Anti-corrosion centralizer

Abstract

The invention provides an anti-corrosion centralizer, and relates to the technical field of oil exploitation machinery, the anti-corrosion centralizer is cylindrical and is provided with an axial through cavity, the anti-corrosion centralizer comprises a cylinder body and two end heads, the two end heads are respectively arranged at two ends of the cylinder body, the cylinder body is provided with a centralizing part expanding outwards in the radial direction, the end heads are annular, and the centralizing part is provided with a through hole. An accommodating cavity is formed in the side wall of the end head, the accommodating cavity is filled with an anti-corrosion agent, and a plurality of release holes communicated with the accommodating cavity are formed in the side wall surface of the end head. The anti-corrosion centralizer can effectively delay corrosion of a casing pipe and prolong the service life of a production well.

Description

Technical Field

[0001] The present invention relates to the technical field of oil extraction machinery, and particularly relates to an anti-corrosion centralizer. Background Art

[0002] Onshore oilfields have successively entered the middle and late stages of development. With the increase in water cut, casing damage in oil and gas wells has become increasingly serious. Among them, the corrosion of oil well cement and the outer wall of the casing by CO2 and H2S is one of the main forms of casing damage in oil and gas wells. With the continuous extension of the development time, the number of damaged wells has increased significantly year by year, resulting in a substantial reduction in the production capacity of the oilfield. Moreover, the effect of multiple production shut-offs after casing rupture is poor, causing the injection-production well pattern to be out of balance, the degree of water drive utilization to be low, the remaining reserves to be unable to be produced, and it is difficult to obtain dynamic monitoring data, seriously affecting the stable production and development efficiency of the oilfield.

[0003] At present, for the problem of production casing corrosion, anti-corrosion coatings on the outer wall of the casing, composite sacrificial anode materials, and combined anti-corrosion of epoxy cold-wrapped tape and zinc sacrificial anode are widely used. However, it is difficult to avoid pore defects on the surface of the anti-corrosion coating due to process or external factors. The above-mentioned pore defects can generate osmotic pressure, and the osmotic pressure further leads to the widespread presence of blisters on the anti-corrosion coating. Moreover, as the soluble salt continuously dissolves, the osmotic pressure continuously increases, a large amount of water continuously penetrates into these areas and the volume continuously expands. In areas where the coating adhesion is weak, the coating will delaminate from the substrate to form blisters. In addition, after the composite anode material is used for a long time, the anode material will become loose after being consumed. Since the centralizer is located in the wellbore, it is very difficult to maintain when it is damaged.

[0004] In view of this, based on the production design experience in this field and related fields for many years, the inventor of the present invention has designed an anti-corrosion centralizer through repeated tests in order to solve the problems existing in the prior art. Summary of the Invention

[0005] The purpose of the present invention is to provide an anti-corrosion centralizer, which can effectively delay the corrosion of the casing and extend the service life of the production well.

[0006] To achieve the above purpose, the present invention provides an anti-corrosion centralizer, wherein the anti-corrosion centralizer is in a cylindrical shape and has an axially penetrating through cavity. The anti-corrosion centralizer includes a cylindrical body and two end heads. The two end heads are respectively arranged at both ends of the cylindrical body. The cylindrical body has a centralizing part that expands radially outward. The end head is in a ring shape, and an accommodation cavity is formed in the side wall of the end head. The accommodation cavity is filled with an anti-corrosion agent, and a plurality of release holes communicating with the accommodation cavity are formed on the side wall surface of the end head.

[0007] For the anti-corrosion centralizer as described above, a temporary plugging agent is filled in the release hole. The temporary plugging agent is used to block the release hole, and the temporary plugging agent will dissolve when it comes into contact with an acidic liquid.

[0008] The anti-corrosion and centralizing device as described above, wherein a chemical addition hole communicating with the accommodation cavity is further formed on the side wall surface of the end head, and the inner diameter of the chemical addition hole is larger than that of the release hole.

[0009] The anti-corrosion and centralizing device as described above, wherein the chemical addition hole is filled with a temporary plugging agent for closing the chemical addition hole, and the temporary plugging agent will dissolve after contacting acidic liquid underground.

[0010] The anti-corrosion and centralizing device as described above, wherein the temporary plugging agent at least comprises soluble lipid compounds, metal oxides, basic salts and binders.

[0011] The anti-corrosion and centralizing device as described above, wherein the accommodation cavity is formed along the circumferential direction of the end head and is connected end to end to form a circular ring.

[0012] The anti-corrosion and centralizing device as described above, wherein a plurality of the release holes are evenly distributed along the circumferential direction of the end head.

[0013] The anti-corrosion and centralizing device as described above, wherein the anti-corrosion chemical agent is a slow-release anti-corrosion chemical agent.

[0014] The anti-corrosion and centralizing device as described above, wherein both the end head and the cylinder body are made of anti-corrosion polyester alloy materials.

[0015] The anti-corrosion and centralizing device as described above, wherein the cylinder body comprises a plurality of bow-shaped centralizing pieces, and the plurality of bow-shaped centralizing pieces are sequentially arranged at intervals along the circumferential direction of the cylinder body, and the bow-shaped centralizing pieces are arc-shaped to form the centralizing part.

[0016] Compared with the prior art, the present invention has the following characteristics and advantages:

[0017] For the anti-corrosion and centralizing device proposed by the present invention, an anti-corrosion chemical agent is pre-set in its end head. After the anti-corrosion and centralizing device is lowered into the well along with the casing, the anti-corrosion chemical agent is released and acts on the outer wall of the casing and the cement sheath, which can not only delay the corrosion of the casing, but also play a protective role on the cement sheath, improve the cementing quality and increase the service life of the oil and gas well.

[0018] The anti-corrosion and centralizing device proposed by the present invention solves the corrosion problem of the outer wall of the casing and the cement sheath, and prolongs the service life of the casing. The anti-corrosion and centralizing device is suitable for popularization and application in the horizontal section of horizontal wells and multilateral horizontal wells with strong medium corrosivity, and has a wide market application prospect. It is applicable to various downhole pipes such as tubing, casing, drill pipe, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Additionally, the shapes and proportional dimensions of the components in the figures are merely schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention. Those skilled in the art can, under the teachings of the present invention, select various possible shapes and proportional dimensions according to specific circumstances to implement the present invention.

[0020] Figure 1 Stereogram of the anti-corrosion centralizer proposed by the present invention;

[0021] Figure 2 Structural schematic diagram of the anti-corrosion centralizer proposed by the present invention;

[0022] Figure 3 Cross-sectional view of the end head in the present invention;

[0023] Figure 4 Schematic diagram of the filling of the anti-corrosion agent in the present invention.

[0024] Explanation of reference numerals in the drawings

[0025] 100, anti-corrosion centralizer; 10, cylinder body;

[0026] 11, bow-shaped centralizing piece; 20, end head;

[0027] 21, accommodating cavity; 22, release hole;

[0028] 23, chemical addition hole; 30, anti-corrosion chemical agent;

[0029] 40, temporary plugging agent; Detailed implementation manners

[0030] Combined with the accompanying drawings and the description of the specific implementation manners of the present invention, the details of the present invention can be more clearly understood. However, the specific implementation manners of the present invention described herein are only for the purpose of explaining the present invention and should not be construed as a limitation of the present invention in any way. Under the teachings of the present invention, those skilled in the art can conceive of any possible variations based on the present invention, and these should all be regarded as belonging to the scope of the present invention.

[0031] As Figures 1 to 4 shown, the present invention provides an anti-corrosion centralizer 100. The anti-corrosion centralizer 100 is cylindrical and has a through cavity that penetrates axially. The anti-corrosion centralizer 100 includes a cylinder body 10 and two end heads 20. The two end heads 20 are respectively arranged at both ends of the cylinder body 10. The cylinder body 10 has a centralizing portion that expands radially outward. The end head 20 is annular. An accommodating cavity 21 is formed in the side wall of the end head 20. The accommodating cavity 21 is filled with an anti-corrosion chemical agent 30. A plurality of release holes 22 that communicate with the accommodating cavity 21 are formed on the side wall surface of the end head 20.

[0032] The anti-corrosion centralizer 100 proposed by the present invention is pre-filled with an anti-corrosion agent 30 in its end 20. After the anti-corrosion centralizer is lowered into the well along with the casing, the anti-corrosion agent 30 is released and acts on the outer wall of the casing and the cement sheath. It can not only delay the corrosion of the casing, but also protect the cement sheath, improve the cementing quality, and increase the service life of the oil and gas well.

[0033] The anti-corrosion centralizer 100 proposed by the present invention solves the corrosion problem of the outer wall of the casing and the cement sheath, and extends the service life of the casing. The anti-corrosion centralizer 100 is suitable for popularization and application in the horizontal section of horizontal wells and multilateral horizontal wells with strong medium corrosivity, and has a wide market application prospect.

[0034] The anti-corrosion centralizer 100 proposed by the present invention has a simple structure. When in use, the anti-corrosion centralizer 100 is sleeved outside the casing, and the end 20 at its bottom will be stuck at the casing collar, so that the anti-corrosion centralizer 100 can be lowered into the well along with the casing. After being lowered into the well, the centralizing part of the cylinder body 10 contacts the inner wall of the wellbore, so that the anti-corrosion centralizer 100 can be located at the central position of the wellbore to achieve the centralizing effect.

[0035] In an optional embodiment of the present invention, the release hole 22 is filled with a temporary plugging agent 40, and the temporary plugging agent 40 is used to seal the release hole 22, and the temporary plugging agent 40 will dissolve after contacting the acidic liquid. With the above solution, the release hole 22 is sealed by the temporary plugging agent 40. When the anti-corrosion centralizer 100 is on the ground or just lowered into the well, the release hole 22 is sealed by the temporary plugging agent 40, which plays a protective role for the anti-corrosion agent 30 in the accommodation cavity 21 and avoids the failure of the anti-corrosion centralizer 100 due to transportation and storage. At the same time, during the casing running operation, the temporary plugging agent 40 can also prevent the fluid in the wellbore from invading the accommodation cavity 21 and damaging the anti-corrosion agent. After the casing equipped with the anti-corrosion centralizer 100 is cemented in the well and exploited for a long time, as the service life extends, due to formation water production, dissolution of acidic gases such as carbon dioxide and hydrogen sulfide, increase in cement humidity, and quality problems such as cracks in the cement sheath, the cement sheath fails and is damaged. Under these conditions, the pH value of the downhole liquid decreases, the temporary plugging agent 40 gradually dissolves in the acidic liquid, the release hole 22 is gradually dissolved through, and the anti-corrosion agent 30 in the accommodation cavity 21 is slowly released from the release hole 22, and the anti-corrosion agent 30 acts on the outer wall of the casing and the cement sheath, effectively delaying the corrosion of the casing and the cement sheath.

[0036] In an optional embodiment of the present invention, a chemical addition hole 23 communicating with the accommodation cavity 21 is further opened on the side wall surface of the end 20, and the inner diameter of the chemical addition hole 23 is larger than the inner diameter of the release hole 22. With the above structure, it is quick and convenient to fill the anti-corrosion agent 30 into the accommodation cavity 21 through the chemical addition hole 23.

[0037] In an alternative example of this embodiment, the chemical addition hole 23 is filled with a temporary plugging agent 40, which is used to seal the chemical addition hole 23, and the temporary plugging agent 40 will dissolve after contacting acidic liquid underground.

[0038] In an alternative embodiment of the present invention, the temporary plugging agent 40 at least includes soluble lipid compounds and binders. The soluble lipid compounds can dissolve in acidic liquid to achieve the slow dissolution of the temporary plugging agent 40.

[0039] In an alternative example of this embodiment, the temporary plugging agent 40 further includes metal oxides and basic salts to improve the plugging effect of the temporary plugging agent 40.

[0040] In an alternative embodiment of the present invention, both the release hole 22 and the chemical addition hole 23 are opened on the outer surface of the side wall of the anti-corrosion centralizer 100.

[0041] In an alternative embodiment of the present invention, the accommodating cavity 21 is opened along the circumferential direction of the end head 20 and is connected end to end to form a circular ring, thereby increasing the capacity of the accommodating cavity 21.

[0042] In an alternative example of this embodiment, a plurality of release holes 22 are evenly distributed along the circumferential direction of the end head 20. With the above structure, the anti-corrosion agent 30 is released at each position around the circumferential direction of the casing, and the anti-corrosion centralizer 100 ensures the effect of delaying the corrosion of the casing and the cement sheath.

[0043] In an alternative example, 100 release holes 22 are opened on the side wall surface of the end head 20.

[0044] In an alternative embodiment of the present invention, the anti-corrosion agent 30 is a slow-release anti-corrosion agent, which can release slowly and extend the time for the anti-corrosion centralizer 100 to have an anti-corrosion effect.

[0045] In an alternative example of this embodiment, the anti-corrosion agent 30 at least includes solid phosphonic acid corrosion inhibitors, imidazoline corrosion inhibitors and curing agents.

[0046] In an alternative example of this embodiment, the specific components and specific contents of the solid phosphonic acid corrosion inhibitors, imidazoline corrosion inhibitors and curing agents in the anti-corrosion agent 30 can be configured according to the characteristics of the on-site corrosion medium to exert the best anti-corrosion effect for a specific underground environment.

[0047] In an alternative embodiment of the present invention, both the end head 20 and the cylinder body 10 are made of anti-corrosion polyester alloy materials, which have good anti-corrosion effects and can effectively extend the service life of the anti-corrosion centralizer 100.

[0048] In an alternative example of this embodiment, the two end heads 20 and the cylinder body 10 are integrally formed.

[0049] In another alternative example of this embodiment, the two ends 20 are respectively detachably connected to the cylinder body 10.

[0050] In an alternative embodiment of the present invention, the cylinder body 10 includes a plurality of arcuate centralizer pieces 11, and the plurality of arcuate centralizer pieces 11 are sequentially arranged at intervals along the circumferential direction of the cylinder body 10. The arcuate centralizer pieces 11 are arc-shaped and form a centralizing portion. With the above structure, the middle portions of the respective arcuate centralizer pieces 11 are bent radially outward along the cylinder body 10, and the positions of the outward bends can contact the inner wall of the wellbore to achieve the centralizing effect.

[0051] Please refer to Figures 1 to 4 , and now in combination with an embodiment, the specific implementation process of the anti-corrosion centralizer 100 proposed by the present invention will be described in detail.

[0052] In this embodiment, the specific implementation process of the anti-corrosion centralizer 100 includes the following eight steps. Specifically,

[0053] The first step is to install the two ends 20 onto the cylinder body 10;

[0054] The second step is to configure the anti-corrosion agent 30 according to the reservoir geological characteristics of the well on site;

[0055] The third step is to perform a cementing design according to the conditions of the well used on site, and design the installation quantity and spacing distance of the anti-corrosion centralizer 100;

[0056] The fourth step is to install the casing string and the anti-corrosion centralizer 100 on site, and install and configure them strictly according to the cementing design;

[0057] The fifth step is to perform the cementing construction;

[0058] The sixth step is to carry out normal production;

[0059] The seventh step is that the cement sheath fails, and the respective release holes 22 on the anti-corrosion centralizer 100 are dissolved and opened;

[0060] The eighth step is that the proprietary anti-corrosion agent 30 in the accommodation cavity 21 is slowly dissolved and released into the outer wall of the casing and the cement sheath;

[0061] The ninth step is that the proprietary anti-corrosion agent 30 exerts its medicinal effect to protect the outer wall of the casing and the cement sheath.

[0062] The anti-corrosion centralizer 100 proposed in the present invention is put into the well with the casing. After long-term exploitation, as time goes by, water is produced from the formation, carbon dioxide and hydrogen sulfide acid gases are dissolved, and the moisture of cement increases, resulting in quality problems such as cracks in the cement ring, and the cement ring becomes invalid and damaged. When the corrosive medium corrodes the outer wall of the rubbing and contacts the anti-corrosion centralizer 100, the anti-corrosion agent 30 preset in the end head 20 is slowly dissolved and released. After the anti-corrosion agent 30 configured according to the characteristics of the formation and the corrosion factors penetrates out, it can effectively prevent corrosion and extend the life of the oil and gas well to the greatest extent, so as to achieve the effect of preventing corrosion of the outer wall of the casing and the cement ring.

[0063] The detailed explanation of the above-mentioned embodiments is only intended to explain the present invention so as to facilitate a better understanding of the present invention. However, these descriptions cannot be interpreted as limitations on the present invention for any reason. In particular, the various features described in different embodiments may also be arbitrarily combined with each other to form other embodiments. Unless there is a clear description to the contrary, these features should be understood to be applicable to any embodiment and are not limited to the described embodiments.

Claims

1. An anti-corrosion and body-strengthening device, characterized in that, The anti-corrosion centralizer is cylindrical and has a through cavity that runs axially through it. The anti-corrosion centralizer includes a cylindrical body and two end heads. The two end heads are respectively arranged at both ends of the cylindrical body. The cylindrical body has a centralizing part that expands radially outwards. The end heads are annular. An accommodation cavity is formed inside the side wall of the end head, and an anti-corrosion agent is filled in the accommodation cavity. A plurality of release holes that communicate with the accommodation cavity are formed on the side wall surface of the end head.

2. The anti-corrosion and body-strengthening device according to claim 1, wherein, The release holes are filled with a temporary plugging agent, which is used to block the release holes, and the temporary plugging agent will dissolve when it comes into contact with acidic liquid.

3. The anti-corrosion and body-strengthening device according to claim 1, wherein, A chemical addition hole that communicates with the accommodation cavity is also formed on the side wall surface of the end head, and the inner diameter of the chemical addition hole is larger than that of the release hole.

4. The anti-corrosion and body-strengthening device according to claim 3, wherein The chemical addition hole is filled with a temporary plugging agent, which is used to block the chemical addition hole, and the temporary plugging agent will dissolve when it comes into contact with acidic liquid underground.

5. The anti-corrosion and health-strengthening device according to claim 2 or 4, characterized in that, The temporary plugging agent at least includes soluble lipid compounds, metal oxides, basic salts, and binders.

6. The anti-corrosion and body-strengthening device according to claim 1, wherein The accommodation cavity is formed along the circumferential direction of the end head and is joined end to end to form a circular ring.

7. The anti-corrosion and body-strengthening device according to claim 6, characterized in that A plurality of the release holes are evenly distributed along the circumferential direction of the end head.

8. The anti-corrosion and body-strengthening device according to claim 1, characterized in that The anti-corrosion agent is a slow-release anti-corrosion agent.

9. The anti-corrosion and body-strengthening device according to claim 1, characterized in that, Both the end head and the cylindrical body are made of anti-corrosion polyester alloy material.

10. The anti-corrosion and body-strengthening device according to claim 1, characterized in that The cylindrical body includes a plurality of bow-shaped centralizing pieces. The plurality of bow-shaped centralizing pieces are sequentially arranged at intervals along the circumferential direction of the cylindrical body. The bow-shaped centralizing pieces are arc-shaped and form the centralizing part.

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