Casing pipe for a well: what is it, plastic, steel, diameter

Quality of the material: (What is your assessment of the article?)

Plastic casing pipes have gained wild popularity and are offered by any drilling company; we are no exception and also lower them into wells. Often plastic is placed inside a steel casing, but some may line the well with only plastic pipes. Now we will leave a detailed review about plastic pipes, in which we will find out which well is better made of plastic or metal, share our experience, dispel some myths, and talk about the main differences between pipes. We’ll also tell you why they started using HDPE pipes in the well and whether it’s a scam.

First, let's decide what is better for a HDPE or PVC well. As PVC is known to be poisonous and release vinyl chloride, some countries have long abandoned its use. The HDPE material is neutral and is widely used not only for water supply to a private home, but also in urban networks.

We’ve sorted this out, then we’ll look at the main sizes of plastic pipes for wells and find out which ones are better.

Other types of pipe piles

In the previous part of the article we looked at bored piles, but there are also other types. In private construction, the technology of installing screw rods is very often used if it is planned to erect lightweight buildings. Their advantage is that they are suitable for any soil except rocky, although even there it is possible to drill holes of a smaller cross-section. Moreover, such a pipe foundation can be easily installed using rotation levers with your own hands. It can be mounted in place of the old base and equipped with headers, which is an undeniable advantage, because a wooden house can be lifted with jacks and installed on a new base.

Screw pile with casing

There is a technology for extending the service life of metal screw rods, for which they are turned into stuffed rods, and the cavities are filled with concrete, which must be tamped. This technique will help protect the supports from corrosion. Read more about foundations on screw piles.

No less often than bored foundations, asbestos-cement foundations are installed, which are additionally equipped with a recessed or suspended grillage. They are installed where the landscape is characterized by heaving soils. Here the technology also involves concreting the cavities, which gives the base strength and increases its service life.

Summarizing the material presented, we can confidently say that with the use of pipe-concrete piles, by adjusting the length of the rod, it is possible to solve the problem of constructing a foundation on slopes, watery and landslide-prone soils. But, despite the many advantages, it is worth remembering that bored piles during installation create vibration with high amplitude, so they can cause damage to buildings erected nearby.

Fiberglass pipes

Few people have heard of fiberglass casings, the production of which was recently organized by a private company.

A glass thread is wound onto a steel base and filled with synthetic resin.
The inner surface is covered with polyethylene film.

Such an element has all the properties of plastic pipes, but has greater strength (withstands 25 tons along the axis), and is 5 times lighter than steel. Can be used repeatedly as casing.

Fastening wells during drilling

Well casing is one of the most important processes during oil production, as it affects:

Well performance;
Well lifespan;
The strength and tightness of the channel through which the extracted product will flow from the horizon to the surface;
Protection of the operating channel from corrosion;
The strength of the well walls in places where the rocks are not stable enough;
Tightness of separation of all permeable horizons from each other.

Securing oil wells involves the use of special columns or packers. The use of columns is the most popular method, which allows you to make the well strong, durable, and also isolate permeable horizons. Such columns are made up of special pipes called casing.

Areas of application

The products are widely used where qualities such as strength and rigidity of plastic bends are in demand:

Laying pressure and non-pressure sewerage pipelines.
Transportation of drinking water and other food liquids.
Construction of drainage networks.
Construction of casing columns on water wells.
Manufacturing of protective equipment for athletes and other areas of human activity.

For well

In well drilling, one of the main problems is ensuring the integrity of the drilling rig and protecting equipment from various external mechanical loads. These problems are successfully solved with the help of casing pipes. Previously, steel and asbestos-cement bends were used for these purposes. Now they are being forced out of the market by cheaper and easier to install plastic pipelines. The most profitable and effective among them are pipes made of unplasticized PVC.

Manufacturing method for some drilling rig structures

For a homemade drilling rig to operate effectively, it must be equipped with parts.

Small drilling rig

Casing

Made from plastic, asbestos cement, cast iron or other metal. They begin to install it at a depth of 4 m. To connect the individual parts, threads are cut at the ends of the pipes or welding is used. If their diameter is less than 50 mm, couplings can be used.

Impact rod

For its manufacture, solid steel blanks are used. To make them heavier, concrete is poured inside. The individual structural elements are connected using bolts or flanges. The use of threads is unacceptable. With a strong impact, such a connection is destroyed, which makes further operation of the impact rod impossible.

Bailer

To make a part with the simplest design, you should use a piece of pipe with a diameter of 90 mm, a ball from a bearing, and a steel transition. The last two elements are thoroughly rubbed with sandpaper. This ensures a tighter fit of the ball to the transition. To make the bailer heavier, concrete is poured into its upper part.

Rope castle

To make it, several elements are used - a metal body (several holes are drilled to remove water), a support washer, and a bushing.
A comb is installed at the top of the lock. In an emergency, it can be used to lift the rope to the surface.

The support washer is necessary to protect the housing from destruction during impacts on the ground.

The end of the cable is pulled into the bushing, separated into pieces and fixed by pouring a light alloy of metal.

What is

A uPVC casing pipe is a hollow cylinder, usually 2 to 6 meters long. It is made of plastic – unplasticized PVC. It is inserted into a drilled well to protect its walls from destruction and ensure normal operation of the pump and other components of the drilling rig.

Available in blue color, it has a range of sections from 80 to 400 mm, with wall thicknesses up to 21.5 mm.

Drilling a well with casing

Drilling wells and installing casing if you have the appropriate equipment and technology does not seem to be a very complicated process; the most common sand wells go as follows:

A drilling rig is driven into the site, after determining the location of the well, the equipment is turned on and with a drill of the appropriate diameter attached to a rod of a standard length of 3 - 4.5 - 6 m, excavation begins. As the rods deepen, they lengthen them by screwing the following elements onto the threads, thus immersing the drill to the required depth until water appears.
Almost all tunnelers use hydraulic drilling technology, directing water from the tank of an auxiliary machine (water truck) into the wellbore during drilling. Water is supplied to the mines through hollow rods; the second method is to construct a small pit at the excavation site, which is constantly replenished with water; it is used in low-cost excavation.
After the required sand or limestone appears in the dump (depending on the type of well), the rods are removed and dismantled one by one, then the drill is removed, replacing it with a downhole uPVC filter. The filter device is a regular factory-made pipe with transverse slots (slit filter); many drillers make it themselves by perforating a series of round holes in the casing pipe and wrapping the casing with a fine-mesh mesh made of metal corrosion-resistant materials (stainless steel, bronze, brass and copper alloys).
A conical plug is attached to the end of the filter using threads or self-tapping screws, after which it is lowered into the borehole channel. Before installing the column, crushed stone and river sand are sometimes poured into the bottom of the well to organize additional filtration.
As it lowers, the next pipe is screwed to the filter and so on until the desired level is reached.
After installing the column, the upper pipe is cut off and the well is pumped, supplying water under pressure into its channel for some time, after which they begin pumping out the muddy water with a submersible electric pump until a clear liquid appears at the outlet.
The complete pumping procedure can take several days, but experts aim to complete the job in a few hours, counting on the sedimentation of suspended particles to the bottom over time.

Rice. 16 Examples of doing drilling work yourself

For well construction, casing pipes made of unplasticized polyvinyl chloride (UPVC) are currently widely used, which have high physical and chemical characteristics, a long service life, and lower cost compared to metals. The use of uPVC casing makes it possible to effectively equip all types of wells with a depth of 5 to 300 m with convenient placement of water intake submersible electric pumps of any model.

Performance characteristics

The pipes are sufficiently durable and have a favorable price. In addition, they are convenient to assemble: they are lightweight, and the installation technology is simple and accessible to non-specialists. The threaded connections are so strong that they allow the polymer pipeline to be pulled out of the drilling rig if necessary.

Bends are produced with and without socket.
The range of working sections used for casing varies from 80 to 225 mm.
The maximum internal pressure for uPVC bends is 25 MPa.
They can be installed at a depth of up to 100 meters, and reinforced versions (with thick walls) - up to 300 meters.

The products have a smooth surface, providing high throughput capacity, resistance to overgrowth and bacterial growth.

Well on site

the presence of aquifers accessible for drilling;
physical properties of soil rocks;
type of drilling tool;
the length of the casing, depending on the depth and direction of the well shaft.

After a geological survey of the area, the owner makes one of the following decisions:

rent a UKB cable drilling rig and carry out the work on your own;
hire a specialized team.

For independent actions, you can make a tripod of your own design. The triangular pyramid is made from available materials - wooden beams or metal profiles. You will need to stock up on a lifting mechanism to lower the casing pipe into the well and manipulate the projectile. The height of the drilling tower is determined by the size of a single casing fragment.

Which well is better made of plastic or metal?

At the end, we will summarize, especially for those who are too lazy to read all the material, we will immediately resolve the question of which casing pipe is better than HDPE or steel. Plastic is good and allows you to reduce the cost of drilling, it works great, but if protected by an iron pipe. A steel pipe is also good, but it is installed before the limestone, and the limestone itself must be lined with plastic. In our area (in the south of the Moscow region) it is impossible to leave limestone without casing. Therefore, the ideal combination is iron and plastic. If you don’t trust HDPE, you can overpay and make metal and metal.

Connection types

When arranging the casing, pipes are connected into a column in the following ways:

Socket threaded. The method is used when joining polymer or metal thin-walled pipes, while an internal thread is cut in the socket, and an external thread is cut in the section of the outer shell of the connected pipe.

Threaded. They are used in thick-walled metal and polymer pipes; the connected elements have external and internal threads; when they are joined, the walls are smooth on the outside and inside.

Coupling. The pipe elements to be connected have an external thread; they are screwed into a connecting coupling with an internal thread until the ends are connected.

Electric welding. Welding can be useful when joining thin-walled steel pipes where the cut threads would be too weak. The welding method is often used when installing steel casing - although it takes some time and requires good welding skills from a specialist, its use can be cost-effective (no need to purchase expensive heavy pipes with threads and thick walls).

Rice. 13 Steel and HDPE casing pipes

Features of installation and connection

Well casing is carried out either after completion of drilling or during the process. Based on what kind of soil you will have to deal with. If the channel is deep and on loose soil, then a pipe is installed and drilling is carried out inside the column with a drill of a smaller diameter. This process is more troublesome, so they often try to drill the well to the end and then begin installing the casing.

It is important to position the first casing correctly. It is checked for level and securely fixed. As it goes down, the pipe is extended with the next bend.

A filter is also installed on the initial pipe. In the column it will be located at the very bottom, ensuring the flow of filtered water into the well. It is made by drilling holes in the lower part of the outlet and wrapping the area with a filter mesh secured with self-tapping screws.

The gap between the walls of the well and the column is filled with fine crushed stone and filled with concrete through a hose. It will prevent melt water from flowing down to the base of the column.

Connection methods

Connections are made in the following ways:

Through a socket with an o-ring. The pipe is inserted into the socket until it stops; the seal must not jump out of the special recess.
Glue method. The inner surface of the socket and the end of the inserted outlet are coated with an adhesive solution.
Threaded method. The end of the upper pipe is screwed onto the pipe below.

Advantages and disadvantages of the method

The technology of percussion-rope drilling of wells has many advantages over other methods:

Using this method, it is possible to qualitatively open the aquifer and exploit it. The service life of the well exceeds 50 years;
When drilling using the percussion method, you do not need to use water or special drilling fluid. It's very practical;
using this method to form a well, you can even drill into rock that very easily absorbs the flushing liquid;
You can start operating the well immediately after completing the entire range of work;
The impact drilling method does not pose a danger to the aquifer. After carrying out the entire complex of work, its clogging is excluded;
Do-it-yourself impact drilling of wells is carried out with the formation of a hole with a large initial diameter;
With the help of this drilling rig it is possible to carry out geological exploration work. The rock is excavated throughout its entire depth.

Installation of casing bored piles

Installation and installation of a pile foundation is carried out directly on the construction site. In principle, the technology for installing such a structure with your own hands is quite simple: you need to lower a pipe into the well, carry out reinforcement and concrete it. In length, such structures can be up to thirty meters with a diameter of up to one and a half meters, although with improved technical support, the length can be doubled and the cross-section increased to 3.5 m. With such parameters, the bearing capacity of bored supports will be 500 tons.

In most cases, the structure is buried 5 - 12 m with a diameter of 25 - 40 cm. Do-it-yourself assembly of metal structures is carried out according to the following scheme:

The well is filled with concrete mortar per meter;
the solution is compacted;
the casing is gradually raised to the level when the concrete drops by 35 - 40 cm;
this process must be repeated until the rod is completely filled with the mortar mass.

Pile design
The walls of the leader hole for the casing pipe during drilling become rough and loose due to collapsed soil, so a gap is formed between the hole and the metal structure, which is compacted with a solution, and the concrete, in turn, seeps into the soil structure and makes it stronger . This technology has one drawback, and it is that you cannot control the density of the concrete pour inside a long shaft. This minus can lead to erosion by groundwater of areas of the mixture that have not set, if there are any, of course.

The well for the pipe foundation is reinforced only in the upper part, while the reinforcement cage is buried 1.5 - 2 m into fresh concrete. Along with the casing pipe, the dry method is also used, suitable for stable and dense soils that can withstand the load without destroying the walls. The frame is installed in the well with your own hands, and then the mortar mass is filled. If bored wells are sunk into weak, watery soils without casing, then their walls must be reinforced with clay coating, the density of which must be at least 1.2 g/m3.

Application for water wells

When drilling water wells, three types of casing pipes are used: plastic, steel and asbestos-cement. In order to save money and simplify installation, it is recommended to use plastic casing (PVC or NVVC).

Installation of casing pipe is carried out when constructing water wells to any depth. The insertion of the casing is performed upon completion of drilling of the cavity. Composite pipes are used, joined by means of a threaded connection.

The diameter of the casing pipe and the well itself is selected based on the required productivity of the source. The section of the casing must be such that a drainage pump can be placed in it. The lower sections of the casing are made of perforated products, the holes of which are blocked by a mesh filter.

There is a lot of debate about which pipes are better to use for casing water wells - steel, asbestos-cement or plastic. The key disadvantage of metal products is their tendency to corrosion, which can cause a characteristic taste of rust and the presence of sediment in the water, for the purification of which you will have to buy expensive filtering equipment, and the iron products themselves are much more expensive than their analogues.

Asbestos cement casing pipes are a budget solution, the disadvantages of which are the large thickness of the walls, which reduces the useful volume of the well, as well as questionable sanitary suitability (there are studies indicating that asbestos cement is a carcinogen).

In general, asbestos-cement products can be used for casing wells subject to the following conditions:

when constructing an artesian well (such a pipe cannot have perforations, which makes it impossible to install a filter column in sand wells);
if there is a hygienic certificate for the product.

In terms of overall performance qualities, plastic casing pipe is best suited for water wells. Such products are easy to install, cheap, corrosion-resistant and durable (service life up to 50 years).

Plastic casing for water wells

Four types of materials can be used for the manufacture of plastic casing pipes:

PVC – polyvinyl chloride;
uPVC is an unplasticized type of polyvinyl chloride;
HDPE – low-density polyethylene;
PP – polypropylene.

The most popular products are uPVC products. Unlike standard PVC products, uPVC pipes are classified as pressure pipes - they have greater mechanical strength and resistance to deformation, which allows them to be used in wells up to 300 m deep.

Plastic casing pipes made of PVC and uPVC for water wells are produced in the following standard sizes:

Diameter 90 mm, wall thickness 5 mm;
DN 110, thickness 6.3 mm;
DN 125, thickness 7.6 mm;
DN 140, thickness 10 mm;
DN 165, thickness 12 mm.

Most often, pipes with a diameter of 90 and 125 mm are used, since most modern borehole pumps are produced for this size.

Pipe sections (length 3-12 meters), depending on the design features, can be joined into the casing in two ways - using a thread or a socket. The greatest reliability and tightness of the casing is ensured by a threaded connection, which is easy to assemble with your own hands, however, products with threads are more expensive than analogues with a socket.

The leading domestic manufacturer of polymer casing pipes made of PVC and uPVC is the Cormell company, which supplies the market with products of all common sizes. In addition to the Cormell company, the products of the companies SPT, Bix and Omega have also proven themselves well.

Well casing (single-pipe and double-pipe)

Depending on the depth of the wells, various casing methods are used, differing in the pipe materials used, installation technology, and dimensional parameters of the casing. All wells for individual water intake are conventionally divided into three categories, in which the following well installation methods are used.

Abyssinian . The sources are designed for water intake from surface underground water layers; the depth of the shaft rarely exceeds 30 m, so the soil pressure on the walls of the column is insignificant. If a surface pumping station is used with a pressure pipe immersion depth of no more than 9 mm, instead of a column of individual pipes, use a long piece of HDPE pipe of suitable diameter on a reel.

If the water surface is below 9 m from the surface of the earth, a submersible electric pump is placed in the well. To install the column, use a thick-walled plastic pipeline made of low-pressure polyethylene HDPE or a thin-walled one made of unplasticized polyvinyl chloride PVC-U.

Since the flow rate of the Abyssinian well is not too high, to save money, it is rational to use a medium-power submersible electric pump with a diameter of 3 inches (75 mm) and you can use polymer pipes with a small transverse size.

It is rational to choose the outer diameter D of the well pipeline for the size of this 3-inch electric pump as a standard value of 90 mm (the bore diameter of the channel Dn is equal to 80 mm). It should be noted that a gap of 5 mm, taking into account errors in pipe manufacturing, is the limit, therefore these casings are used with transverse dimensions of electric pumps no more than 75 mm (suitable for Grundfos SQ with Dn=74 mm, Aquario ASP with Dn=75 mm) or choose the next, higher pipe size (the best option is outer diameter D = 110 mm with a wall thickness of 7 or 9 mm).

Rice. 11 Casing options

Wells in the sand . The depth of sand wells reaches 70 m, so the column experiences stronger soil pressure. Also, the flow rate of sand wells is higher than that of Abyssinian sources - this requires the use of more powerful electric pumps with a standard diameter of 4 inches (100 mm).

PVC-U polymer pipes with thick walls are suitable for equipping a borehole; the permissible installation depth does not exceed 100 m. The optimal option for placing 4-inch electric pumps is a pipe with an outer diameter of 125 mm; with a wall thickness of 7 or 9 mm, its bore diameter Dn will be equal to 111 or 107 mm respectively.

Artesian wells. Artesian underground springs are considered the deepest; in domestic wells, the distance from the surface of the earth to the water basin can reach 200 m. Therefore, strong steel pipes are used for their installation, but due to the fact that they are susceptible to corrosion, a corrosion-resistant polymer pipeline is usually inserted into them. Double-pipe well casing can withstand significant external loads and is optimal from the point of view of financial savings - the service life of artesian wells reaches 50 years, so the column should have a similar longevity.

For external piping, from the point of view of corrosion resistance, steel pipes with a high carbon content made of high-quality steel grade St20 or St45 are well suited; they can also be used directly in a well source with drinking water with high wall thickness.

It should be noted that, according to GOST, polymer and steel pipes have consistent transverse dimensions for organizing double casing: if you choose the diameter of casing pipes for wells made of steel D = 140 mm, according to the table in Fig. 3 for a 7 mm wall we get the internal dimension Dn = 125.7 mm - this space is perfect for installation inside a polymer pipe with a diameter of D = 125 mm.

If the depth of the artesian well does not exceed 100 m, you can use cheaper double casing with HDPE or PVC-U polymer pipelines; in any case, it is better to leave the final decision to experienced specialists from organizations that drill and tie up well sources.

Rice. 12 Types of pipe connections

Work order

It is recommended to start with preparatory activities. The first stage is the formation of a platform for mounting the tripod. It is necessary to dig a small pit measuring 1.5x1.5 m and up to 2 m deep. A homemade drilling rig is subsequently installed in this pit. Panel board structures fixed to the walls of the pit prevent collapses of loose rocks contained in the surface layers.

The next step is to install a DIY tripod on the prepared site. At the top of the triangular pyramid, a winch with a cable is mounted on which the impact tool is attached. A prerequisite is the vertical orientation of the structural parts of the drilling equipment. The slightest deviations will not allow installing a casing pipe in the drilled shaft.

Subsequent work on drilling wells using the percussion-rope method is carried out according to the following algorithm:

from a two-meter height, a homemade driving glass with the help of an impact rod is immersed in the ground, destroying it;
using a winch or well gate, the working body rises to the surface, removing crushed soil particles;
the projectile is freed from destroyed soil fragments, and the procedure is repeated cyclically;
Depending on the characteristics of the rock, the drilling tool is replaced with a bailer or a chisel.

In some cases, surface layers are moistened by pouring water over the excavation. In other situations, dry soil is poured into the face.

Abyssinian

This type of well has a shallow depth of up to 30 meters. Water is lifted using surface pumps from a depth of 8 - 9 m. Therefore, the diameter of the casing pipe is of little importance.

A polyethylene pipeline from a coil is used as casing, which does not require docking. You can combine the casing and the supply pipe of the electric pump.

Criterias of choice

To arrange the casing, you must have the following information: well depth, volume of water supply, diameter of the submersible electric pump, and the choice is also greatly influenced by the consumer’s financial resources. To determine which pipe is best for a well, consider several options for well sources for water supply.

For water intake using a submersible electric pump from a shallow well (up to 30 m) of the Abyssinian type, it is best to use a polymer pipeline made of uPVC. Depending on financial capabilities, choose thin-walled products with a threaded socket connection or thick-walled ones with versatile external and internal threads.
For wells in sand up to 60 m deep, a good option is thick-walled uPVC; for further depths up to 100 m, you can consider various methods with double casing made of polymers. A good option is to use a rigid PVC-U pipeline on the outside, and an elastic and less load-resistant HDPE shell on the inside.
For depths above 100 m, it is rational to use a rigid metal casing, inside of which an elastic HDPE or rigid PVC-U pipeline can be placed.

Rice. 14 Appearance of PVC-U pipes

In any case, when choosing a single-pipe or double-pipe casing, the composition of the soil, geological factors, and groundwater levels should be taken into account. It wouldn’t hurt to listen to the feedback of highly qualified specialists on the issue of casing.
When purchasing HDPE products, you should be careful because the retail chain sells recycled technical polyethylene and food-grade primary material. Their main easily distinguishable difference is the color: a pipe made from recycled granules usually has a dark blue or rich blue color, sometimes there is a green tint. HDPE products made from primary raw materials, in accordance with GOST, have a bright blue or light blue color.
Another criterion for determining a low-quality HDPE product is the smell of plastic. Oon may resemble the aroma of confectionery products, detergents, washing powder, etc. - all this indicates that the material is made from recycled granules. Pure virgin polyethylene is odorless and can be used in drinking water systems without harm to human health, while polyethylene from recycled materials can be used in water intake systems for technical needs.
When choosing the diameter of the column, they are guided by the flow rate (performance) of the source and the dimensional parameters of the electric pump; for large volumes of water intake, they try to increase the diameter of the casing. The pump is selected so that its diameter is not less than 5 mm of the internal diameter of the wellbore; if a soft HDPE pipeline is used or water intake is carried out at great depths, a larger internal diameter of the column is selected taking into account the deformation of the channel when compressed by soil.
The quality of a PVC-U threaded connection is determined as follows: screw a pipe into another or its branch pipe three turns and then move one of the parts to the sides - a large gap indicates a weak fastening. Such a connection has low tightness, and if it is necessary to dismantle the casing and remove the string from the wellbore, the thread will most likely be torn off.

Rice. 15 Well filters and cone plug

How to choose the right diameter

It must be said right away that the standard casing diameters are the following: 60, 90, 108 and 125 mm. These numbers are typical for plastic.

It must also be said that performance does not depend on size, or rather, it depends slightly.

Wells with a diameter of 108 and 125 mm differ in that the drill for them has a slightly larger diameter. Therefore, a space is formed between the outer walls of the products and the walls of the well itself, which is extremely difficult to fill with anything, especially if the depth is large. This leads to water from the upper layers entering clean water, which is inferior in quality.

Steel casing pipes

As for products with a diameter smaller than 125, for example, the same 60 mm, here this problem is completely solved. And the solution was found to be very simple - the drill has a diameter even smaller than the internal diameter of the product itself, that is, casing pipes for wells are first installed, and only then drilling begins inside them.

Now one logical question arises: why make wells with a diameter of 125 mm or even more? The answer is simple.

Very often the water level is very low, deeper than 10 meters. At such a depth, a surface pump is simply not able to work, and it is used with small diameter pipes. Therefore, it is necessary to use submersible pumps, which can only be installed in wells with a diameter of 90, 108 and 125 mm or more.

Now it remains to make a simple conclusion: if the water level is above 8 meters, then columns with a diameter of 60 mm can be used, but if the water is below this mark, then columns with diameters of 90, 108, 125 mm or even larger are used.

Fastening wells with pipes

Casing pipes are special pipes manufactured in industry with the clear purpose of its use, which is to prevent collapses of insufficiently stable rocks in the walls of various wells.

So, in order to secure the well with the help of columns, casing pipes are immersed in the well, after which the annulus is cemented.

Thanks to the presence of casing pipes in the well, the well is completely protected from complex stresses, namely:

External pressure that rocks form;
Internal pressure resulting from the flow of working agents through pipes;
Longitudinal stretching;
Bending that may occur under its own weight;
Temperature extension, the probability of which in some cases is very high.

It is the pipes that experience all this, thereby protecting the well and ensuring its integrity.

Currently, there are many types of casing pipes, which differ in material of manufacture, diameter, length, connection method, etc. This number of pipes is due to their use in different wells for specific operational purposes. However, oil wells require very strong and durable pipes. Such pipes are produced either seamlessly drawn or solid-rolled. And they are connected by means of couplings or welding. The length of the casing pipes ranges from 6 to 13 meters.

Before the casing pipes are immersed inside the well, the internal diameter of the well is determined using a caliper, and the volume of cement slurry required for cementing the annulus is calculated.

This process is mandatory, since it is thanks to the quality of the cement mortar and its pouring that success in the extraction of minerals will be determined. After all, cement mortar not only ensures complete tightness of the well, but is also an excellent protection for pipes from the effects of aggressive environments, such as saline solutions and groundwater. When the process of securing the well with pipes is completely completed, the well is left to “rest” for a period of 16 to 24 hours. This is done to ensure that the cement hardens completely. However, the rate of hardening of the solution can be controlled by using various chemicals. So, the hardening time can either be increased or decreased.

Also a very important point is the fact that during the preparation of cement mortar for fastening wells with pipes, fresh water is not used. This is due to the fact that fresh water cement does not provide proper sealing of the well due to the formation of a loose boundary layer. The reason for the formation of such a layer is the interaction of excess fresh water in solution with rocks. A much higher quality of interaction between cement and clay, for example, is ensured by a saturated aqueous salt solution.

When cementing a wellbore using pipes, a fairly concentrated solution of table salt is used to flush the wells before cementation, as well as during cement pushing. In the latter case, for proper distribution of cement in the annulus, the speed of the supplied saturated salt solution must be at least 1.2 m/sec.

Well before starting operation. Trial

Wellbore casing is considered complete only after the well has been tested, which involves two stages.
The first stage is carried out immediately after the cement mortar hardens. If the well is not deep, then the column is tested under a pressure 2-3 times greater than the pressure that the working agent has directly during development. Strength testing of deep wells is carried out at a pressure of 600-1000 MPa.

The second stage of testing oil wells in the pipe and under the casing string after the cement shoe is drilled out. In this case, the optimal pressure for testing is one that is equal to double the pressure of the working agent.

Carrying out all the necessary tests allows you to timely determine the presence or absence of damage and all sorts of malfunctions that could harm the well, and eliminate them in a timely manner.

Thus, a well formed taking into account all the details is a durable and durable tool for oil production.

Well development from scratch

A person involved in the construction of wells with water flushing from A to Z must take into account that all known drilling methods have their advantages and disadvantages, which will be discussed below.

Screw method.

This option is deservedly considered simple and budget-friendly. The vast majority of units used today are developed on the basis of auger equipment. In this case, an Archimedes Screw, rotated by hand or by an electric motor, removes the earth. A significant disadvantage of this method is that the depth of the well will not exceed 10 meters. Washing is not required for such work.

Rotary method.

If the desired depth exceeds 10 meters, then the deepening is carried out using a rotor. In reality, the process looks like this:

The core structure, which has already been discussed above (a hollow product with a rotor and a chisel inside), is immersed in the ground. A rotating rotor creates a channel of a given depth, while flushing is carried out in a direct (the solution enters through the pipes and exits outside the structure) or reverse (the solution is pumped outside the part and removed using a pump) method;
Optimal opening of the aquifer is more easily achieved through the second type of flushing. At the same time, the result is guaranteed through the use of complex equipment, the use of which inevitably entails impressive costs. That is why, most often, at the expense of efficiency, direct flushing is used, the result is satisfactory, and costs are significantly reduced.

Percussion-rope drilling.

Despite its own moral and technical obsolescence, as well as labor intensity, this option continues to be in great demand. This state of affairs is due to the high quality and impressive service life of the well. This method is implemented as follows: a projectile is repeatedly dropped onto the ground surface from a certain height, punching a hole. Most often, this process is automated using a winch.

The need to use the solution during the work does not arise, which should also be considered a positive feature of the method under consideration.

The uncontrolled method is relevant provided that the channel depth does not exceed 10 meters. As in the case of other methods described above, when constructing wells with RVA machines, it is necessary to use a drilling mixture, which helps remove waste from the well and form reliable supports (walls) of the channel. In addition, the composition in question significantly contributes to softening the soil, which in itself simplifies the work performed and reduces the load on equipment.

The technique under consideration is more often used on an industrial scale rather than for creating water-bearing canals on the sites of private houses, since the use of the system involves the delivery and installation of complex equipment, which is not always appropriate and quite inconvenient.

Video about the features of choosing pipes for drilling wells:

At what dynamic level are pumps installed?

The equipment is lowered into the well based on its total depth and dynamic level height. The body of the device should be as high as possible, but without the risk of diving to the surface. When it is necessary to perform a deep dive, it is important not to exceed the depth allowed according to the data sheet of a given model.

As a rule, automation allows you to prevent the most common risks. An important addition to any model of well pump is a check valve. Some models already have a built-in one, but experts insist on installing an external one. The reason is simple: if the valve is built-in, then if a blockage occurs, there will be no choice but to remove the pump and send it for repair. If the valve is external, then it is easy to remove and clean it yourself. Its diameter is selected, in principle, equal to the adapter (connector) or the lumen of the pump outlet pipe.

On the section of the route from the pump to the entrance to the house, it is best to use HDPE plastic pipes. It is not only reliable, but also cheap. But when purchasing, it is important to make sure that the pipe is food grade and not technical. The technical specifications must indicate the marking - SDR 11. Such pipes comply with GOST 18599-2001 and can withstand pressures of up to 16 atmospheres.

To suspend the pump in the well, use a stainless steel cable and clamps (clamps). To avoid chafing of the cable at the attachment point, it is allowed to use thimbles. Particular care is taken to ensure that the weight of the pump is distributed along the cable. For safety reasons, it is prohibited to hang it on a pipe or cable.

Drilling technology

The drilling rig is installed with your own hands only on a site prepared for work. The homemade device is installed in a small hole - a pit. It should have a depth of 2 m and dimensions of 5x1.5 m. This will prevent the collapse of loose soil, which is usually located on the surface itself. The walls of the pit are reinforced with plank boards.

A tower operating on the UKB principle is installed only on a prepared site. At the same time, the vertical installation of the main structural elements is carefully checked. The slightest curvature of the driving tool’s trajectory will make it impossible to install the casing pipe and further operate the created structure.

The destruction of the soil begins with the help of a homemade glass from a piece of pipe. Using a shock rod, it is sharply lowered to the surface from a height of 1.5 m. Using a cable with a winch, the glass is removed out and the process is repeated from the beginning. If necessary, change the driving tool to a bailer or chisel, moisten the soil or add some dry rock.

Video: Cable-percussion drilling

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Strengthening the walls of the pit

The need to install a casing pipe to secure the walls of the well often arises at the stage of excavation, which is a set of operations for lowering and lifting a drilling tool attached to the end of a prefabricated rod and oscillating during vertical movement, causing partial collapse of the rock.

To prevent the bottom of the hole from falling asleep, once again, when the drill string is raised, casing pipes are lowered into the excavation if the penetration depth exceeds the height of the tool increased by two-thirds of the length of the selected pipe for the well. The operations are repeated a number of times, depending on the depth of penetration to be performed and the length of the casing segment.

Device

High-quality development of the mouth has several goals:

Easy installation of the pumping mechanism and its subsequent operation.
Permanent access to mine shaft devices.
Prevents dirt and impurities from entering drinking water.
Reliable sealing of the casing pipe.
Prevents the trunk from freezing during the cold season.

Wellhead fittings

The first is the header. It is installed directly on the casing and secured with special bolts. A rubber O-ring is placed on the outside to prevent leakage.

The second is the unloading harness. A complex element of the water supply unit from the mouth. In the upper section there are tees, ball valves, check valves, and coarse filters. All components and assemblies work in interaction with each other. The arrangement of the units depends on the number of intake devices and the volume of water consumption. Each project is calculated individually.

Third is the caisson. To protect the source from the ingress of clay, soil, and high water, as well as to prevent freezing, the equipment is covered with a caisson. This is a box made of plastic, brick, concrete or any other durable material that completely covers the casing along with all the units. The caisson can be purchased ready-made or assembled yourself.

Fourth - pump. The most important element in extracting liquid from the subsoil. The shorter the distance from the surface of the water to the pumping station, the easier it is for the impeller to draw in and direct water. That is why it is better to place the device near the head.

Fifth - equipment for automatic monitoring of problems, alarms, sensors for the proper operation of the water supply system. The automation is mounted next to the pump, which allows all components to work almost autonomously.

Scheme

A casing pipe that extends a meter out of the ground to the surface. The head is where all the equipment is hung. Submersible, cable, hose, water distribution unit. Pumping station for deep artesian mines. Electronic sensors for autonomous operation of the source. The exit is completely closed with a protective box or caisson.

Design features of the equipment used

Impact-rope drilling of wells involves the sequential destruction of rock by crushing it. To perform the work, a Sheetz drilling rig is used. It consists of a complex of parts.

Cup. When drilling wells using the percussion-rope method, this particular tool is used, which is formed from a piece of pipe of a suitable diameter. Its end is sharpened, which improves soil cutting during operation. There may also be sharp teeth at the end of the pipe. This facilitates the process of resolving soil that is formed from wet clay or a mixture of clay and sand. As a result, the soil sticks to the walls of the glass and is removed out.

Bailer. It is a piece of pipe equipped with a valve. It allows the soil to penetrate inside, but does not let it out. This allows the well to be cleared of rock destroyed during drilling.

Bit. It is used for percussion-rope drilling of wells with your own hands, when it is necessary to destroy rocky soils.

Winch. It is installed to facilitate the lowering of the impact nozzle, which ensures the drilling process.

Frame with shock rod. It looks like a tripod. To operate effectively, the height of the structure must exceed the length by 1.5 m or more.

Cable. Provides movement of the cutting glass to the required depth. The cable is usually made of steel. It must have a diameter greater than 12 mm. This provides a sufficient margin of safety. The cable must withstand loads of non-standard magnitude that may appear during the drilling process.

Rope rope laying left and right

Marking features

Every meter, markings are applied to the surface of the product. It represents mandatory information, the content of which is determined by the requirements of GOST.