EP0512331B1 - Device for cleaning the well-bore-surrounding-zone - Google Patents

Description

The present device relates to devices for cleaning the zone near the borehole using hydrodynamic waves.

It is a device for cleaning the borehole zone (SM Godiev "Inspolzovanie vibratsii v. Dobyche nefti" (exploitation of vibrations in oil production), 1977, publisher "Nedra" (Moscow), p. 50, Fig. 27) known includes a hollow body with a hydrodynamic wave generating assembly disposed therein, which is a sleeve housed in the body at a minimum distance from its walls. The sleeve is rotatably arranged about its axis in rolling bearings. There are openings on the walls of the body and the sleeve which serve as channels for the passage of the liquid. The body has radial and the sleeve tangential outlet channels. In order to prevent leakage of the liquid through the annular gap, a sleeve seal is arranged in the upper part between the body and the sleeve. The outlet channels of the sleeve and the body lie in the same plane.

The device with risers is lowered into a borehole to the level of the arrangement of perforation openings. A working fluid is injected through the risers. The liquid flows by coming into the cavity of the sleeve, also in its tangentially arranged outlet channels. From them, the liquid flows into the radial channels of the body and from there into the annulus of the borehole.

If the liquid flows out through the tangential channels of the sleeve at a high speed, a reaction torque is generated on the sleeve, causing it to rotate around the body. Here, the channels of the sleeve and the body are periodically closed and opened at a certain frequency. The periodic covering of the channels in the zone near the borehole generates hydrodynamic fluid pressure pulses. The amplitude and frequency hydrodynamic impulses depend on the pressure of the flushed fluid and the frequency of rotation of the sleeve around the body.

However, due to their insufficient strength, the generated hydrodynamic impulses do not contribute to the destruction of various deposits on the borehole walls, and do not enable the clogged pore channels of an oil layer to be cleaned.

In addition, the known device has a complicated construction, which increases its manufacturing costs and reduces its operational safety, while the presence of the movable assemblies and parts in the construction causes their intensive mechanical wear and a reduction in the operating life of the device.

All of this means that the known device does not ensure effective cleaning of the zone near the borehole and does not promote an increase in the productivity of a borehole and the oil release of a layer.

A device for cleaning the zone near the borehole according to the preamble of claim 1 is already known from GB-A-2 224 054. There it is proposed that the cavity formed by the swirl chamber and its outlet channel be made mushroom-shaped in order to be in the area outside the outlet channel to form an essentially annularly rotating vortex which spreads radially outwards with the distance from the outlet channel and which has a negative pressure in the center and generates a counterflow parallel to the longitudinal direction there. This vortex, which spreads from the outlet channel, has the task of cleaning cutting teeth, crushing rollers or the like which are arranged outside the outlet channel from the vortex chamber.

The invention has for its object to further improve such a device in terms of its cleaning effect in a simple manner.

The invention is characterized in claim 1 and further improvements are claimed in the subclaims thereof.

The design of the assembly for generating hydrodynamic waves in the form of a swirl chamber with the tangentially arranged inlet channels makes it possible to generate hydroacoustic waves with a wide frequency spectrum for acting on a productive layer. In addition, the use of the swirl chamber allows a vacuum zone, i.e. to create a depression in the borehole zone. All of this significantly improves the cleaning of the pore channels and increases the oil flow to the well.

The narrowing of the outlet channel of the swirl chamber is due to the fact that as the channel diameter decreases, the frequency of rotation of the liquid increases in proportion to the ratio of the diameter of the swirl chamber and the outlet nozzle, and accordingly the frequency of the wave radiation also increases.

According to the invention, the assembly for generating hydrodynamic waves is provided with at least one additional swirl chamber, which is arranged in the direction of flow in front of the swirl chamber and is also connected to the cavity of the hollow body by tangentially arranged inlet channels and has two conically tapering, oppositely directed outlet channels, which essentially have run at right angles to the longitudinal direction of the hollow body.

This allows the zone of exposure to a petroleum layer to be enlarged and the process of cleaning the zone near the borehole to be intensified.

It is expedient that a toroidal cavity connected to the interior of the vortex chamber is made in the wall of the vortex chamber on the section of the arrangement of its outlet channel.

The toroidal resonance chamber in the wall of the vortex chamber serves to amplify the generated waves under the resonance conditions. Waves that are generated by a sharp edge of the inlet channel of the toroidal cavity also contribute to the amplification of the amplitude. When the radial-tangentian current hits the sharp edge at the entrance of the resonance chamber at a high speed, self-oscillations of low amplitude are excited, which produce cutting-edge sound waves whose frequency depends on the outflow speed and the density of the injected Liquid and the stiffness of the resonator wall itself is dependent.

It is advantageous that the assembly for generating hydrodynamic waves is provided with a guide vane, which is arranged in the lower part of the vortex chamber in such a way that a rounded between the outer end face of the vortex chamber and the inner surface of the vane facing it Ring channel is formed.

The guide vane arranged near the end face of the wall of the vortex chamber forms an annular channel - nozzle - and forms an annular flow from the radial-tangential flow flowing out of the outlet channel and directs it upward through the annular space. This helps to improve the quality of the vacuum and the effect of depression on the zone near the borehole.

The design of the end face of the wall of the swirl chamber with a radial rounding makes it possible to keep the hydrodynamic losses lower when the upward flow is deflected and formed.

In order to generate a vacuum core in the swirl chamber and to increase the oscillation amplitude of the liquid pressure, it is necessary that the tangentially arranged inlet channels of the additional swirl chamber are designed at an angle to their axis and are directed to opposite sides.

It is expedient that the cavity of the swirl chamber is spherical.

The choice of the shape of the swirl chamber in spherical shape is due to a high amplitude of the waves generated by spherical emitters working in the self-oscillation state with a periodic hydraulic self-locking of the outlet channel.

ermittelt wird, worin

ϕ

die Kegelverjüngung der Seitenfläche des Hohlleiters;

0'

der kritische Gleitwinkel einer in der Wirbelkammer erzeugten, auf den Hohlleiter einfallenden Welle

ist.It is preferred that the swirl chamber is provided with a conical waveguide running in this direction of its longitudinal axis and fixed in its upper part, the conical tapering of its side surface from the relationship $$\text{θ <ϕ ≤ 20 '}$$

is determined wherein

ϕ

the taper of the side surface of the waveguide;

0 '

the critical sliding angle of a wave generated in the swirl chamber and incident on the waveguide

is.

The purpose of equipping the vortex chamber with the conical waveguide is to prevent hydrodynamic and hydroacoustic cavitation wear on the central part of the head of the vortex chamber. In addition, the conical waveguide brings the cavitation bubbles outside the vortex chamber.

worin

c

die Schallgeschwindigkeit in der injizierten Flüssigkeit;

c₁

die Schallgeschwindigkeit im Metall;

n

der Brechungskoeffizient

ist.The choice of the taper taper ϕ of the waveguide not above a double value of the critical sliding angle 0 'of an incident wave (ie θ <ϕ ≤ 20') is due to the fact that the interface of the two media (injected liquid and metal) with different densities and compressivities is a reflection - represents absorption and refractive surface. If the slip angle 0 of the incident wave is not above the critical slip angle 0 ', there is a total reflection of the incident wave, such wave does not transfer energy from the first medium (from the liquid) to the second medium (to the metal), and the total energy of the incident wave is from the Surface of the waveguide retroreflected to the first medium. An angle between the propagation angle of the shaft and the interface is referred to as the sliding angle 0. The cosine of the critical sliding angle 0 'is equal to the refractive index of the second medium with respect to the first medium (Snellius's law), ie $${\text{cos 0 '= c / c}}_{\text{1}}\text{= n}$$

wherein

c

the speed of sound in the injected liquid;

c ₁

the speed of sound in the metal;

n

the refractive index

is.

The taper taper ϕ of the waveguide must not be above 20 ', i.e. 0 <ϕ ≤ 20 '.

It also makes sense that the assembly for generating hydrodynamic waves is provided with a resonance chamber, the cavity of which is connected to the cavity of the swirl chamber and in which a piston with a rod is accommodated with the possibility of displacement in the longitudinal direction.

This allows the frequency of the waves generated to be tuned to a resonance frequency at different flow rates and densities of the injected liquid. The tuning to the resonance frequency takes place by moving the piston by means of a worm rod and by changing the volume of the resonance chamber under the piston.

The device for cleaning the zone near the borehole, which is provided with the swirl chamber according to the invention, makes it possible to carry out a complex borehole treatment in connection with thermal-physical-chemical processes and to increase the productivity and the oil release of a layer. The device has a simple construction, is reliable and suitable for production.

• Fig. 1 die Gesamtansicht einer Einrichtung zur Reinigung der bohrlochnahen Zone;
• Fig. 2 einen II-II-Schnitt nach Fig. 1;
• Fig. 3 eine Ansicht in Pfeilrichtung A zu Fig. 1;
• Fig. 4 eine Ansicht in Pfeilrichtung B. zu Fig. 2;
• Fig. 5 die Gesamtansicht der erfindungsgemäßen Einrichtung zur Reinigung der bohrlochnahen Zone mit zwei zusätzlichen Wirbelkammern;
• Fig. 6 die Gesamtansicht einer Einrichtung zur Reinigung der bohrlochnahen Zone mit einem toroidalen Hohlraum in der Wand der Wirbelkammer;
• Fig. 7 einen VII-VII-Schnitt zu Fig. 6;
• Fig. 8 eine Wirbelkammer mit einem kegelförmigen Hohlleiter;
• Fig. 9 einen kegelförmigen Hohlleiter;
• Fig. 10 eine Wirbelkammer mit einer Resonanzkammer;
• Fig. 11 eine Wirbelkammer mit einem kugelförmigen Innenraum;
• Fig. 12 eine Skizze für den Ausfluß einer Arbeitsflüssigkeit aus dem Austrittskanal der Wirbelkammer.

The present invention is explained in more detail below using specific exemplary embodiments with reference to the accompanying drawings. Show it:

• 1 shows the overall view of a device for cleaning the zone near the borehole;
• FIG. 2 shows a II-II section according to FIG. 1;
• Fig. 3 is a view in the direction of arrow A to Fig. 1;
• Fig. 4 is a view in the direction of arrow B. to Fig. 2;
• 5 shows the overall view of the device according to the invention for cleaning the zone near the borehole with two additional swirl chambers;
• 6 shows the overall view of a device for cleaning the zone near the borehole with a toroidal cavity in the wall of the vortex chamber;
• Fig. 7 is a VII-VII section to Fig. 6;
• 8 shows a swirl chamber with a conical waveguide;
• 9 shows a conical waveguide;
• 10 shows a swirl chamber with a resonance chamber;
• 11 shows a swirl chamber with a spherical interior;
• Fig. 12 is a sketch for the outflow of a working fluid from the outlet channel of the swirl chamber.

Best embodiment of the invention

The device according to the invention for cleaning the zone near the borehole contains a hollow body 1 (FIGS. 1 to 4) with an inlet channel 2. Inside the body 1, a swirl chamber 3 of an assembly for generating hydrodynamic waves with tangentially directed inlet channels 4 is arranged. The swirl chamber 3 has a conically tapering (funnel-shaped) outlet channel 5 for the outlet of a working medium. The end face 6 of the chamber 3 is radially rounded, and a guide vane 8 is screwed onto it by means of screws 7 such that an annular channel 9 is formed between them, which communicates with the annular space of the bore. An annular mixing chamber 11 is formed in the borehole between the chamber 3 and a casing column 10, while an annular diffuser 12 is formed between the body 1 and the casing column 10. In this way, the channel 10, the mixing chamber 11 and the diffuser 12 form a jet pump, which generates a negative pressure in the working process and exerts a depression effect on a productive layer. The device is centered in the borehole by ribs 13. The device is connected to the casing column 14 by means of a conical thread.

In order to increase the wave effect on a layer, the assembly for generating hydrodynamic waves has at least one additional swirl joint. FIG. 5 shows an embodiment of the assembly for generating hydrodynamic waves with two additional swirl chambers 16, 17, which are arranged perpendicular to the axis of the body 1. The swirl chamber 17 is designed with two oppositely directed outlet channels 18. The tangentially directed inlet channels 19 and 20 of the chambers 16 and 17 are at an angle to their axes and are directed to opposite sides. The intersection of the tangential channels 19 and 20 can be circular or slit-shaped.

In order to increase the amplitude of the waves generated, a toroidal resonance chamber can be built into the wall of chamber 3 (FIGS. 6, 7) 21 with a combined annular inlet and outlet channel 22 (FIG. 6) and with a sharp edge 23.

In order to keep cavitation wear of the swirl chamber 3 (FIGS. 8, 9) lower, it is provided with a conical waveguide 24.

To increase the effectiveness of the wave effect on a layer, the swirl chamber 3 (FIG. 10) is provided with a resonance chamber 25, in which a piston 26 with a rod 27 is accommodated. The rod 27 is connected to the resonance chamber 25 by means of a screw connection. By screwing the rod 27 in and out, the volume of the resonance chamber 25 and consequently also the amplitude-frequency characteristic of the device is changed.

In order to increase the amplitude of the waves generated and the effectiveness of the wave effect on a layer, the cavity of the swirl chamber 3 (FIG. 11) is designed in a spherical shape.

The device according to the invention for cleaning the zone near the borehole works as follows. The working medium (liquid, gas or multi-phase liquid) is conveyed through the pipes 14 (FIG. 1) into the inlet channel 2, from where it flows through the tangentially directed channels 4 into the swirl chamber 3. In the swirl chamber 3, the liquid begins to circulate at a high rotation frequency (within the range of 10 ³ to 1.5.10 ³ s ^-1 ). Here 5 hydroacoustic waves are generated in the outlet channel. Furthermore, the turbulent pulsating flow from the outlet channel 5 is conveyed at a high speed in tangentially divergent directions, as indicated in FIGS. 1 and 12, and flows into the ring channel 9. The liquid is directed upwards from the annular channel 9 at a high speed and comes into an annular space - a mixing chamber 11 - and entrains the injected liquid from the zone near the borehole. In the chamber 11, the velocities of the flows to be mixed are balanced, and the kinetic energy of the working flow is partly converted into the potential energy of the mixed flow. The further conversion of the kinetic energy of the mixed flow into one Pressure energy occurs in the cavity of the diffuser 12. In this way, the effect of a jet pump is realized in the annular space, and an additional depression is created in the zone of a productive layer. The productive layer is exposed to both a depression and a wave effect. This creates mechanical activation processes in the zone near the borehole with signs of various nonlinear effects, the most important of which is the occurrence of hydrodynamic and hydroacoustic cavitation.

In the presence of the toroidal resonance chamber 21 (FIG. 6), the turbulently pulsating current is conveyed from the outlet channel 5 of the vortex chamber 3 in tangentially divergent directions and runs onto the sharp edge 23. At the leading edge 23, hydroacoustic cutting-tone waves of low amplitude and self-excited bending vibrations of the edge 23 themselves (as with plate radiators) are excited. 6, the vibration of the leading edge 23 itself is indicated by dashed lines. The radial-tangential flow partly comes into the toroidal resonance chamber 21. The bending vibrations of the leading edge 23 cause a pressure pulsation in the toroidal resonance chamber 21. The ring channel 22 serves for the entry and exit of the liquid. In connection with this, the current emerging from the toroidal resonance chamber 21 interrupts the incoming current with the oscillation frequency of the leading edge 23, which is why hydroacoustic waves are additionally generated at the edge 23.

worin f₁, f₂, f₃ die jeweiligen eigene Schwingungsfrequenzen der Wirbelkammer 3, der Platte der Eintrittskante 23, der toroidalen Resonanzkammer 21 sind.To excite intense hydroacoustic waves, it is necessary that the natural frequencies of all sources of wave generation and all resonators located in the generator are equal or close to one another in terms of amount, ie $${\text{f}}_{\text{1}}{\text{f}}_{\text{2nd}}{\text{f}}_{\text{3rd}}\text{,}$$

where f ₁ , f ₂ , f _{3 are} the respective own oscillation frequencies of the swirl chamber 3, the plate of the leading edge 23 and the toroidal resonance chamber 21.

The hydroacoustic waves and the cavitation effects in the zone near the borehole lead to the destruction of various deposits on the borehole wall and to the cleaning of the blocked pore channels in an oil layer. The action of depression activates the development of cavitation, accelerates it the inflow of stratified petroleum to the borehole contributes to the removal of cleaning products from the pore channels. In addition, the wave field has a significant effect on reducing the viscosity of the layer fluid and petroleum, while the simultaneous depression effect increases their inflow to the borehole.

Industrial applicability

The device according to the invention can be used to clean the zone of a layer near the borehole in press-in bores in order to increase the absorption capacity of the layer. Without any design changes, it can be used as a shaft disperser, emulsifier, homogenizer of multi-phase liquids, for dispersing the drilling fluid and the cement slurry directly in the bore when carrying out the technological operations.

Claims (9)

1. A device for cleaning a well-bore-surrounding zone comprising a hollow body (1) with an assembly being disposed therein for generating hydrodynamic waves, wherein a whirl chamber (3) extending in the longitudinal direction of hollow body (1) is connected with the cavity of the hollow body (1) via tangentially disposed entrance channels (4) and comprises a conically tapering exit channel (5) in the longitudinal direction and wherein the entrance channels (4) are situated in the region of the side opposite the exit channel (5)
   characterized in
   that the assembly comprises at least one additional whirl chamber (16, 17) which is disposed in the flow direction before the whirl chamber (3) and connected with the cavity of the hollow body (1) via tangentially disposed entrance channels (19, 20) and comprises two conically tapering, oppositely directed exit channels (18) extending substantially perpendicularly to the longitudinal direction of the hollow body (1).
2. A device according to claim 1,
   characterized in
   that the substantially tangentially disposed entrance channels (19, 20) of the additional whirl chamber (16, 17) are realized under an angle with respect to the axis thereof and directed to opposite sides.
3. A device according to claim 1 or 2,
   characterized in
   that two additional whirl chambers (16, 17) are disposed within the hollow body (1) before the whirl chamber (3) disposed at the end thereof.
4. A device according to any of claims 1-3,
   characterized in
   that the cavity of the whirl chamber (3) is formed to be spherical.
5. A device according to any of the preceding claims,
   characterized in
   that a toroidal resonance chamber (21) is disposed in the wall of the whirl chamber (3) on the section where the exit channel (5) thereof is disposed, the entrance channel (22) of said resonance chamber (21) being disposed in the region of the exit channel (5) from the whirl chamber (3) and at the same time constituting the exit channel thereof.
6. A device according to claim 5,
   characterized in
   that the entrance channel (22) from the resonance chamber (21) comprises a sharp entrance edge (23).
7. A device accorrding to any of the preceding claims,
   characterized in
   that a rounded guide blade (8) is disposed in the lower part of the whirl chamber (3) in such a manner that an annular channel (9) is formed between the outer front face of the whirl chamber (3) and the inner surface of the guide blade (8) facing it.
8. A device according to any of the preceding claims,
   characterized in
   that the whirl chamber (3) comprises, in the region of the side opposite to the exit channel (5), a hollow-conical reflector (24) substantially extending in the longitudinal direction whose conical tapering for its side faces results from the relation $$\text{Θ < ϕ < 20',}$$

   

   wherein ϕ is the conical tapering of the side faces of the reflector (24) and Θ' is the critical gliding angle of a wave being generated in the whirl chamber and incident on the reflector (24).
9. A device according to any of the preceding claims,
   characterized in
   that the cavity of the whirl chamber (3) is connected with a resonance chamber (25) wherein a piston (26) being adjustable in the longitudinal direction and comprising a rod (27) is situated.

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