RU2513788C1 - Universal device for drilling, cleaning of cavern and installing of cement plug - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to the area of well-workover operations and can be used for drilling in sludge underflow, cleaning of cavern and installing of a cement plug. The device contains a hollow barrel 1 with though radial holes 2 and outside collar 3, upper and lower sleeves 4, 5 installed with formation of tilted annular slit 6 between their upper and lower surfaces respectively. The lower sleeve 5 can move along the axis of the hollow barrel 1. The outside collar 3 of the hollow barrel 1 is formed below through radial holes 2. The lower sleeve 5 in the upper part has an inner groove 7 for the outside collar 3 of the hollow barrel 1 corresponding to the length of its axial movement along the hollow barrel 1. The lower edge of through radial holes 2 of the hollow barrel 1 is placed above the level of the tilted annular slit 6. Inner surfaces of the upper and lower sleeves 4, 5 and the lower surface of the hollow barrel matching them form an annular cavity A connected hydraulically to a cavity of the hollow barrel 1 through radial through holes 2. The device contains the upper and lower crossover shoes 8, 9. The upper crossover shoe 8 is connected from outside to the upper sleeve 4 and from inside to the hollow barrel 1; it has a prolonged bladed centraliser 10. The lower crossover shoe 9 is connected from inside to the hollow barrel 1 and presses the lower sleeve 5 through a rubber resilient element 11 with pressing force calculated as per inequality. In the middle part the lower crossover shoe 9 has an inner collar 12. In the hollow barrel 1 there are located in-series a thrust bush 13, a hollow piston 14 and a spring 15 resting on the collar 12 of the lower crossover shoe 9 with pressing force calculated as per inequality. The hollow piston 14 has a saddle for a setting ball 16; it is installed with tight covering of through radial holes 2 of the hollow barrel 1. The device contains a rock destruction tool 17 connected to the lower crossover shoe 9.

EFFECT: improving quality of cavern cleaning, installing of cement plug, increasing operating reliability and expanding technological capabilities of the device due to potential drilling into sludge underflow, automatic cleaning and centring of the device in regard to the well axis with rated diameter.

1 dwg

Description

The invention relates to the field of overhaul of wells and can be used for drilling in sludge, cleaning the cavity and installing a cement bridge.

A device for installing a cement bridge is described, described in the method of installing a cement bridge (see cl. RF 2170334 from 08.24.1999 according to CL E21B 33/13, publ. 10.07.2001), containing a hollow barrel with through radial holes, the upper sleeve ( a skirt) and a lower sleeve installed to form an inclined annular gap between their lower and upper surfaces, respectively. The inner surfaces of the upper and lower bushings and the outer surface of the hollow barrel corresponding to them form an annular cavity hydraulically connected to the cavity of the hollow barrel through through radial holes located at the level of the inclined annular gap. The lower sleeve is mounted axially movable along the hollow barrel and has an inner annular groove, and the hollow barrel has an outer annular groove. A thrust ring is installed in these grooves, restricting the upward movement of the lower sleeve. In the gap between the lower sleeve and the hollow barrel, rubber rings are placed. The device comprises a housing with a connecting thread and a passage channel. The housing in the lower part is connected to the hollow barrel, and on the outside with the upper sleeve. A shoe armed with a blade is attached to the bottom of the hollow barrel. A rubber elastic element is installed between the shoe and the lower sleeve.

The disadvantages of the device is the following.

The elastic rubber element is installed without taking into account the differential pressure of the working fluid during operation of the device. During operation, the openness of the inclined annular gap will increase due to the effect of hydraulic force on the movable lower sleeve, which will lead to a decrease in the flow rate and, as a consequence, to poor-quality cleaning of the cavity and the installation of a poor-quality cement bridge.

The location of the through radial holes at the level of the inclined annular gap is the reason that prevents the creation of a uniform flow around the circumference. The jets of the working fluid emerging from the through radial holes, overcoming the inclined annular gap, do not have time to form a continuous stream.

In addition, the presence of a gap between the lower sleeve and the hollow barrel can lead to a deviation of the lower sleeve relative to the axis of the device, which will affect the uniformity of the opening of the inclined annular gap and will prevent the creation of a uniform jet.

The movement of the lower sleeve up is limited by the thrust ring, which is not reliable enough, since if the sleeve is repeatedly moved, it can be damaged, and metal elements falling into the gap between the hollow barrel and the lower sleeve will jam the latter.

The device cannot destroy the slurry sludge (plug) formed in the wellbore, including after expanding the cavity or shedding its arch with instability of the wellbore. A shoe armed with a blade can only penetrate into the sludge plug. The presence in the well of sludge particles, the size of which can reach a value that exceeds the difference between the inner diameter of the production string and the outer diameter of the device lowered into the well, prevents their removal, and therefore reduces the quality of cleaning the cavity. The technological operation for the destruction of large particles of sludge is carried out by additional descent and working out a bit. Replacing the shoe with a rock cutting tool is not possible due to its relationship with other structural elements.

The absence of a centralizer determines the eccentric position of the device when it enters the bore interval of the nominal diameter, as a result of which the uniformity of the distribution of the jet stream in the cross section of the annular space of the well is violated.

As a prototype, a device for installing a cement bridge was selected (see clause of the Russian Federation No. 2331756 of July 14, 2006, class E21B 33/13, publ. 08.20.2008), containing a hollow barrel (pipe) with through radial holes and an outer ring protrusion upper and lower bushings. The upper and lower bushings are installed with the formation of an inclined annular gap between their lower and upper surfaces, respectively. The inner surfaces of the upper and lower bushings and the corresponding outer surface of the hollow barrel form an annular cavity. The annular cavity is hydraulically connected to the channel of the hollow barrel through the through radial holes located above the inclined annular gap. The lower sleeve is installed with the possibility of axial movement along the hollow barrel. The device comprises a shoe rigidly connected to the lower part of the hollow barrel. The shoe has an internal flushing hole and is made with a landing seat under the ball. The upper part of the shoe has an internal groove in which the lower part of the lower sleeve fixed by a pin relative to the shoe is located. The shoe has a lobed peak with a l-shaped notch.

The disadvantages are the inability to drill the device into the sludge, unreliable operation of the device, insufficient quality of the cement bridge installation, as well as cleaning the cavity.

The shoe of the device is made in a form that provides interconnection with other structural elements, which does not allow replacing it with a rock cutting tool. Despite the presence in the shoe of the blade of a complex configuration, it is impossible for them to destroy large particles of sludge. In this regard, it is necessary to pre-work the slurry sediment in the wellbore and the cavity with a chisel.

In case of clogging of the inclined annular gap, the pin is cut and the lower sleeve moves down, this prevents an emergency situation, however, further operation of the device without removing it to the surface and replacing the pin is impossible. In case of insufficient cleaning of the working fluid, it may be necessary to repeatedly clean the inclined annular gap. The inability to automatically return the device to operating mode indicates the unreliability of the device.

During the cleaning process, the fluid flow through the hollow barrel and the shoe of the device enters the sludge sediment, as well as through radial holes and an inclined annular gap in the annular space. The separation of the flow reduces the hydraulic effect on the sludge. The axial jet intensity may not be sufficient to disaggregate the compressed sludge. As a result, it becomes impossible to deepen the device to the entire height of the sludge sludge. This leads to poor-quality cleaning of the wellbore and cavity. Poor cleaning of the cavity subsequently becomes the cause of poor-quality installation of the cement bridge.

The absence of a centralizer determines the eccentric position of the device when it enters the bore interval of the nominal diameter, as a result of which the uniformity of the distribution of the jet stream in the cross section of the annular space of the well is violated.

The technical result is to improve the quality of cleaning the cavity, the installation of a cement bridge, improving the reliability and expanding the technological capabilities of the device by providing the possibility of drilling the device into sludge, automatic self-cleaning and centering of the device relative to the axis of the borehole of nominal diameter.

The technical result is achieved using a universal device for drilling, cleaning the cavity and installing a cement bridge containing a hollow shaft with through radial holes and an outer annular protrusion, upper and lower bushings installed with the formation of an inclined annular gap between their lower and upper surfaces, respectively, with internal the surfaces of the upper and lower bushings and the outer surface of the hollow barrel corresponding to them form an annular cavity hydraulically connected to the channel of the hollow barrel through the through radial holes located above the inclined annular gap, and the lower sleeve is mounted with the possibility of axial movement along the hollow barrel. According to the invention, the device comprises an upper sub, made with a longitudinal blade centralizer, connected externally to the upper sleeve, and from the inside to the hollow barrel, and a lower sub connected from the inside to the hollow barrel. The device comprises a rock cutting tool connected to a lower sub. The connections of the upper and lower sub with the hollow shaft provide torque transmission to the rock cutting tool. The lower sub has an inner annular protrusion in the middle part and presses the lower sleeve through the rubber elastic element with a pressing force determined by the inequality

$$\frac{\Delta R\cdot \pi \cdot \left(d_{\mathrm{one}}^2-d_2^2\right)}{\mathrm{four}}\le F_{\mathrm{one}}\le \frac{\Delta R\cdot \pi \cdot d_{\mathrm{one}}\cdot \delta }{2\cdot k},$$

where F ₁ is the pressing force of the lower sleeve with a rubber elastic element, N;

Δр - pressure drop on the working device, Pa;

d ₁ - the inner diameter of the inclined annular gap, m;

d ₂ - the outer diameter of the hollow trunk, m;

δ is the openness of the inclined annular gap, m;

k is the coefficient of friction of sludge on wetted metal.

The outer annular protrusion of the hollow shaft is formed below the through radial holes. The lower sleeve in the upper part has an internal groove under the specified protrusion on the length of its axial movement along the hollow barrel. In the hollow shaft, a thrust sleeve, a hollow piston, made with a saddle for a ball being reset, mounted with a tight seal of the through radial holes of the hollow barrel, and a spring abutting in the annular protrusion of the lower sub with the pressing force determined by the inequality

$$\frac{\mathrm{four}\cdot \mathrm{but}\cdot \rho \cdot Q^2\cdot \left(d_3^2-d_{\mathrm{four}}^2\right)}{\pi \cdot d_{\mathrm{four}}^{\mathrm{four}}}\le F_2\le \frac{\Delta R\cdot \pi \cdot d_3^2}{\mathrm{four}},$$

where F ₂ - spring compression force, N;

a is the pressure loss coefficient in the hollow piston;

ρ is the density of the liquid, kg / m ³ ;

Q - fluid supply, m ³ / s;

d ₃ - the outer diameter of the hollow piston, m;

d ₄ - the inner diameter of the hollow piston, m

The figure shows a longitudinal section of the device.

A universal device for drilling, cleaning the cavity and installing a cement bridge contains a hollow shaft 1 with through radial holes 2 and an external annular protrusion 3, upper and lower bushings 4, 5, installed with the formation of an inclined annular gap 6 between their lower and upper surfaces, respectively. The lower sleeve 5 is mounted axially movable along the hollow barrel 1. The outer annular protrusion 3 of the hollow barrel 1 is formed below the through radial holes 2.

The lower sleeve 5 in the upper part has an internal groove 7 under the outer annular protrusion 3 of the hollow barrel 1 by the length of its axial movement along the hollow barrel 1.

The lower edge of the through radial holes 2 of the hollow barrel 1 is located above the level of the inclined annular gap 6. The inner surfaces of the upper and lower bushings 4, 5 and the corresponding outer surface of the hollow barrel 1 form an annular cavity A hydraulically connected to the cavity of the hollow barrel 1 through the through radial holes 2.

The device contains upper and lower sub 8, 9. The upper sub 8 is connected externally to the upper sleeve 4, and from the inside to the hollow barrel 1 and is made with a longitudinal blade centralizer 10.

The lower sub 9 is connected internally to the hollow barrel 1 and presses the lower sleeve 5 through the rubber elastic element 11 with a pressing force determined by the inequality

$$\frac{\Delta R\cdot \pi \cdot \left(d_{\mathrm{one}}^2-d_2^2\right)}{\mathrm{four}}\le F_{\mathrm{one}}\le \frac{\Delta R\cdot \pi \cdot d_{\mathrm{one}}\cdot \delta }{2\cdot k},$$

where F ₁ is the pressing force of the lower sleeve with a rubber elastic element, N;

Δр - pressure drop on the working device, Pa;

d ₁ - the inner diameter of the inclined annular gap, m;

d ₂ - the outer diameter of the hollow trunk, m;

δ is the openness of the inclined annular gap, m;

k is the coefficient of friction of sludge on wetted metal.

The lower sub 9 has in the middle part an inner annular protrusion 12. In the hollow shaft 1, a thrust sleeve 13, a hollow piston 14 and a spring 15 are arranged in series, abutting against the annular protrusion 12 of the lower sub 9 with a pressing force determined by the inequality

$$\frac{\mathrm{four}\cdot \mathrm{but}\cdot \rho \cdot Q^2\cdot \left(d_3^2-d_{\mathrm{four}}^2\right)}{\pi \cdot d_{\mathrm{four}}^{\mathrm{four}}}\le F_2\le \frac{\Delta R\cdot \pi \cdot d_3^2}{\mathrm{four}},$$

where F ₂ - spring compression force, N;

a is the pressure loss coefficient in the hollow piston;

ρ is the density of the liquid, kg / m ³ ;

Q - fluid supply, m ³ / s;

d ₃ - the outer diameter of the hollow piston, m;

d ₄ - the inner diameter of the hollow piston, m

The hollow piston 14 is made with a saddle under the ball being discharged 16 and is installed with a tight seal of the through radial holes 2 of the hollow barrel 1. The device contains a rock cutting tool 17 connected to the lower sub 9.

The tightness of the movable and fixed joints is ensured by the installation of rubber o-rings. The connections of the upper and lower sub 8 and 9 with the hollow barrel 1 provide the transmission of torque to the rock cutting tool 17.

The device is connected to the bottom of the drill pipe string and lowered into the well to the upper boundary of the barrel cleaning interval (cement bridge installation).

The presence of a longitudinal blade centralizer 10 allows you to freely lower the device, preventing contact of the borehole wall and possible clogging of the inclined annular gap 6, which increases the reliability of the device.

Restore circulation. By rotating and creating a load on the bit, sludge is drilled to the lower boundary of the wellbore cleaning (cement bridge installation). Mechanical failure is accompanied by the action of axial jets of fluid flowing out from the rock cutting tool (chisel) 17, which increases the rate of drilling of sludge. The overlapping of the through radial holes 2 with a hollow piston 14 allows a sufficiently high hydraulic power flow to be obtained at the entrance to the rock cutting tool 17. In this case, the elastic force of the spring 15 should balance the hydraulic force exerted on the hollow piston 14 when pumping fluid through it.

If the spring force 15 of the spring is less than the hydraulic force, the hollow piston 14 will move down and open the through radial holes 2 in the hollow barrel 1. As a result, the fluid flow is divided into two parts. One part will go to the rock cutting tool 17, and the second through the cavity A into the inclined annular gap 6 and further into the annular space. In this case, the hydraulic power of the flow supplied to the rock cutting tool 17 will be significantly reduced, which will lead to a decrease in the efficiency of drilling sludge sludge.

Stop circulation. A ball 16 is thrown into the drill pipe string, which, having reached the hollow piston 14, blocks the axial channel of the latter. Restore circulation. Under the action of pressure, the closed hollow piston 14 moves down. At the moment of opening of the through radial holes 2, the device begins to rise. The fluid flow rushes through the through radial holes 2 into the annular cavity A and through the inclined annular gap 6, forming an inextricable annular stream, cleans the walls of the cavity from the filter cake and cleans the cavity from sludge. When lifting the device, the sludge is kept in suspension due to the action of an inextricable stream and a toroidal vortex formed during its reflection from the borehole wall or cavity. The maximum required compression force of the spring 15 should balance the hydraulic force on the closed hollow piston 14 due to the pressure drop across the working device. If the compression force of the spring is greater, the hollow piston 14 blocked by the ball 16 does not budge or when it moves, the through holes 2 in the hollow barrel 1 will not fully open. As a result, the fluid will not flow into the cavity A and then into the inclined annular gap 6, t. e. a continuous ring jet is not formed. Or, the pressure of the fluid pumping at the pump will increase sharply (up to going beyond the operating range). At the same time, in the incompletely open through radial holes 2, the hydraulic power will act to overcome the local hydraulic resistance. As a result of this, reduced hydraulic energy will be supplied to the inclined annular gap 6, and the formed inextricable annular jet will be insufficiently intense and will not be able to provide high-quality cleaning of the cavity (installation of a cement bridge).

The lower sleeve 5 retains its original location (remains stationary), while maintaining the openness of the inclined annular gap 6 at a working pressure drop, which ensures the necessary flow rate of the jet from the inclined annular gap 6 and, as a result, high-quality cleaning of the cavity and the installation of a cement bridge.

The immobility of the lower sleeve 5 is achieved by pressing it from below by a rubber elastic element 11. The minimum required pressure compensates for the pressure on the bottom of the annular cavity A. When the pressing force is less than the minimum necessary value, the lower sleeve 5 will shift downward, increasing the openness of the inclined ring gap 6 and reducing the flow rate liquids. The maximum required amount of pressing provides the condition of self-cleaning of the inclined annular gap 6.

When the inner perimeter of the inclined annular slit 6 is completely filled with slurry, the slurry is retained due to friction against the upper and lower surfaces of the inclined annular slit 6. The minimum pressure force of the slurry to the upper and lower surfaces of the inclined annular slit 6 is equal to the minimum required value of the lower sleeve 5 being pressed by the rubber elastic element 11 . In this case, the hydraulic force acting on the sludge in the inclined annular gap 6, is balanced by the forces of friction. With an increase in the pressing force, self-cleaning of the inclined annular gap 6 at a given working pressure drop on the device will not occur.

The possibility of working out the cleaning interval (installation of a cement bridge) allows you to guarantee the implementation of the device to the lower boundary of the cleaning interval. The device is lifted to the upper limit of the cleaning interval (installation of a cement bridge). The location of the through radial holes 2 above the level of the inclined annular gap 6, the presence of the cavity A and the inclined annular gap 6 allow the formation of an inextricable stream of washing liquid. The presence of a longitudinal blade centralizer 10 provides uniform exposure to a jet of flushing fluid along the entire perimeter of the well when the device moves from the cavity to the borehole of a nominal diameter. If necessary, the cleaning can be repeated until the best result.

To install a cement bridge, the device is lowered to the lower boundary and a portion of the grout is fed through the drill string. When the cement slurry approaches the inclined annular gap 6 without stopping its forcing, the device is raised to the upper boundary of the cement bridge installation interval. The location of the through radial holes 2 above the level of the inclined annular gap 6, the presence of the cavity A and the inclined annular gap 6 allow the formation of an inextricable stream of cement slurry. The presence of a longitudinal paddle centralizer 10 provides a uniform effect of a jet of cement slurry around the entire perimeter of the well during the transition of the device from the cavity to the borehole of a nominal diameter. High-quality cleaning of the cavity and the use of an indissoluble annular jet provide a more complete filling of the cavity of the cavity with cement slurry not mixed with the flushing fluid, and increase the quality of the cement bridge installation.

Upon reaching the upper limit of the cement bridge installation interval, pumping of flushing fluid into the drill pipe string is continued with the aim of washing out excess cement slurry from the well. After that, the device is lifted, and the well is left for the period of waiting for the hardening of the cement slurry.

The possibility of implementing the proposed technical solution is illustrated by the following example.

The device was tested during well overhaul. The wellbore is cased to a depth of 876 m with a production casing with a diameter of 0.168 m. In the uncased part of the bore, in the interval 876-887 m, a clay cover of the reservoir, in which a cylindrical cavern with a diameter of 0.4 m is formed as a result of instability of the open bore, is formed.

To eliminate the cavity in the well, a cement bridge is installed in the interval of 887 m (the cavity bottom corresponding to the lower boundary of the cement bridge installation interval) - 876 m (the depth of the production casing string descent corresponding to the upper boundary of the cement bridge installation interval).

To install a cement bridge, use a device with an open sloping annular gap δ = 0.004 m, which allows the passage through it of cement particles with a diameter of up to δ / 3 = 0.004 / 3 = 0.001 m remaining in the grout during mixing with subsequent cleaning through a mesh filter. The device is connected to the bottom of the drill pipe string with a diameter of 0.114 m and lowered into the well. During the descent, the device and the inner cavity of the drill pipe are self-filling with flushing fluid through the flushing holes of the rock cutting tool 17, the lower sub 9, the hollow barrel 1 with the hollow piston 14 and the upper sub 8. The annular cavity A of the device is filled through an inclined annular gap 6. Longitudinal blade centralizer 10 excludes contact of the device with the casing and clogging of the inclined annular gap 6.

At a depth of 880 m, a compacted sludge was encountered. To drill sludge, a lead pipe with a swivel is connected to the drill pipe string and the direct circulation of the flushing fluid is restored with a flow rate of Q = 0.015 m ³ / s. In this case, the washing liquid is pumped by cementing pump pumps into the drill pipe string, from which it enters the upper device sub 8, then into the thrust sleeve 13, the hollow piston 14, the hollow barrel 1, the lower sub 9, and the washing holes of the rock cutting tool 17. As a rock cutting tool 17 used a three-cone chisel with milled teeth. The full flow of washing liquid, leaving the washing holes of the rock cutting tool 17, hydraulically breaks down the sludge.

For more effective destruction of sludge, the drill string is simultaneously rotated at a speed of 20 min ^-1 and an axial load on the rock cutting tool of 17 to 15 kN is created.

The torque transmitted by the rotor to the drill string comes to the upper sub 8 of the device. The upper and lower sub 8, 9 are connected to the hollow barrel 1 by thrust threads to enable the transmission of torque and axial load to the rock cutting tool 17, represented by a three-cone bit. The armament of the rock cutting tool 17 mechanically destroys the compressed sludge in the sediment.

The spring 15 in the process of pumping the flushing fluid compresses the hollow piston 14 against the thrust sleeve 13.

The minimum required value of the pressing force of the hollow piston 14 by the spring 15 when pumping the flushing fluid with a density ρ = 1100 kg / m ³ is

$$F_{2\min }=\frac{\mathrm{four}\cdot \mathrm{but}\cdot \rho \cdot Q^2\cdot \left(d_3^2-d_{\mathrm{four}}^2\right)}{\pi \cdot d_{\mathrm{four}}^{\mathrm{four}}}=\frac{\mathrm{four}\cdot \mathrm{1,2}\cdot 1100\cdot {0.015}^2\cdot \left({0.05}^2-{\mathrm{0,025}}^2\right)}{3.14\cdot {\mathrm{0,025}}^{\mathrm{four}}}=1816\text{N}$$

Here a = 1, 2 is the coefficient of pressure loss in the hollow piston, taken according to the reference data, taking into account the translation of the unit of dimension into the SI system (Eliyashevsky I.V., Sidersky M.N., Orsulyak Y.M. Typical tasks and calculations in drilling . - M. Nedra, 1982, p. 130);

d ₃ = 0.05 m is the outer diameter of the hollow piston;

d ₄ = 0,025 m is the internal diameter of the hollow piston.

By ensuring the minimum necessary amount of pressing force, the hollow piston 14 remains in the upper position, which excludes the opening of the through radial holes 2 in the hollow shaft 1 and the flow of the washing liquid into the annular cavity A of the device and then through the inclined annular gap 6 into the annular space of the well.

The maximum required force in the spring 15 is

$$F_{2\max }=\frac{\Delta R\cdot \pi \cdot d_3^2}{\mathrm{four}}=\frac{\mathrm{1,0}\cdot {10}^6\cdot 3.14\cdot {0.05}^2}{\mathrm{four}}=1962\text{N}$$

If the forces in the spring 15 after closing the channel in the hollow piston 14 are greater than the maximum required value, the hollow piston 14 will not move down and the through radial holes 2 in the hollow barrel 1 will not be open. As a result, in a closed hydraulic system, pumps of cementing units - drill string - the device will experience a water hammer, which will cause the safety devices to operate on the pumps and stop circulation or damage the device.

The entire flow of flushing fluid rises from the bottom in the annular space to the day surface, taking out fine sludge.

Upon reaching a depth of 887 m — the lower boundary of the cement bridge installation interval — the rotation of the drill pipe string is stopped, the well is washed until the cuttings are removed, and then the circulation of the flushing fluid is stopped.

A ball 16 with a diameter of 0.027 mm is dropped into the drill pipe string. Ball 16 under the action of its own weight falls into the saddle of the hollow piston 14 and blocks the channel in it.

Restore the circulation of flushing fluid with a flow rate of Q = 0.015 m ³ / s. Under the action of hydraulic force, the hollow piston 14, overlapped by the ball 16, overcomes the force of the spring 15 and moves down the hollow shaft 1, thus opening through radial holes 2. The entire flow of drilling fluid flows from the drill pipe string through the upper sub 8 and the upper part of the hollow shaft 1 into cavity A of the device through radial openings 2. From cavity A, the entire flow of flushing fluid flows out pressure into the annular space of the well through an inclined annular gap 6 formed by the lower surface of the well hney bush 8 and the upper surface of the lower sleeve 9. From the inclined annular gap 6 the device exits jet inseparable whole washing fluid flow in the direction of the axis of the device between its outer surface and the cavity wall.

At the same time, the device is lifted at a speed of 0.05 m / s to the upper boundary of the cement bridge installation interval of 876 m. An unbroken jet of flushing liquid, reflected from the wall of the cavity, forms a toroidal flow acting above the inclined annular gap 6. The toroidal flow captures and holds in suspension large particles of sludge until the device enters the production casing, where the upward velocity in the annular space is sufficient to carry large sludge to the surface.

The longitudinal blade centralizer 10 of the upper sub 8 eliminates the contact of the inclined annular gap 6 with the inner surface of the casing when the device enters it at the level of the upper boundary of the cement bridge installation. As a result, the rupture of the toroidal flow and the loss of large sludge from it back to the face are eliminated.

In the process of forming an indissoluble jet of flushing fluid, the rubber elastic element 11 provides compression of the lower sleeve with the minimum required force

$$F_{\mathrm{one}\min }=\frac{\Delta R\cdot \pi \cdot \left(d_{\mathrm{one}}^2-d_2^2\right)}{\mathrm{four}}=\frac{{1.010}^6\cdot 3.14\cdot \left({\mathrm{0,084}}^2-{\mathrm{0,068}}^2\right)}{\mathrm{four}}=1900\text{N}$$

Here d ₁ = 0,084 m is the inner diameter of the inclined annular gap;

d ₂ = 0,068 m - the outer diameter of the hollow barrel, taken from structural considerations;

Δр = 1.0 MPa - adopted according to experimental data.

The specified force maintains the lower sleeve 5 in its highest position (pressed against the outer annular protrusion 3 of the hollow barrel 1).

This ensures the constancy of the opening of the inclined annular gap 6 and the specified hydraulic characteristics of the continuous stream.

In case of clogging, the maximum required amount of pressing of the lower sleeve is

$$F_{\mathrm{one}\max }=\frac{\Delta R\cdot \pi \cdot d_{\mathrm{one}}\cdot \delta }{2\cdot k}=\frac{\mathrm{1,0}\cdot {10}^6\cdot 3.14\cdot \mathrm{0,084}\cdot 0.004}{2\cdot 0.4}=2375\text{N}$$

Here k = 0.4 - adopted according to reference materials for friction of steel on siltstone during washing with water (Spivak A.I., Popov A.N. Rock failure during drilling. M. Nedra, 1979, p. 117 )

The pressing force of the rubber elastic element 11 in the event of clogging of the inclined annular gap 6 should not exceed the amount of hydraulic force acting downward on the lower sleeve 5. If the pressing force of the rubber elastic element 11 exceeds this value, the lower sleeve 5 will not shift and the opening of the inclined ring will increase slit 6, from which the polluting sludge will be washed with a fluid stream.

After washing the sludge, the lower sleeve 4 under the action of the elasticity of the rubber elastic element 11 will move up to its original position and the device will automatically return to the specified operating mode.

After reaching the upper limit of the cement bridge installation interval of 876 m without stopping circulation, the device is again lowered to the lower boundary of the cement bridge installation interval.

A portion of the cement slurry is pumped into the drill pipe string in a volume of 1.4 m ^{3 with a} density of 1800 kg / m ³ , flowability of 0.018-0.020 m along the AzNII cone prepared from Portland cement cement PTCI-SS-50. The grouting solution is pushed along the drill pipe string to the device by injecting 5.6 m ^{3 of} flushing fluid with a flow of 0.015 m ³ / s. In this case, the drilling fluid, and then the cement slurry, as a whole, comes from the drill pipe string through the upper sub 8, the thrust sleeve 13, the upper part of the hollow shaft 1 through the radial openings 2 into the cavity A of the device. From cavity A, the entire flow of fluid flows out pressure into the annular space through an inclined annular gap 6.

With the beginning of the cement slurry exit from the inclined annular gap 6, the device is lifted on the drill pipe string with a design speed of 0.05 m / s to the upper boundary of the cement bridge installation interval, without stopping the bursting in the volume of 1.4 m ³ . During the rise, an inextricable stream of grouting mortar at the same time along the cross section of the cavity fills its cavity without mixing with the flushing fluid. Upon reaching the upper limit of the cement bridge installation interval of 876 m, the device is stopped rising and the well is flushed to wash out excess cement slurry by pumping a flushing fluid in a volume of 6.5 m ³ . After this, the circulation is stopped, as a result of the removal of hydraulic force due to the elasticity of the spring 15, the hollow piston 14 rises to its original upper position. If necessary, the dropping ball 16 can be raised to the surface by reverse circulation. The device is lifted, and the well is left to wait for the hardening of the cement slurry.

At the end of the waiting period for the hardening of the cement slurry, a bit with a diameter of 0.14 m was lowered through the drill pipe string, which revealed the roof of the cement bridge at a depth of 876 m.The strength and bearing capacity of the cement bridge were confirmed by loading the drill pipe string to 3 kN. Moreover, a “failure” was not observed. The tightness of the cement bridge was confirmed by pressure testing of the wellbore to an overpressure of 12 MPa. This indicates the quality of the cement bridge installation.

After drilling the cement bridge, the outfall of pieces of cement was not observed, this made it possible to equip the well with a filter and put it into operation.

The present invention meets the condition of patentability, as it is new, has an inventive step and is industrially applicable.

Claims (1)

A universal device for drilling, cleaning the cavity and installing a cement bridge, comprising a hollow shaft with through radial holes and an outer annular protrusion, upper and lower bushings installed with the formation of an inclined annular gap between their lower and upper surfaces, respectively, with the inner surfaces of the upper and lower bushings and the outer surface of the hollow barrel mating to them form an annular cavity hydraulically connected to the channel of the hollow barrel through the through radial holes located above the inclined annular gap, and the lower sleeve is mounted with the possibility of axial movement along the hollow shaft, characterized in that it contains an upper sub made with a longitudinal blade centralizer, connected externally to the upper sleeve, and from the inside to the hollow shaft, and the lower sub connected from the inside to the hollow shaft, as well as a rock cutting tool connected to the lower sub, moreover, the connections of the upper and lower sub to the hollow shaft ensure the transmission of torque to the rock Collapsing instrument and bottom sub is in the middle of the inner annular protrusion and biases the lower sleeve through a rubber elastic member with the pressing force determined by the inequality
$$\frac{\Delta R\cdot \pi \cdot \left(d_{\mathrm{one}}^2-d_2^2\right)}{\mathrm{four}}\le F_{\mathrm{one}}\le \frac{\Delta R\cdot \pi \cdot d_{\mathrm{one}}\cdot \delta }{2\cdot k},$$

where F ₁ is the pressing force of the lower sleeve with a rubber elastic element, N;
Δр - pressure drop on the working device, Pa;
d ₁ - the inner diameter of the inclined annular gap, m;
d ₂ - the outer diameter of the hollow trunk, m;
δ is the openness of the inclined annular gap, m;
k is the coefficient of friction of the sludge on the wetted metal,
and the outer annular protrusion of the hollow barrel is formed below the through radial holes, while the lower sleeve in the upper part has an internal groove for the specified protrusion for the length of its axial movement along the hollow barrel, and in the hollow barrel, a thrust sleeve, a hollow piston made with a saddle underneath a resettable ball mounted with a sealed overlap of the through radial holes of the hollow barrel, and a spring abutting against the annular protrusion of the lower sub with the pressing force determined by the inequality ohm
$$\frac{\mathrm{four}\cdot \mathrm{but}\cdot \rho \cdot Q^2\cdot \left(d_3^2-d_{\mathrm{four}}^2\right)}{\pi \cdot d_{\mathrm{four}}^{\mathrm{four}}}\le F_2\le \frac{\Delta R\cdot \pi \cdot d_3^2}{\mathrm{four}},$$

where F ₂ - spring compression force, N;
a is the pressure loss coefficient in the hollow piston;
ρ is the density of the liquid, kg / m ³ ;
Q - fluid supply, m ³ / s;
d ₃ - the outer diameter of the hollow piston, m;
d ₄ - the inner diameter of the hollow piston, m