systems for multi-layer deposits and individual deposits (single-layer deposits).
Development object is one or more productive formations of a field, identified according to geological and technical conditions and economic considerations for drilling and operation with a single system of wells.
When selecting objects, you should consider:
- geological and physical properties of reservoir rocks;
- physical and chemical properties of oil, water and gas;
- phase state of hydrocarbons and formation regime;
- equipment and technology of well operation.
Development objects are divided into independent and returnable. Returnable objects, unlike independent ones, are supposed to be developed by wells that primarily exploit some other object.
Well placement grid
Well grid – the nature of the relative arrangement of production and injection wells at a production facility, indicating the distances between them (grid density). Wells are located on a uniform grid and an uneven grid (mainly in rows). Meshes are shaped like square, triangular and polygonal. With a triangular grid, 15.5% more wells are placed on the area than with a square grid in the case of equal distances between wells.
Well pattern density refers to the ratio of oil-bearing area to the number of producing wells. However, this concept is very complex. The mesh density is determined taking into account specific conditions. Since the late 50s, fields have been exploited with a grid density of (3060)·10 4 m 2 /well. At the Tuymazinskoye field, the grid density is 2010 4 m 2 /well. with a distance between wells in rows of 400 m, Romashkinskoye -6010 4 m 2 /well. – 1000 m 600 m, Samotlor – 6410 4 m 2 /well.
Field development stages
A stage is a period of the development process, characterized by a certain natural change in technological and technical-economic indicators. Technological and technical-economic indicators of the reservoir development process include current (average annual) and total (cumulative) oil production, current and total liquid production (oil and water), water cut of the produced liquid (the ratio of current water production to current liquid production), current and accumulated water-oil factor (the ratio of water production to oil production), current and accumulated water injection, compensation for recovery by injection (the ratio of the injected volume to the volume withdrawn under reservoir conditions), oil recovery factor, number of wells (producing, injection), reservoir and bottomhole pressure, current gas factor, average flow rate of production wells and injectivity of injection wells, production cost, performance labor, capital investments, operating costs, reduced costs, etc.
Based on the dynamics of oil production, there are four stages in the process of developing reservoir-type deposits in granular reservoirs under water pressure conditions (Fig. 6.1). The graphs are plotted depending on dimensionless time, which is the ratio of accumulated liquid production to balance oil reserves.
Rice. 6.1.
The first stage - development of an operational facility - is characterized by:
The duration of the stage depends on the industrial value of the deposit and is 4-5 years; the end of the stage is taken to be the point of sharp inflection of the oil production rate curve (the ratio of the average annual oil production to its balance reserves).
The second stage – maintaining a high level of oil production – is characterized by:
The third stage – a significant decrease in oil production – is characterized by:
This stage is the most difficult and complex for the entire development process; its main task is to slow down the rate of decline in oil production. The duration of the stage depends on the duration of the previous stages and ranges from 5 to 10 years or more. It is usually difficult to determine the boundary between the third and fourth stages based on changes in the average annual rate of oil production. It can be most clearly determined by the inflection point of the water cut curve.
Together, the first, second and third stages are called the main development period. During the main period, 80–90% of recoverable oil reserves are taken from deposits.
The fourth stage – final – is characterized by:
The duration of the fourth stage is comparable to the duration of the entire previous period of deposit development, amounting to 15–20 years or more, determined by the limit of economic profitability, i.e., the minimum flow rate at which the operation of wells is still profitable. The profitability limit usually occurs when the product water cut is approximately 98%.
Placement of production and injection wells at the field
To maintain reservoir pressure and increase the reservoir recovery factor, which varies widely in different fields, pressure injection of water or gas into productive formations through injection wells is used. The first method is associated with the injection of specially prepared water into oil reservoirs under high pressure (about 20 MPa). There are contour, intra-circuit and areal flooding of oil reservoirs.
Introduction
Field development system
1 Multi-layer field development system. Identification of operational facilities
2 Systems for simultaneous development of objects
3 Systems for sequential development of objects
Development systems for production facilities (deposits)
2.1 Development systems with well placement on a uniform grid
2 Development systems with placement of wells along an uneven grid
Rational development system
Oil storage tanks
1 Classification of tanks
5. a brief description of tanks of various types
5.1 Reinforced concrete tanks
2 Vertical steel tanks (VS)
5.3 Vertical steel tanks type RVS low pressure
4 Vertical steel tanks type RVS high pressure
5 Tanks with floating roof and pontoons
6 Horizontal cylindrical tanks (HCT)
7 Drop-shaped tanks
8 Ball tanks
Conclusion
List of used literature
Introduction
A development system is a set of technical, technological and organizational interrelated engineering solutions aimed at moving oil (gas) in productive formations to the bottom of production wells. The development system includes the sequence and pace of drilling of the deposit; number, ratio, relative position of injection, production, special (monitoring, etc.) wells, the order of their commissioning; measures and methods for influencing productive formations in order to obtain specified rates of hydrocarbon extraction; measures to control and regulate the process of deposit development. The development of an oil field must be carried out according to a system that ensures best use natural properties of the oil reservoir, its operating mode, technology and equipment for the operation of wells and other objects and structures, subject to mandatory compliance with subsoil and environmental protection standards.
The deposit development system must ensure continuous monitoring and regulation of the deposit development process, taking into account new information about the geological structure obtained during drilling and exploitation of the deposit. To obtain information about the development object, about the conditions and intensity of fluid influx into the well, about changes occurring in the formation during its development, methods for studying wells and formations are intended.
Gathering of produced oil is the process of transporting oil, water and gas through pipelines from wells to a central collection point. Oil tanks are intended for accumulation, short-term storage and accounting of oil. The main requirement for tanks is reliability.
The purpose of the research of this work is to study the methods of the field development system, determine rational system extracting oil from the subsoil, choosing equipment for storing oil after extraction from deposits and transportation.
Research objectives:
Explore reservoir development systems and equipment for oil and gas storage.
1. Field development system
The system of development of oil fields and deposits is understood as a form of organizing the movement of oil in layers to production wells. The development system includes a set of technological and technical measures that ensure control of the process of developing oil deposits and aimed at achieving high production of oil reserves from productive formations while observing subsoil protection conditions. The oil field development system determines: the procedure for putting operational facilities of a multi-layer field into development; well placement grids at sites and their number; the pace and order of their introduction into work; ways to regulate the balance and use of reservoir energy.
It is necessary to distinguish between development systems for multi-layer deposits and individual deposits (single-layer deposits.)
1 Multi-layer field development system. Identification of operational facilities
In a multi-layer field, several productive layers are distinguished. A productive formation can be divided into interlayers, layers of reservoir rocks that are not developed everywhere. A separate layer reliably isolated from above and below by impermeable rocks, as well as several layers hydrodynamically connected to each other within the considered field area or part thereof, constitute an elementary development object.
An operational object (development object) is an elementary object or a set of elementary objects developed by an independent network of wells while ensuring control and regulation of the process of their operation.
Operational objects are identified on the basis of geological, technological and economic analyzes during the development design period. When deciding on the allocation of production facilities, it is recommended to take into account the following: the range of oil and gas content along the section (the thickness of the productive section); number of productive layers in the section; depth of productive formations; the thickness of intermediate unproductive strata and the presence of zones of confluence of productive strata; position of oil-water contacts in layers; lithological characteristics of productive formations; reservoir properties (especially permeability and effective thickness), the range of their change; difference in types of deposits by strata; deposit regimes and their possible changes; properties of oil in reservoir and surface conditions; oil reserves by reservoir.
If these conditions do not prevent the combination of layers into a single object, then hydrodynamic calculations are carried out to determine technological indicators, taking into account methods for regulating the balance of reservoir energy, monitoring and regulating the development process, as well as technical means of oil production. Then the economic efficiency of various options for combining individual formations into production facilities is determined. The scientifically based allocation of operational facilities is an important factor in saving and increasing development efficiency.
Depending on the order in which production facilities are put into development, two groups of multilayer oil field development systems are distinguished:
· systems for simultaneous development of objects;
· systems for sequential development of objects.
1.2 Systems for simultaneous development of objects
The advantage of systems for simultaneous development of objects is the ability to use the reserves of all objects after they are drilled. These systems can be implemented using one of the following options:
· separate development, when each object is operated by an independent network of wells. Requires a large number of wells, which leads to significant capital investments. Can be used when there are highly productive objects and the ability to quickly drill them out. Its advantage is to ensure reliable control over the development process and its regulation.
· joint development, in which two or more formations in the form of a single production facility are developed by a single network of production and injection wells. Its sub-variants are possible: with an increase in the number of production wells for low-productivity objects and with an increase in the number of injection wells for low-productivity objects. Its advantage is to ensure high current production levels for a given number of wells. However, unregulated development of reservoirs is generally observed, which leads to a deterioration in technical and economic indicators.
· joint-separate development, in which production wells are equipped with installations for simultaneous-separate operation, injection wells - with installations for simultaneous-separate injection of water. It allows you to overcome the disadvantages of the first two options, while maintaining their advantages.
3 Systems for sequential development of objects
Systems for sequential development of objects can be implemented according to the following main options:
· top-down development, in which each underlying object is exploited after the overlying one. It was used in the first period of development of the oil industry and is now recognized as largely irrational, as it delays the exploration and development of underlying objects, increases the volume of drilling and metal consumption for casing pipes, and increases the risk of violating the rules for protecting the subsoil of overlying objects when drilling underlying objects.
· bottom-up development, in which they begin to develop objects from the lower, so-called reference object, and then move on to return objects. If there are many objects, the most studied and highly productive objects with sufficiently large oil reserves are also chosen as reference objects, and the remaining objects are chosen as return objects. Then they begin to develop supporting objects, thereby not delaying the operation of overlying productive objects with large reserves.
It should be noted that the best performance can be achieved by a combination of all of the above options for multi-layer field development systems.
2. Development systems for production facilities (deposits)
Reservoir development systems are classified depending on the placement of wells and the type of energy used to move the oil.
Well placement refers to the placement grid and the distance between wells (grid density), the pace and order of putting the well into operation.
Development systems are divided into:
with placement of wells on a uniform grid
· with placement of wells along an uneven grid (mainly in rows).
1 Development systems with well placement on a uniform grid
Development systems with well placement on a uniform grid are distinguished: by the shape of the grid; by mesh density; according to the rate at which the well is put into operation; according to the order in which wells are put into operation relative to each other and the structural elements of the deposit.
The meshes are shaped like square and triangular.
Well pattern density refers to the ratio of oil-bearing area to the number of production wells.
Based on the rate at which wells are put into operation, we can distinguish between simultaneous (continuous) and slow deposit development systems.
In the first case, the pace of putting wells into operation is fast - all wells are put into operation almost simultaneously within one to three years of development of the facility.
A system is called slow when the input period is long.
According to the order of commissioning, a distinction is made between thickening and creeping systems.
At sites with a complex geological structure, a thickening system is used. The creeping system, oriented in relation to the structure of the formation, is divided into systems: down-dip; the top of the uprising; along strike.
2 Development systems with placement of wells along an uneven grid
Development systems with well placement along an uneven grid are similarly distinguished: by grid density; by the pace of putting a well into operation (putting rows of wells into operation); according to the order in which wells are put into operation. Additionally they are divided:
· according to the shape of the rows - with open rows and closed (circular) rows;
Depending on the type of energy used to move oil, there are:
· systems for developing oil deposits under natural conditions (natural reservoir energy is used);
· development system with maintaining reservoir pressure (methods are used to regulate the balance of reservoir energy by artificially replenishing it).
According to the methods of regulating the balance of reservoir energy, the following are distinguished:
· development systems with artificial flooding of formations;
· development systems with gas injection into the reservoir.
Development systems with artificial waterflooding of formations can be carried out according to the following main options:
Contour flooding - water is pumped into a number of injection wells located beyond the outer oil-bearing contour at a distance of 100-1000 meters.
Contour flooding - injection wells are placed in the oil-water zone in close proximity to the external oil-bearing contour.
Intra-circuit flooding - used at sites with large oil-bearing areas, and, if necessary, combined with contour or near-contour flooding.
Crown flooding - a series of injection wells are placed at or near the crown of a structure. This flooding is combined with contour flooding.
Focal flooding - used as an independent method in highly heterogeneous and discontinuous formations, as well as in combination with contour and especially intra-circuit flooding.
Area flooding is a dispersed injection of water into a reservoir over the entire area of its oil-bearing capacity.
The development system with gas injection into the reservoir is used in two main options: gas injection into the elevated parts of the reservoir (into the gas cap); area gas injection. Successful gas injection is possible only at significant inclination angles of homogeneous formations, low reservoir pressure, close values of reservoir pressure and oil saturation pressure with gas, or the presence of a natural gas cap, low oil viscosity. In terms of economic efficiency, it is significantly inferior to waterflooding, therefore its application is limited.
3. Rational development system
For the same field, one can name many systems that differ in the number of production wells, their location on the structure, the method of influencing productive formations, etc., so there is a need to formulate the concept of a rational development system. The following basic provisions are accepted as criteria for a rational development system.
· A rational development system should ensure the least degree of interaction between wells.
Minimal interaction between wells is achieved by increasing the distance between them. On the other hand, as the distance between wells increases, their total number in the field decreases, which leads to a decrease in the total production rate of wells. In addition, in conditions of a heterogeneous formation, an increase in the distance between wells can lead to the fact that some of the oil-saturated lenses, semi-lenses or interlayers will not be covered by the wells and they will not be included in development. Thus, the least interaction between wells cannot serve as the only all-encompassing criterion for the rationality of a development system.
· A rational system should ensure the highest oil recovery factor.
Maximum oil recovery can be achieved with full coverage of the oil-producing formation by the displacement process. This condition, especially in heterogeneous formations, can be met by placing wells closer together. In addition, since the highest coefficients are achieved under water pressure mode, and natural water inflows often do not provide high development rates, there is a need to create an artificial water pressure mode by injecting water or gas into the formation.
· A rational development system should ensure the minimum cost of oil.
From several development options considered during the design process, the option that provides the highest oil recovery is selected. Although the above criteria correctly define guidelines for choosing a development system, none of them can be accepted as decisive, since they do not take into account the need for oil production. Therefore, the concept of a rational development system in its final form is formulated as follows: a rational development system should ensure a given oil production at minimal costs and the highest possible oil recovery factors.
Development design consists of selecting an option that would meet the requirements of a rational development system.
When starting to design a development, the initial geological and physical data on the oil-producing formation and the properties of the liquids and gases saturating it are consistently determined; hydrodynamic calculations are performed to establish technological development indicators for several options that differ in the number of wells, the method of influencing productive formations, well operating conditions, etc.; calculated economic efficiency development options; economic and technological indicators of development are analyzed and the option of a rational development system is selected.
The introduction of a rational development system makes it possible to achieve high technical and economic indicators in field development.
Since field development begins with the selection of oil from the first exploration wells, it can be noted that the development system is dynamic and must be continuously improved over time.
4. Oil storage tanks
Produced oil is a mixture of oil, gas, mineralized water, mechanical impurities and other associated components - must be collected and dispersed over a large area of wells and processed as raw materials to obtain commercial products - commercial oil, oil gas, as well as formation water, which could be returned to the reservoir.
Gathering of produced oil is the process of transporting oil, water and gas through pipelines from wells to a central collection point. Oil tanks are intended for accumulation, short-term storage and accounting of oil.
1 Classification of tanks
Tanks for storing oil and petroleum products can be divided according to the following criteria:
· according to the material from which they are made - metal, reinforced concrete, earthen, synthetic and in mining;
· by design - vertical cylindrical with conical, floating and spherical roofs, with pontoons (mainly RVS type), horizontal cylindrical with flat and spatial bottoms (RGS type), teardrop-shaped, cylindrical, rectangular and trench tanks;
· according to the value of excess pressure - low-pressure tanks< = 0,002 МПа) и резервуары высокого (ри >0.002 MPa) pressure;
· by purpose - raw materials; technological; commodity.
Raw material tanks are designed to store water-flooded oil. Preliminary discharge of formation water is carried out in process tanks. Commercial tanks are designed for storing dehydrated and desalted oil.
Depending on their vertical location in relation to the adjacent territory, reservoirs are divided into above-ground, underground and semi-underground. Ground tanks are those whose bottom is at the same level or higher than the lowest level of the adjacent site. Reservoirs are called underground when highest level the oil in them is at least 0.2 m below the lowest level of the adjacent site, as well as tanks that are lined at least 0.2 m above the permissible highest level of oil in the tank and at least 3 m wide. Semi-underground tanks are called tanks , the bottom of which is buried to at least half its height, and the highest level of oil is no higher than 2 m above the surface of the adjacent territory.
Each operating tank must always have a full set of appropriate equipment provided for by the design and be in good working order. Disassembly during operation is not permitted.
The following equipment is installed on the tank, meeting the requirements of the standards and designed to ensure reliable operation of the tank:
· breathing valves;
· fire fuses;
· control and signaling devices (level gauges, level indicators, reduced POR samplers, gas pressure gauges;
· firecrackers;
· fire-fighting equipment;
· heating equipment;
· receiving and distributing pipes;
· stripping pipe;
· ventilation pipes;
· manholes;
· skylight;
· Measuring hatch.
Horizontal tanks are equipped with additional permanently built-in equipment: oil heaters; stairs; measuring pipes and other necessary devices.
The main requirement for tanks is reliability. Reliability of tanks is the property of their design to perform the functions of receiving, storing and releasing oil and petroleum products from them under given parameters.
Reliability criteria for tanks are: operability, reliability and durability. Performance is the state in which the tank is able to perform its functions. To maintain the operability of tanks, it is necessary to carry out routine and major repairs in a timely manner, as well as carry out prevention and early diagnosis of defects. Reliability is the ability of a tank to remain operational without forced interruptions in operation. Durability is the property of a tank to remain operational to its limiting state with the necessary breaks for Maintenance and repairs. An indicator of durability is service life.
5. Brief characteristics of various types of tanks
1 Reinforced concrete tanks
The normal range of reinforced concrete tanks in terms of their shape and volume includes: cylindrical oil tanks with a volume of 1, 3, 5, 10, 20, 30 and 40 thousand m 3; rectangular oil tanks with a volume of 0.1; 0.25; 0.5; 1, 2 and 3 thousand m3.
Picture 1. General form prefabricated reinforced concrete cylindrical tank. (1 - side panels; 2 - central support column; 3 - peripheral support column; 4 - metal cladding; 5 - monolithic reinforced concrete bottom; 6 - roof).
oil field gas reservoir
Crude oil and fuel oil do not have a chemical effect on concrete and calm the pores in concrete, thereby increasing the impermeability of tanks.
To create excess pressure and reduce losses in tanks up to 200 mm water. Art. constructive solutions should be provided to increase the gas impermeability of the coating, such as: installing a water screen with a layer of water of 100-150 mm on the tank coating; laying a carpet made of rubber-fabric or synthetic materials on the surface, followed by backfilling with a layer of earth 20-25 cm thick on top; sealing the coating with thin sheet steel, applying insulation from various solutions and mastics to the inner surface of the coating.
Underground reinforced concrete reservoirs have great buoyancy and when the groundwater level rises, this can lead to the floating of the tank and its failure. To protect against floating, the bottom of the tank is weighted, anchored, or removed from the groundwater zone with a device for sprinkling with soil.
2 Vertical steel tanks (VS)
Vertical low-pressure steel cylindrical tanks with a shielded conical or spherical roof, so-called atmospheric tanks, are the most common for oil storage. They are relatively simple to manufacture and the most economical in cost.
There are vertical cylindrical tanks of low and high pressure, with flat and spatial bottoms, with floating roofs and with pontoons.
The use of a tank roof of one design or another is dictated by the properties of the stored petroleum products and climatic conditions.
3 Vertical steel tanks type RVS low pressure
The pressure in such tanks differs little from atmospheric pressure, so their body is designed for hydrostatic pressure.
The covering deck is mounted and welded from separate sheets directly on the tank.
Tanks with a volume of 10, 20, 30 and 50 thousand m 3 for storing oil with a density of up to 0.9 t/m 3 are assembled from separate rolls of the body, bottom and panels, which form a spherical shape of the ceiling.
The shields rest on the body stiffening ring and the central ring.
Figure 2. General view of RVS-10000
A very important element is the foundation for the tank. Tanks with a capacity of up to 5000 m 3 (inclusive) are installed on an artificial foundation of a normal type, consisting of a soil backfill, a sand cushion and a waterproofing layer. To protect the metal of the tank bottom from corrosion by groundwater and from condensation, a waterproofing layer 100 mm thick is placed on top of the sand cushion, consisting of 90% sandy loam soil and 10% binder (bitumen, fuel oil, coal tar). For tanks with a volume of 10,000 m 3 or more, a reinforced concrete ring 1 m wide and 20-30 cm thick is provided under the junction of the tank body with the bottom. The settlement of the base of each tank must be systematically monitored.
4 Vertical steel tanks type RVS high pressure
High pressure tanks are designed to store oil with high pressure saturated vapors. They have a cylindrical body, a spherical roof and a flat bottom.
Figure 3. Vertical cylindrical high-pressure tank (1 - body; 2 - spherical coating; 3 - mating ring of the cylindrical body with the spherical surface of the coating; 4 - bottom; 5 - anchor fastenings; 6- top ring rigidity; 7 - anchor console; 8 - lower stiffening ring; 9 - wall; 10 - anchor bolt; 11 - concrete slab.)
To avoid possible lifting of the peripheral part of the bottom under the influence of excess pressure, the lower chord of the hull is fixed in the ground using anchor bolts and reinforced concrete slabs. The anchor bolts are fastened to the tank wall using welded consoles.
To absorb wind loads and vacuum, the tank body (upper chords) must be reinforced with stiffening rings.
5 Tanks with floating roof and pontoons
These tanks are used to reduce oil losses from evaporation.
The pontoon is built in tanks with a stationary shield roof, which protects against precipitation from reaching the surface of the pontoon. Pontoons in tanks can be made of either metal or synthetic materials.
The buoyancy of a metal pontoon is ensured by the installation of hermetic boxes or open compartments along the contour.
A sealing valve is installed along the circumference of the pontoon between the pontoon and the wall of the tank to reduce the evaporation area to a minimum. The shutter can be hard or soft. Soft shutters are made of rubberized fabric, polyurethane foam and other materials. Rigid valves consist of lever-type metal elements.
It is especially advisable to use these tanks for sour oils, because Due to the absence of a gas space, corrosion from the decomposition of sulfur compounds is practically absent.
The floating roof is made of steel sheets with a thickness of at least 4 mm, with a diameter of 400 mm less than the internal diameter of the tank.
A floating roof is usually of two types: double pontoon, consisting of a number of sealed compartments that ensure unsinkability if the pontoon seal is broken; single with a central disk made of steel sheets, along the periphery of which there is a ring pontoon, divided by radial partitions into hermetic compartments that prevent the roof from sinking.
When operating floating roof tanks in winter time it is necessary: carefully inspect the valves before starting pumping or pumping, and if they freeze to the tank body, carefully tear them off using a wooden wedge; do not allow one-sided snow load (excess snow should be removed when the roof is in the upper extreme position).
Figure 4. Tank with a floating roof (1 - shutter; 2 - floating roof; 3 - mobile articulated ladder; 4 - safety valve; 5 - drainage system for removing atmospheric water; 6 - sampling pipe; 7 - support posts; 8 - gauging hatch).
5.6 Horizontal cylindrical tanks (HCT)
These tanks have received wide application for storing oil in small quantities. The advantages of horizontal tanks include the possibility of serial production at factories, storage of oil under high excess pressure and vacuum, and the convenience of underground installation. RGS volumes are from 3 to 200 m 3 . Working pressure up to 2.5 MPa and vacuum up to 0.09 MPa. The bottom of the tanks is made spherical, flat or cylindrical. For high pressures, spherical bottoms are used.
The tanks are equipped with metal platforms and ladders for maintenance, and when storing viscous oil that requires heating, with sectional heaters. When installed above ground, the tank is installed on two saddle-shaped supports 300-400 mm wide made of prefabricated concrete blocks or monolithic concrete. When installed underground, the tank should be laid on a profiled sand cushion with a thickness of at least 200 mm with an angle of coverage of the sand cushion of 900. For above-ground installation, in addition, a layer of hydrophobic sand 100 mm thick should be laid between the sand cushion and the tank.
5.7 Drop tanks
Their main purpose is to store oils with high saturated vapor pressure under an excess pressure of 0.4 kgf/cm 2 and a vacuum of up to 500 mm of water. Art., which can significantly reduce losses from evaporation compared to “atmospheric” reservoirs. However, the cost of a cylindrical “atmospheric” tank is significantly less than a drop-shaped one of the same volume. Therefore, an indispensable condition for the widespread introduction of drop-shaped tanks is its efficiency, which is determined by comparison additional cost and savings from reducing losses during the depreciation period.
8 Ball tanks
These are high-pressure tanks designed for storing oils with high pressure of saturated vapors and liquefied gases (Figure 6).
Figure 5. Ball tank (1 - breathing valve assembly; 2 - float level indicator; 3 - combined unit for measuring level, oil temperature and sampling; 4 - shut-off valves; 5 - receiving and distributing pipes; 6 - drain valve).
The material is low alloy steel.
Tank volume: 300, 600, 900, 2000 and 4000 m3.
Conclusion
The development and operation of oil and gas fields includes a scientifically based production process for extracting from the subsoil the hydrocarbons and associated minerals they contain; the process of designing systems for the development of oil and gas deposits, the relative position of the bottoms of production, injection, reserve and other wells, drilling of the field in accordance with the approved technological documentation, the development of oil and gas reserves.
Successful development of oil and gas fields is determined by how correctly the development system is chosen. During the development process, there is a need to monitor and clarify the state of deposits, taking into account new information about the geological structure obtained during their drilling and operation.
It should be noted that for the same field one can name many systems that differ in the number of production wells, their location on the structure, the method of influencing productive formations, etc., therefore there is a need to use a rational development system.
Everything that comes out of wells - oil with associated gas, water and other impurities - is measured, determining the percentage of water and associated gas. Technological processes Oil preparation for all collection systems is similar: separation or phase separation, product demulsification, desalting, oil stabilization.
After stabilization, the oil is sent to process tanks, where further separation of oil from water occurs, and from there it goes to the commodity tanks of the RVS. Oil tanks are containers designed for accumulation, short-term storage and accounting of crude and commercial oil. The most widely used tanks are the RVS type (vertical steel tank).
The main requirement for tanks is reliability. Reliability criteria for tanks are: operability, reliability and durability. Performance is the state in which the tank is able to perform its functions. To maintain the operability of tanks, it is necessary to carry out routine and major repairs in a timely manner, as well as carry out prevention and early diagnosis of defects. Reliability is the ability of a tank to remain operational without forced interruptions in operation. Durability is the property of a tank to remain operational up to its limit state with the necessary breaks for maintenance and repairs. An indicator of durability is service life.
List of used literature
1. Control over the development of oil and gas fields / a manual for self-study for students of advanced training courses in the specialty "Geophysics" / Kazan: Kazansky State University/ V.E. Kosarev / 2009.
Operator of dewatering and desalting plant / M. Nedra / Kashtanov A.A., Zhukov S.S. / 1985.
Development and operation of oil fields: a textbook for universities / M.: Nedra / Boyko V.S. / 1990.
Development of oil and gas fields / tutorial/ Pokrepin B.V.
Development and operation of oil and gas fields / educational and methodological manual / Perm: Perm Publishing House. national research Polytechnic University / I.R. Yushkov, G.P. Khizhnyak, P.Yu. Ilyushin / 2013.
A reference guide for designing the development and operation of oil and gas fields. / M.: Nedra / Gimatudinov Sh.K., Borisov Yu.P., Rlzenberg M.D. / 1983.
Oil refinery directory / M., Nedra Lastovin G.A., Radchenko E.D., Rudina M.G. / 1986.
Technological foundations of technology / M.: Metallurgy / I.M. Glushchenko. GI. / 1990.
Operation of oil and gas wells. / M: Nedra / Muravyov V.M. / 1978.
Reservoir development systems are classified depending on the placement of wells and the type of energy used to move the oil.
Well placement. Well placement refers to the placement grid and distances between wells (grid density), the pace and order of putting wells into operation. Development systems are divided into the following: with wells placed on a uniform grid and with wells placed on an uneven grid (mainly in rows).
Development systems with well placement on a uniform grid are distinguished: according to the shape of the grid; by mesh density; by the rate of commissioning of wells; according to the order in which wells are put into operation relative to each other and the structural elements of the deposit. Meshes are shaped like square and triangular (hexagonal). With a triangular grid, 15.5% more wells are placed on the area than with a square grid in the case of equal distances between wells.
Under mesh density wells imply the ratio of oil-bearing area to the number of producing wells. However, this concept is very complex. Researchers often put different meanings into the concept of well pattern density: they take only the area of the drilled part of the deposit; the number of wells is limited by different values of the total oil production from them; whether or not injection wells are included in the calculation; in the process of field development, the number of wells changes significantly, the oil-bearing area under pressure conditions decreases, this is taken into account in different ways, etc. Sometimes a distinction is made between small, medium and large degrees of well compaction. These concepts are very conventional and different for different oil-field regions and periods of development of the oil industry. The problem of optimal well pattern density, ensuring the most efficient development of fields, was the most acute at all stages of development of the oil industry. Previously, the density of the well grid varied from 10 4 m 2 / well (the distance between the wells is 100 m) to (4-9)-10 4 m 2 / well, and from the late 40s - early 50s they switched to well grids with density (30-60)10 4 m 2 /well. Based on the theory of interference and a simplified schematization of the process of displacement of oil by water from a homogeneous formation, it was believed that when developing oil fields under water pressure, the number of wells does not significantly affect oil recovery.
Development practice and further research have established that in real heterogeneous formations, the density of the well pattern has a significant impact on oil recovery. This influence is greater the more heterogeneous and discontinuous the productive formations are, the worse the lithological and physical properties of the reservoirs are, the higher the viscosity of oil in reservoir conditions, more oil initially contained in water-oil and sub-gas zones. Compaction of a well pattern in heterogeneous lens-shaped formations significantly increases oil recovery (development coverage), especially with successful placement of wells relative to various lenses and screens. The greatest influence is exerted by the mesh density in the range of mesh densities of more than (25 - 30) 10 4 m 2 /sq. In the range of grid densities less than (25-30) 10 4 m 2 /sq, although the influence is noted, it is not as significant as with rarer grids. In each specific case, the choice of mesh density should be determined taking into account specific conditions.
Nowadays, two-stage drilling of initially sparse well patterns and their subsequent selective compaction are used in order to increase the coverage of heterogeneous formations by waterflooding, increase final oil recovery and stabilize oil production. In the first stage, the so-called main stock of production and injection wells is drilled at a low grid density. To be determined based on drilling and testing data from the main stock wells geological structure heterogeneous object, as a result of which changes in the density of the well pattern are possible, which are drilled in the second stage and are called reserve ones. Reserve wells are provided for the purpose of involving in the development of individual lenses, pinch-out zones and stagnant zones, which are not involved in the development of wells of the main stock within the contour of their location. The number of reserve wells is justified taking into account the nature and heterogeneity of the formations (their discontinuity), the density of the well pattern, the viscosity ratio of oil and water, etc. The number of reserve wells can be up to 30 % main well stock. Their placement should be planned in more early dates development. Note that to replace actually<* ликвидированных скважин из-за старения (физического износа) или по техническим причинам (в результате аварий при эксплуатации добывающих и нагнетательных скважин) требуется обосновывать также число скважин-дублеров, которое может достигать 10 - 20 % фонда.
Based on the rate at which wells are put into operation, we can distinguish simultaneous(also called “solid”) and slow deposit development system. In the first case, the pace of putting wells into operation is fast - all wells are put into operation almost simultaneously during the first one to three years of development of the facility. If the commissioning period is long, the system is called slow, which, according to the order in which wells are put into operation, is distinguished into thickening and creeping systems. It is advisable to use a thickening system on objects with a complex geological structure. It corresponds to the principle of two-stage drilling. The creeping system, oriented in relation to the structure of the formation, is divided into systems: a) down dip; b) up the uprising; c) along strike. In the practice of developing large domestic fields, creeping and condensing development systems are comprehensively combined. Only difficult natural (swamps, swamps) and geological conditions determined the use of a creeping system at the Samotlor field.
Development systems with placement of wells along a uniform grid are considered appropriate in reservoir operating modes with fixed contours (dissolved gas mode,
gravitational mode), i.e. with uniform distribution of reservoir energy over the area.
Development systems with well placement in uneven The mesh is similarly distinguished: by mesh density; by the pace of putting wells into operation (putting rows of wells into operation - one row, two, three are in operation); according to the order in which wells are put into operation. Additionally, they are divided: according to the shape of the rows - with open rows and with closed (circular) rows; according to the relative position of rows and wells - with maintained distances between rows and between wells in rows and with compaction of the central part of the area.
Such systems were widely used in reservoir operating modes with moving contours (water, gas pressure, pressure-gravity and mixed modes). In this case, the wells were placed in rows parallel to the original oil-bearing contour. With modern design, the initial spacing of wells is almost always uniform.
Type of energy used. Depending on the type of energy used to move oil, there are: systems for developing oil deposits under natural conditions, when only natural reservoir energy is used (without pressure maintenance); systems that maintain reservoir pressure, when methods are used to regulate the balance of reservoir energy by artificially replenishing it.
According to the methods of regulating the balance of reservoir energy, there are: development systems with artificial flooding of reservoirs; development systems with gas injection into the reservoir.
Development systems with artificial waterflooding can be carried out according to the following main options: contour, peripheral, intra-circuit, barrier, block, bottom, focal, areal flooding.
Development systems with gas injection into the reservoir can be used in two main options: gas injection into elevated parts of the reservoir (into the gas cap), area gas injection.