Oil well depth. Construction of oil and gas wells

In short, there are two main processes going on inside:
separation of gas from liquid- gas entering the pump may disrupt its operation. For this purpose, gas separators are used (or a gas separator-dispersant, or simply a dispersant, or a dual gas separator, or even a dual gas separator-dispersant). In addition, for normal operation pump, it is necessary to filter out sand and solid impurities contained in the liquid.
rise of liquid to the surface- the pump consists of many impellers or impellers, which, when rotating, accelerate the fluid.

As I already wrote, electric centrifugal submersible pumps can be used in deep and inclined oil wells (and even horizontal ones), in heavily watered wells, in wells with iodine-bromide waters, with high salinity of formation waters, for lifting salt and acid solutions. In addition, electric centrifugal pumps have been developed and produced for the simultaneous and separate operation of several horizons in one well. Sometimes electric centrifugal pumps are also used to inject mineralized formation water into an oil reservoir in order to maintain reservoir pressure.

The assembled ESP looks like this:

Once the liquid is brought to the surface, it must be prepared for transfer to the pipeline. Coming from oil and gas wells the products do not represent pure oil and gas, respectively. Produced water, associated (petroleum) gas, and solid particles of mechanical impurities (rocks, hardened cement) come from wells along with oil.
Produced water is a highly mineralized medium with a salt content of up to 300 g/l. The content of formation water in oil can reach 80%. Mineral water causes increased corrosive destruction of pipes and tanks; solid particles coming with the oil flow from the well cause wear and tear on pipelines and equipment. Associated (petroleum) gas is used as raw material and fuel. It is technically and economically feasible to subject oil to special preparation before entering the main oil pipeline for the purpose of desalting, dehydrating, degassing, and removing solid particles.

First, the oil enters automated group metering units (AGMU). From each well, oil along with gas and formation water is supplied to the AGSU through an individual pipeline. The AGZU records the exact amount of oil coming from each well, as well as primary separation for partial separation of formation water, oil gas and mechanical impurities with the direction of the separated gas through a gas pipeline to the GPP (gas processing plant).

All production data - daily flow rate, pressure, etc. are recorded by operators in the cultural booth. Then this data is analyzed and taken into account when choosing a production mode.
By the way, readers, does anyone know why the cultural booth is called that?

Next, the oil, partially separated from water and impurities, is sent to an integrated oil treatment unit (ITU) for final purification and delivery to the main pipeline. However, in our case, the oil first passes to the booster pump station (BPS).

As a rule, booster pumping stations are used in remote fields. The need to use booster pumping stations is due to the fact that often in such fields the energy of the oil and gas bearing formation is not enough to transport the oil and gas mixture to the treatment unit.
Booster pumping stations also perform the functions of separating oil from gas, purifying gas from dropping liquid and subsequent separate transportation of hydrocarbons. In this case, oil is pumped by a centrifugal pump, and gas is pumped under separation pressure. DNS differ in types depending on the ability to pass various liquids through them. Booster pump station full cycle it consists of a buffer tank, a unit for collecting and pumping out oil leaks, the pumping unit itself, as well as a group of spark plugs for emergency gas release.

In oil fields, after passing through group metering units, oil is taken into buffer tanks and, after separation, enters the buffer tank in order to ensure a uniform supply of oil to the transfer pump.

UKPN is a small plant where oil undergoes final preparation:

• Degassing(final separation of gas from oil)
• Dehydration(destruction of the water-oil emulsion formed during lifting of products from the well and transporting it to the UKPF)
• Desalting(removal of salts by adding fresh water and repeated dehydration)
• Stabilization(removal of light fractions in order to reduce oil losses during its further transportation)

For more effective preparation Chemical and thermochemical methods, as well as electrical dehydration and desalting, are often used.
Prepared (marketable) oil is sent to a commodity fleet, which includes tanks of various capacities: from 1000 m³ to 50,000 m³. Next, the oil is fed through the main pumping station into the main oil pipeline and sent for processing. But we'll talk about this in the next post :)

In previous releases:
How to drill your own well? Oil and Gas Drilling Basics in One Post -

Vladimir Khomutko

Reading time: 5 minutes

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What is an oil well?

It’s hard to imagine without petroleum products modern life. They are made from oil, which is extracted using special mining operations. Many of us have heard the term "oil well", but hardly everyone knows what it really is. Let's try to figure out what this structure is and what they are like.

A well is a cylindrical mine opening whose diameter is many times less than the total length of its shaft (depth).

In addition to the well, there are also mining workings such as a well and a mine. How do they differ from the definition we are considering? It's actually quite simple. A person can get into a mine or well, but not into a well. Thus, an additional definition of this structure is as follows: a mine opening, the layout and shape of which excludes human access to it.

The upper part of such a working is called the mouth, and the lower part is called the face. The walls going down form the so-called trunk.

Everyone knows that wells are made by drilling. However, to say that they are simply drilled would be incorrect. These capital structures, complex in their structure, are rather built underground, and therefore they are classified as the organization’s fixed assets, and the costs of their drilling and arrangement are capital investments.

Construction of oil and gas wells

The well design is selected at the design stage and must meet the following requirements:

• the design should provide free access to the bottom of geophysical instruments and downhole equipment;
• the design must prevent the collapse of the barrel walls;
• it must also ensure reliable separation of all passable layers from each other and prevent the flow of fluids from layer to layer;
• if necessary, the design of this excavation should make it possible to seal its mouth if such a need arises.

The construction and installation of oil and gas wells is carried out as follows:

1. The first step is to drill an initial large-diameter shaft. Its depth is about 30 meters. Then a metal pipe, which is called a direction, is lowered into the drilled hole, and the space surrounding it is installed with special casing pipes and cemented. The purpose of the direction is to prevent erosion of the upper soil layer during further drilling.
2. Further, to a depth of 500 to 800 meters, a shaft of smaller diameter is drilled, into which a column of pipes, called a conductor, is lowered. The space between the pipe walls and the rock is also filled with cement mortar to its entire depth.
3. Only after the direction and conductor have been arranged, the well is drilled to the depth specified by the design, and a pipe string of even smaller diameter is lowered into it. This column is called operational. If the formation depth is large, then it is possible to use so-called intermediate pipe columns. The entire space between the wellbore and the surrounding rock is filled with cement.

What is the main purpose of a conductor? The fact is that at depths of up to 500 meters there is an active zone of fresh water, and below this depth (depending on the development region) a zone with difficult water exchange begins, in which there is a lot of salt water and other mobile fluids (including gases and oil ). So, the main task of the conductor is additional protection that prevents salinization of surface fresh waters and does not allow harmful substances that are concentrated in the lower layers to penetrate into them.

What types of wells are there?

Depending on the geological conditions in which they are located oil fields, are drilling different types such workings.

Main types of wells:

• vertical;
• oblique directional;
• horizontal;
• multi-barrel or multi-hole.

A well is called vertical if the angle of deviation of its trunk from the vertical is no more than five degrees.

If this angle is more than five degrees, then it is already an oblique-directional type.

A well is called horizontal if the angle of deviation of its trunk from the vertical is approximately 90 degrees. However, there are some nuances to this definition. Since “straight lines” are rarely found in living nature, and the developed strata most often lie with some slope, then from a practical point of view, as a rule, there is no point in drilling strictly horizontal wells.

It is easier and more efficient to direct the barrel along the optimal trajectory. Based on this, we can define the horizontal type of such workings as a well that has an extended shaft, drilled as close as possible to the direction of the target productive formation while maintaining the optimal azimuth.

Wells that have two or more trunks are called multilateral or multilateral. Their difference from each other is in the location of the branching point, at which additional ones depart from the main table. If this point is located above the level of the productive horizon, then this type of development is called multi-shaft. If this point is located within the productive horizon, then this is a multilateral well type.

Simply put, if the main trunk is drilled to the developed formation, and additional branches are drilled inside it, then this is a multilateral type (the productive formation is broken through at one point). All other workings with several shafts are classified as multi-barrel (several points of penetration of the formation). Also, this type of well is typical in cases where the layers are located at different horizons.

In addition, there are also cluster wells. In this case, several trunks diverge at different angles and to different depths, and their mouths are close to each other (like a bush planted upside down).

This classification provides for the following categories of such mine workings:

Exploration drilling is carried out in areas whose oil or gas content has already been established, in order to clarify the volumes of discovered hydrocarbon deposits and to clarify the initial parameters of the field, which are necessary when designing a method for developing a field, therefore special attention is paid to exploration.

Production drilling creates the following types of workings:

• main (production and injection);
• reserve;
• control;
• evaluative;
• duplicating;
• wells special purpose(absorbing, water intake and so on).

The extraction of raw materials itself is carried out through mining workings, which are pumping, gas-lift and fountain.

Purpose injection wells– impact on the developed formation by injecting steam, gas or water into it, as well as other working media. They are intra-contour, peri-contour and contour.

Reserve ones are necessary for the development of individual and stagnant zones, as well as pinch-out zones that are not included in the contour of the main wells.

Controls are needed to monitor the current position of the contact zones of the extracted resource and water and other changes in the formation under development. In addition, they help control pressure in productive formations.

Estimators are needed for a preliminary assessment of fields being prepared for development. They help determine the boundaries and sizes of reserves, as well as other necessary preliminary parameters.

Duplicate ones are used during the replacement of wells in the main stock that are being liquidated due to physical wear or accidents.

Through special ones, process water is extracted, industrial water is discharged, open fountains are eliminated with their help, and so on.

The process of drilling an oil well, by the nature of its impact on rocks, is:

• mechanical;
• thermal;
• physico-chemical;
• electric and so on.

Oil well design

Industrial development of deposits involves the use of only mechanical methods that use different modes drilling All other drilling methods are in experimental development.

Mechanical drilling methods are divided into rotary and percussion.

The impact method is the mechanical destruction of rock, which is carried out by a special tool suspended on a rope - a chisel. Such a drilling complex also includes a rope lock and a shock rod. This device is suspended on a rope, which is thrown over a block mounted on the drilling mast. The reciprocating movement of the bit is provided by a special drilling rig. The barrel acquires a cylindrical shape due to the rotation of the bit during operation.

The process of constructing a well by destroying rocks is called drilling. A borehole is a mine opening with a circular cross-section, constructed without access to people, and whose length is many times greater than its diameter.

Rice. 3.1. Basic elements of a well

The upper part of the well, located on the ground, is called mouth, well bottom face, the side surface is a wall, and the space limited by the wall is barrel wells (Fig. 3.1). The length of the well is the distance from the mouth to the bottom along the axis of the wellbore, and the depth is the projection of the length onto the vertical axis. The length and depth are numerically equal only for vertical wells, but for inclined and curved wells they do not coincide.

The wellbore is secured using columns casing pipes of different diameters, concentrically located one inside the other (Fig. 3.2).

Since the wellhead usually lies in an area of ​​easily eroded rocks, it needs to be strengthened. To do this, they first drill a pit - a well 4...8 m long to the depth of stable rocks. A pipe is installed in the well, and the space between the pipe and the rock wall is filled with rubble stone and filled with cement mortar. This area is called direction.

Rice. 3.2. Scheme of fastening the wellbore with casing columns:

4 – production string; 5 – oil reservoir

Next, a section is drilled to a depth of 50 to 400 m with a diameter of up to 900 mm. This section of the well is secured using a casing string called conductor. The annulus of the conductor is cemented. With the help of a conductor, the upper aquifers are blocked, as well as unstable, soft and fractured rocks, which complicate the drilling process.

After installing the casing, it is not always possible to drill a well to the designed depth due to the passage of new complex horizons or due to the need to isolate productive formations that are not planned to be exploited by this well. In such cases, another casing string called intermediate. If the productive formation lies very deep, then the number of intermediate columns may be more than one.

The last, longest casing string is called operational column. It is designed to cover the productive formation and allow oil to enter the production pipes. To avoid the flow of oil and gas into overlying horizons, and water into productive formations, the space between the production casing and the well wall is also filled with cement mortar.

Various methods are used to extract oil from a reservoir. In most cases (more than 90%), the well is drilled to the bottom of the productive formation. Then it is produced formation opening.

Rice. 3.3. Scheme of oil flow into the wellbore after opening the formation:

1 – production string; 2 – cement ring; 3 – oil reservoir;

4 – bottom of the formation

To do this, in the lower part of the production string located in the oil reservoir, using special perforating devices, a series of holes are shot in the pipe wall and cement ring. These holes serve as channels for oil to enter the production pipes (Fig. 3.3).

If the oil reservoir is composed of dense rocks, then the bottomhole zone is not cemented or the production string is lowered only to the top of the reservoir (open bottom hole).

Wells designed for oil and gas production are called operational.

When searching, exploring and developing oil fields, other types of wells are also used. For injection of water and gas into a reservoir they are used injection wells. Supporting the wells are designed to study the composition and age of rocks. Parametric wells are being laid to clarify the geological structure and oil and gas prospects of the area. Structural wells are drilled to identify promising areas and prepare them for exploration drilling Search engines wells are drilled to discover new deposits. Exploration wells are drilled to study the size and structure of the deposit, to calculate oil and gas reserves and to design its development. Observational wells are drilled to control the development of deposits.

General information about drilling oil And gas wells

1.1. BASIC TERMS AND DEFINITIONS

Rice. 1. Well design elements

A borehole is a cylindrical mine opening, constructed without human access and having a diameter many times smaller than its length (Fig. 1).

Main elements of a borehole:

Wellhead (1) – intersection of the well route with the surface

Borehole bottom (2) – the bottom of the borehole, moving as a result of the impact of the rock-cutting tool on the rock

Well walls (3) – side surfaces drilling rig wells

Well axis (6) - an imaginary line connecting the centers of the cross sections of the drill hole

*Wellbore (5) is the space in the subsurface occupied by a borehole.

Casing strings (4) – strings of interconnected casing pipes. If the well walls are made of stable rocks, then casing strings are not lowered into the well

The wells are deepened, destroying the rock over the entire face area (with a continuous face, Fig. 2 a) or along its peripheral part (with an annular face, Fig. 2 b). In the latter case, a column of rock - a core - remains in the center of the well, which is periodically raised to the surface for direct study.

The diameter of wells, as a rule, decreases from the mouth to the bottom in steps at certain intervals. Initial diameter oil And gas wells usually do not exceed 900 mm, and the final one is rarely less than 165 mm. Depths oil And gas wells vary within several thousand meters.

According to their spatial location in the earth's crust, boreholes are divided (Fig. 3):

1. Vertical;

2. Inclined;

3. Rectilinearly curved;

4. Curved;

5. Rectilinearly curved (with a horizontal section);

Rice. 3. Spatial arrangement of wells

Complexly curved.

Oil and gas Wells are drilled on land and offshore using drilling rigs. In the latter case, drilling rigs are mounted on racks, floating drilling platforms or ships (Fig. 4).

Rice. 4. Types of boreholes

IN oil and gas industries drill wells for the following purposes:

1. Operational- For oil production, gas And gas condensate

2. Injection - for pumping water into productive horizons (less often air, gas) in order to maintain reservoir pressure and extend the flow period of field development, increase production operational wells equipped with pumps and air lifts.

3. Exploration – to identify productive horizons, delineate, test and assess their industrial significance.

4. Special - reference, parametric, evaluation, control - for studying the geological structure of a little-known area, determining changes in reservoir properties of productive formations, monitoring reservoir pressure and the front of movement of the oil-water contact, the degree of production of individual sections of the formation, thermal effects on the formation, ensuring in-situ combustion , oil gasification, reset Wastewater into deep-seated absorption layers, etc.

5. Structural search - to clarify the position of promising oil-gas-bearing structures according to the upper marking (defining) horizons repeating their outlines, according to the data of drilling small, less expensive wells of small diameter.

Today oil And gas wells are capital, expensive structures that last for many decades. This is achieved by connecting the productive formation to the surface with a sealed, strong and durable channel. However, the drilled wellbore does not yet represent such a channel, due to the instability of rocks, the presence of layers saturated with various fluids (water, oil, gas and mixtures thereof), which are under different pressures. Therefore, when constructing a well, it is necessary to secure its trunk and isolate (isolate) the layers containing different fluids.

Casing

Fig.5. Casing pipe in a well

The wellbore is secured by lowering special pipes called casing into it. A series of casing pipes connected in series with each other makes up the casing string. Steel casing pipes are used to secure wells (Fig. 5).

The layers saturated with various fluids are separated by impenetrable rocks - “tires”. When drilling a well, these impermeable isolation seals are broken and the possibility of interlayer flows, spontaneous outflow of formation fluids to the surface, watering of productive formations, pollution of water supply sources and the atmosphere, and corrosion of casing strings lowered into the well is created.

During the process of drilling a well in unstable rocks, intensive cavern formation, screes, landslides, etc. are possible. In some cases, further deepening of the wellbore becomes impossible without first securing its walls.

To eliminate such phenomena, the annular channel (annular space) between the well wall and the casing string lowered into it is filled with plugging (insulating) material (Fig. 6). These are compositions that include a binder, inert and active fillers, and chemical reagents. They are prepared in the form of solutions (usually aqueous) and pumped into the well with pumps. Of the binders, Portland cement cements are the most widely used. Therefore, the process of separation of layers is called cementation.

Thus, as a result of drilling a shaft, its subsequent fastening and isolation of layers, a stable underground structure of a certain design is created.

Well design is understood as a set of data on the number and dimensions (diameter and length) of casing strings, wellbore diameters for each string, cementing intervals, as well as methods and intervals for connecting the well to the productive formation (Fig. 7).

Information on the diameters, wall thicknesses and steel grades of casing pipes at intervals, on types of casing pipes, equipment The bottom of the casing is included in the concept of casing design.

Casing strings for a specific purpose are lowered into the well: direction, conductor, intermediate columns, operational Column.

The direction is lowered into the well to prevent erosion and collapse of rocks around the mouth when drilling under the conductor, as well as to connect the well to the drilling fluid cleaning system. The annular space behind the direction is filled along the entire length with cement mortar or concrete. The direction goes down to a depth of several meters in stable rocks, to tens of meters in swamps and muddy soils.

The conductor usually covers the upper part of the geological section, where there are unstable rocks, layers that absorb drilling rig solution or developing, supplying formation fluids to the surface, i.e. all those intervals that will complicate the process of further drilling and cause environmental pollution natural environment. The conductor must cover all layers saturated with fresh water.

Rice. 7. Well design diagram

The conductor also serves to install a blowout preventer wellhead equipment and suspension of subsequent casing strings. The conductor is lowered to a depth of several hundred meters. To ensure reliable separation of layers and impart sufficient strength and stability, the conductor is cemented along its entire length.

Operational the column is lowered into the well to extract oil, gas or injection of water into the productive horizon or gas in order to maintain reservoir pressure. The height of rise of the cement slurry above the roof of productive horizons, as well as the device for stage cementing or the connection unit for the upper sections of casing strings in oil And gas wells should be at least 150-300 m and 500 m, respectively.

Intermediate (technical) columns must be lowered if it is impossible to drill to the designed depth without first isolating the zones of complications (shows, collapses). The decision to lower them is made after analyzing the pressure ratio that occurs during drilling in the well-reservoir system.

If the pressure in the well Рс is less than the formation Рpl (pressure of the fluids saturating the formation), then fluids from the formation will flow into the well, and manifestation will occur. Depending on the intensity, manifestations are accompanied by self-outflow of fluid ( gas) at the wellhead (overflows), emissions, open (uncontrolled) flowing. These phenomena complicate the well construction process and create the threat of poisoning, fires, and explosions.

When the pressure in the well increases to a certain value, called the absorption onset pressure Rpogl, fluid from the well enters the formation. This process is called absorption drilling solution. Рgl can be close to or equal to the reservoir pressure, and sometimes approaches the value of vertical rock pressure, determined by the weight of the rocks located above.

Sometimes absorption is accompanied by fluid flows from one formation to another, which leads to contamination of water supplies and productive horizons. A decrease in the fluid level in the well due to absorption in one of the formations causes a decrease in pressure in the other formation and the possibility of manifestations from it.

The pressure at which natural closed cracks open or new ones form is called hydraulic fracturing pressure Pgrp. This phenomenon is accompanied by catastrophic absorption drilling solution.

It is characteristic that in many oil and gas bearing areas reservoir pressure Ppl is close to the hydrostatic pressure of the fresh water column Pg (hereinafter simply hydrostatic pressure) with a height Hj equal to the depth Hp at which the given formation lies. This is explained by the fact that the fluid pressure in the formation is often caused by the pressure of marginal waters, the feeding area of ​​which is connected with the day surface at significant distances from the field.

Since the absolute values ​​of pressures depend on the depth H, it is more convenient to analyze their ratios using the values ​​of relative pressures, which are the ratios of the absolute values ​​of the corresponding pressures to the hydrostatic pressure Pr, i.e.:

Rpl* = Rpl / Rg;

Рgr* = Рgr / Рг;

Rpogl* = Ppogl / Pr;

Rgrp* = Rgrp / Rg.

Here Рпл – reservoir pressure; Рgr – hydrostatic pressure of drilling fluid; Рpgl – absorption onset pressure; Pgrp – hydraulic fracturing pressure.

Relative reservoir pressure Ppl* is often called the anomaly coefficient Ka. When Rpl* is approximately equal to 1.0, the reservoir pressure is considered normal, when Rpl* is greater than 1.0 it is considered abnormally high (ABPD), and when Rpl* is less than 1.0 it is considered abnormally low (ANPD).

One of the conditions for a normal uncomplicated drilling process is the ratio

a) Rpl*< Ргр* < Рпогл*(Ргрп*)

The drilling process becomes more complicated if, for some reason, the relative pressures end up in the following ratio:

b) Rpl* > Rgr*< Рпогл*

or

c) Rpl*< Ргр* >Rpogl* (Rgrp*)

If relation b) is true, then only manifestations are observed, if c), then both manifestations and absorptions are observed.

Intermediate columns can be solid (they are lowered from the mouth to the bottom) or non-solid (not reaching the mouth). The latter are called shanks.

It is generally accepted that a well has a single-column structure if no intermediate columns are lowered into it, although both the direction and the conductor are lowered. With one intermediate string, the well has a two-string design. When there are two or more technical strings, the well is considered multi-string.

The well design is specified as follows: 426, 324, 219, 146 – casing diameters in mm; 40, 450, 1600, 2700 – casing running depths in m; 350, 1500 – level of cement slurry behind the shank and operational column in m; 295, 190 – bit diameters in mm for drilling a well for 219 and 146 mm columns.

1.2. WELL DRILLING METHODS

Wells can be drilled using mechanical, thermal, electric pulse and other methods (several dozen). However industrial application Only mechanical drilling methods are found - impact and rotary. The rest have not yet left the experimental development stage.

1.2.1. IMPACT DRILLING

Impact drilling. Of all its varieties, percussion-rope drilling is the most widespread (Fig. 8).

Rice. 8. Scheme of percussion-rope drilling of wells

The drill bit, which consists of a bit 1, an impact rod 2, a sliding scissor rod 3 and a rope lock 4, is lowered into the well on a rope 5, which, bending around the block 6, the draw roller 8 and the guide roller 10, is unwound from the drum 11 of the drilling rig . The speed of descent of the drilling rig is controlled by brake 12. Block 6 is installed on the top of the mast 18. Shock absorbers 7 are used to dampen vibrations that occur during drilling.

The crank 14, with the help of the connecting rod 15, sets the balancing frame 9 into oscillatory motion. When the frame is lowered, the draw roller 8 pulls the rope and lifts the drill bit above the bottom. When the frame is raised, the rope is lowered, the projectile falls, and when the bit hits the rock, the latter is destroyed.

As the well deepens, the rope is lengthened by unwinding it from drum 11. The cylindricity of the well is ensured by turning the bit as a result of the rope unwinding under load (during the lifting of the drill bit) and twisting it when the load is removed (during the bit hitting the rock).

The efficiency of rock destruction during percussion-rope drilling is directly proportional to the mass of the drill, the height of its fall, the acceleration of the fall, the number of impacts of the bit on the bottom per unit time and is inversely proportional to the square of the borehole diameter.

During drilling of fractured and viscous rocks, the bit may jam. To release the bit in the drill, a scissor rod is used, made in the form of two elongated rings connected to each other like chain links.

The drilling process will be more effective the less resistance the drill bit has to the drill bit that accumulates at the bottom of the well, mixed with formation fluid. If there is no or insufficient flow of formation fluid into the well from the wellhead, water is periodically added. Uniform distribution of drilled rock particles in the water is achieved by periodic pacing (raising and lowering) drilling projectile. As destroyed rock (sludge) accumulates at the bottom, the need arises to clean the well. To do this, with the help of a drum, they lift the drill bit out of the well and repeatedly lower the bailer 13 into it on a rope 17, wound from the drum 16. There is a valve at the bottom of the bailer. When the bailer is immersed in the slurry liquid, the valve opens and the bailer is filled with this mixture; when the bailer is lifted, the valve closes. The sludge-laden liquid raised to the surface is poured into a collection container. To completely clean the well, you have to lower the bailer several times in a row.

After cleaning the bottom, a drill bit is lowered into the hole and the drilling process continues.

With shock drilling the well is usually not filled with liquid. Therefore, in order to avoid the collapse of the rock from its walls, a casing string is lowered, consisting of metal casing pipes connected to each other by threading or welding. As the well deepens, the casing is advanced to the bottom and periodically extended (increased) by one pipe.

The impact method has not been used for more than 50 years oil and gas industries of Russia. However, in exploration drilling in placer deposits, during engineering-geological surveys, drilling water wells, etc. finds its application.

1.2.2. ROTAL DRILLING OF WELLS

During rotary drilling, rock destruction occurs as a result of the simultaneous impact of load and torque on the bit. Under the influence of load, the bit penetrates into the rock, and under the influence of torque, it breaks it off.

There are two types of rotary drilling - rotary and with downhole motors.

During rotary drilling (Fig. 9), power from engines 9 is transmitted through winch 8 to rotor 16 - a special rotational mechanism installed above the wellhead in the center of the tower. The rotor rotates drilling column and a bit screwed to it 1. The drill string consists of a leading pipe 15 and drill pipes 5 screwed to it using a special sub 6.

Consequently, during rotary drilling, the bit deepens into the rock when the rotating drill string moves along the axis of the well, and when drilling with downhole motor – non-rotating drilling columns. Characteristic feature rotary drilling is flushing

At drilling with a downhole motor, bit 1 is screwed to the shaft, and the drill string is screwed to the motor housing 2. When the motor is running, its shaft with the bit rotates, and the drill string receives the reactive torque of the motor housing, which is damped by a non-rotating rotor (a special plug is installed in the rotor).

Mud pump 20, driven by engine 21, pumps drilling fluid through the manifold (pipeline high pressure) 19 into the riser - pipe 17, vertically installed in the right corner of the tower, then into the flexible drilling hose (sleeve) 14, swivel 10 and into drilling column. Having reached the bit, the flushing fluid passes through the holes in it and rises to the surface through the annular space between the well wall and the drill string. Here in the system of tanks 18 and cleaning mechanisms (not shown in the figure) drilling rig the solution is cleared of drilled rock, then enters the receiving tanks of 22 mud pumps and is pumped back into the well.

Currently, three types of downhole motors are used - turbo drill, screw motor and electric drill (the latter is used extremely rarely).

When drilling with a turbodrill or screw motor, the hydraulic energy of the flow of drilling fluid moving down the drill string is converted into mechanical energy on the shaft of the downhole motor to which the bit is connected.

When drilling with an electric drill Electric Energy supplied via cable, sections of which are mounted inside drilling column and is converted by an electric motor into mechanical energy on the shaft, which is directly transmitted to the bit.

As the well deepens drilling a column suspended from a pulley system consisting of a crown block (not shown in the figure), a traveling block 12, a hook 13 and a traveling rope 11 is fed into the well. When the leading pipe 15 enters the rotor 16 to its full length, turn on the winch, lift the drill string to the length of the leading pipe and hang the drill string using wedges on the rotor table. Then the leading pipe 15 is unscrewed together with the swivel 10 and lowered into a pit (casing pipe pre-installed in a specially drilled inclined well) with a length equal to the length of the leading pipe. A hole for the pit is drilled in advance in the right corner of the tower approximately halfway from the center to its foot. After this, the drill string is extended (increased) by screwing a two-pipe or three-pipe stand (two or three drill pipes screwed together) onto it, removing it from the wedges, lowering it into the well to the length of the stand, hanging it using wedges on the rotor table, lifting it out drill the leading pipe with a swivel, screw it to the drill string, free the drill string from the wedges, bring the bit to the bottom and continue drilling.

To replace a worn bit, the entire drill string is lifted out of the well and then lowered again. Lifting and hoisting work is also carried out using a pulley system. When the winch drum rotates, the traveling rope is wound onto or from the drum, which ensures the raising or lowering of the traveling block and hook. The drill string being raised or lowered is suspended from the latter using slings and an elevator.

When lifting, the BC is unscrewed onto the candles and installed inside the tower with the lower ends on the candlesticks, and the upper ends are placed behind special fingers on the balcony of the riding worker. The BC is lowered into the well in the reverse order.

Thus, the process of operation of the bit at the bottom of the well is interrupted by the extension of the drill string and tripping operations (HRO) to change the worn bit.

As a rule, the upper sections of the well section are easily eroded deposits. Therefore, before drilling a well, a shaft (pit) is built to stable rocks (3-30 m) and a pipe of 7 or several screwed pipes (with a cut-out window in the upper part) 1-2 m long greater than the depth of the pit is lowered into it. The annulus is cemented or concreted. As a result, the wellhead is reliably strengthened.

A short metal trench is welded to the window in the pipe, through which, during the drilling process, the drilling fluid is directed into the system of tanks 18 and then, after passing through the cleaning mechanisms (not shown in the figure), it enters the receiving tank 22 of the mud pumps.

The pipe (pipe column) 7 installed in the pit is called the direction. Setting the direction and a number of other works performed before the start drilling, are considered preparatory. After their completion, an act of commissioning is drawn up exploitation drilling rig and begin drilling the well.

Drilling through unstable, soft, fractured and cavernous rocks that complicate the process drilling(usually 400-800 m), cover these horizons with a conductor 4 and cement the annular space 3 to the mouth. With further deepening, horizons may be encountered that also need to be isolated; such horizons are covered with intermediate (technical) casing columns.

Having drilled the well to the design depth, it is lowered and cemented operational column (EC).

After this, all casing strings at the wellhead are tied to each other using a special equipment. Then, several tens (hundreds) of holes are punched against the productive formation in the EC and cement stone, through which, during testing, development and subsequent oil exploitation (gas) will flow into the well.

The essence of well development is to ensure that the pressure of the drilling fluid column located in the well becomes less than the formation pressure. As a result of the created pressure difference, oil ( gas) from the formation will begin to flow into the well. After the complex research work the well is handed over to exploitation.

A passport is created for each well, where its design, location of the mouth, bottom and spatial position of the trunk are accurately noted according to inclinometer measurements of its deviations from the vertical (zenith angles) and azimuth (azimuth angles). The latest data is especially important when cluster drilling directional wells in order to avoid the barrel of a drilled well from falling into the barrel of a previously drilled or already operating well. The actual deviation of the face from the design one should not exceed the specified tolerances.

Drilling operations must be carried out in compliance with labor protection and environmental laws. Construction of a drilling site, routes for moving the drilling rig, access roads, power lines, communications, pipelines for water supply, collection oil And gas, earthen pits, treatment facilities, sludge dumps should be carried out only in areas specially designated by the relevant organizations. After completion of the construction of a well or well cluster, all pits and trenches must be backfilled, and the entire drilling site must be restored (reclaimed) to the maximum extent possible for economic use.

1.3. BRIEF HISTORY OF DRILLING OIL AND GAS WELLS

The first wells in human history were drilled using the percussion-rope method 2000 BC for production pickles in China.

Until mid-19th century oil was mined in small quantities, mainly from shallow wells near its natural outlets to the surface. Since the second half of the 19th century, the demand for oil began to increase due to the widespread use of steam engines and the development of industry based on them, which required large quantities of lubricants and more powerful light sources than tallow candles.

Research in recent years has established that the first well in oil was drilled using a manual rotary method on the Absheron Peninsula (Russia) in 1847 on the initiative of V.N. Semenov. In the USA, the first well oil(25m) was drilled in Pennsylvania by Edwin Drake in 1959. This year is considered the beginning of development oil producing US industry. The birth of Russian oil industry is usually counted from 1964, when in the Kuban in the valley of the Kudako River A.N. Novosiltsev began drilling the first well in oil(depth 55 m) using mechanical percussion-rope drilling.

At the turn of the 19th and 20th centuries, diesel and gasoline internal combustion engines were invented. Their introduction into practice led to the rapid development of the world oil producing industry.

In 1901, in the USA, rotary rotary drilling with flushing of the bottom with a circulating fluid flow was first used. It should be noted that the removal of drilled rock by a circulating stream of water was invented in 1848 by the French engineer Fauvelle and first used this method when drilling an artesian well in the monastery of St. Dominica. In Russia, the first well was drilled using the rotary method in 1902 to a depth of 345 m in the Grozny region.

One of the most difficult problems that arose when drilling wells, especially with the rotary method, was the problem of sealing the annular space between the casing pipes and the walls of the well. The Russian engineer A.A. solved this problem. Bogushevsky, who developed and patented in 1906 a method of pumping cement slurry into a casing string and then displacing it through the bottom (shoe) of the casing string into the annulus. This cementing method quickly spread in domestic and foreign practice. drilling.

In 1923, a graduate of the Tomsk Technological Institute M.A. Kapelyushnikov in collaboration with S.M. Volokh and N.A. Korneev invented a hydraulic downhole motor - a turbodrill, which determined a fundamentally new path for the development of technology and equipment drilling oil and gas wells In 1924, the world's first well was drilled in Azerbaijan using a single-stage turbodrill, called the Kapelyushnikov turbodrill.

Turbo drills occupy a special place in the history of development drilling inclined wells. The first inclined well was drilled using the turbine method in 1941 in Azerbaijan. The improvement of such drilling has made it possible to accelerate the development of deposits located under the seabed or under very rough terrain (swamps Western Siberia). In these cases, several inclined wells are drilled from one small site, the construction of which requires significantly less costs than the construction of sites for each drilling site. drilling vertical wells. This method of constructing wells is called cluster drilling.

In 1937-40. A.P. Ostrovsky, N.G. Grigoryan, N.V. Aleksandrov and others developed the design of a fundamentally new downhole motor - an electric drill.

In the USA in 1964, a single-pass hydraulic screw downhole motor was developed, and in 1966 in Russia a multi-pass screw motor was developed, allowing drilling of directional and horizontal wells for oil and gas.

In Western Siberia, the first well that produced a powerful fountain of natural gas On September 23, 1953 it was drilled near the village. Berezovo in the north of the Tyumen region. Here, in the Berezovsky district, it originated in 1963. gas production industry of Western Siberia. The first oil well in Western Siberia flowed on June 21, 1960 at the Mulyminskaya area in the Konda River basin.

In the process of deep drilling of oil wells, the need arises to secure their walls. This must be done to achieve the following goals:

Figure 1. Well design diagram.

• consolidation and cementation of unstable rocks;
• separation of aquifers;
• separation of oil-bearing and gas-bearing formations of a well;
• creating a sealed channel for the unhindered rise of oil and gas to the surface;
• reducing hydraulic losses.

The separation and fastening of the well walls is carried out using casing pipes, and the space between the casing pipes and the excavation wall is cemented with a special solution. This process is called cementation.

The location of the casing pipes in the well, their diameter, the depth of descent, the height of cementation, and the diameters of the drill bits determine the well design. The design itself is a set of well support elements indicating the lateral dimensions, depth and length, which ensures its correct exploration, evaluation, drilling, production and operation. Increased attention is paid to slaughter.

Development and design

The well design is determined by the technical project for development, construction and drilling for a specific region. Its main goal is unhindered drilling to a given depth to open productive oil and gas formations in common system mining and field development. The design scheme directly depends on a number of factors, namely:

• geological structure;
• methods and methods of drilling operations;
• direct purpose of the well;
• technologies for opening productive formations;
• safety requirements.

The reliability, budget cost, debit rate and long-term operation of an oil or gas well depend on the correctness of design decisions. The working design must contain a full range of decisions and justifications on well casing issues, taking into account the geographical location of the region and the geological conditions of drilling operations.

This is, first of all, justification for the design of various sections of the well, methods and intervals for cementing the casing, calculation and selection of materials for the casing, adoption technical solutions on methods of opening oil and gas formations, increasing the stability of the shaft, waterproofing.

Initial data for design and justification of the structure should include:

• coordinates of the mouth location;
• drilling depths and methods;
• column diameters at intervals and depending on expected debit;
• data on the geology of the region and geological sections;
• rock features applicable to drilling methods;
• presence and composition of formation fluids;
• type and purpose of the well;
• profile;
• data on productive strata intervals;
• methods of operation;
• pressure inside the formations;
• pressure for hydraulic fracturing.

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Structural features

In Fig. 1 shows various well design diagrams:

• a - well profile;
• b - concentric arrangement of columns;
• c - graphic diagram of the excavation design;
• d - working diagram.

When drawing up a working diagram, the diameter of each row of casing columns in millimeters is indicated in the upper part, and the installation depth in meters is indicated in the lower part. The height of the rise of the cement mortar is shown by shading, indicating the end point in meters. The diagram also indicates the number of the bit for drilling operations.

The well design may include the following columns:

1. Direction. This column is lowered first, has a shallow depth and is installed before drilling begins. Its function is to protect the mouth from destruction, collapse and erosion by drilling fluid.
2. Conductor. This column is installed after the direction and serves to retain aquifers and weakly resistant upper rock layers. Next, the shoe is mounted. This is a thickened pipe at the bottom of the conductor. When drilling in areas low temperatures with frozen rocks, the direction and conductor are selected taking into account the increase in temperature inside the rock.
3. In order to prevent complications during drilling, intermediate columns, of which there may be several, are lowered into the well.
4. The production column completes this chain. It is intended directly for the exploitation of productive formations.
5. The liner is a hidden column in the structure, which is necessary for securing wells with great depths.