STRESS-BUFFER RELEASE LEVER AND DOWNHOLE PLUGGING APPARATUS

The present invention discloses a stress-buffer release lever, which comprises an outer lever and an inner lever; the outer lever consists of a front end and a back end, wherein external threads are provided on both ends of the outer lever; a weakened section is set between the front end and the back end of outer lever; a co-axial through-hole is provided inside the outer lever, and internal threads are set on an inner surface of the through-hole; the inner lever's outer surface is provided with an external thread, the inner lever is set within the through-hole of the outer lever and is connected to the outer lever by the threads; the tensile strength of the inner lever is lower than that of the outer lever. The current invention also discloses a downhole plugging apparatus.

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Description
CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to Chinese patent application 201420105534.6, filed Mar. 10, 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 OF THE INVENTION

1. Field of the Invention

The present invention relates to a oil-gas production and a mineral mining field, particularly, to a downhole plugging apparatus and stress-buffer release lever which are used for downhole blocking.

2. General Background of the Invention

In the oil-gas production or mineral mining process, a wellbore might need to be blocked. Currently the most common way of the downhole blocking is by using apparatus for plugging. The existing downhole plugging apparatus is composed of an anchor component which is set on a mandrel, a seal component and a release lever. After said existing plugging apparatus is put into a predetermined position in a well, it will be fixed by squeezing the anchor component to have it anchored into a casing wall. Meanwhile, the anchor component would squeeze the seal component, and lead to its radial expansion so that the seal component would engage with a wellbore tubing to seal thereof.

The release lever is connected to an external claw by threads; the claw also includes a clamping device that contacts with an upper anchor; the clamping device would compress the upper anchor and gets both the upper anchor and a lower anchor squeezing the seal component, so that it would constrict in an axial direction and expand in an radial direction, then the seal component could be pressed against the casing wall tightly and a good sealing performance could be achieved. Finally, the anchor component would anchor into the wall and the release lever will be cut when being pulled, and the existing downhole plugging apparatus will be left in the well.

Because a connecting part of the release lever and the mandrel would bear a large stress during the setting process, the release lever needs to have a high tensile strength to ensure a reliable connection between the release lever and the external claw as well as the mandrel, also to ensure no deformation.

However, when it fractures, the release lever would bear very large stress which is close to its maximum strength, this will cause great transient impact for the existing downhole plugging apparatus when the release lever fractures, which impacts effective fixation of said downhole plugging apparatus.

BRIEF DESCRIPTION OF DRAWINGS

For a further understanding of the nature, objects and advantages of the present invention, reference should be had to detailed description hereafter, read in conjunction with the following drawings:

FIG. 1 is a structural diagram of a stress-buffer release lever.

FIG. 2 is a structural diagram for a downhole plugging apparatus.

FIG. 3 is a state diagram of a downhole plugging apparatus in a setting state.

FIG. 4 is a structural diagram of a upper anchor assembly.

FIG. 5 is a structural diagram of a lower anchor assembly.

FIG. 6 is a structural diagram of a upper lock nut.

FIG. 7 is a structural diagram of a lower lock nut.

FIG. 8 is a structural diagram of a stripper ring.

FIG. 9 is a structural schematic diagram of a slips.

FIG. 10 is a structural schematic diagram of a conical slip holder.

Wherein the names of related components are as below: 1—mandrel, 2—upper lock nut, 3—stripper ring, 4—slips, 5—conical slip holder, 6—middle rubber sleeve, 7—end rubber sleeve, 8—lower lock nut, 9—outer lever, 10—inner lever, 11—wellbore wall—31—conical surface, 32—separate protrusions, 51—conical surface, 52—separate protrusions, 81—conical surface, 82—separate protrusions, 91—front end, 92—back end, 93—weakened section, 94—through-hole.

DESCRIPTION OF THE INVENTION

One objective of the present invention is to provide a stress-buffer release lever having a high tensile strength as well as a enhanced anti-brittle fracturing feature, which would lower the stress when it breaks and avoid a transient high intensity impact on a downhole plugging apparatus.

Yet another objective of the present invention is to provide the downhole plugging apparatus which includes the stress-buffer release lever.

Objectives of the present invention are realized as followed:

The stress-buffer release lever comprises an outer lever and an inner lever; the outer lever includes a front end and a back end, wherein both the front end and the back end of the outer lever are threaded externally, and a weakened section is provided between the front end and the back end of the outer lever; a coaxial through-hole is provided inside the outer lever, wherein said through-hole's inner surface is threaded; the inner lever's out surface is externally threaded, wherein the inner lever is set within the through-hole of the outer lever and is connected to the outer lever by threading; the tensile strength of inner lever is lower than that of the outer lever.

To ensure the stress-buffer release lever could connect with an external claw and a mandrel reliably without deformation during releasing process, said release lever needs to have a high tensile strength. However, its anti-brittle strength will decrease with the increase of tensile strength, thus a brittle fracture might occur when said release lever breaks.

To solve this problem, an bi-layer structure of the outer lever and the inner lever is applied. The outer lever is of a high tensile strength so it can bear larger force without deformation, and a reliable connection between the claw and the mandrel can be guaranteed; the inner lever is of a low tensile strength and it has strong anti-brittle ability. When pulling the release lever, the inner lever and the outer lever will work as a whole and greatly reduce the stress when the release lever breaks. Therefore, the transient high intensity impact on the downhole plugging apparatus is avoided, which will effectively solve the problem that a looseness would possibly occur of the downhole plugging apparatus caused by transient high intensity impact when the release lever is departing from the mandrel.

Preferably, the weakened section is an annular groove on the outer lever. Preferably, a cross section of the said annular groove is semicircle-shaped, which can effectively avoid stress concentration.

Preferably, the cross-section of said annular groove is U-shaped.

Preferably, the outer lever is made of hard alloy steel; the inner lever is made of copper.

Another objective of the present invention is realized As followed:

The downhole plugging apparatus comprises the mandrel, a seal assembly set on the mandrel, an upper anchor assembly and a lower anchor assembly which are connected to an upper end and a lower end of the mandrel, respectively, the stress-buffer release lever that is connected to the top of mandrel by threading. The stress-buffer release lever includes the outer lever and the inner lever; the outer lever consists of the front end and the back end, both the front end and the back end of the outer lever are externally threaded, and the back end is connected with the upper end of the mandrel by threading; the weakened section is provided between the front end and the back end of the outer lever; the coaxial through-hole is provided inside the outer lever, the interior surface of the through-hole is internally threaded; the outer surface of the inner lever is externally threaded, the inner lever is set in the through-hole of the outer lever and is connected to the outer lever by threading; the tensile strength of inner lever is lower than that of the outer lever.

Preferably, the weakened section is the annular groove on the outer lever

Preferably, the cross-section of the annular groove is semicircle-shaped or U-shaped.

Preferably, the outer lever is made of hard alloy steel; and the inner lever is made of copper.

Further, the upper anchor assembly includes (a) a upper lock nut which is connected to a thread at the top of the mandrel, (b) a stripper ring that contacts the upper lock nut, (c) a plurality of slips that contact the stripper ring, and (d) a conical slip holder that contacts the slips; the conical slip holder also contacts the seal assembly;

The lower anchor assembly includes (a) a lower lock nut which is connected to a thread at the bottom of the mandrel, (b) a plurality of slips that contact the lower lock nut and (c) a conical slip holder that contact the slips. The conical slip holder also contacts the said seal assembly.

To sum up, the present invention is advantaged as followed:

1. The stress-buffer release lever has the high external tensile strength and the enhanced anti-brittle fracturing ability, which help to reduce the stress when it breaks, and the transient high intensity impact on the downhole plugging apparatus can be avoided, thus it can effectively prevent the downhole apparatus from being loosened by transient high intensity impact when the release lever is departing from the mandrel.

2. The downhole plugging apparatus, comprising the stress buffer release lever, can effectively solve the problem that looseness possibly caused by the transient high intensity impact when the release lever is departing from the mandrel.

To provide a better understanding for this utility, Embodiments will be illustrated hereafter:

Embodiment 1

As shown in FIG. 1, the stress-buffer release lever includes the outer lever 9 and the inner lever 10; the outer lever consists of the front end 91 and the back end 92; the external threads are threaded on both the front end 91 and the back end 92 of the outer lever 9; the weakened section 93 is set between the front end 91 and the back end 92 of the outer lever 9; the coaxial through-hole 94 is provided inside the outer lever 9, and the internal thread is threaded in the interior surface of the through-hole; the external thread is threaded on the outer surface of the inner lever 10; the inner lever 10 is arranged in the through-hole 94 of the outer lever 9 and is connected to the outer lever 9 by threading; the tensile strength of inner lever 10 is lower than that of the outer lever 9.

The bi-layer structure, namely, the outer lever 9 and the inner lever 10 is applied in the Embodiment; the outer lever 9 is made of the high tensile strength so it can bear larger stress without deformation, and the reliable connection between the claw and the mandrel could be guaranteed; the inner lever 10 is made of the low tensile strength, and of the good anti-brittle ability. Since the inner lever 10 and outer lever 9 would work as a whole, when the fracture occurs, the breaking stress of the outer lever 9 would be reduced by the malleability of the inner lever 10, thus the fracture stress of the release lever will be significantly reduced; therefore the transient high intensity impact on the downhole plugging apparatus can be avoided.

Preferably, the outer lever 9 should be made of materials with the high tensile strength, like WQ890, WH100Q, WQ960, 45CrNiMoVA, 45 steel or hard alloy such as YG6 and YG8N etc can be used to manufacture an outer lever 9; and theoretically, the inner lever 10 is only required to be made of materials with lower tensile strength than that of the outer lever 9 to reduce the stress when fracturing; however in practice, using materials with good plasticity and anti-brittle fracture will work better, such as pure copper, pure aluminum, pure iron, low carbon steel and composite materials such as PTFE, etc.

Embodiment 2

As shown in FIG. 1, the weakened section 93 is the annular groove on the outer lever 9.

Embodiment 3

the cross-section of the annular groove is semicircle-shaped as shown in FIG. 3.

The semicircle-shaped cross-section of the annular groove can effectively avoid stress concentration.

Embodiment 4

the cross-section of the annular groove is U-shaped as shown in FIG. 3.

The U-shaped cross-section of the annular groove can effectively prevent stress concentration; moreover, it can reduce the width of the annular groove and increase the depth of the annular groove, making it easier to control a fracturing position of the annular stress-buffer release lever.

Embodiment 5

As shown in FIGS. 1, 2 and 3, 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 connected to the upper and the lower end of the mandrel 1, respectively.

The downhole plugging apparatus also comprises (e) the stress-buffer release lever that is connected to the top of the mandrel by threading. The stress-buffer release lever includes the outer lever 9 and the inner lever 10; the outer lever consists of the front end 91 and the back end 92; the external threads are threaded on both the front end 91 and the back end 92 of the outer lever 9; the weakened section 93 is set between the front end 91 and the back end 92 of the outer lever 9; the coaxial through-hole 94 is provided inside the outer lever 9, and the internal thread is threaded in the interior surface of the through-hole; the external thread is threaded on the outer surface of the inner lever 10; the inner lever 10 is arranged in the through-hole 94 of the outer lever 9 and is connected to the outer lever 9 by threading; the tensile strength of inner lever 10 is lower than that of the outer lever 9.

As shown in FIG. 3, the front end 91 of the outer lever 9 is connected to an external claw by threading; the claw includes the clamping device which contacts the upper anchor assembly; when the clamping device exert a force on the upper anchor assembly, and the upper anchor assembly together with the lower anchor assembly would squeeze the seal assembly, leading to an axial constriction as well as a radial expansion of the seal assembly; this would force the upper anchor assembly and the lower anchor assembly anchoring into a wellbore wall 11 to accomplish fixing of the downhole plugging apparatus and the sealing of seal assembly, then the stress-buffer release lever will be pulled to break and the downhole plugging apparatus will be left in the well.

When it breaks, the fracture stress on the stress-buffer release lever is relatively small, so is the transient impact strength for the downhole plugging apparatus, thus it will not influence the connection between the wellbore wall 11 and the upper anchor assembly or the lower anchor assembly, and the downhole plugging apparatus can be fixed more firmly in the wellbore wall 11.

In the current Embodiment, the stress-buffer release lever could be any of that described in embodiments 1˜4.

Embodiment 6

The current Embodiment provides a further illustration for the downhole plugging apparatus.

As shown in FIG. 2 and FIG. 4, the upper anchor assembly includes (a) the upper lock nut 2 which is connected to the threads 101 at the top of the mandrel 1, (b) the stripper ring 3 that contacts the upper lock nut 2, (c) the plurality of the slips 4 that contact the stripper ring 3 and (d) the conical slip holder 5 that contacts the slips 4. The conical slip holder 5 also contacts the said seal assembly.

As shown in FIG. 6, there is a threaded hole inside the upper lock nut 2 so that the upper lock nut 2 could be connected with the mandrel 1 by thread 101.

As shown in FIG. 8, the mandrel 1 is sleeved by the stripper ring 3, which could move axially along the mandrel 1; an end face of the stripper ring 3 that contacts the upper lock nut 2 is plane; an opposite end face of the stripper ring 3 is a conical surface 31 on which at least one separate protrusions 32 are arranged evenly. As shown in FIG. 9, each of the slips 4 contacts the conical surface 31 and is set between two adjacent separate protrusions 32.

As shown in FIG. 10, the mandrel 1 is sleeved by the conical slip holder 5, which could travel axially along the mandrel 1 when bearing force; the end face of the conical slip holder 5 facing the stripper ring 3 is a conical surface 51 on which the separated protrusions 52 are arranged; the opposite end face of each of the slips 4 is in contact with the conical surface 51 and is between two adjacent separate protrusions 52; the opposite end face of conical slip holder is flat and it contacts with the seal assembly.

As shown in FIG. 2 and FIG. 5, the lower anchor assembly includes (a) the lower lock nut 8 which is connected to the threads 101 at the bottom of the mandrel 1, (b) the plurality of the slips 4 that contacts the lower lock nut 8, and (c) the conical slip holder 5 that contact the slips 4. The conical slip holder 5 also contacts the said seal assembly.

As shown in FIG. 7, there is a threaded hole inside the lower lock nut 8 so that the lower lock nut 8 could be connected with the mandrel 1 by thread 101; the end face of the lower lock nut 8 contacting with the seal assembly is the conical surface 81 on which the separate protrusions 82 are arranged; as shown in FIG. 10, one end of each of the slips 4 is contacted with the conical surface 81 and is set between two adjacent separate protrusions 82.

As shown in FIG. 10, the mandrel 1 is sleeved by the conical slip holder 5, which could travel axially along the mandrel 1 when bearing force. The end face of the conical slip holder 5 facing with the stripper ring 3 is the conical surface 51 on which the separate protrusions 52 are arranged; the opposite end of each of the slips 4 is in contact with the conical surface 51 and is between two adjacent separate protrusions 52; the opposite end face of conical slip holder is flat and it contacts with the seal assembly.

While operating, the mandrel is first fixed via the stress-buffer release lever, then force is applied on the stripper ring 3. The stripper ring 3 and the lower lock nut 8 would push the slips 4 traveling on the conical surface 51 of the conical slip holder 5. At the same time, the force will be transmitted to the seal assembly through the conical slip holder 5, leading to the axial constriction as well as the radial expansion of the seal assembly and the teeth of the slips 4 would anchor into the wellbore wall 11, keeping the seal assembly in the state of compression and to realize sealing.

The seal assembly consists of a middle rubber sleeve 6 that sleeves the mandrel 1 and an end rubber sleeves 7 set at both ends of the middle rubber sleeve 6.

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 stress-buffer release lever, comprising:

an outer lever 9 and an inner lever 10, wherein the outer lever 9 consists of a front end 91 and a back end 92, external threads are threaded on both the front end 91 and the back end 92;
a weakened section 93 is provided between the front end 91 and the back end 92;
a coaxial through-hole 94 is provided inside the outer lever 9, wherein an interior surface of the through-hole is internally threaded;
an external thread is threaded on an outer surface of the inner lever 10, wherein the inner lever 10 is arranged in the through-hole 94 of the outer lever 9 and is connected to the outer lever 9 by threading; and,
a tensile strength of inner lever 10 is lower than that of the outer lever 9.

2. According to claim 1, the stress-buffer release lever further comprising: the weakened section 93 is an annular groove on the outer lever 9.

3. According to claim 2, the stress-buffer release lever further comprising:

a cross-section of the annular groove is semicircle-shaped.

4. According to claim 2, the stress-buffer release lever further comprising:

The cross section of the annular groove is U-shaped.

5. According to claim 1, the stress-buffer release lever further comprising: the outer lever 9 is made of hard alloy steel, the inner lever 10 is made of copper.

6. According to claim 2, the stress-buffer release lever further comprising: the outer lever 9 is made of hard alloy steel, the inner lever 10 is made of copper.

7. According to claim 3, the stress-buffer release lever further comprising: the outer lever 9 is made of hard alloy steel, the inner lever 10 is made of copper.

8. According to claim 4, the stress-buffer release lever further comprising: the outer lever 9 is made of hard alloy steel, the inner lever 10 is made of copper.

9. A downhole plugging apparatus, comprising:

(a) a mandrel 1;
(b) a seal assembly set on the mandrel 1;
(c) an upper anchor assembly and (d) a lower anchor assembly, both of which are connected to the upper and the lower end of the mandrel 1, respectively;
(e) a stress-buffer release lever that is connected to the top of mandrel 1 by threading;
the stress-buffer release lever includes an outer lever 9 and an inner lever 10,
Wherein the outer lever consists of a front end 91 and a back end 92, external threads are threaded on both ends, and the back end 92 is connected to a upper end of the mandrel 1 by threading, and, a weakened section 93 is set between the front end 91 and the back end 92 of outer lever 9;
a coaxial through-hole 94 inside the outer lever 9, and internal thread was provided on an inner surface of the coaxial through-hole 94, wherein an external thread is threaded on an outer surface of the inner lever 10, and the inner lever 10 is arranged within the through-hole 94 of the outer lever 9 and is connected to the outer lever 9 by threading; and,
a tensile strength of inner lever 10 is lower than that of the outer lever 9.

10. According to claim 9, the downhole plugging apparatus further comprises: the weakened section 93 is an annular groove on the outer lever 9.

11. According to claim 10, the downhole plugging apparatus further comprises: a cross-section of the annular groove is semicircle-shaped or U-shaped.

12. According to claim 9, the downhole plugging apparatus further comprises: the outer lever 9 is made of hard alloy steel; the said inner lever 10 is made of copper.

13. According to claim 10, the downhole plugging apparatus further comprises: the outer lever 9 is made of hard alloy steel; the said inner lever 10 is made of copper.

14. According to claim 11, the downhole plugging apparatus further comprises: the outer lever 9 is made of hard alloy steel; the said inner lever 10 is made of copper.

15. According to claim 9, the downhole plugging apparatus further comprises:

the upper anchor assembly comprises (a) a upper lock nut 2 which is connected to threads 101 at an upper end of the mandrel 1, (b) a stripper ring 3 that contacts the upper lock nut 2, (c) a plurality of slips 4 that contact the stripper ring 3 and (d) a conical slip holder 5 that contact the slips 4, and the conical slip holder 5 also contacts the seal assembly;
the said lower anchor assembly comprises (a) a lower lock nut 8 which is connected to the threads 101 at a lower end of the mandrel 1, (b) the plurality of the slips that contact the lower lock nut 8, (c) the conical slip holder 5 that contact the slips 4, and the conical slip holder 5 also contacts the seal assembly.

16. According to claim 10, the downhole plugging apparatus further comprises:

the upper anchor assembly comprises (a) a upper lock nut 2 which is connected to threads 101 at an upper end of the mandrel 1, (b) a stripper ring 3 that contacts the upper lock nut 2, (c) a plurality of slips 4 that contact the stripper ring 3 and (d) a conical slip holder 5 that contact the slips 4, and the conical slip holder 5 also contacts the seal assembly;
the said lower anchor assembly comprises (a) a lower lock nut 8 which is connected to the threads 101 at a lower end of the mandrel 1, (b) the plurality of the slips that contact the lower lock nut 8, (c) the conical slip holder 5 that contact the slips 4, and the conical slip holder 5 also contacts the seal assembly.

17. According to claim 11, the downhole plugging apparatus further comprises:

the upper anchor assembly comprises (a) a upper lock nut 2 which is connected to threads 101 at an upper end of the mandrel 1, (b) a stripper ring 3 that contacts the upper lock nut 2, (c) a plurality of slips 4 that contact the stripper ring 3 and (d) a conical slip holder 5 that contact the slips 4, and the conical slip holder 5 also contacts the seal assembly;
the said lower anchor assembly comprises (a) a lower lock nut 8 which is connected to the threads 101 at a lower end of the mandrel 1, (b) the plurality of the slips that contact the lower lock nut 8, (c) the conical slip holder 5 that contact the slips 4, and the conical slip holder 5 also contacts the seal assembly.
Patent History
Publication number: 20150252647
Type: Application
Filed: Mar 9, 2015
Publication Date: Sep 10, 2015
Inventors: Shuhao Liu (Chengdu), Zihan Ma (Chengdu)
Application Number: 14/642,642
Classifications
International Classification: E21B 33/129 (20060101); E21B 23/06 (20060101); E21B 33/128 (20060101);