Rubber Sleeve Protection Ring and Downhole Plugging Apparatus

Abstract

A rubber sleeve protection ring and a downhole plugging apparatus are described in the present invention. Said rubber sleeve protection ring comprises several protection units which are arranged in a circle; each protection unit has a seal protrusion extending outwards and a seal groove corresponding to the seal protrusions, wherein the seal protrusions are embedded in the seal grooves on each adjacent protection unit; at least one end faces of the protection unit is an inclined surface, wherein the direction of said inclined surface leads the protection unit moving radially and outwards when applying force on the end face.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to Chinese patent application 201420006039.X, filed on Jan. 7, 2014, the disclosure of which is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

Not Applicable

BACKGROUND

The present application claims priority under 35 U.S.C. §119 to Chinese patent application 201420006039.X, filed on Jan. 7, 2014, the disclosure of which is incorporated herein by reference.

1. Field of the Invention

The present invention relates to oil-gas productions and mineral mining fields, particularly to a downhole plugging apparatus and a rubber sleeve protection ring used for downhole blocking.

2. General Background of the Invention

In the process of the oil-gas productions and the mineral mining, blocking of a well is required. At present, the downhole plugging apparatus is used to accomplish the blocking. The current available downhole plugging apparatus consists of a mandrel and an anchor structure as well as a seal structure. After the downhole plugging apparatus is being put into the pre-calculated position in a well, the plugging device would be fixed through squeezing the anchor structure to anchor it to a wellbore wall. During the process, the anchor structure squeezes the seal structure, leading to its radial expansion, and then to sealing.

However, the seal structure is plastic which is easily extended into a gap between the anchor structure and the wellbore wall. As the result, the sealing performance would be impacted, and the seal structure would be damaged.

To solve this problem, an umbrella-shaped protection structure setting between the anchor structure and the seal structure is developed. When the anchor structure squeezes the seal structure, the umbrella-shaped protection structure would be forced to open to prevent the seal structure from extending into the space between the anchor structure and the wellbore wall.

However, because the umbrella-shaped protection structure is contacting with the wellbore wall by points when it opened, it is likely to be damaged due to excessive stress acting thereupon and the damage would be out of control, which will decrease the force applied on the seal structure and the seal structure could not seal against the wellbore wall due to insufficient force, thus the sealing performance will be greatly reduced.

BRIEF DESCRIPTION OF THE DRAWING

For further understanding of the nature, objects and advantages of the present invention, reference should be made to following detailed descriptions, read in conjunction with following drawings, wherein like reference numerals denote like elements and wherein:

FIG. 1 is a structural diagram of a rubber sleeve protection ring;

FIG. 2 is a structural diagram A of a protection unit;

FIG. 3 is a structural diagram B of a protection unit;

FIG. 4 is a structural diagram C of a protection unit;

FIG. 5 is a structural diagram D of a protection unit;

FIG. 6 is a structural diagram of an upper anchor assembly;

FIG. 7 is a structural diagram of a lower anchor assembly;

FIG. 8 is a structural diagram of an upper locking nut;

FIG. 9 is a structural diagram of a lower locking nut;

FIG. 10 is a structural diagram of a striper ring;

FIG. 11 is a structural diagram of slips;

FIG. 12 is a structural diagram of a conical slip holder;

FIG. 13 is a structural diagram of a rubber sleeve conical protection ring holder;

FIG. 14 is a structural diagram of a downhole plugging apparatus.

FIG. 15 is a state diagram of a downhole plugging apparatus in a setting state;

FIG. 16 is a structural diagram of a radially expanded rubber sleeve protection ring;

Wherein the names of the corresponding parts are shown as follow:

• a. mandrel, 2-upper locking nut, 3-striper ring, 4-slips, 5-conical slip holder, 6-conical protection ring holder, 7-protection unit, 8-lower locking nut, 9-middle rubber sleeve, 10-end rubber sleeve, 11-release lever, 12-wellbore wall, 31-conical surface, 32-separate protrusions, 51-conical surface, 52-separate protrusions, 61-sliding groove, 62-circular groove, 63-conical surface, 701-seal protrusion, 702-seal groove, 703-sliding protrusions, 81-conical surface, 82-separate protrusions.

DETAILED DESCRIPTION OF THE INVENTION

One objective of the present invention is to provide a rubber sleeve protection ring that can overcome shortcomings of existing technology. Namely, it prevents a seal assembly from extending into space between an anchor assembly and a wellbore wall. Particularly, the rubber sleeve protection ring is in surface-contact with the wellbore wall instead of point-contact, which avoids damage to the rubber sleeve protection ring.

Another objective of the present invention is to provide a downhole plugging apparatus with better sealing performance.

The objectives of the present invention are realized through the following technical schemes:

The rubber sleeve protection ring comprises several protection units which are arranged in a circle, each of the protection units has a seal protrusion extending outwards, and each of the seal protrusions is corresponded to a seal groove; the seal protrusions are embedded into the seal grooves on the adjacent protection unit; at least one end face of the protection unit is an inclined surface, the direction of the inclined surface leads the protection unit moving radially and outwards under pressure.

The rubber sleeve protection ring is set between a seal assembly and the anchor assembly of the downhole plugging apparatus. During a setting process, the anchor assembly would squeeze the rubber sleeve protection ring and the seal assembly. Because at least one end face of the protection unit is the inclined surface, the protection units would move radially outwards when being compressed. Therefore, the seal assembly is protected while extending.

Compared to existing umbrella-shaped protection structure, the protection unit of the present invention can move radially outwards and its contact with the wellbore wall is the surface-contact instead of the point-contact, thus damages to the protection structure caused by the excessive contact stress can be avoided.

In the setting process, there would be gaps among the protection units when the protection units move radially outwards and the seal assembly would extend into the gaps, which may affect the sealing performance. To solve this problem, the seal protrusions and the seal grooves are arranged on each of the protection unit, thus the gaps could be filled by the seal protrusions, and the seal assembly could be prevented from getting into the gap. Therefore, an improved sealing performance can be ensured.

According to one embodiment of the present invention, the seal protrusion and the seal groove are arranged on the ends of the protection units.

Preferably, a sliding protrusion is set on one end face of the said protection unit; said setting enables the protection unit to work better with the anchor assembly by providing a sliding rail for the radial expansion of the protection unit.

One end face of said protection unit is arc-shaped in radial direction, and the protection unit could be better positioned in the anchoring assembly by using this structure.

Some objectives of the present invention are realized through the following technical schemes:

The downhole plugging apparatus comprises (a) a mandrel, (b) the seal assembly set on the mandrel, (c) an upper anchor assembly and (d) a lower anchor assembly that are connected to the mandrel, the upper anchor assembly and the lower anchor assembly are set above and below the seal assembly, respectively.

The rubber sleeve protection rings are set between the seal assembly and the upper anchor assembly; said rubber sleeve protection rings are also set between the seal assembly and the lower anchor assembly; the rubber sleeve protection ring consists of a plurality of the protection units which are arranged in a circle; each of the protection unit is provided with the seal protrusion extending outwards and the seal groove corresponding thereto; the seal protrusion are embedded in the seal groove of the adjacent protection units; at least one end face of the protection unit is the inclined surface; the direction of the inclined surface would lead the protection units moving radially and outwards when being compressed by the lower anchor assembly or the upper anchor assembly.

Preferably, said seal protrusion and the seal groove are set on the end of the protection units, the seal protrusion contacts with the seal assembly.

Accordingly, said upper anchor assembly consists of (a) an upper lock nut connected to a thread at a upper end of the mandrel, (b) a stripper ring that is in contact with the upper lock nut, (c) a plurality of a first set of slips that are in contact with the stripper ring, (d) a first conical slip holder that is in contact with the first set of the slips and a first conical protection ring holder contacted with the first conical slip holder, the first conical protection ring holder also contacts with the rubber sleeve protection ring.

The lower anchor assembly consists of (a) a lower lock nut connected to the thread at a bottom end of the mandrel, (b) a plurality of a second set of slips in contact with the lower lock nut, (c) a second conical slip holder in contact with the second set of slips and (d) a second conical protection ring holder contacted with the second conical slip holder, the second conical protection ring holder also contacts with the rubber sleeve protection ring.

The sliding protrusions are set on the end face of one of the said protection unit; there are several sliding grooves on a conical surface of the conical protection ring holder, the sliding protrusions are embedded in the sliding grooves.

Preferably, one end face of the protection unit is arc-shaped in the radial direction; a plurality of circular grooves is set on the conical surface of the conical protection ring holder, and the arc-shaped face of the protection unit is set in the circular grooves.

Advantages and benefits of the present invention are:

Compared with prior art umbrella-shaped protection structure, the rubber sleeve protection ring of the present invention is in the surface-contact with the wellbore wall instead of the point-contact, thus damage to the protection structure caused by excessive contact stress can be avoided and the sealing performance can be improved.

The seal protrusions and the seal grooves are arranged on the protection units to prevent the seal assembly from getting into the gaps among the protection units, thus the sealing performance can be further improved;

The seal assembly contacts the seal protrusions, which can prevent the seal assembly from getting into the gaps among the protection units, thus the sealing performance can be further improved;

4. The sliding protrusions are set on the end faces of the protection unit; multiple sliding grooves are set on the conical surface of both the upper and lower conical protection ring holders to provide the sliding rails for the protection units; the sliding protrusions are embedded in the sliding grooves and can slide in the upper sliding grooves or the lower sliding grooves, thus the protection units can move exactly in the direction as needed for better sealing.

5. Multiple circular grooves are set on the conical surface of the upper conical protection ring holder and the lower conical protection ring holder, the arc-shaped end surface of the protection units are embedded in the circular grooves. With this structure, the protection unit can be better positioned in the anchor assembly.

Embodiment 1

As shown in FIGS. 1-5, the rubber sleeve protection ring has the plurality of the protection units 7 which are arranged in a circle, each protection unit 7 is provided with the seal protrusion 701 extending outwards, and the seal groove 702 corresponding to the seal protrusions; the seal protrusions 701 are embedded into the seal grooves 702 on the protection unit 7; at least one end face of the protection unit 7 is the inclined surface, the direction of the inclined surface would lead the protection unit 7 moving radially outwards when bearing the force on the end face.

According to the Embodiment 1, when using the rubber sleeve protection ring, it shall be set between the upper seal assembly and the anchor assembly of the downhole plugging apparatus. During the setting process, the anchor assembly would squeeze the rubber sleeve protection ring and the seal assembly. Since at least one end face of the protection unit 7 is the inclined surface, the protection unit 7 can move radially outwards when being compressed. Therefore, the seal assembly can be protected while extending.

During the setting process, the gaps may accrue among the protection units 7 when the protection unit 7 moving radially outwards. The seal assembly would extend into the gaps, which may affect the sealing performance.

To solve this problem, the seal protrusion 701 and the seal groove 702 are provided on each of the protection unit, thus the gaps could be fulfilled by the seal protrusions 701, and the seal assembly could be prevented from getting into the gaps. Therefore, a good sealing performance is ensured.

Embodiment 2

FIG. 2 is a plan view of the protection unit 7. The protection unit 7 is provided with the arc-shape surface, and the contact between the arc-shape surface and the wellbore wall is the surface-contact. As shown in FIG. 1, the plurality of the protection units 7 are arranged in the circle, the arc-shape surfaces of the protection units 7 constitute the complete outer round surface.

FIG. 4 is a side view of the protection unit 7, the two end faces of the protection unit 7 are inclined surfaces and they incline in the opposite directions, which mean the volume of the protection unit 7 would decrease from the outside to the inside. In fact, only one of the end faces of the protection unit 7 is needed to be set as inclined face and another can be set as a vertical face to enable the protection unit 7 to be pushed to move radially outwards. In this embodiment, two inclined faces are set to ensure the protection unit 7 would move outwards more reliably.

As shown in FIG. 2 and FIG. 5, wherein FIG. 5 is a three-dimensional structure diagram of the protection unit 7. The seal protrusion 701 and the seal groove 702 are provided to the protection unit 7, the seal protrusion 701 and the seal groove 702 have corresponding shapes. As shown in FIG. 1, when the protection units 7 constructs as the rubber sleeve protection ring, the seal protrusions 701 are embedded in the seal groove 702. And as shown in FIG. 16, when the protection unit 7 moves radially outwards, the gaps occur among the protection units 7, and the seal protrusions 701 can fulfill the gaps to prevent the seal assembly from getting into the gaps.

Accordingly, the seal protrusion 701 and the seal groove 702 do not necessarily have to be set at the end of the protection unit 7. If the seal protrusion 701 and the seal groove 702 are set in the middle of the protection units 7, the seal assembly can also be prevented from extending into the space between the anchor assembly and the wellbore wall. However in such situation, part of the seal assembly would extend into the gaps among the protection units 7 and the sealing performance will be impacted. To solve this problem, the seal protrusion 701 and the seal groove 702 may be arranged on the ends of the protection unit 7. Since the end is in contact with the seal assembly, the seal assembly can be prevented from extending into the space among the protection units 7.

FIG. 3 is a bottom view of the protection units 7, the sliding protrusions 703 is set on the end face of the protection units 7.

The sliding protrusions 703 shall work with the sliding groove on the anchor assembly, which functions as a rail for the radial movement of the protection units 7, thus the protection units 7 would move in a correct direction as needed for better sealing performance.

As shown in FIG. 2, one of the end faces of the protection units 7 is arc-shaped in the radial direction and it contacts with the anchor assembly, therefore the protection units 7 can be positioned on the anchor assembly better.

Embodiment 3

As shown in FIG. 14, the downhole plugging apparatus comprises (a) the mandrel 1, (b) the seal assembly set on the mandrel 1, (c) the upper anchor assembly and (d) the lower anchor assembly which is connected to the mandrel, the upper anchor assembly and the lower anchor assembly are set above and below the seal assembly respectively. The rubber sleeve protection rings are set between the seal assembly and the upper anchor assembly; the rubber sleeve protection rings are also set between the seal assembly and the lower anchor assembly. The rubber sleeve protection ring consists of several of the protection units 7 which are arranged in the circle, each protection unit 7 has the seal protrusion 701 and the seal groove 702; the seal protrusion 701 is embedded in the seal groove 702 of the adjacent protection units 7; at least one end face of the protection unit 7 is inclined surface, the direction of the inclined surface would lead the protection unit 7 move radially and outwards under the pressure from lower anchor assembly or upper anchor assembly.

While working, a top of the mandrel 1 connects with a release lever 11; the release lever is gripped by an external claw, and the external claw has a clamping device contacting with the anchor assembly; the clamping device would compress the upper anchor assembly, then both the upper anchor assembly and the lower anchor would compress the seal assembly to get it constrict in an axial direction and expand in the radial direction; at the same time the protection units 7 would move radially outwards, preventing the seal assembly from getting into the space between the anchor assembly and the wellbore wall. Finally, both the upper anchor assembly and the lower anchor assembly would anchor into the wellbore wall, and the downhole plugging apparatus can be fixed in the well, also the seal assembly is engaged with the wellbore wall tightly to achieve a good sealing performance. Then the release lever 11 will be cut when being pulled, and the downhole plugging apparatus will be left in the well.

Embodiment 4

As shown in FIG. 6, the upper anchor assembly includes (a) the upper locking nut 2 screwed on the thread on the upper part of the mandrel 1, (b) the striper ring 3 that contacts with the upper locking nut 2, (c) the multiple slips 4 that contact with the striper ring 3, (d) the conical slip holder 5 that contacts with the slips 4 and (e) the rubber sleeve conical protection ring holder 6 that contacts with the conical slip holders 5; wherein the rubber sleeve conical protection ring holder 6 is also in contact with the rubber sleeve protection ring.

As shown in FIG. 8, a threaded hole in the upper locking nut 2, the upper locking nut 2 connects with the upper end of the mandrel 1 by threading.

As shown in FIG. 10, the mandrel 1 is sleeved by the stripper ring 3, which could travel along the axial direction of the mandrel 1; an end face of the stripper ring 3 contacting with the upper lock nut 2 is plane and the other end face of the stripper ring 3 is a conical surface 31, on which separate protrusions 32 are arranged evenly. As shown in FIG. 11, one end of each of the slips 4 is contacted with the conical surface 31, and is set between two adjacent separate protrusions 32.

As shown in FIG. 12, the conical slip holder 5 sleeves the mandrel 1, and it can move axially along the mandrel when bearing forced, the face of conical slip holder 5 that facing the striper ring 3 is a conical surface 51, there are several separate protrusions 52 on the conical surface 51, the other end of the slips 4 contact the conical surface 51 and are located between two adjacent separate protrusions 52; the other end face of the conical slip holder 5 is a flat face.

As shown in FIG. 13, the mandrel 1 is sleeved by the rubber sleeve conical protection ring holder 6, which could travel axially along the mandrel 1; the end face of the rubber sleeve conical protection ring holder 6 contacting with the conical slip holder 5 is plane and the other end face of the rubber sleeve conical protection ring holder 6 is a conical surface 63; the conical surface 63 is in contact with the rubber sleeve protection ring.

As shown in FIG. 7, the lower anchor assembly consists of (a) a lower lock nut 8 connected to the thread at the bottom end of the mandrel 1, (b) the slips 4 which are in contact with the lower lock nut 8, (c) a conical slip holder 5 which is in contact with the slips 4, and (d) a conical protection ring holder 6 that contacts with the conical slip holder 5; the conical protection ring holder 6 also contacts the rubber sleeve protection ring.

As shown in FIG. 9, there is a threaded hole provided on the lower lock nut 8 and the lower lock nut 8 connects with the lower end of the mandrel 1 by thread; the end face of the lower lock nut 8 which is close to the seal assembly is a conical surface 81; there are multiple separate protrusions 82 on the conical surface 81. As shown in FIG. 11, the end of the slips 4 and the conical surface 81 are connected, and each of the slips 4 is set between two adjacent separate protrusions 82.

As shown in FIG. 12, the conical slip holder 5 sleeves the mandrel 1, and it can move axially along the mandrel when bearing force, the face of conical slip holder 5 that faces the striper ring 3 is a conical surface 51, there are several separate protrusions 52 on the conical surface 51; the other end of the slips 4 is connected with the conical surface 51 and is set between two adjacent separate protrusions 52; the other end face of the conical slip holder 5 is a flat face.

As shown in FIG. 13, the mandrel 1 is sleeved by the rubber sleeve conical protection ring holder 6, which could travel axially along the mandrel 1; the end face of the rubber sleeve conical protection ring holder 6 contacting with the conical slip holder 5 is plane and the other end face of the rubber sleeve conical protection ring holder 6 is the conical surface 63; the conical surface 63 is in contact with the rubber sleeve protection ring.

As shown in FIG. 14, the seal assembly is between the two rubber sleeve protection rings; the seal assembly consists of the middle rubber sleeve 9 set on the mandrel 1 and two end rubber sleeves 10 set on both ends of the middle rubber sleeve 9; both the middle rubber sleeve 9 and the end rubber sleeves 10 can move axially along the mandrel 1.

As shown in FIG. 4, the end face of the protection unit 7 which contacts the conical surface 63 of the rubber sleeve protection ring 6 is inclined, the end face which contacts with the end rubber sleeve 10 is inclined as well.

FIG. 15 shows the state diagram of the downhole plugging apparatus in setting state. First fix the mandrel 1 via the release lever 11, then apply a force on stripper ring 3, the stripper ring 3 as well as the lower lock nut 8 would push the slips 4 travel on the conical surface 51 of the conical slip holder 5, meanwhile, the force will be transmitted to the seal assembly through the conical slip holder 5 conical protection ring holder 6 and the rubber sleeve protection ring, and the seal assembly would contract axially and expand radially; at the same time the protection unit 7 would move radially to prevent seal assembly from extending axially. Finally, the teeth of slips 4 would anchor into the wellbore wall 12 and keep the seal assembly remains in the state of compression, and the sealing is accomplished.

Embodiment 5

As shown in FIG. 2 and FIG. 5, this embodiment is based on embodiment 4; the seal protrusion 701 and the seal groove 702 are set on the ends of the protection units 7, and the seal protrusion 701 is in contact with the said seal assembly.

If the seal protrusion 701 and the seal groove 702 are set in the middle of the protection units 7, they can prevent the seal assembly from extending into the space between the anchor assembly and wellbore wall as well. However in this situation some parts of the seal assembly would extend to the gaps among the protection units 7, and the performance of sealing would be impacted. To solve this problem, the seal protrusion 701 and the seal groove 702 are set on the ends of the protection unit 7 and these ends are in contacts with the seal assembly, thus the seal assembly is prevented from getting into the gaps among the protection units 7.

Embodiment 6

This embodiment is based on the embodiment 4 and embodiment 5.

As shown in FIG. 3, there is the sliding protrusions 703 on the protection unit 7; as shown in FIG. 13, several of the sliding grooves are set on the conical surface 63 of the rubber sleeve conical protection ring holder 6; the sliding protrusions 703 can move in the sliding grooves 61, which provides the sliding rails for the protection units 7, and ensures the protection units 7 would move in the correct direction as needed.

Embodiment 7

This embodiment is based on the embodiments 4, 5 and 6.

As shown in FIG. 2, one end face of the said protection unit 7 is arc-shaped in the radial direction; as shown in FIG. 13, several of the circular grooves 62 are set on the conical surface 63 of the conical protection ring holder 6, and the arc-shaped end face of the protection unit 7 is embedded in the circular grooves 62.

Although each of the embodiment have been described in great detail, it is to be understood that numerous modifications, variations and adaptations may be made to the particular embodiments of the invention described above without departing from the scope of the invention which is defined in the claims:

Claims

1. A rubber sleeve protection ring, comprising:

a plurality of protection units 7 which are arranged in a circle; each of the protection unit 7 is provided with a seal protrusion 701 that extends outwards, and each of the protection unit is provided with a seal groove 702 corresponding to the seal protrusion 701, the seal protrusions 701 could be embedded in the seal grooves 702 of the adjacent protection unit 7;

at least one end face of the protection unit 7 is set as inclined surface, wherein a direction of the inclined face would ensure the protection unit 7 moving radially outwards under pressure.

2. The seal protrusion 701 and the seal groove 702 from claim 1, wherein both are set at the ends of the protection unit 7.

3. The sliding protrusion 703 from claim 1, wherein it is set on one end face of the said protection unit 7.

4. The end face of the protection unit 7 from claim 1, wherein at least one is arc-shaped in radial direction.

5. A downhole plugging apparatus comprises:

a mandrel 1, a seal assembly which is set on the mandrel 1, a upper anchor assembly and a lower anchor assembly which are arranged above and below the seal assembly respectively on the mandrel;

a rubber sleeve protection rings are set between the seal assembly and the upper anchor assembly; the rubber sleeve protection rings are also set between the seal assembly and the lower anchor assembly;

the rubber sleeve protection ring comprising a plurality of protection units 7 and the protection units 7 are arranged in a circle, a seal protrusion 701 and a seal groove 702 are provided to each of the protection unit 7, the seal protrusion 701 is embedded in the seal groove 702 of the adjacent protection units 7; at least one end face of the protection unit 7 is of a inclined surface, a direction of the inclined surface leads the protection unit 7 moving radially and outwards when being pressed by the lower anchor assembly or the upper anchor assembly.

6. The seal protrusion 701 and the said seal groove 702 from claim 5, wherein both are set on the ends of the protection unit 7, and said seal protrusion 701 is in contact with said seal assembly.

7. The downhole plugging apparatus from claim 5, further comprising:

the upper anchor assembly comprising: (a) a upper locking nut 2 which connects to a upper end of the mandrel 1 by a thread, (b) a striper ring 3 contacted with the upper locking nut 2, (c) a plurality of slips 4 contacted with the striper ring 3, (d) a conical slip holders 5 contacted with the the slips 4 and (e) aconical protection ring holder 6 contacted with the conical slip holders 5 and with the rubber sleeve protection ring;

the lower anchor assembly comprising (a) a lower locking nut 8 connected with a lower end of the mandrel 1 by the thread, (b) the plurality of slips 4 that contact the lower locking nut 8, (c) the conical slip holders 5 contacted with the slips 4 and (d) the conical protection ring holder 6 that contacts with the conical slip holders 5, wherein the conical protection ring holder 6 contacts with the rubber sleeve protection ring.

8. The downhole plugging apparatus from claim 7, further comprising: a slide protrusion 703 set on one end face of the said protection unit 7; wherein several slide grooves 61 on the conical surface of the conical protection ring holder 6, and the slide protrusions 703 can travel along the slide grooves 61.

9. The downhole plugging apparatus from claim 7, further comprising:

one of end faces of the protection unit 7 is arc-shaped in a radial direction;

a plurality of circular grooves 62 set on the conical surface of the conical protection ring holder 6; and the arc-shaped end face of the said protection unit 7 is embedded in the circular grooves 62.