What is plugging of drainage wells. A device for shutting off (plugging) a sewer pipeline. Packing materials

S.V. MIRONOV,

Head of Surgut Plugging Department

OAO Surgutneftegaz

PLUG-UP WORKS DURING CONSTRUCTION OF WELLS

S. MIRONOV, STU, Surgutneftegas JSC

During 35 years "Surgutneftegas" JSC "s special production division - Surgut plug-up department makes all types of plug-up works, ensuring annual service of more than 4.5 mln. m drilling.

Key words: cementing of wells, new technologies

Cement work during well construction

In the well construction cycle, a very important role is given to the cementing process as the most important stage of its construction. The special importance and significance of backfill operations are due to the fact that failures during their implementation can minimize the success of previous stages of well construction.

All types of plugging operations have been carried out for 35 years by a specialized production unit of OJSC “Surgutneftegas” - the Surgut Plugging Department, providing services for more than 4.5 million m of drilling rocks in year. In the period of its formation, the company's staff sought to fit into the labor rhythm of drilling enterprises, becoming their reliable partner. At present, the Surgut Plugging Department is the largest in the industry specialized enterprise for cementing casing strings, which has the necessary modern plugging equipment, technological equipment and plugging materials for the timely and high-quality performance of plugging operations throughout the entire territory of OJSC “Surgutneftegas”. Pos-

constantly increasing drilling volumes, requirements for the quality of work performed are reflected in the structure of the enterprise, the number and location of production shops and sites. The department includes five well casing shops and four sites, including a site for the repair and maintenance of special equipment, two laboratories for cement slurries (including one in Yakutia). As new deposits are commissioned, the geography of plugging operations expands. Today, work is underway at the fields of the Khanty-Mansiysk regions autonomous region- Yugra, as well as beyond its borders - in the Tomsk, Omsk, Novosibirsk and Tyumen regions, the Krasnoyarsk Territory and in the Republic of Sakha (Yakutia).

In connection with the drilling of new fields and an increase in the average depth

wells under construction, the requirements for the quality of cementing work have been significantly increased, the implementation of which has become possible due to the introduction of new cementing materials, special equipment and technological equipment, improvement technological processes cementing.

One of the important directions for improving the quality of casing string cementing is the use of prefabricated lightweight oil-well cements that ensure the minimum density of the prepared cement slurry while maintaining strength.

In the laboratory of cement mortars

ny and adhesive properties cement stone. Over the course of a number recent years a large volume of laboratory and field tests of lightweight oil well cements of various compositions and plants, manufacturers (PCT I-50, PCT II-50, PCT III Ob 5-50,

PCT III About 5-100, MTO-5-100, PCT III About 2-50, OTM-4, TsTOA-1-50, TsTOS 5-100, TsTOS 4-100, TsTRO). The results of the tests made it possible to choose the most effective lightweight well cements, in comparison with those previously used. In order to prepare for the mass transition to lightweight factory-ready cements in bulk form, work was carried out to reconstruct all cement warehouses in order to increase the volume of cement storage, reduce negative impact on the environment.

In order to improve the quality of adhesion of cement stone to the production casing in the interval of productive formations, various grouting cements were used for moderate (PCT I-100, PCT I G SS-1, TsTR-1-100, TsTRS-100, RTM-75) and elevated temperatures ( ShPTsS-120, TsTTS, TsTVA-1-160). In 2011 in Western Siberia switched to the use of class G grout cement instead of the previously used PCT-I-100. With its use, more than 70% of production strings were cemented, which made it possible to improve the quality of adhesion in the interval of productive horizons. In order to improve contact in the zone of productive formations, field tests of expanding grouting materials were also carried out, which provided a significant increase in continuous contact of cement stone with casing in these wells.

Since 2010, magnesian backfill material (MTM-S) has been used to improve the quality of well casing, which is being built in the salt deposits of the Talakanskoye field (Yakutia), which was specially developed for these geological conditions. In all wells where MTM-S was used, continuous contact of the cement stone with the column was obtained. In 2011, all production strings at the Talakanskoye field were cemented using magnesian cementing material.

An important factor in improving the quality of oil well cements used for cementing casing strings in Yakutia is the commissioning of a site for unpacking oil well cement. Modern equipment, which the site is equipped with, made it possible to mechanize the process of cement unpacking from soft containers, significantly reduce its losses in the form of cement dust and from the impact environment by improving the conditions of its storage and increasing the culture of production. A non-core function was removed from the drilling crews and heavy physical work when filling cement into cement mixing machines was excluded.

A lot of work has been done to introduce new types and methods of cementing. The technologies of sleeve, selective-sleeve, staged cementing of production strings were mastered, using various couplings and packers. Together with the introduction of new types of cementing, the range of plugging materials and cement slurry formulations used is expanding, and chemical reagents are being tested that improve the quality of well casing.

Only a helicopter can fly

In the cementing process control station

In the laboratories of cement management, which are equipped with modern imported equipment, input control of all incoming tampon materials, the selection of formulations of tampon solutions for specific conditions wells, various chemicals are tested to improve the quality of cement stone.

Since 2010, a new cement slurry laboratory has been put into operation in the Talakan well casing shop, equipped with modern equipment for the analysis of cement slurries and stone. In addition, there is a portable laboratory equipment that allows, immediately before cementing, to analyze the plugging material on the prepared mixing fluid,

That is necessary condition high-quality cementing operation with the use of magnesia cementing material.

An important factor in improving the quality of cementing is the use of more productive and reliable special equipment, process equipment. Plugging workers, together with specialists from domestic machine-building plants, carried out a lot of work on the development and introduction into production of a two-pump plunger cementing unit, a cement mixing machine with increased load capacity, special equipment on a sledge (for servicing exploration wells), a cement truck on an off-road chassis that ensures the delivery of cement directly to the drilling rig for additional filling of cement mixing machines.

The twin-pump cementing unit was designed to operate in harsh northern conditions, which, with a slight increase in mass, significantly exceeds the technical specifications two conventional units with piston pumps. These units are found wide application when performing work on cementing and development of wells.

A prototype was made and field tests of a cement-mixing unit were carried out on a chassis with increased carrying capacity, which will allow transporting 1.5 times more cement materials.

Due to the manifestation in organizational structure OJSC “Surgutneftegas” of the department of prospecting and exploration operations, it became necessary to create special plugging equipment that can be transported on an external helicopter sling on an insulated

Heavy-duty cement truck

Exploration well cementing

drilled wells. Cementing units (ATsS-320), cement mixing machines (1CMP-20), compressor stations on sledges (PKS 7/100S), which could be transported from one well to another by helicopters. Currently, work is underway to further modernize special equipment. Three cement-mixing machines with an increased volume of the bunker were manufactured, which will reduce the cost of helicopter transportation due to a decrease in the required amount of special equipment for cementing.

The department operates eleven averaging units UOP-20, seven of which have been modernized. In 2011, 505 production strings were cemented using UOP-20. The modernized averaging plants allow stabilizing the parameters of simultaneously prepared cement slurries of light and normal densities, carrying out their hydroactivation, and ensuring a stable concentration of chemical reagents in the entire volume of prepared cement slurries. The use of averaging plants allowed to improve the quality of adhesion of cement stone to the casing string in the interval of productive horizons.

In order to strengthen control over the quality of the casing string cementing process, the department operates 11 complexes of new generation cementing monitoring and control stations, which were developed jointly with CJSC Elektrotekh. Today it is one of the most reliable and accurate cementing control stations. domestic production in which he was for the first time

N. A. Aksenova, M. V. Luzan, V. P. OVCHINNIKOV, N. V. Parkhomchuk, O. V. Rozhkova, and V. A. Fedorovskaya - 2015

Packing a well is a set of works to isolate its individual intervals. Plugging is carried out in order to prevent well collapses and erosion of rocks in the space behind the casing pipes, to separate aquifers or other horizons for their study, to bridge cracks, voids, caverns, to eliminate water intrusions, and to absorb flushing fluid during drilling.

Rice. 8.1. General scheme of plugging:

1 – casing string; 2 – backfill material; 3, 4, 5 - isolated, waterproof and aquifer, respectively.

When drilling for liquid and gaseous minerals, as well as for mineral salts, it is necessary to isolate the mineral layer from the overlying layers. Isolation of individual horizons in the well is necessary to prevent the penetration of ground and formation waters into the mineral reservoir. When approaching the productive formation, the drilling of the well stops in the watertight formation above. Then a string of casing pipes is lowered into the well, and the annular space between the bottom of the string and the walls of the well is filled with a waterproof material. . By plugging the annular space, the casing string is protected from compression by pressure and the corrosive effect of mineralized groundwater.

Apply permanent and temporary plugging. Permanent plugging is carried out for a long time. With constant plugging, the near-wellbore space is isolated from the wellbore. Temporary plugging is intended to isolate individual horizons and is carried out for the duration of the well test.

Plugging is carried out to isolate and isolate aquifers with different chemical composition. For example, to isolate bitter-salty water from drinking water, to isolate aquifers from oil and gas bearing ones, to produce experimental water injections into a porous reservoir, to protect casing pipes from corrosion with mineral waters, to eliminate groundwater circulation through the wellbore when extracting casing pipes and abandoning the well .

Clay, cement, clay-cement mixtures with fillers, quick-setting mixtures (BSS), bitumen and resins are used as grouting materials.

Clay plugging is used when drilling shallow exploratory or hydrogeological wells. If a clay layer 2-3 m thick lies at the site of the planned plugging, plugging is carried out by pressing the casing shoe into the clay, having previously drilled this layer by 0.5-0.6 m.

If there is no clay at the bottom or if its formation is insufficient, the lower part of the well is filled with viscous clay, a cone plug is inserted into the casing shoe, which squeezes the clay into the annulus. At the end of plugging, the plugs are drilled.

Plugging with cement is called cementirovanity wells. Cementing is used when drilling wells for water, oil, gas and in cases where it is necessary to obtain a strong and dense tampon for a very long time.

For cementing wells, well cement based on Portland cement is used.

After mixing with water, oil well cement should give a mobile solution pumped over by pumps, which thickens over time and then turns into a waterproof cement stone. The cement slurry must be prepared as quickly as possible to prevent it from setting during injection into the well. Cement mortar is prepared in cement mixers or in special cementing units mounted on a car.

The most widely used method of cementing in exploratory drilling is the immersion of the casing shoe in a cement slurry poured onto the bottom of the well. Downhole cementing is carried out to isolate the lower wellbore part of the casing string. The cement mortar is poured into the well through the pouring pipes to a height of 2-3 m.

After extraction of the pouring pipes from the well, a string of casing pipes is lowered to the bottom. After the cement slurry has hardened, a plug is drilled in the casing pipes and the drilling of the well is continued.

Temporary packing wells are produced for a short period of separate study of aquifers (oil and gas) horizons.

To isolate individual sections of the well that are subject to research (pumping, injection), special swabs are used, called packers. According to the principle of operation, packers are distinguished between single and double action. Single-acting packers divide the well into two sections isolated from each other, and double-acting - into three.

The principle of operation of the packer is based on the fact that when the rubber cuff or cushion expands, the gap between the walls of the well and the pipe string, on which the plug is lowered, is reliably sealed. Rubber cuff(cushion) in the well can be compacted mechanically, using water or compressed air.

Hydraulic packer (fig. 8.2.) with two rubber chambers 3 (double action) lowered into the well on a pipe string 1. Pressurized water through pipes 2 in camera 3, presses them against the walls of the well. Thus, the well is divided into three sections. Through the filter pipe 4 after the packer is installed, experimental pumping or filling is carried out.

Rice. 8.2. Hydraulic packer:

I - aquiclude; II - porous aquifer; 1 – casing string; 2 - tube for water injection; 3 - camera; 4 - connecting tube; 5 - filter pipe; 6 - blind plug

Plugging without casing pipes. To combat the absorption of drilling fluid without reducing the diameter of the well, BSS of various compositions is used. The dosage of a mixture containing Portland cement, clay mortar, liquid glass, caustic soda and water depends on the quality of the cement and clay. By changing the amount of liquid glass and caustic soda, the properties of the mixture and the timing of its setting are regulated. In 20-35 minutes after preparation, the BSS loses its mobility, and after 1-1.5 hours its setting ends. Cement mixtures based on synthetic resins are also used by mixing them with a filler and then adding a hardener to the mixture.

Cement mixtures must be delivered to the place of absorption of the drilling fluid before the loss of mobility. The mixture is delivered by one of the following methods: 1) by pouring through the mouth of a shallow well; 2) pumping through the drill string, 3) in a core set, closed from below with a clay plug, followed by extrusion with flushing fluid; 4) using special plugging devices.

The cement mixture delivered to the absorption zone after holding for the time necessary for its solidification is drilled out.

Well cementing with two plugs

If a large lifting height of cement in the annulus is required (at any distance from the bottomhole, up to the wellhead), pressure cementingwith separating plugs. In this case, two separating plugs and a cementing head are used. Separating plugs are equipped with sealing rubber cuffs. The upper plug is solid, and the lower one has an axial channel covered with a glass disc or a rubber membrane.

Annular flushing. Through outlet 1 (Fig. 8.1, a) of the cementing head, flushing fluid is injected to flush the well. In this case, the casing string is suspended at the wellhead with the help of a fire monitor collar and does not touch the bottomhole.

Introduction to bottom plug casing. To do this, the cementing head is unscrewed from the string and the bottom plug is inserted into the mouth of the casing string. After that, the cementing head is screwed on with the top plug fixed in it.

Injection of cement mortar into the casing string. Releasing the top plug and pushing it along the string. The retractable stoppers 6 of the cementing head are unscrewed, thereby releasing the top plug, and flushing liquid (clay mortar or water) is injected through the outlet to push through the plugs. Then the system, consisting of two plugs and a cement mortar between them, will move down.

Forcing cement slurry into the annulus. When the bottom plug rests against the stop (retaining) ring fixed between the pipes and the shoe, then the increased pressure of the pump crushes the glass plate that covers the hole in the bottom plug, and the cement slurry is forced through this hole into the annular annulus (Fig. 8.1, c). The end of injection of cement mortar into the annulus corresponds to the moment of convergence of the plugs (Fig. 8.1, d), determined by a sharp increase in pressure on the pressure gauge.

Removing the casing string from the fire monitor collar and lowering the string to the bottom.

To do this, the column is lifted with the help of an elevator, a hook, a traveling system and a winch of a drilling rig, removed from the body of the fire monitor clamp and the column is lowered to the bottom.

aging casing strings under pressure (with closed branches 1 and 2) for 12-24 hours until the end of setting and hardening of the cement.

Removing the cementing head, drilling out plugs and thrust ring, bottom hole cleaning.

Checking the result of plugging. To do this, the fluid level in the well is lowered by pumping below (at least 10 m) the static level of the plugged aquifer. If during the day the water level in the well did not rise (not taking into account the rise in the level to 1 m due to the moaning of drops along the walls of the pipes), then it is considered that the aquifer has been plugged and an act is drawn up about this.

Rice. 8.1. Scheme of well plugging with cement according to the “two plugs” method:

a – start of cement pumping; b – end of cement injection; c - the beginning of the rise of cement into the annulus; d – end of cementation

1 - stopcock; 2 - manometer; 3 – head for grouting; 4 - the upper part of the cork; 5 - rubber cuffs; 6 - the lower part of the cork; 7 - casing pipe; 8 - top plug; 9 - bottom plug

Well cementing, or as it is also called plugging, is one of the most milestones their construction, and this applies not only to oil, but also to water intake facilities.
The essence of this operation is that the space formed between the walls of the pipe and the penetration must be filled cement mortar. That's what we'll talk about in this article.

All about packing

Cementation of deep wells is carried out taking into account the experience of previous years, using modern equipment and scientific research. Typical schemes The production of these works has been worked out to the smallest nuances, and their competent implementation is very important.
First, the tampon prevents the impact pressure water and quicksand on the wellbore, preventing them from washing out the mine. Secondly, the solidified solution rigidly fixes the structure, preventing the columns from moving.
So:

• Wells are plugged (see) not only during the construction process, but also during conservation and liquidation - only the technologies are somewhat different. Although, absolutely everything is impossible to take into account, since in each case there are different conditions works: technical equipment, well design, geological conditions, cement bridge length.

Therefore, technologies are often refined in the course of work, and this is normal.
The main thing that this process provided the following requirements:

• To meet these conditions, it is necessary to control and adjust the characteristics of the flushing fluid in order to reduce its viscosity. Recall that flushing is carried out during the drilling process, which allows you to soften the soil and wash out the cuttings from the penetration.
  The cement slurry is injected into the annulus at a rate that can provide a turbulent regime.
• In each case, the formulation of the solution is selected individually. Its properties determine both the duration of plugging operations and the modes of injection and punching of the solution.
  By the way, normal building cement not used in this case. There is a grade specially designed for wells, which is called "gypsum alumina cement."

It tends to expand, and this is the most important thing in plugging work. A solution of such cement is not absorbed into the soil, but fills all the voids and tiny cracks, clogging them according to the principle of a tampon - hence the name of the technology.
If there are large voids and quicksand in the penetration, add to the gypsum-alumina solution dolomite flour, bentonite clay, or asbestos or cellulose fibers.

One-cycle plugging, with two plugs

When cementing using this method, the bottom plug is first installed in the desired wellbore segment. It has a channel for the passage of the solution, which is temporarily blocked by a diaphragm.
Further, a head is installed in the upper part of the column, through which the cement slurry is supplied from the mixer. The top plug, held in place by studs, is positioned on the cementing head.

So:

• When, according to the calculation, the entire volume of the solution is completely pumped into the barrel, this plug is released, and the flow of fluid for punching begins. Under high pressure, the mass of the cement column, together with the cork, moves down.
• Along the way, it displaces drilling fluid from the wellbore. This happens due to the own weight of the cement slurry, as well as its high density. In the process of liquid displacement, the pressure level on the head through which the solution is injected is significantly reduced.

The plugging mixture column moves along the shaft together with the plug installed at the bottom mark. And as soon as it stumbles upon the thrust ring, there is a sharp increase in pressure.
As a result, the jumper diaphragm, which blocked the hole, is destroyed. After that, the solution freely enters the annular sinuses.
The volume of fluid pushing through the cement plug is continuously monitored, and when the last couple of bottoms remain, the pumping rate is reduced. As soon as the plugs that cut off the interval come into contact, as evidenced by a sharply increasing pressure, the injection of the cement mixture stops.

Two-cycle cementing

In this way, two intervals are sequentially plugged at once. Compared to single cycle cementing, this method has some advantages.
At the same time, the probability of penetration of the flushing liquid into the cement mortar is significantly reduced, and the pressure on the soil during its lifting is reduced. Importantly, the lift height can be increased significantly even if the pressure does not increase.
So:

• The preparatory work preceding plugging is carried out according to the same scheme as mentioned above. Only now, in the lower part of the segment of the casing, which is being prepared for plugging, is the casting sleeve installed.
  At the end of flushing, the head is installed, and the injection of that volume begins cement mixture, which is necessary to fill the first stage.

• At the next stage, an intermediate plug is introduced into the wellbore through the filling sleeve, which completes the first cycle, and, under the influence of the displacement fluid, moves the injected mixture deep into the hole. Its quantity, at the same time, is equal to the volume of that segment of the casing string, which is located between the thrust ring and the filling valve. Then, the bottom plug of the second segment, which is located in the body of the cementing head, is released and forced through.
• Under the influence of pressure, the plug will be pressed against the coupling, it will sit on the sleeve, and, moving down, will open the through passage. Further actions may have two options.
  In one of them, after the completion of the cementation of the first stage, immediately proceed to the second cycle. This method is a continuous cementing process.

• The second option is called: two-cycle plugging with a gap. In this case, the pouring of the second section of the column is carried out only after the already pumped cement mixture has set.
  During this period, drilling fluid circulation is maintained in the filling valve. This option allows you to adjust the level of dynamic pressure that occurs in the annular sinuses, and, accordingly, improve the quality of plugging.

As soon as the supply of the calculated volume of the cement mixture intended for the second segment is completed, the last, upper plug is installed in the column and forced through with liquid. Now she, moving down along with the sleeve, will block the through hole.

Sleeve and reverse cementation methods

The decision in favor of the sleeve method is made in cases where the formation is cemented at low pressure, or it is necessary to prevent the entry of the solution into the filter column. Its essence is that at the lower mark of the plugged sector, a sleeve is installed with holes for the passage of the solution, and a tarpaulin cuff.
So:

• A valve is located just below the sleeve, blocking the access of the solution to the inside of the column. And the cuff, in the process of injecting the solution, covers the annulus so that the cement column can only move upwards.
• There is another option in which cementation is performed in the opposite direction (from bottom to top). In short, it is done like this: the casing along the lower perimeter is covered with a special shoe; the solution, through a special sleeve, is pumped directly into the annulus.
  At the same time, the drilling fluid located there is displaced, and, through the casing pipes, comes to the surface.

This method attracts drillers, but it is not suitable for cementing ultra-deep wells. The reason for this is a number of technical difficulties.
For example, it is difficult to control when the cement slurry reaches the bottom of the casing string. Accordingly, it is also impossible to assess the quality of cementation - and this part of the wellbore is the most critical.

The final stage of cementing

The hardening period of the cement column may vary, depending on the composition of the mortar. It also matters which column was plugged.
For a conductor, for example, 16 hours are enough, and for a production string, a day is needed. After this period, an electrothermometer is lowered into the well.
So:

• With its help, by temperature changes, determine the height of the rise of the solution in the cemented space. The maximum release of heat by the solution occurs within a few hours after its hardening.
  Therefore, to determine this indicator, the device must be lowered into the well within a day after the end of plugging.

• An acoustic probe (borehole locator) is widely used to control the quality of cementing. Areas not filled with a solution are determined by the amplitudes of sound vibrations. If there are no complaints about the quality of plugging work, the wellhead is tied up.
  Then, a pointed chisel or a bailer is lowered into it, with the help of which the hardened solution residues and filling plugs are drilled.

Next comes the turn of pressure testing the barrel, that is, checking it for tightness. For this, water is pumped into it at a pressure exceeding the calculated one by 20%.
If, after half an hour, the pressure drops by no more than 0.5 MPa, and there is no gas evolution and no water overflow, the well is considered tight.

Measures, the purpose of which is the elimination of water intake, are called cementing or plugging the well. Such work is carried out in order to protect the aquifer from possible chemical or bacteriological contamination from the surface. Well plugging is translated from French as "cork".

This term indicates that in the process of work, a solution is injected inside, which strengthens the rocks, forming an anti-filtration and waterproofing curtain. Liquidation plugging is carried out when the well is out of order, this can happen different reasons. The following are the main ones:

• the source fulfilled its purpose;
• not in demand or abandoned;
• geological reasons;
• technical reasons;
• environmental or technological reasons.

Description of the types of plugging

If we consider geological reasons in more detail, we can say that in this case, water intake may simply cease to fulfill its role, which quite often becomes a consequence of geological processes. Technical reasons - this is the case when the water intake was not maintained for a long time.

As alternative may be disturbed during drilling. The work may have been carried out using inappropriate materials, repairs have not been carried out for a long time, and maintenance has not been carried out. Well plugging is also carried out in the case when the water intake was built for temporary use.

Grounds for liquidation of water intake

If the well fits into one of the categories that were listed above, then it should be liquidated, because there is a possibility that the aquifers will be contaminated, and they can be used by other water intakes. After reviewing the Subsoil Law, you will be able to find out that the user must ensure the elimination of the source and the safety of the water intake.

Work rules

When carrying out plugging, specialists should use the rules of liquidation plugging of wells, they suggest the need for design work. At this stage, you should find a passport, which contains information about the type of protective structure, it can be a building, a caisson or a pavilion. In the documents you can find the parameters and characteristics, as well as the absence or presence of underground tracks.

Next, you need to carry out a study, which is called logging. As a result, it will be possible to determine the depth of the well, assess the condition, or rather, the walls. All this can be called a revision of the source. Plugging must be accompanied by a definition of the cause, then the elimination category is assigned.

A two-meter pit is dug along the perimeter of the source, the width of which should be 1 m. 30 cm above the bottom of the pit should be cut casing pipe. Drilling equipment will allow you to clean the source of foreign objects and debris.

Work technology

Liquidation plugging rules provide for disinfection and flushing of the water intake special solutions. The filter column must be covered with gravel or crushed stone to the full depth. Then it is prepared and poured. If the water intake has an impressive depth, backfilling and cementing can alternate.

Using cement, the mouth is poured, then the plug is welded. Liquidation plugging wells provides for backfilling of crushed stone cushion. It should be 50 cm below the ground. Upper layer can form fertile soil or pour concrete, everything will depend on the purpose of further use. The final stage will be the survey of water intake from the register.

When well killing is required

The well is shut off when the aquifer begins to flow. To do this, the bottomhole pressure must be increased so that the in-situ pressure values ​​are exceeded. If a 5-meter fountain has clogged from a source, a high-density technical liquid should be pumped into it. The total mass in this case should create a pressure higher than that observed in the aquifer.

Jamming will eliminate the accident and eliminate its consequences, eliminating the risk of recurrence. After the repair is completed, the technical fluid is pumped out, flushed, and only after the source can be used again. Sometimes the killing is carried out tightly, in which case the well can no longer be used.

Such plugging of wells may involve the use of chemical or biological agent, in which case the source will not be usable. As an alternative solution, cement mortar can also be used. Sometimes seasonal stunning is also required, in which case water is drained from the system, and the caisson is insulated. An event of this kind is held in summer cottages.

Liquidation of wells for various purposes

The rules for abandonment plugging of wells for various purposes require the use of different methods. For example, if the well turned out to be dry, then it can be filled with a clay solution or thrown with clay to the full depth. Engineering-geological, hydro-geological, mapping and geological prospecting wells that have already fulfilled their purpose, and also did not give positive results, can be eliminated by the extraction of casing pipes.

If after completion of work it is not possible to carry out such manipulations, then the wellbore should be covered with clean sand, and the overlying part should be covered with clay, poured with clay or cement mortar. Liquidation plugging of wells for various purposes in this case requires compliance with the requirements of the sanitary and epidemiological service.

According to them, wells and workings, which exist for quite a long time, are subject to plugging. They may be inactive, silted or clogged. In this case, washing can be carried out with a clay solution or water using drilling tool. Then the well is filled with chlorinated water, the volume of which should be equal to three times the volume of the wellbore.

If the water intake is within the aquifer, then it should be covered with clean sand, the volume of which should be equal to the volume of the wellbore within the aquifer. Top part it is poured with clay mortar, thrown with clay and rammed, cement mortar can be used as an alternative solution.

Liquidation of an artesian well

Plugging an artesian well may involve the use of clay and tampons. To do this, apply oily clay, in which there are no impurities. Why is it mixed with a stirrer, and balls are rolled from the resulting rock, the size of each of which should be equal to a fist.

The balls are dried, for this they should be left in the sun. Then they are stacked in the production of 15 pieces at a time. Sometimes the balls are lowered inward with the help of a bailer, at the end of which there should be a valve that opens outward. If this method is used, the beads are not pre-dried. Each portion is well compacted, the pipe rises at the same time. The height of the cork should be 1.5 m.

The second way to eliminate an artesian well

Plugging wells of artesian type can be carried out using concrete mortar prepared according to special technology. Some believe that the first method is not so relevant. However, this statement is erroneous. After all, sometimes temporary tamponing is required. But if the well is no longer used, then its liquidation should be carried out with concrete. When the water intake is to be divided into segments for some time, swabs called packers should be used. They are used in the process of studying rocks, which differ in the presence or absence of pores and cracks. Thanks to them, it is possible to check the quality of rock cementing.

Conclusion

To carry out plugging, you will need certain equipment, this is a metal rammer, a pump and drill pipes. The pump will be required to inject the cement slurry with the help of drill pipes, which will be lowered to the bottom.

Well plugging is a set of measures aimed at protecting the subsoil and strengthening the annulus and casing from the damaging effects of rock and groundwater. Many readers who begin independent drilling are often interested in whether plugging a well for water is necessary, and how to do it on their own.

We will try to answer.

Well cementing

Purpose

Let's start by defining the term itself. Plugging is the filling of rocks and the cracks present in them with cement mortar to prevent the seepage of water, oil or other minerals through the rock and the penetration of these substances into other layers and horizons of the soil.

Distinguish:

• direct cementing of the annulus of wells in order to strengthen the wellbore and prevent leakage of perched water and groundwater into the limestone layer;
• cementing for the purpose of abandoning a well - abandonment plugging.

Liquidation is needed due to the fact that in some cases an old well begins to pose a threat of contamination of aquifers. Artesian water reserves are considered strategic reserves of the state, so their security is the security of the country.

On the basis of analyzes and examinations, the competent authorities decide on the need for liquidation plugging of the object, then draw up a project of work, and, after its approval, cementing is carried out by professional organizations.

Important!
Production cementing makes sense only in the case of a large depth of the well and certain characteristics of the cut of the rock.
For drilled wells “on the sand”, this measure does not make practical sense, since in this case there is no danger of communication between different aquifers.

When drilling artesian wells the decision on the need for cementing is made by the organization performing the work.

When is tamponage needed?

To concretize the article, it is necessary to immediately determine the signs by which it is possible to establish the need for cementing and abandonment of the well.

So, plugging is necessary in cases where:

• The quality of the water in the well has deteriorated, and restoration or improvement is impossible or impractical due to technical, physical or economic considerations;
• The object has exhausted its resource and is no longer in operation;
• Temporary wells of small diameters are no longer of interest due to the emergence of other sources of water supply;
• Defects in the design of the facility are found, the flow rate has decreased or an accident has occurred, and the restoration is economically unprofitable or technically unfeasible;
• Geological exploration or exploratory drilling has completed its task and is no longer needed;
• Springs with pressure gushing waters ceased to be constantly exploited;
• Absorbing wells began to pose a threat of contamination of aquifers.

It should be said that plugging is most often performed when drilling oil and gas developments. When water is extracted, objects are rarely cemented, in special cases.

There are no clear rules here when concrete should or should not be made, everything is decided in the process of designing and performing work on the basis of intelligence data, the structure of the rock cut, its composition, etc.

In practice, everything looks like this: after drilling is completed, the owner of the well receives a passport for the object, which indicates exactly how to monitor him and what measures to take in certain circumstances. Among other things, it says that in the event of an accident, breakdown, deterioration in quality and other force majeure circumstances, the owner is obliged to notify the SES.

Further, the SES takes water for analysis and inspection of the facility. Based on the data received, the station issues a verdict on the state of the well and its future fate, and the owner receives instructions for actions that he must take to eliminate the breakdown or object.

Important!
Responsibility for proper conduct of all prescribed measures falls entirely on the owner, and failure to comply with these requirements threatens with criminal prosecution for violating the law on the protection of subsoil.

Work on proper plugging is carried out using special equipment, the price of which is unbearable for a private person or a summer resident. Therefore, many are interested in whether do-it-yourself cementing is possible? There is no single answer here, it is necessary to consider each individual case.

Mounting

For owners of private homemade wells, you should know that their abyssinian wells and sand wells do not require cementing. This is explained very simply: these objects do not pose a threat of contamination to stocks fresh water, since they do not cross different aquifers, but draw groundwater from a sandy aquifer.

However, for such objects, another danger remains: perched water and sedimentary water can penetrate along the casing string or needle into sand layer and pollute ground water, reducing the characteristics of the source.