RU2388903C2 - Device and method of energy control of explosion in well bore - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device includes explosive charge and at least one element capable of influencing explosion energy released with explosive charge after detonation, and containing the first part for absorption of explosion energy, which has the first thickness, and the second part to direct explosion energy, which has the second thickness. As per the first absorption version, cover or another obstructive element can be located directly near explosive charge prior to detonation. Size and arrangement of element relative to explosive charge can vary so that optimum explosion orientation can be reached. Annular element having a through hole can be used for direction of explosion energy of charge after detonation.

EFFECT: effective control of explosion energy in well bore, increasing safe use of cumulative perforators.

22 cl, 10 dwg

Description

The present invention relates generally to perforators used in wells, and more particularly, to a device and method for controlling the explosive charge energy of an explosive in a downhole perforator in a wellbore.

A device, such as a downhole perforator, can be lowered into the well and detonated to create gaps in an adjacent formation. After detonation of the downhole perforator, fluid usually flows into the well and to the surface through a tubing located inside the well.

Typically, downhole drills, including perforator bodies and cumulative charges mounted on / in the perforator bodies, are lowered through tubing or other pipes to the desired interval of the well. The cumulative charges carried by the downhole gun often explode in several directions around the circumference of the wellbore. After the explosion, the cumulative charges create perforation jets that form holes in the surrounding column, as well as deepen the perforation channels into the surrounding formation.

It may be necessary to control the amount of energy, for example to reduce or focus, released by the explosive charge. For example, in some cases it may be appropriate to break through the perforator body (or other hollow chamber or pressurized cavity) without opening the surrounding string and / or opening the wellbore.

A device is known for controlling the energy of an explosion in a wellbore containing an explosive charge and at least one element capable of influencing the explosion energy released by an explosive charge after detonation (see, for example, Russian patent 6408 U1, 04.16.98) .

The aim of the present invention is to provide a device and method for efficiently controlling the energy of an explosion in a wellbore.

According to the invention, a device is developed for controlling the energy of an explosion in a wellbore, containing an explosive charge and at least one element capable of influencing the explosion energy released by an explosive charge after detonation, comprising a first part for absorbing explosion energy having a first thickness, and a second part for directing explosion energy having a second thickness greater than the first thickness.

At least a portion of said element may consist of a brittle material selected from the group consisting of plastic, polymer, metal, cellulose and rubber.

The specified element may contain walls forming at least one cavity. The cavity can be designed to conduct energy of the explosion. The cavity may have a generally cylindrical configuration or a conical configuration.

An explosive charge may be a cumulative charge.

The specified element may contain a charge cover.

The device may further comprise a casing for installing the explosive charge and the element in the downhole drill.

The device may further comprise a shell forming a recessed region, and the specified element contains a charge cover having a first part and a second part and at least partially located in the recessed region.

The charge cover may comprise a first surface facing the recessed region and a second surface facing away from the recessed region and substantially located at the same level as the outer rim of the wall of the charge shell defining the outer perimeter of the recessed region.

The specified element may contain a charge cover having a first and second part and which is essentially flat.

In another embodiment, a device for controlling the energy of an explosion in a wellbore comprises an explosive charge for placement in a downhole perforator and at least one element capable of influencing the explosion energy released by said explosive charge after detonation, having walls forming at least one cavity for directing the energy of the explosion, located between the explosive charge and the downhole perforator and containing a first part for absorbing the energy of the explosion, having a first lschinu and a second portion for directing energy explosion having a second thickness greater than a first thickness.

At least a portion of said element may consist of a brittle material selected from the group consisting of plastic, polymer, metal, cellulose and rubber.

The cavity may have a generally cylindrical configuration or a conical configuration.

According to the invention also created a method of controlling the energy of the explosion in the wellbore, comprising the following steps:

the use of a downhole perforator containing at least one explosive charge;

placing between at least one explosive charge and a perforator of at least one element capable of influencing the explosion energy released by the explosive charge after detonation, and containing the first part for absorbing the explosion energy and the second part for directing the explosion energy ;

detonation of at least one explosive charge.

The specified element may contain walls that form at least one cavity for directing the energy of the explosion.

The charge cover may comprise a first surface facing the recessed area and a second surface facing away from the recessed area, and when the charge cover is at least partially placed in the recessed area, the cover is positioned so that the second surface is substantially at the same level as the outer rim of the wall of the shell of the charge, which determines the outer perimeter of the deepened region.

From the foregoing, it is clear that the present invention provides a device capable of influencing the energy of an explosion during its use in a wellbore. In one embodiment, the cap or other obstruction element can be placed immediately adjacent to the explosive charge before detonation. The size and location of the element relative to the explosive charge may vary to achieve the optimal orientation of the explosion.

The element used in the present invention may be a ring having a through hole for directing the energy of the explosion of the charge after detonation. Further, the charge cover may include a portion having a thinner wall than the rest of the cover. During operation, the thicker part of the lid absorbs part of the energy of the explosion of the charge and a thinner part (or hole) passes / directs the energy of the explosion. The exact thickness of the "absorbing" volume of the lid and the thickness of the "transmitting" volume of the lid can be determined and selected to achieve a specific result.

A more complete assessment of the invention and many of its attendant advantages will be clear from the following detailed description with reference to the accompanying drawings, which depict the following:

figure 1 is an enlarged sectional view of an embodiment of a cumulative charge;

figa is a vertical section of a variant embodiment of the downhole drill;

2B is a cross-sectional view of a variant of the downhole drill of FIG. 2A;

figure 3 is a side view of an embodiment of a string of downhole perforators lowered into a cased wellbore;

4A is a side view of an embodiment of a string of downhole drills detonated in a cased wellbore;

4B is a side view of an embodiment of a string of downhole drills detonated in an open wellbore;

5A-6B are cross-sectional views of several embodiments of a downhole drill of the present invention.

However, it should be noted that the accompanying drawings illustrate only typical embodiments of the present invention and, therefore, should not be construed as limiting its scope, since the invention may allow other, equally effective, embodiments.

The following description sets forth many details to provide an understanding of the present invention. However, those skilled in the art should understand that the present invention can be practiced without these details and that many variations and modifications of the described embodiments are possible.

In the description and the attached claims, the following terms are used: “connect”, “connection”, “connected”, “connected to” and “connecting” mean “directly connected to” or “connected through another element”; “Kit” means “one item” or “more than one item”. The terms “up” and “down”, “above” and “below”, “up” and “down”, “upstream” and “downstream”; “Above” and “below” and other similar terms designating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. However, when used with respect to equipment and methods used in deviated or horizontal wells, such terms may indicate left to right, right to left, or other relative positions depending on situations.

The cumulative charge 10, as shown in figure 1, includes an outer shell 12, which acts as a protective shell. Common materials for the outer shell 12 include steel or some other metal. The main explosive charge 16 is contained inside the outer shell 12 and is located between the inner wall of the outer shell 12 and the outer holding surface 20. The ignition column 14 is a sensitive zone that provides a detonation connection between the main explosive charge 16 and the detonation cord 15 that is attached to back of the cumulative charge 10.

To detonate the cumulative charge 10, the detonation wave moving through the detonation cord 15, when passing past the ignition column 14, initiates it, the ignition column 14, in turn, initiates the detonation of the main charge 16 of the explosive to create a detonation wave, which is displaced through the cumulative charge 10.

A series of cumulative charges 10, as shown in FIG. 2, can be delivered into the borehole by a casing punch 30. Cumulative charges 10 can be capsule-free charges, since the cumulative charges are protected from the external environment by the casing 30 of the punch, which is usually airtight. The punch body 30 may also include a series of recesses 32 formed in the outer wall. The recesses 32 are usually localized areas where the wall thickness of the housing 30 is reduced to optimize the functioning of the entire system. A loading pipe 40 is located inside the housing 30. The loading pipe 40 includes a series of closely spaced openings 42 for receiving and installing cumulative charges 10. The holes 42 of the loading pipe 40 are usually located on the same axis as the recesses 32 of the housing 30.

Groups of casing punchers 50A and 50B, as shown in FIG. 3, can be assembled together to form a casing 50 of downhole drills having a desired length. For example, the length of each hammer drill (50A and 50B, respectively) can be about twenty feet. To make a drill string 50, several hundred feet long or more, multiple drills can be joined together in groups using adapters 52. Each of the adapters 52 contains a ballistic transfer element, which can be in the form of a donor and recipient intermediate explosive charge. Ballistic transfer occurs from one perforator to another when the detonation wave travels from the donor intermediate charge to the recipient intermediate charge. At the end of the recipient intermediate charge there is a detonation cord that transmits the wave and undermines the cumulative charges in the next perforator. Examples of explosives that can be used in various explosive elements (e.g., cumulative charges 10, detonation cord 15, intermediate charges) include RDX, HMX, hexanitrostilbene, triaminotrinitrobenzene and others.

Typically, after assembly, the drill string 50 is located in the cased string 62 of the wellbore 60. The tubing or other pipe 64 extends into the string 62 to allow the passage of the borehole fluids to the wellhead equipment (not shown). A portion of the wellbore 60 is insulated by packers 66 mounted between the outside of the tubing 64 and the inside of the string 62. The string 50 of downhole drills can be lowered through the tubing or another pipe 54 on a support cable 70 (eg, wireline, wireline rope, flexible, pipe). After being placed at a predetermined interval in the wellbore, the drill string 50 explodes to create perforations in the surrounding string and formation (as shown in FIG. 4A).

In another embodiment, as shown in FIG. 4B, the drill string 50 includes one or more pressurized housings 30. In other embodiments, the drill string 50 may include one or more pressurized chambers (or other pressurized cavities), each of which has one or multiple explosive charges. The pressure inside the punch body 30 is lower than the pressure in the intended interval of the wellbore. The column 50 of sealed perforators located in the open hole 100 of the well. The casing 50 of downhole drills can be lowered through the open borehole 100 of the well on a support cable 70 (for example, a wireline, wireline or flexible pipe). After being placed at the desired interval of the wellbore, the drill string 50 explodes to create holes or tears in the sealed enclosure 30, while substantially harming the environment. After the detonation of one or more explosive charges and the subsequent formation of a gap in the body 30, a fluid wave is generated towards the body, thereby creating a temporary pressure drop in the interval of the wellbore. This temporary pressure drop can be used to clean perforation tunnels in the surrounding formation to eliminate filter cake from the walls of the wellbore or to remove debris from the interval of the wellbore.

In other embodiments, the sealed well drill string 50 may be placed in a cased wellbore and may be used to simultaneously perforate the sealed casings and the casing to create a temporary pressure drop in order to wave clean the perforation channels in the formation and remove fragments of the wellbore in the intended interval of the well. This effectively increases well productivity.

The allocated energy of the explosion and the resulting perforation obtained by detonation of perforators, discussed above, can be a function of the physical size and geometric arrangement of explosive charges. An embodiment of the present invention is directed to controlling the release of explosive energy.

As shown in FIGS. 5A-5B, a cap or other obstruction element 80 can be placed directly adjacent to charge 10 to absorb part of the energy. The size and specific placement of the cover 80 relative to the charge 10 can be determined to achieve optimal explosion characteristics for the selected result. For example, by controlling the release of charge explosion energy, the volume of debris ejected into the wellbore and excessive deformation of the downhole drill can be limited.

The charge cover 80 of the present invention can also be used to direct or focus the explosion energy release to achieve a specific result. For example, the cap 80 may be of such a size and be placed to focus the energy of the explosion in the charge so as to destroy the fragments into sufficiently small fragments that do not reduce the productivity of the well.

The charge cover 80 of the present invention can be used in various perforation or other blasting downhole operations. For example, charge cover 80 can be used to direct and control the explosion energy released by charges in a conventional downhole drill 30 used to perforate a formation and / or column and formation. In another example, the charge cap can be used to direct and control the explosion energy released by charges in a sealed chamber (for example, a perforator housing or other sealed cavity), so as to form gaps in the chamber, but not damage the surrounding column. Thus, charges can be used to create a temporary differential pressure to clean the perforation channel from debris.

5A and 5B illustrate embodiments of a charge cover (80) of the present invention coupled to a cumulative charge 10. A charge cover or other obstruction element can be designed so that it can be inserted without a gap between the branches 10A of the explosive charge 10. This embodiment of the present invention is ideal for use with cumulative charges that can be mounted relatively tightly in the interior of the loading tube 40.

In one embodiment, the charge cap of the present invention has a section 88A for absorbing explosion energy and another section 88D for transmitting and / or directing explosion energy. In one embodiment, the charge cover section 88A for absorbing explosion energy is designed to interact with the inner surface 101 of one or more explosive charge branches 10A. In one embodiment, section 88D for transmitting and / or directing blast energy forms a central portion of the charge cap.

In one embodiment, the charge cap section 88A for absorbing explosion energy may be composed of a relatively thick and / or dense material most suitable for absorbing explosion energy. Further, the charge cover section 88D for transmitting and / or directing the energy of the explosion may consist of a thinner and / or less dense material than that used for the absorption section 88A. Thus, the charge cap allows the most efficient use of the explosion energy after detonation. The exact thickness and / or density of each section (88A and 88D, respectively) of the charge cover can be determined and selected to achieve any number of desired results.

In one embodiment, one or more walls 82 of the charge cap may form one or more cavities 84 that can direct the energy of the explosion. Such cavities may have any number of orientations and / or configurations intended to achieve specific results. For example, one or more cavities provided by the present invention may have a generally conical or cylindrical configuration designed to direct the energy of the explosion in a particular way. It is understood that the configuration data are only examples and may not be restrictive. An annular element having a through hole can also be used to direct the energy of the explosion of the charge after detonation.

6A and 6B illustrate embodiments of a charge cover 80 connected to a cumulative charge 10. In these embodiments, a cumulative charge and a charge cover are installed in the casing 86 for insertion into the loading tube 40. The loading tube can accommodate a series of cumulative charges 10, each of which has a 80 charge cover. The loading tube is inserted into the housing 30 of the perforator. The perforator body 30 may have an arcuate recess 32 formed on the outer surface to align with each cumulative charge 10.

In one embodiment, the charge cap 80 of the present invention is designed to interact with the outer surfaces 102 of the branches 10A of the explosive charge 10. The charge cover can be used in conjunction with the casing 86 to conveniently install the charge cover / charge / casing set inside the loading tube. This feature of the present invention allows the successful installation of smaller explosive charges inside loading tubes having large diameters. As discussed above, the present invention can use as many placement and / or configurations of the charge cap as necessary to achieve a specific result. Further, the thickness and / or density of the materials constituting each section of the charge cap may vary. An annular element having a through hole can also be used to direct the energy of the explosion of the charge after detonation, as discussed above.

In some embodiments, the charge cover 80 may be made of a material that remains intact enough that the cover does not come out through gaps in the perforator. Thus, the cover can be removed from the well together with a perforator and does not affect the productivity of the well. In other embodiments, the charge cap 80 may be made of a very brittle material, such that the cap breaks into sufficiently small fragments so as not to affect well productivity, even if the fragments exit the perforator. For example, the charge cap may be made of plastic, polymer, metal, cellulose, rubber, or other suitable materials.

Although the invention has been described with reference to certain embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as other embodiments of the invention, will become apparent to those skilled in the art when referring to the description of the invention. Therefore, it is intended that the appended claims cover such modifications that are within the scope of the invention.

Claims (24)

1. Device for controlling the energy of the explosion in the wellbore, containing an explosive charge and at least one element capable of influencing the explosion energy released by the explosive charge after detonation, and containing a first part for absorbing explosion energy having a first thickness, and a second part for directing explosion energy having a second thickness greater than the first thickness. 2. The device according to claim 1, in which said element contains walls forming at least one cavity. 3. The device according to claim 2, in which the cavity is designed to conduct energy of the explosion. 4. The device according to claim 2, in which the cavity has a generally cylindrical configuration. 5. The device according to claim 2, in which the cavity has a generally conical configuration. 6. The device according to claim 1, in which at least part of the specified element consists of a brittle material. 7. The device according to claim 6, in which at least part of the specified element consists of a material selected from the group consisting of plastic, polymer, metal, cellulose and rubber. 8. The device according to claim 1, in which the explosive charge is a cumulative charge. 9. The device according to claim 1, wherein said element contains a charge cover. 10. The device according to claim 1, additionally containing a casing for installing the explosive charge and the specified element in the downhole drill. 11. The device according to claim 1, additionally containing a shell forming a recessed region, and said element contains a charge cover having a first part and a second part and at least partially located in the recessed region. 12. The device according to claim 11, in which the charge cover contains a first surface facing the recessed region, and a second surface facing away from the recessed region and essentially located at the same level with the outer rim of the wall of the charge shell defining the outer perimeter of the recessed region. 13. The device according to claim 1, in which the specified element contains a charge cover having a first and second part and which is essentially flat. 14. Device for controlling the energy of an explosion in a wellbore, containing an explosive charge for placement in a downhole perforator and at least one element capable of influencing the explosion energy released by an explosive charge after detonation, having walls forming at least , one cavity for directing the energy of the explosion, located between the explosive charge and the downhole perforator and containing the first part for absorbing the energy of the explosion, having a first thickness, and the second part for directing Ia explosion energy having a second thickness greater than the first thickness. 15. The device according to 14, in which at least part of the specified element consists of a brittle material. 16. The device according to clause 15, in which the brittle material is selected from the group consisting of plastic, polymer, metal, cellulose and rubber. 17. The device according to clause 16, in which the cavity has a generally cylindrical configuration. 18. The device according to clause 16, in which the cavity has a generally conical configuration. 19. A method of controlling the energy of an explosion in a wellbore, comprising the following steps: using a downhole perforator containing at least one explosive charge; placing between at least one explosive charge and a perforator of at least one element capable of influencing the explosion energy released by the explosive charge after detonation, and containing the first part for absorbing the explosion energy and the second part for directing the explosion energy ; detonation of at least one explosive charge. 20. The method according to claim 19, in which said element contains walls forming at least one cavity for directing the energy of the explosion. 21. The method according to claim 19, wherein said element comprises a charge cover having a first part and a second part, and at least partially place the charge cover in a recessed region formed by the charge shell. 22. The method according to item 21, in which the charge cover contains a first surface facing the recessed region, and a second surface facing from the recessed region, and with at least partial placement of the charge cover in the recessed region, the lid is located so that the second the surface is substantially flush with the outer rim of the wall of the charge shell defining the outer perimeter of the recessed region.
Priority on points: 03/08/2005 - claims 1-3, 5-13, 15-22; December 16, 2005 - pp. 4, 14.

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