RU2633904C1 - Sectional sand jet perforator - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to devices for directed opening of a production formation in a horizontal well with a casing string and for performing hydraulic fracturing of the formation. A sectional hydro-sandblasted perforator contains a hollow bod and consists of a coupling, separate sections with radial holes and jet nozzles installed therein, centralisers, the separate sections are interconnected by spacers. The radial holes in the sections are formed at a predetermined angle with respect to the axis of the body. The holes in the sections are offset from the axis of the body. The diameter of the holes in the sections is less than the diameter of the holes in the coupling and in the spacers provided with rigid centralisers outside. The coupling, the sections and the spacers are separated by a bearing and pulled together by a shaft with nuts screwed onto it from both sides. The shaft is installed eccentrically relative to the axis of the body and rigidly connected to individual sections, and the nuts are contacted with the coupling and the last section that has been killed by the bearings. The coupling, the individual sections and the spacers are sealed together by the sealing elements, and the individual sections are configured to co-rotate with the shaft with respect to the fixed couplings and spacers. The jet nozzles are pressed into separate sections made of hard-alloy material in the form of a cone and equipped with external and internal conical surfaces tapering outward from a separate section of the hollow body. The radius of the jet nozzle pressed into a separate section is less than the radial extension of the coupling centralisers and the spacer, and the diameter of the jet nozzle corresponds to six grain diameters of the proppant fraction.

EFFECT: invention anables to perform hydro-sandblasting perforation in the well casing string in the direction of minimum formation stress, regardless of the device cposition in the borehole, increase the efficiency and reliability of operation, and prevent the proppant hole from plugging the jet nozzle opening.

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Description

The invention relates to the oil and gas industry, in particular to devices for directed opening of a productive formation in a horizontal well with a casing and hydraulic fracturing.

Known pulse hydroperforator (patent RU No. 2061849, IPC ЕВВ 43/114, publ. 06/10/1996, bull. No. 16), comprising a hydraulic monitor housing with a longitudinal channel, a shaft located in the housing, an opening-closing element of the side openings of the housing and nozzles placed in the side openings. The hydraulic perforator is equipped with a rubber shock absorber located above the hydraulic monitor housing and a hydraulic clamp-centralizer with retractable rods placed under the hydraulic monitor housing, which is made with a radial channel in a plane perpendicular to the plane of the side openings, is covered with covers with bearings and is tangentially communicated in the middle part with the longitudinal channel having an outlet in the lower part of the housing at the ends of the radial channel. The shaft is located in the covers of the radial channel and is made with a one-sided rod tide in the middle part with a length corresponding to the radius of the radial channel and the area of the end part not less than the clearance of the side holes. The shock absorber consists of an upper stop, a two-stage sleeve and a corresponding lower stage of the pipe, placed inside the two-stage sleeve with the possibility of axial movement and having a ledge in the middle part, above which up to the upper stop and below which rubber elements of rectangular section are placed.

The disadvantages of this device:

- firstly, the complexity of the design, due to the large number of nodes and parts (two-stage bushings, shock absorbers, covers, stops, etc.);

- secondly, the inability to perforate in a given direction relative to the axis of the well, for example, perforation in the casing or cavities in the open hole in the direction of the minimum stress of the formation rocks;

- thirdly, the low efficiency of the device, due to the fact that the direction of the caverns relative to the axis of the well from the jet nozzles of the perforator in the near-wellbore zone and the direction of the hydraulic fracturing (Fracturing), which develops in the direction of the minimum formation stress, do not coincide. As a result, a crack formed from caverns during subsequent hydraulic fracturing unfolds in the bottom-hole zone of the formation in the direction of minimum stress, which leads to an increase in pressure during hydraulic fracturing and can lead to premature termination of the hydraulic fracturing process;

- fourthly, a high duration of perforation due to the pulsed principle of the device, i.e. perforation time increases due to intermittent action of the jet on the casing and / or open hole.

The closest in technical essence and the achieved result is a sectional sandblasting punch (patent RU No. 2466270, IPC ЕВВ 43/114, publ. 10.11.2012, bull. No. 31), containing a hollow body, consisting of separate sections with radial holes and jet nozzles installed in them, centralizer. The punch for connecting the sections is equipped with spacers of various lengths and couplings, the connection being made end-to-end by means of couplings located outside, and the connecting ends of the couplings, spacers and each section are made with right and left threads.

The disadvantages of this device:

- firstly, the inability to perform sandblasting perforation in the casing or an open wellbore in a predetermined direction (for example, upward relative to the axis of a horizontal well) regardless of the position of the device in the well, for example, to perform perforation in the casing or to perform cavities in the open hole in direction of minimum stress of formation rocks;

- secondly, the low efficiency of the device, due to the fact that the direction of the caverns relative to the axis of the well from the jet nozzles of the perforator in the near-well zone and the direction of the hydraulic fracture, which develops in the direction of the minimum formation stress, do not coincide. As a result, a crack formed from caverns during subsequent hydraulic fracturing unfolds in the bottom-hole zone of the formation in the direction of minimum stress, which leads to an increase in pressure during hydraulic fracturing and can lead to premature termination of the hydraulic fracturing process;

- thirdly, the low reliability of the drill, due to the fact that there is a significant distance between the nozzle and the wall of the casing, which leads to dispersion of the flow of the hydroabrasive liquid (water-proppant mixture) and to its reverse impact from the casing to the nozzle. As a result, the attachment points of the nozzles to the perforator body are destroyed in one borehole operation and require the perforator to be raised to the surface to replace the nozzles;

- fourthly, there is a high probability of clogging of the jet nozzle hole with proppant, since structurally the diameter of the jet nozzle hole does not depend on the proppant grain diameter, which is fraught with a sharp increase in pressure and cessation of perforation.

The technical objectives of the invention are the ability to perform perforation in the casing or caverns in the open hole in the specified direction, increasing the efficiency and reliability of the sectional sandblasting punch, preventing clogging of the nozzle holes with sand or proppant grains during perforation.

The stated technical problems are solved by a sectional sandblasting puncher containing a hollow casing, consisting of a coupling, separate sections with radial holes and jet nozzles installed in them, centralizers, separate sections are interconnected by spacers.

What is new is that in sections the radial holes are made at a predetermined angle relative to the axis of the housing, while in the sections the holes are made upward from the axis of the housing, and the diameter of the holes in the sections is less than the diameter of the holes in the coupling and in the spacers provided with rigid centralizers on the outside wherein the coupling, sections and spacers are separated by bearings and pulled together by a shaft with nuts screwed on it on both sides, the shaft being mounted eccentrically relative to the axis of the housing and rigidly connected to individual sections and, and the nuts are in contact with the coupling and the last section muffled by the bearings, while the coupling, individual sections and spacers are hermetically separated by sealing elements, and individual sections have the possibility of joint rotation with the shaft relative to the stationary coupling and spacers, and the jet nozzles are pressed into separate sections , made of carbide material under the cone, equipped with external and internal conical surfaces, tapering outward from a separate section of the hollow body, while the radial The jet nozzle pressed into a separate section is smaller than the radial radius of the coupling and spacer centralizers, and the diameter of the jet nozzle corresponds to six grains of the proppant fraction.

In FIG. 1 schematically shows the proposed sectional sandblasting punch.

In FIG. 2 shows a section through a separate section of a sectional sandblasting punch.

In FIG. 3 shows a section of a spacer for a sectional sandblasting punch.

In FIG. 4 shows a jet nozzle screwed into a radial hole in a section of a sectional sandblasting perforator.

Sectional sandblasting puncher contains a hollow body 1 (see Fig. 1), consisting of a sleeve 2, individual sections 3 with radial holes 4 and installed jet nozzles 5. The individual sections 3 are interconnected by spacers 6.

The number of individual sections 3 and, respectively, spacers 6 depends on the number of perforation intervals that must be performed in a horizontal wellbore with a casing or open hole.

For example, consider a sectional sandblasting punch with two sections 3 and one spacer 6. If necessary, increase the intervals of perforation in a horizontal well, the number of sections 3 and spacers 6 is increased.

To conduct sandblasting perforation with subsequent hydraulic fracturing, the specified angle is determined based on the direction of the minimum stress σ _{min of the} formation in which it is necessary to perform hydraulic fracturing. For example, the direction of the minimum stress σ _{min of the} formation relative to the axis 7 of the hollow body 1 is directed upward (see Fig. 1), therefore, the radial holes 4 in section 3 are directed upwards, i.e. perform at an angle α = 90 ° (see Fig. 2) to the axis 7 of the hollow body 1.

The holes 8 (see Fig. 1) in sections 3 are made with an upward offset from the axis 7 of the hollow body 1. The diameter d (see Fig. 1, 2, 3) of the holes 8 in sections 3 is smaller than the diameter D of the holes 9 in the coupling 2 and in spacer 6, provided with rigid centralizers 6 'externally. The coupling 2, sections 3 and the spacer 6 (see Fig. 1) are separated by bearings 10 and pulled together by a shaft 11 with nuts 12 screwed onto it from both sides.

The shaft 11 is mounted eccentrically with an offset of e (see FIGS. 1 and 2, 3) relative to the axis 7 of the hollow body 1 and is rigidly connected to the individual sections 3 by any known connection, for example, using a key 7 '(in Fig. 1 and 2 is shown conditionally). The nuts 12 (see Fig. 1) are in contact with the coupling 2 on the one hand, and on the other hand with the last section 3, muffled by the bearings 10.

The coupling 2, the individual sections 3 and the spacer 6 are hermetically separated by sealing elements 13. The individual sections 3, thanks to the key 7, can rotate together with the shaft 11 relative to the stationary coupling 2 and the spacer 6.

The jet nozzles 5 are pressed into separate sections 3, made of carbide material under the cone, equipped with an outer 14 and an inner 15 conical surfaces, tapering from a separate section 3 of the hollow body 1.

The radial radius r (see Fig. 1) of the jet nozzle 5 pressed into a separate section 3 is smaller than the radial radius R of the centralizers 6 'of the coupling 2 and the spacer 6.

To press the jet nozzles 5 into separate sections 3 of the hollow body 1, separate sections 3 are heated, and then press the jet nozzles 5 into the radial holes 4. The bore diameter d _{n of the} jet nozzle 5 (see Fig. 4) corresponds to six sand or proppant grain diameters.

The proposed sectional sandblasting punch works as follows.

Before carrying out work with a perforator using any known method, the direction of the minimum stress of the formation rocks is determined, in the direction of which the hydraulic fracture will develop after the sandblasting.

Radial holes 4 in individual sections 3 are performed (drilled before assembly of the punch) in the direction of minimum voltage according to the results of the acoustic method.

For example, during the drilling of a horizontal well by the acoustic method, it is determined that the minimum stress of the formation rocks is directed upward (see Fig. 1), therefore, the radial holes 4 in the individual sections 3 are made upward (see Fig. 2) and the perforator is assembled, as shown in FIG. one.

If, according to the results of the acoustic method, the minimum stress of the formation rocks is directed downward (Fig. 1-4 is not shown), then the radial holes 4 in the individual sections 3 are directed downward, after which the perforator is assembled.

Due to the fact that the holes 8 (see Fig. 1) in sections 3 are made with an upward displacement from the axis 7 of the hollow body 1, and they have a shaft 11 mounted eccentrically with an offset of e (see Figs. 1 and 2, 3) relative to the axis 7 of the hollow body 1 and is rigidly connected to the individual sections 3, the radial holes 4 in the sections 3 will be placed in the direction of minimum voltage regardless of the position of the tool in a horizontal well.

This allows you to get the perforation in the direction of minimum stress relative to the circumference of the casing of the horizontal well.

Also, depending on the diameter of the grains of the proppant fractions (see Table 1), designed to perform hydro-sandblasting perforation, the passage diameter d _{n of the} jet nozzle 5 is selected from the condition that it matches the six diameters of the proppant fraction grains, which was obtained experimentally.

For example, for proppant fractions 16/20 mesh use jet nozzles 5 with a diameter of d _n = 8 mm

The selection of the nozzle diameter depending on the proppant fraction used during the hydro sandblasting perforation eliminates the clogging of the nozzle nozzle holes by the proppant and eliminates a sharp increase (jump) in pressure during the perforation and, as a result, termination of the perforation.

At the mouth of a horizontal well, at the lower end of the tubing string 16 (see FIG. 1), the proposed sectional sandblasting gun is screwed. On the tubing string 16, a sandblasting hammer is lowered into a horizontal well at a predetermined casing perforation interval. During descent into the required perforation interval, the punch is centered in the casing by centralizers 6 '(see Figs. 1 and 2), which simultaneously protect the jet nozzles 5 from damage, since R> r, which eliminates the contact of the jet nozzles 5 with the walls of the casing since the conical surface 14 of the jet nozzles 5 increases their length, which makes it possible to bring the upper end 17 (see FIG. 2) of the jet nozzles 5 closer to the wall of the perforated casing.

In a given interval of perforation of a horizontal well, the individual sections 3 rotate independently of the stationary coupling 2 and the spacer 6 and, due to the eccentricity e, occupy a position in which the radial holes 4 of the individual sections occupy an upward position.

Then pump the abrasive liquid (water-proppant mixture) through the tubing string 16, which enters the hollow body 1 through the sleeve 2 and the spacer 6 in section 3.

In sections 3, the hydroabrasive fluid enters the radial holes 4, then to the input of the jet nozzles 5, where a gradual process of increasing the flow rate to the maximum value takes place in the inner conical surface 15. The fluid with abrasive, flowing out of the jet nozzles 5 with high speed, creates a perforation hole in the casing and a channel (cavity) in the reservoir of increased dimensions, since lengthening the process of increasing the velocity at the inlet allows you to form the most compact jet of abrasive fluid and get their greatest breakdown ability to increase the efficiency of perforation. The approach of the upper end 17 of the jet nozzle 5 to the wall of the perforated casing also increases the efficiency of perforation. During cutting of the casing string, abrasive fluid jets flowing from the inclined jet nozzles 5 are reflected from the casing wall and act on the carbide materials of the jet nozzles 5 along the outer conical surface 14 without damaging sections 3 of the hollow body 1, while maintaining the integrity of individual sections 3 hollow body 1 of the perforator and increases the reliability of its operation, as the wear of the device is reduced, and this allows you to perform a hydro-sandblasting tubing string in one round trip perforation at several intervals of a horizontal well.

After cutting through the perforations in the casing and the formation of caverns in the formation in the direction of the minimum stress of the rocks of the formation, the process of sandblasting perforation continues with hydraulic fracturing, i.e. the formation and development of a fracture crack in the direction of the minimum stress of the rocks of the reservoir. The development of the hydraulic fracture continues until pumping into the fracture (not shown in Fig. 1-4) a predetermined proppant mass according to the work plan, for example, 2 t.

The efficiency of the device is increased, due to the fact that the direction of the caverns relative to the axis of the well from the jet nozzles of the perforator in the bottomhole zone coincides with the direction of the development of the hydraulic fracture in the direction of the minimum formation stress.

As a result, the crack formed from the caverns during the subsequent hydraulic fracturing does not develop in the bottom-hole zone of the formation in the direction of minimum stress, as would happen when performing work using the prototype. This does not lead to an increase in pressure in the process of hydraulic fracturing and eliminates the premature termination of the hydraulic fracturing process.

The proposed sectional sandblasting punch allows you to:

- perform sandblasting perforation in the casing of the well in the direction of the minimum stress σ _{min of the} formation, regardless of the position of the device in the wellbore;

- increase the efficiency and reliability of the work;

- exclude clogging of the hole of the jet nozzle with proppant.

Claims (1)

Sectional sandblasting puncher contains a hollow body, consisting of a sleeve, separate sections with radial holes and jet nozzles installed in them, centralizers, separate sections are interconnected by spacers, characterized in that the radial holes in the sections are made at a predetermined angle relative to the axis of the body, while in the sections, the openings are offset upward from the axis of the housing, and the diameter of the holes in the sections is less than the diameter of the holes in the coupling and in the spacers provided with a rigid center on the outside at the same time, the coupling, the sections and the spacers are separated by bearings and pulled together by a shaft with nuts screwed on it from both sides, the shaft being eccentrically mounted relative to the axis of the housing and rigidly connected to individual sections, and the nuts are in contact with the coupling and the section that was last muffled by the bearings, while the coupling, individual sections and spacers are hermetically separated by sealing elements, and individual sections have the possibility of joint rotation with the shaft relative to the stationary coupling and spacers, and the jet nozzles are pressed into separate sections, made of carbide material under the cone, equipped with outer and inner conical surfaces tapering outward from a separate section of the hollow body, while the radial outreach of the jet nozzle pressed into a separate section is less than the radial outreach of the coupling centralizers and spacers, and the diameter of the inkjet nozzles corresponds to six diameters of grains of the proppant fraction.

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