阅读说明：本技术 分级注水泥装置 (Stage cementing device ) 是由 秦金立 刘阳 陈武君 刘奔 郭朝辉 曾艳军 刘明 杨德锴 朱玉杰 廖洪千 于 2020-06-28 设计创作，主要内容包括：一种分级注水泥装置,包括：具有内腔的圆柱形本体,在本体的壁上设有循环孔和朝向内腔敞开的进液孔；设置在本体内的打开组件,其包括打开套和设置在打开套内的打开座,其中在初始状态下,打开套通过第一剪切销与本体连接并覆盖了循环孔,而打开座通过第二剪切销与打开套连接并覆盖了进液孔；以及封隔器,其包括封隔阀体和胶筒,封隔阀体包括与进液孔连通的流道,胶筒包括与流道连通的容液腔。第二剪切销构造成能够在一级固井结束后响应于本体内腔中的憋压而剪断,导致打开座向下游运动而打开进液孔。由此,在一级固井期间进入到本体内腔中的膨胀液能够经进液孔和流道而进入容液腔,从而导致胶筒膨胀。(A staged cementing apparatus comprising: the liquid-feeding device comprises a cylindrical body with an inner cavity, wherein a circulating hole and a liquid inlet hole which is opened towards the inner cavity are formed in the wall of the body; an opening assembly disposed in the body, including an opening sleeve and an opening seat disposed in the opening sleeve, wherein in an initial state, the opening sleeve is connected to the body through a first shearing pin and covers the circulation hole, and the opening seat is connected to the opening sleeve through a second shearing pin and covers the liquid inlet hole; and the packer comprises a packing valve body and a packing element, the packing valve body comprises a flow channel communicated with the liquid inlet hole, and the packing element comprises a liquid accommodating cavity communicated with the flow channel. The second shear pin is configured to shear in response to a choke pressure in the body cavity after completion of the first stage of cementing, causing the opening seat to move downstream to open the fluid inlet. Therefore, expansion liquid entering the inner cavity of the body during primary cementing can enter the liquid containing cavity through the liquid inlet hole and the flow channel, so that the rubber cylinder is expanded.)

1. A staged cementing apparatus (10) comprising:

a hollow cylindrical body (100) having an inner cavity (110), a through circulation hole (120) provided on the wall of the body, and a liquid inlet hole (130) open to the inner cavity;

an opening assembly (300) disposed within the body, the opening assembly including an opening sleeve (310) and an opening seat (320) disposed within the opening sleeve (310), wherein, in an initial state, the opening sleeve (310) is connected to the body (100) by a first shear pin (180) and covers the circulation hole (120), and the opening seat (320) is connected to the opening sleeve (310) by a second shear pin (182) and covers the liquid inlet hole (130); and

a packer (200) comprising a packing valve body (210) connected to the downstream end of the body and a packing drum (220) arranged downstream of the packing valve body, the packing valve body (210) comprising a flow passage (230) communicating with the liquid inlet hole (130), the packing drum (220) comprising a liquid accommodating chamber (240) communicating with the flow passage (230),

wherein the second shear pin (182) is configured to shear in response to a choke pressure in the body (100) after completion of a first stage of cementing, causing the opening seat (320) to move downstream to open the inlet opening (130), whereby expansion fluid entering the inner cavity (110) of the body (100) during the first stage of cementing is able to enter the fluid containing chamber (240) via the inlet opening (130) and the flow passage (230), thereby causing the rubber cartridge (220) to expand.

2. The staged cementing device according to claim 1, wherein an accelerator is filled in the liquid receiving chamber (240), and the accelerator can react with the expansion liquid to cause secondary expansion of the rubber sleeve (220).

3. The stage cementing apparatus according to claim 2, characterized in that the expansion fluid is part of a displacement fluid.

4. Stage cementing installation according to any one of the claims 1 to 3, characterized in that the primary pressure build-up is achieved by the lowering of an opening tool (400) engageable with the opening seat (320).

5. Stage cementing device according to claim 4, characterized in that a socket (330) is further provided at the lower end of the opening sleeve (310) for limiting the stroke of the downstream movement of the opening seat (320).

6. Stage cementing installation according to any one of the claims 1 to 5, characterized in that the liquid inlet hole (130) is configured as a groove formed on the inner wall of the body (100), the flow channel (230) being formed in the wall of the packing valve body (210) and extending axially through the packing valve body (210).

7. The cementing apparatus according to any one of the claims 1 to 6, characterized in that the packer (200) further comprises a base pipe (250) fixedly connected with the packing valve body (210), wherein the base pipe (250) is located radially inside the packing element (230), and a gap between the base pipe and the packing element is formed as the fluid accommodating chamber (240).

8. Stage cementing device according to claim 7, characterized in that two support sleeves (260) are provided on the outer surface of the glue cartridge (230) spaced apart from each other for limiting the axial position of the glue cartridge (230) for expansion.

9. Stage cementing installation according to any one of the claims 1 to 8, characterized in that the first shear pin (180) is shearable in response to a secondary pressure hold in the body (100), causing the opening sleeve (310) to move downstream, opening the circulation hole (120) and closing the liquid inlet hole (130).

10. Stage cementing device according to any one of the claims 1 to 9, characterized in that a closing sleeve (450) is provided upstream of the opening sleeve (310), which closing sleeve (450) is connected with the body (100) by a third shear pin (184),

wherein the third shear pin (184) is configured to shear in response to three hold-downs in the body (100) during a second stage cementing process, causing the closure sleeve (450) to move downstream to close the circulation hole (120).

11. Cementing device according to claim 10, characterized in that a shut-off seat (460) is provided in the shut-off sleeve (450), the three times being achieved by lowering a shut-off tool (410) engageable with the shut-off seat (460).

12. The stage cementing apparatus according to claim 10 or 11, characterized in that an elastic member (462) is provided on an outer wall of the closing sleeve (450), and an elastic member receiving groove (118) is provided on an inner wall of the body for receiving the elastic member (462) after the closing sleeve (450) closes the circulation hole (120) to maintain the position of the closing sleeve (450).

13. The stage cementing apparatus according to any one of claims 1 to 12, characterized in that the rubber sleeve is made of hydrocarbon-swellable rubber.

14. A stage cementing method using the stage cementing apparatus according to any one of the claims 1 to 13, comprising the steps of:

-lowering an opening tool (400) in the stage cementing apparatus into engagement with the opening seat (320), carrying out a set-back pressure to shear the second shear pin (182), causing the opening seat (320) to move downstream to open the inlet orifice (130);

the expansion liquid enters the liquid containing cavity (240) through the inner cavity (110) of the body (100), the liquid inlet hole (130) and the flow channel (230), so that the rubber cylinder (220) is expanded;

carrying out secondary pressure holding to shear the first shearing pin (180), leading the opening sleeve (310) to move downstream to open the circulating hole (120), and simultaneously cutting off the communication between the liquid inlet hole (130) and the flow passage (230); and

the closing tool (410) is lowered into engagement with the closure seat (460) and three hold downs are made to shear the third shear pin (184), causing the closure sleeve (450) to move downstream to close the circulation hole (120) again.

15. The staged cementing method according to claim 14, wherein the expansion fluid is reacted with an accelerator in the fluid chamber (240) to promote a secondary expansion of the cement drum (220).

Technical Field

The invention relates to a petroleum well cementation technology, in particular to a staged cementing device, and particularly relates to an expansion packing type staged cementing device and a staged cementing method using the same.

Background

The well cementation technology is an important technical link in the well drilling and completion process. The quality of well cementation directly affects the subsequent oil and gas exploitation operation.

The stage cementing process is a common process in well cementing technology. With the continuous deepening of exploration and development, ultra-deep wells are increasing. When the technical casing is used for the graded well cementation of partial wells, the graded well cementation process can reduce the pressure of a liquid column and reduce the leakage due to the poor cementing capability and low pressure bearing capability of the stratum. However, for the ultra-deep leakage well, the staged cementing process also has a first-stage leakage, and after the first-stage cementing, the leakage layer is not sealed, so the leakage problem, even the loss-back leakage, also occurs in the second-stage cementing process. Even if the later stage is remedied by squeezing cement, the well cementation quality is difficult to ensure, the cost-effectiveness ratio is low, and the requirement of accelerating the speed and improving the efficiency of oil field development is difficult to realize. In addition, after the casting in partial areas, the annular space of the technical casing pipe has the problem of pressure with different degrees. In order to ensure safe production, protective liquid needs to be injected into the annular space, but the cost is high, and the management difficulty is high.

The leakage layer or reservoir can be blocked by adopting the packing type graded cementing device, and the leakage problem is partially solved. However, the packer swelling fluid uses a drilling fluid without strength. After construction is finished, the packer is always under hydraulic pressure, so that the risks of packer aging and liquid leakage exist. In addition, the wellbore presents irregularities that can lead to the appearance of micro-gaps during packer swelling. When gas is in the well, the gas can penetrate the packer to cause the problem of annulus pressure.

Therefore, the current staged cementing and cementing process is difficult to meet the requirements of modern cementing.

Disclosure of Invention

In view of the above problems, the present invention provides a staged cementing apparatus and a method for staged cementing using the same.

According to a first aspect of the present invention, there is provided a staged cementing apparatus comprising: the device comprises a hollow cylindrical body with an inner cavity, wherein a through circulation hole and a liquid inlet hole which is opened towards the inner cavity are formed in the wall of the body; an opening assembly disposed in the body, the opening assembly including an opening sleeve and an opening seat disposed in the opening sleeve, wherein, in an initial state, the opening sleeve is connected to the body by a first shear pin and covers the circulation hole, and the opening seat is connected to the opening sleeve by a second shear pin and covers the liquid inlet hole; and the packer comprises a packing valve body connected with the downstream end of the body and a rubber sleeve arranged on the downstream of the packing valve body, the packing valve body comprises a flow channel communicated with the liquid inlet hole, and the rubber sleeve comprises a liquid containing cavity communicated with the flow channel. Wherein the second shear pin is configured to shear in response to a build-up of pressure in the internal cavity of the body after completion of the first stage of cementing, causing the opening seat to move downstream to open the inlet orifice, whereby expansion fluid entering the internal cavity of the body during the first stage of cementing is able to enter the fluid holding chamber via the inlet orifice and the flow passage to cause the cement barrel to expand.

In one embodiment, an accelerator is filled in the liquid containing cavity, and the accelerator can react with the expansion liquid to cause secondary expansion of the rubber cylinder.

In one embodiment, the expansion fluid is part of a displacement fluid, preferably a liquid epoxy resin, and the accelerator is a liquid adjuvant.

In one embodiment, said one hold-back pressure is achieved by lowering an opening tool engageable with said opening seat.

In one embodiment, a bearing seat is further provided at the lower end of the opening sleeve for limiting the stroke of the downstream movement of the opening seat.

In one embodiment, the liquid inlet hole is configured as a groove formed on the inner wall of the body, and the flow passage is formed in the cylindrical wall of the packing valve body and extends axially through the packing valve body.

In one embodiment, the packer further comprises a base pipe fixedly connected with the packing valve body, wherein the base pipe is located on the radial inner side of the rubber cylinder, and a gap between the base pipe and the rubber cylinder is formed into the liquid accommodating cavity.

In one embodiment, two spaced apart support sleeves are provided on the outer surface of the cartridge to limit the axial position at which expansion of the cartridge occurs.

In one embodiment, the first shear pin is capable of shearing in response to a second hold back causing the opening sleeve to move downstream, thereby opening the circulation orifice and closing the liquid inlet orifice.

In one embodiment, a closure sleeve is provided at an upstream end of the opening sleeve, the closure sleeve being connected to the body by a third shear pin, wherein the third shear pin is configured to shear in response to three hold-downs during a two-stage cementing process, causing the closure sleeve to move downstream to close the circulation hole.

In one embodiment, a closing seat is provided in the closure sleeve, said three pressure taps being achieved by lowering a closing tool engageable with said closing seat.

In one embodiment, an elastic member is disposed on an outer wall of the closing sleeve, and an elastic member receiving groove is disposed on an inner wall of the body, for receiving the elastic member after the closing sleeve closes the circulation hole to limit a position of the closing sleeve.

In one embodiment, the rubber sleeve is made of hydrocarbon-absorbing expanded rubber.

According to a second aspect of the present invention, there is provided a stage cementing method using the above-described stage cementing apparatus, comprising the steps of: lowering an opening tool into the stage cementing device to engage with the opening seat, and carrying out primary pressure holding to shear the second shearing pin, so that the opening seat moves downstream to open the liquid inlet hole; the expansion liquid enters the liquid containing cavity through the inner cavity of the body, the liquid inlet hole and the flow channel, so that the rubber cylinder is expanded; carrying out secondary pressure building to shear the first shearing pin, leading the opening sleeve to move downstream to open the circulation hole, and simultaneously cutting off the communication between the liquid inlet hole and the flow channel; and lowering the closure tool into engagement with the closure seat, and performing three hold downs to shear the third shear pin, causing the closure sleeve to move downstream to again close the circulation hole.

In one embodiment, the expansion liquid reacts with the accelerator in the liquid containing cavity, so that the rubber cylinder is promoted to expand secondarily.

According to the stage cementing device, the packer is not influenced by the pressure in the pipe, and the liquid injection channel can be opened only by running an opening tool, so that the mistaken opening operation caused by the pressure in the pipe is avoided. Secondly, after the liquid injection channel is opened, displacement liquid enters a liquid containing cavity of the rubber barrel, and primary expansion of the packer is achieved to seal the annular space. Therefore, after the circulation hole is opened, the annular space is sealed due to the primary expansion seal of the packer, so that the liquid column pressure is reduced, the leakage of primary cement slurry is reduced, the leakage of cement during secondary cementing is prevented, and the cementing quality is improved. Thirdly, the accelerator arranged in the packer can chemically react with the displacement fluid to realize solidification in a preset time and is integrated with the rubber sleeve. Therefore, the volume of the rubber sleeve is not shrunk but slightly expanded after being cured, and secondary expansion of the packer is realized. Therefore, the rubber sleeve can be prevented from being aged and damaged to enable liquid to flow out, and finally the packer can be prevented from failing. And fourthly, the rubber sleeve of the packer is prepared from rubber which expands when encountering hydrocarbon, and can continue to expand (i.e. expand for three times) when encountering hydrocarbon media such as gas or oil in a reservoir layer on the basis of the previous expansion, so that the tiny gap is filled, and the long-term sealing capability of the packer is further improved.

Drawings

The invention will be explained in more detail below with reference to the drawings and by means of exemplary embodiments which are schematic. In the figure:

FIG. 1 shows the overall structure of a stage cementing installation according to one embodiment of the present invention, wherein the installation is in an initial state;

FIG. 2 is an enlarged partial view of the device of FIG. 1 showing the position of the opening seat and opening sleeve;

FIG. 3 shows a stage cementing apparatus according to the present invention, wherein the glue cartridge is in an expanded state, but the circulation holes are still closed;

FIG. 4 shows a stage cementing apparatus according to the present invention, wherein the glue cartridge is in an expanded state and the circulation holes have been opened;

FIG. 5 is a partial schematic view of a stage cementing apparatus according to the present invention, showing the circulation holes again in a closed state;

FIG. 6 shows an opening tool according to one embodiment of the present invention; and

fig. 7 shows a closing tool according to an embodiment of the invention.

In the drawings, like parts are provided with like reference numerals. The figures are not drawn to scale.

Detailed Description

The invention will be further described with reference to the accompanying drawings. In the following, directional terms "lower," "downstream," "downward," etc. refer to a direction away from the wellhead, while "upper," "upstream," "upward," etc. refer to a direction toward the wellhead.

Fig. 1 shows a schematic construction of a stage cementing installation according to the present invention. In this particular embodiment, the stage cementing apparatus is an expansion pack stage cementing apparatus 10.

As shown in fig. 1, the expansion packing stage cementing apparatus 10 comprises a hollow cylindrical body 100. The body 100 includes an inner cavity 110 formed therein, a circulation hole 120 penetrating through a wall of the body, and a liquid inlet hole 130 (see fig. 2) communicating with the inner cavity 110 but not penetrating through the wall of the body. An upper fitting 140 is attached to the upstream end of the body 100 for connection to other components of the bushing. The liquid inlet hole 130 is disposed downstream of the circulation hole 120. The circulation hole 120 is a circulation hole for secondary cementing, the function of which is well known in the art and will not be described in detail herein. The function of the liquid inlet hole 130 will be described in detail below.

In accordance with the present invention, an opening assembly 300 is provided within the cylindrical body 100 of the expansion pack cementing apparatus 10, which includes an opening sleeve 310 disposed within the body 100, and an opening seat 320 disposed within the opening sleeve 310. Wherein the opening sleeve 310 is coupled with the body 100 by the first shear pin 180 and covers the circulation hole 120 in an initial state as shown in fig. 1. As shown in fig. 2, the opening seat 320 is connected to the opening housing 310 by the second shear pin 182 and covers the inlet hole 130. In the embodiment shown in fig. 1 and 2, the first shear pin 180 is disposed downstream of the circulation hole 120, but upstream of the second shear pin 182. Wherein the shear stress of the first shear pin 180 is set to be greater than the shear stress of the second shear pin 182, i.e. the second shear pin 182 will shear before the first shear pin 180.

In this document, the term "initial state" is also referred to as "first state", i.e. the state after primary cementing and before secondary cementing. Figures 1 to 3 all show the stage cementing apparatus 10 in an initial state.

Additionally, according to an embodiment of the present invention, the opening assembly 300 may further include a socket 330. As shown more clearly in fig. 2, the socket 330 is secured, such as by threads, within the opening sleeve 310, preferably at the downstream end of the opening sleeve 310. The receptacle 330 is for receiving the opening seat 320 moved downward, i.e., defining a stroke of the downward movement of the opening seat 320. This downward movement of the opening seat 320 will be described in detail below.

As shown in fig. 1, the inflatable packer stage cementing apparatus 100 further comprises a packer 200 disposed downstream of the cylindrical body 100 in accordance with the present invention. The packer 200 includes a packing valve body 210 that is fixedly coupled to the downstream end of the body 100, such as by threaded engagement. The isolation valve body 210 is, for example, a cylindrical structure, and a step 215 is provided on an inner wall thereof. Packer 200 further includes a base pipe 250, for example, fixedly connected to the downstream end of packing valve body 210, and a packing element 220 disposed outside base pipe 250. In the illustrated embodiment, the upstream end of the base pipe 250 extends into the interior cavity of the isolation valve body 210 and is threadably connected to the downstream end of the isolation valve body 210. A lower joint 270 is provided at the downstream end of the cartridge 220. The lower sub 270, together with a short sleeve 272 secured thereto, is used to connect subsequent tools.

As shown in fig. 2, the packing valve body 210 includes a flow passage 230 extending axially therein that communicates with the inlet port 130 in the body 100 (specific communication details are not shown in the cross-section of fig. 2). The flow passage 230 extends axially through the isolation valve body 210. In addition, as shown in fig. 1, the cartridge 220 includes a liquid containing chamber 240 communicating with the flow passage 230. The liquid-containing chamber 240 may also be formed to extend axially within the glue cartridge 230. In an alternative embodiment, fluid chamber 240 may be formed by a gap between base pipe 250 and gel cartridge 230. In addition, two support sleeves 260 spaced apart from each other are provided outside the rubber cylinder 230. Wherein the upstream first support sleeve 260 is connected to the packing valve body 210 and the downstream second support sleeve 260 is connected to the lower coupling 270. The two support sleeves 260 may serve to limit the axial position at which the rubber cartridge 220 expands. That is, the portion of the rubber sleeve 220 between the two support sleeves 260 can be expanded outward.

The liquid containing chamber 240 in the rubber cylinder 230 is filled with an accelerator. The accelerator is a liquid that can be uniformly mixed with an expansion liquid (which is, for example, a part of a displacement liquid, preferably a liquid epoxy resin) and cured, thereby achieving secondary expansion of the cartridge 220, which will be described in detail below. The person skilled in the art will be able to easily select the type of accelerator depending on the specific swelling liquid used. In addition, by adding a necessary component to the accelerator, the time for the accelerator to react with the expansion liquid can be controlled, that is, the accelerator and the expansion liquid are allowed to react at a predetermined time, and the secondary expansion of the rubber tube can be achieved at a predetermined time.

According to one embodiment of the present invention, the rubber sleeve 220 is made of hydrocarbon-absorbing expandable rubber, which can be expanded continuously when encountering hydrocarbon, and can meet the performance requirements of primary and secondary expansion seals.

Further, as shown in fig. 1, a closing sleeve 450 is further provided in the body 100 at an upstream of the opening sleeve 310. In the initial state, the closing sleeve 450 directly abuts the opening sleeve 310 and is connected to the body 100 by the third shear pin 184. A closing seat 460 is provided at the upper end of the closing sleeve 450. In a preferred embodiment, as shown in fig. 5, a snap spring 462 is provided on an outer wall of the closing sleeve 450, and a snap spring groove 118 capable of being engaged with the snap spring 462 is provided on an inner wall of the body 100. The specific function of the closure sleeve 450 and closure seat 460, as well as the circlip 462 and the circlip slot 118, will be described below.

As shown in fig. 1 and 2, in an initial state, the opening sleeve 310 of the opening assembly 300 is connected to the body 100 by the first shear pin 180 and covers the circulation hole 120. Meanwhile, the opening seat 320 of the opening assembly 300 is connected to the opening housing 310 by the second shear pin 182 and covers the fluid inlet hole 130. At this time, the inner cavity 110 of the body 100 is not communicated with the flow passage 230 in the packing valve body 210 of the packer 200. Thus, the displacement fluid entering the inner cavity 110 of the body 100 during the first stage cementing process cannot enter the flow channel 230 in the packing valve body 210 of the packer 200, so that the displacement fluid is physically isolated from the accelerator in the fluid containing cavity 240.

As shown in fig. 3, when an opening tool 400 as shown in fig. 6 is inputted into the expansion packing type stage cementing apparatus 100 according to the present invention, the opening tool 400 is engaged with the opening seat 320 during the downward movement, thereby blocking the inner cavity 110 of the body 100. By performing a hold down (which is referred to herein as a "primary hold down") in the body 100, the second shear pin 182 shears off. In this case, the opening tool 400 moves downward together with the opening seat 320 until the opening seat 320 abuts on the socket 330. At this time, the liquid inlet hole 130 is no longer blocked by the opening seat 320 due to the downward movement of the opening seat 320, thereby communicating with the inner cavity 110. Thus, the displacement fluid in the inner cavity 110 can enter the fluid containing cavity 240 in the rubber cylinder 220 through the fluid inlet hole 130 and the fluid passage 230 in the packing valve body 210. Under the hydraulic pressure of the expansion fluid, the rubber sleeve 220 expands (i.e., first expands) to engage the borehole wall, separating the annulus into upper and lower portions.

Thereafter, the hold-down (which is referred to herein as "secondary hold-down") continues in the body 100, causing the first shear pin 180 to shear. In this case, the opening sleeve 310 can move downward relative to the body 100 until it abuts on the step 215 of the packing valve body 210, as shown in fig. 4. At this time, the circulation hole 120 is exposed, and the liquid inlet hole 130 is blocked again by the opening sleeve 310 moved downward, thereby cutting off its communication with the inner chamber 110 again. In this case, a secondary cementing operation may be performed.

In the process of secondary circulation and well cementation, the expansion fluid and the accelerator are uniformly mixed and are solidified with the rubber cylinder 220 into a whole. In this case, the secondary expansion of the rubber cartridge 220 can be achieved. At this point, a shut-off tool 410 as shown in FIG. 7 may be run in and replaced with slurry. As shown in fig. 5, when the closing tool 410 is dropped onto the closing seat 460 and forms a seal, the upper portion of the closing seat 460 forms a closed cavity. At this point, a hold pressure (referred to herein as "three hold pressures") is performed in the body 100, causing the third shear pin 184 to shear. In this way, the closure sleeve 450 descends relative to the body 110 and closes the circulation hole 120 again. In this position, the snap spring 462 provided on the outer wall of the closing sleeve 450 enters the snap spring groove 118 provided on the inner wall of the body 100. The reverse movement of the closing sleeve 450 can be prevented by the engagement of the circlip 462 and the circlip groove 118, thereby achieving permanent closing of the circulation hole 120.

After the second-stage cementing, if hydrocarbon media such as oil, gas and the like enter the annulus in the production process, the rubber sleeve 220 made of the hydrocarbon-absorbing expansion rubber can absorb the hydrocarbon media from the well and continue to expand (i.e. expand for three times), so that a tiny gap is filled, oil, gas and water are prevented from channeling upwards, and the problem of annulus pressure is avoided.

As described above, according to the stage cementing apparatus 100 of the present invention, the packer 200 is not affected by the pressure in the pipe. The opening tool 400 must be lowered to open the filling channel, thereby preventing erroneous opening operation due to the pressure in the tube. Secondly, after the injection channel is opened, the displacement fluid enters the fluid containing cavity 240 of the rubber barrel 220, and the primary expansion sealing of the packer is realized through the hydraulic pressure of the expansion fluid to seal off the annulus. Thus, after the circulation hole 120 is opened, the liquid column pressure is reduced, thereby reducing the leakage of the primary cement slurry, preventing the leakage of the secondary cement and improving the well cementation quality. Third, the accelerator built into the packer 200 chemically reacts with the displacement fluid, achieves curing in a short time, and is integrated with the packing element 220. Thus, after curing, the volume of the packing element 220 does not shrink but slightly expands, enabling secondary expansion of the packer 200. Thus, the cement sleeve 220 is prevented from aging and damaging, thereby allowing fluid to flow out, which ultimately results in failure of the packer 200. Fourthly, the rubber sleeve 220 of the packer 200 is made of rubber which swells when encountering hydrocarbon, and on the basis of the previous expansion, the rubber sleeve can continue to swell (i.e. expand for three times) when encountering hydrocarbon media such as gas or oil in a reservoir, so as to fill up a tiny gap and further improve the long-term sealing capability of the packer.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the features mentioned in the embodiments can be combined in any way, without structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.