Operating method for righting tubular column and righting tool

Abstract

The invention relates to an operation method for centralizing a tubular column and a centralizing tool, and the operation method for centralizing the tubular column comprises the following steps: S1, determining the number and the material of centralizing rings; wherein the centralizing ring comprises a central ring and a plurality of centralizing blocks which are circumferentially arranged on the outer wall of the central ring at intervals; s2, a plurality of centralizing rings are arranged on the central pipe in a sleeving mode, and a distance ring is installed between every two adjacent centralizing rings so that a centralizing tool can be assembled; s3, connecting a plurality of centralizing tools in the centralizing pipe column in series, and descending the centralizing tools into the well along with the centralizing pipe column; and after the centralizing pipe column descends to a preset position, the centralizing ring is gradually expanded and enlarged, and the central ring is expanded in the circumferential direction and pushes the centralizing blocks outwards, so that the centralizing ring is set on a corresponding well wall or a corresponding pipe wall outside the centralizing pipe column. According to the self-expansion type self-centering packer, centering of a pipe column can be achieved before setting, self-expansion type automatic adjusting and centering are adopted, the adaptability is wider, the centering height can be automatically adjusted, and it can be guaranteed that the setting effect is better.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy oil thermal recovery well completion or hot dry rock well completion, and particularly relates to an operation method for straightening a pipe string and a straightening tool. Background Technique

[0002] Hot dry rock (HDR) geothermal resources are a highly competitive clean and renewable energy source with great resource potential, safety, and environmental friendliness, and are increasingly attracting attention in the energy strategy. During the well completion process of hot dry rock, if the wellbore dogleg severity is relatively large, a pipe string centralizer needs to be lowered. However, conventional centralizers cannot change the centralizing height and cannot perform self-centering adaptively according to the wellbore size, so it is necessary to develop a high-temperature and high-pressure resistant centralizing tool to achieve the pipe string centralizing function under downhole high-temperature and high-pressure conditions.

[0003] In a certain area, there are more than 1300 horizontal wells in the oilfield, more than 80% of which are heavy oil thermal recovery horizontal wells, and most of them use screen completions, and general steam injection is mostly used during steam injection. Due to the lack of effective isolation between the wellbore, the formation and the annulus between the screens, and the heterogeneity of the reservoir in the plane and vertical directions, the phenomenon of uneven utilization is widespread. Analysis of production data and liquid production profile data shows that more than 85% of the horizontal wells have uneven utilization in 1 / 3 to 1 / 2 of the horizontal section, and the steam fingering phenomenon seriously affects the production capacity advantage of the horizontal wells. Therefore, research and development have been carried out for different geological and well conditions, forming key tools such as external packers and steam umbrellas and different uniform steam injection process technologies, effectively improving the utilization degree of the horizontal section of heavy oil horizontal wells. The horizontal well staged steam injection process technology includes in-pipe staged steam injection process technology and staged completion staged steam injection process technology. The in-pipe staged steam injection string generally consists of a vacuum heat insulation pipe + tubing + steam umbrella + steam injection valve. The number, position, and aperture of the steam injection valves are determined according to geological, fluid parameters, and the length of the horizontal section, and the position and number of the steam umbrellas are determined according to the requirements of the number of stages to achieve in-pipe staging and improve the implementation effect of staged steam injection. However, this steam injection string lacks a centralizer, which often leads to unsatisfactory steam injection effects, slow expansion speed of the production layer temperature after steam injection, and affects the later production. It is necessary to add a centralizing tool to this steam injection string to achieve centralizing steam injection for the steam injection string.

[0004] However, a common type of centralizer in the prior art is a mechanical centralizer composed of a spring and a centralizing block. When this centralizer works, since the centralizing block will always press against the wellbore under the action of the spring force, it can only be applied to wells with a smooth wellbore and no gaps or faults. When applied to wells with a non-smooth wellbore and gaps or faults, problems such as jamming are likely to occur, affecting the smooth lowering of the pipe string. Moreover, this type of centralizer cannot be applied to environments with high temperature and high pressure resistance. If the material of this centralizer is selected as a high-temperature and high-pressure-resistant material, the entire structure of the centralizer needs to be redesigned. Therefore, this type of centralizer cannot be used for centralizing the completion pipe string of high-temperature and high-pressure wells such as dry hot rocks, nor can it be used for centralizing the steam injection pipe string of heavy oil.

[0005] Another common type of centralizer in the prior art is a soluble centralizer, which includes a soluble centralizer body made of soluble magnesium alloy. The soluble magnesium alloy of this centralizer can react with the water in the wellbore to generate magnesium hydroxide and hydrogen, and dissolve within a certain period of time. However, this type of centralizer can only be used in environments with not too high temperature and a smooth wellbore. It is prone to failure in environments with relatively high temperature, and problems such as jamming are likely to occur when used in wells with a non-smooth wellbore and gaps or faults. Currently, this type of centralizer is only used for centralizing the casing, and cannot be used for centralizing the steam injection pipe string of heavy oil or the downhole pipe string of high-temperature and high-pressure dry hot rocks. Therefore, its application range is relatively small, and it is difficult to meet the high-temperature and high-pressure technical requirements of downhole heavy oil steam injection and dry hot rock completion. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for operating a centralizing pipe string and a centralizing tool, which can centralize the pipe string before setting, and adopt self-expanding automatic adjustment for centralizing, with a wider adaptability, can automatically adjust the centralizing height, and can ensure a better setting effect.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a method for operating a centralizing pipe string, including the following steps: S1. Determine the number and material of the centralizing rings; wherein, the centralizing rings include a central ring and a plurality of centralizing blocks circumferentially spaced on the outer wall of the central ring; S2. Sleeve a plurality of centralizing rings on the central pipe, and install spacer rings between adjacent two centralizing rings to assemble into a centralizing tool; S3. String a plurality of centralizing tools in the centralizing pipe string and lower them into the well together with the centralizing pipe string; after the centralizing pipe string is lowered to a preset position, the centralizing rings gradually expand and become larger, the central ring expands circumferentially and pushes each centralizing block outwards, so that the centralizing rings are set on the corresponding wellbore or corresponding pipe wall outside the centralizing pipe string.

[0009] In a preferred embodiment of the present invention, the centralizing string is a steam injection string applied to a heavy oil well, and step S3 includes: connecting a plurality of centralizing tools in series in the steam injection string and lowering them into the completion string together with the steam injection string; during the process of lowering the steam injection string, as the downhole temperature continuously increases, the centralizing ring gradually expands and becomes larger when heated; after the steam injection string is lowered to a preset position, high-temperature steam is injected into the steam injection string, and the centralizing ring continues to expand and become larger when heated, so that the centralizing ring is set on the wall of the completion string.

[0010] In a preferred embodiment of the present invention, in step S1, the number of centralizing rings is determined according to the well section to be centralized, and the material of the centralizing ring is determined according to the temperature, pressure and steam injection volume of the steam injection; the centralizing ring includes fluorine, silicon, sodium and polyethylene, and the mass ratio is (5-7):(1-3):(1-2):(0.5-1.5).

[0011] In a preferred embodiment of the present invention, after step S3, it further includes: soaking the well for a preset time. During the process of injecting high-temperature steam into the steam injection string and soaking the well, the centralizing ring gradually dissolves under the action of high-temperature steam; after the soaking of the well ends, the self-dissolution of the centralizing ring ends, the centralizing tool is released; and the steam injection string is pulled out.

[0012] In a preferred embodiment of the present invention, the centralizing string is a completion string applied to a high-temperature and high-pressure well, and step S3 includes: connecting a plurality of centralizing tools in series in the completion string and lowering them into the open-hole well together with the completion string; during the process of lowering the completion string, the centralizing ring continuously absorbs water in the open-hole well and gradually expands and becomes larger; after the completion string is lowered to a preset position, the centralizing ring continues to absorb water and expand and become larger in the open-hole well, so that the centralizing ring is set on the wall of the open-hole well.

[0013] In a preferred embodiment of the present invention, in step S1, the number of centralizing rings is determined according to the centralized position calculated based on the well diameter after completion, and the material of the centralizing ring is determined according to the temperature and pressure of the high-temperature and high-pressure well; the centralizing ring includes oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent and cross-linking agent, and the mass ratio is 12:(4-3):(30-52):(20-32):(4-8).

[0014] In a preferred embodiment of the present invention, after step S3, it further includes: the centralizing ring is permanently hardened in the open-hole well.

[0015] The present invention also provides a centralizing tool, which includes a central pipe and two retaining rings sleeved on the central pipe. A plurality of centralizing rings are sleeved on the central pipe and located between the two retaining rings, and a spacer ring is clamped between adjacent two centralizing rings; the centralizing ring includes a central ring and a plurality of centralizing blocks circumferentially spaced on the outer wall of the central ring; the centralizing tool is configured to be able to be connected in series in the steam injection string applied to heavy oil wells and can gradually expand and become larger when heated to seal on the completion string, and can also gradually dissolve under the action of water vapor; or the centralizing tool is configured to be able to be connected in series in the completion string applied to high-temperature and high-pressure wells and can gradually expand and become larger by absorbing water to seal on the well wall.

[0016] In a preferred embodiment of the present invention, the centralizing ring includes fluorine, silicon, sodium and polyethylene, and the mass ratio is (5-7):(1-3):(1-2):(0.5-1.5); or the centralizing ring includes an oil-absorbing resin, rubber, a water-absorbing resin, a reinforcing agent and a cross-linking agent, and the mass ratio is 12:(4-3):(30-52):(20-32):(4-8).

[0017] In a preferred embodiment of the present invention, the longitudinal section of the centralizing block along the axial direction of the centralizing ring is an isosceles trapezoid; the outer wall of each retaining ring far from the centralizing ring is a conical surface with the outer diameter gradually decreasing in the direction away from the centralizing ring.

[0018] In a preferred embodiment of the present invention, two connectors are respectively connected to both ends of the central pipe, and the two retaining rings can be axially limited between the two connectors; the interval length between the two connectors is greater than the total axial length of the two retaining rings, a plurality of centralizing rings and a plurality of spacer rings.

[0019] As described above, in the operation method of the present invention, by connecting the centralizing tool in series in the centralizing string, after the centralizing string is lowered to the preset position, the centralizing ring that can gradually expand and become larger is used. The central ring expands circumferentially and pushes each centralizing block outwards. Each centralizing block first supports and clings to the corresponding well wall or pipe wall. During the continuous expansion of the centralizing ring, each centralizing block can realize the adaptive adjustment and centralization of the pipe string, and thus can seal more tightly when the entire centralizing ring is sealed. Since during the process of lowering the pipe string, the centralizing ring expands slowly and its outer diameter is still smaller than the inner diameter of the corresponding well wall or pipe wall, it will not cause damage to the centralizing ring and can play a good protective role for the centralizing ring. Since the entire centralizing ring is an expanding type for centralization, it can automatically adjust the centralizing height according to the inner diameter size of the external well wall or pipe wall, and has stronger adaptability. The entire operation method is simple in operation, good in centralizing and sealing effects, and has broad application prospects.

[0020] The centralizing tool of the present invention has a simple structure. By providing a centralizing ring that can gradually expand, and designing the centralizing ring in the form of a central ring and multiple centralizing blocks, when heated or absorbing water, the central ring expands circumferentially and pushes each centralizing block outwards. Each centralizing block first supports and clings to the corresponding wellbore wall or pipe wall. During the continuous expansion of the centralizing ring, each centralizing block can achieve adaptive adjustment and centralization of the pipe string. Furthermore, when the entire centralizing ring is set, it can achieve a tighter seal. The entire centralizing ring is an expanding type, which can automatically adjust the centralizing height according to the inner diameter of the external wellbore wall or pipe wall, with stronger adaptability. It can be applied to centralize the steam injection pipe string in heavy oil wells, etc., and can also centralize the completion pipe string in high-temperature and high-pressure wells such as dry hot rocks. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following drawings are only intended to illustrate and explain the present invention schematically and do not limit the scope of the present invention.

[0022] Among them:

[0023] Figure 1 : is a flowchart of the operation method when the centralizing pipe string provided by the present invention is applied to the steam injection pipe string in a heavy oil well.

[0024] Figure 2 : is a flowchart of the operation method when the centralizing pipe string provided by the present invention is applied to the completion pipe string in a high-temperature and high-pressure well.

[0025] Figure 3 : is a schematic diagram of the centralizing tool provided by the present invention.

[0026] Figure 4 : is a schematic diagram of the central pipe provided by the present invention.

[0027] Figure 5 : is a schematic diagram of the retaining ring provided by the present invention.

[0028] Figure 6 : is a schematic diagram of the centralizing ring provided by the present invention Figure 1 .

[0029] Figure 7 : is a schematic diagram of the centralizing ring provided by the present invention Figure 2 .

[0030] Description of the reference numerals in the drawings:

[0031] 1, central pipe; 2, retaining ring; 3, centralizing ring; 31, central ring; 32, centralizing block; 4, spacer ring; 5, joint. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention are now described with reference to the drawings.

[0033] Embodiment 1

[0034] As Figures 1 to 7 shown, the present application provides an operation method for straightening a pipe string, including the following steps:

[0035] S1. Determine the quantity and material of the centralizer rings 3; wherein, the centralizer ring 3 includes a central ring 31 and a plurality of centralizer blocks 32 circumferentially spaced on the outer wall of the central ring 31;

[0036] S2. Sleeve a plurality of centralizer rings 3 on the central pipe 1, and install spacer rings 4 between two adjacent centralizer rings 3 to assemble a centralizing tool;

[0037] S3. String a plurality of centralizing tools in the straightening pipe string and lower them into the well together with the straightening pipe string; after the straightening pipe string is lowered to a preset position, the centralizer ring 3 gradually expands and becomes larger, the central ring 31 expands circumferentially and pushes each centralizer block 32 outwards, so that the centralizer ring 3 is set on the corresponding well wall or pipe wall outside the straightening pipe string.

[0038] Thus, in the operation method of the present application, by stringing centralizing tools in the straightening pipe string, after the straightening pipe string is lowered to a preset position, using the centralizer ring 3 that can gradually expand and become larger, through the circumferential expansion of the central ring 31 and pushing each centralizer block 32 outwards, each centralizer block 32 first supports and clings to the corresponding well wall or pipe wall. During the continuous expansion of the centralizer ring 3, each centralizer block 32 can realize the adaptive adjustment and straightening of the pipe string, and then can be more tightly sealed when the entire centralizer ring 3 is set. Since during the process of lowering the pipe string, the centralizer ring 3 expands slowly, and its outer diameter is still smaller than the inner diameter of the corresponding well wall or pipe wall, it will not cause damage to the centralizer ring 3, and can play a good protective role for the centralizer ring 3. Since the entire centralizer ring 3 is an expandable type for straightening, it can automatically adjust the straightening height according to the inner diameter size of the external well wall or pipe wall, and has stronger adaptability. The entire operation method is simple in operation, good in straightening and setting effects, and has broad application prospects.

[0039] In a specific implementation manner, the above operation method is more applicable to the case where the straightening pipe string is a high-temperature and high-pressure pipe string, which can make the centralizer ring 3 expand and set better. Especially for the soluble centralizer ring that can expand by heat, it is easier to expand and self-dissolve in a high-temperature environment. Correspondingly, the centralizer ring 3 should be made of a material resistant to high temperature and high pressure, and the materials of the centralizer block 32 and the central ring 31 are the same, and the two can be integrally formed.

[0040] The above high-temperature and high-pressure pipe string can be a steam injection pipe string applied to a heavy oil well, or a completion pipe string applied to a high-temperature and high-pressure well, specifically as follows:

[0041] (1) The straightening pipe string is a steam injection pipe string applied to a heavy oil well

[0042] In this case, step S3 specifically includes the following steps:

[0043] Connect multiple centralizing tools in series in the steam injection string and lower them into the completion string together with the steam injection string.

[0044] During the process of lowering the steam injection string, as the downhole temperature continuously increases, the centralizing ring 3 gradually expands and becomes larger when heated.

[0045] After the steam injection string is lowered to the preset position, inject high-temperature steam into the steam injection string. The centralizing ring 3 continues to expand and become larger when heated, so that the centralizing ring 3 is set on the wall of the completion string.

[0046] It can be understood that due to the temperature gradient in the downhole, the deeper the downhole, the higher the temperature. As the temperature rises, the centralizing ring 3 will gradually expand when heated. And before the steam injection string reaches the preset position, the expansion of the centralizing ring 3 is slow, and its outer diameter is always smaller than the inner diameter of the completion string; when the steam injection string reaches the preset position, the centralizing ring 3 continues to expand under the action of the injected steam and sticks to the wall of the completion string to play a centralizing role, and then is set on the completion string. Due to the large setting force, each centralizing block 32 will be compressed and extruded during setting, and the entire central ring 31 extrudes the centralizing block 32 outward to closely fit on the wall of the completion string to achieve setting, and the sealing performance is good.

[0047] Further, in step S1, the number of centralizing rings 3 is determined according to the well section to be centralized, and the material of the centralizing ring 3 is determined according to the temperature, pressure and steam injection volume of the steam injection.

[0048] In this embodiment, the centralizing ring 3 is made of a composite rubber material that is resistant to high temperature and high pressure. It can not only expand when heated, but also dissolve under the action of water vapor. Specifically, it includes fluorine, silicon, sodium and polyethylene, and the mass ratio is (5 - 7):(1 - 3):(1 - 2):(0.5 - 1.5). The specific ratio of each component in the centralizing ring 3 is determined according to the expansion speed and dissolution speed of the required centralizing ring 3. For example, in this embodiment, the mass ratio of fluorine, silicon, sodium and polyethylene is 6:2:1:1.

[0049] Further, after step S3, it also includes:

[0050] Soak the well for a preset time. During the process of injecting high-temperature steam into the steam injection string and soaking the well, the centralizing ring 3 gradually dissolves under the action of high-temperature water vapor.

[0051] After the well soaking ends, the self-dissolution of the centralizing ring 3 ends, and the centralizing tool is released.

[0052] Pull out the steam injection string.

[0053] It can be understood that the dissolution of the entire righting ring 3 has a certain period. After the high-temperature steam is injected, the righting ring 3 will gradually begin to dissolve with the high-temperature steam, but the slow dissolution will not affect the setting. After a certain period of dissolution, it will slowly dissolve to the wall of the completion string. The specific dissolution time of the righting ring 3 depends on its components and the ratio of the components. It can be formulated according to actual needs to ensure that after the steam injection is completed and the well is finished, the righting ring 3 can be dissolved to the wall of the well to achieve smooth unsealing.

[0054] For more details, in a specific embodiment, refer to Figure 1 , when applied to the steam injection string of heavy oil wells, the specific operation method is as follows:

[0055] Determine the number of righting rings 3 according to the well section that needs to be righted; in this embodiment, the number of righting rings 3 is three, and the number of righting blocks 32 in each righting ring 3 is six;

[0056] The material of the righting ring 3 is selected according to the temperature, pressure and gas injection volume of the steam injection; in this embodiment, the material of the righting ring 3 includes fluorine, silicon, sodium and polyethylene in a mass ratio of 6:2:1:1;

[0057] Assemble the straightening tool, and lower it along with the steam injection pipe string; before lowering the tool, the entire wellbore needs to be cleared to prevent sharp objects from scratching the straightening ring 3.

[0058] Install the steam injection wellhead, connect the steam injection pipeline, start injecting high-temperature steam after the annulus is insulated with nitrogen, and the straightening ring 3 slowly expands to achieve straightening inside the pipe, and finally achieves sealing inside the pipe;

[0059] After steam injection, the well should be kept warm for about 20 days;

[0060] After the well is soaked, the straightening tool will dissolve and unseal itself;

[0061] The steam injection pipe column is lifted and the construction is completed;

[0062] Lower the oil pump, start pumping oil, and calculate the recovery rate.

[0063] When applying the above operation method to the steam injection string of a heavy oil well, it solves the problems such as the lack of an effective high-temperature and high-pressure centralizer tool during heavy oil steam injection, the non-centralization of the steam injection string, poor steam injection effect, and low later recovery rate. By designing a high-temperature and high-pressure centralizer tool and an operation method for centralizing the string, it can ensure that the steam injection string is in a centralized state during steam injection, achieve balanced steam injection, and improve the final recovery rate of heavy oil; it solves the problem that during heavy oil steam injection, it is easy for the steam injection string to be lowered, but the sealing is not tight, and after steam injection, the steam injection string cannot be retrieved. By designing a soluble centralizing ring 3, during steam injection, the material of the centralizing ring 3 reacts with water vapor, continuously reducing its diameter until the centralizing ring 3 detaches from the completion string after steam injection, which can ensure that the steam injection string will not be stuck and can be retrieved smoothly, preventing safety accidents.

[0064] (2) The centralizing string is a completion string applied to high-temperature and high-pressure wells

[0065] In this case, step S3 specifically includes the following steps:

[0066] Connect multiple centralizer tools in series in the completion string and lower them into the open-hole well together with the completion string;

[0067] During the process of lowering the completion string, the centralizing ring 3 continuously absorbs water in the open-hole well and gradually expands;

[0068] After the completion string is lowered to the preset position, the centralizing ring 3 continues to absorb water in the open-hole well and expands further, so that the centralizing ring 3 is set on the wellbore wall of the open-hole well.

[0069] Here, the high-temperature and high-pressure well can be a heavy oil well or a geothermal well such as a hot dry rock; here, the completion string can be a screen completion string applied to a heavy oil well, or a casing completion string or a screen completion string applied to a geothermal well.

[0070] There is water in the high-temperature and high-pressure well. After the completion string is lowered into the well, it will continuously absorb water and expand in volume. However, before the completion string reaches the preset position, the expansion of the centralizing ring 3 is slow, and its outer diameter is always smaller than the inner diameter of the open-hole well; when the completion string reaches the preset position, the centralizing ring 3 continues to absorb water and gradually expands until it adheres to the wellbore wall of the open-hole well to play a centralizing role, and then it is set. The setting force is relatively large, and the sealing effect after the centralizing ring 3 is set is good.

[0071] Furthermore, in step S1, the number of centralizing rings 3 is determined according to the centralizing position calculated based on the well diameter after completion, and the material of the centralizing ring 3 is determined according to the temperature and pressure of the high-temperature and high-pressure well.

[0072] In this embodiment, the centralizer 3 is made of a water-swellable material resistant to high temperature and high pressure, which can absorb water and swell, and will not dissolve but automatically harden permanently. Specifically, it includes oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent and cross-linking agent, and the mass ratio is 12:(4 - 3):(30 - 52):(20 - 32):(4 - 8).

[0073] In practical applications, the components of the centralizer 3 also include other additives. The other additives include surfactants, antioxidants and / or plasticizers, etc. Among them, by mass fraction, the other additives are 3 - 12 parts, that is, the mass ratio of oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent, cross-linking agent and other additives is 12:(4 - 3):(30 - 52):(20 - 32):(4 - 8):(3 - 12); among them, the surfactant is 0.2 - 0.5 parts, the antioxidant is 0 - 0.05 parts, and the plasticizer is 0 - 0.03 parts.

[0074] Specifically, the proportion of each component in the centralizer 3 is determined according to the expansion rate and hardening rate of the required centralizer 3. For example, in this embodiment, the mass ratio of oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent, cross-linking agent, surfactant, antioxidant and plasticizer is 12:3:31:25:15:0.3:0.02:0.01.

[0075] Furthermore, after step S3, it also includes:

[0076] The centralizer 3 hardens permanently in the open hole well.

[0077] Since the completion string ultimately needs to remain in the well, therefore, the centralizer 3 will ultimately harden permanently and remain in the well after absorbing water for a certain time. It can be understood that when the completion string is a casing completion string, after the centralizer 3 is set, it is necessary to first inject cement slurry into the annulus between the casing completion string and the open hole well for cementing, and the centralizer 3 will permanently harden after the cementing is completed; when the completion string is a screen completion string, after the centralizer 3 is set, as time goes by, the centralizer 3 will permanently harden.

[0078] In addition, when the completion string is a screen completion string applied to a heavy oil well, after the centralizer 3 permanently hardens, steam can be injected into the screen completion string for production; when the completion string is a casing completion string or a screen completion string applied to a geothermal well, after the centralizer 3 permanently hardens, a pump is lowered into the completion string to start pumping water for production.

[0079] More specifically, in a specific embodiment, referring to Figure 2 , when applied to the completion string of a high-temperature and high-pressure well, the specific operation method is as follows:

[0080] After completion, judge the size of the wellbore diameter according to the logging data;

[0081] Calculate the straightening position and determine the number of groups of the centralizer 3; in this embodiment, the number of centralizers 3 is three, and the number of centralizing blocks 32 in each centralizer 3 is six;

[0082] Select the material of the centralizer 3 according to the temperature, pressure, etc. of the application well; in this embodiment, the material of the centralizer 3 includes an oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent, cross-linking agent, surfactant, antioxidant and plasticizer with a mass ratio of 12:3:31:25:15:0.3:0.02:0.01;

[0083] Assemble the centralizing tool, and the centralizing tool is lowered together with the completion string; among them, before the tool is lowered, it is also necessary to circulate the wall protection mud repeatedly for many times to keep the wellbore smooth and free of collapse, which is convenient for the smooth lowering of the completion string.

[0084] Under high-temperature and high-pressure working conditions, the centralizer 3 slowly absorbs water and expands to achieve straightening, and finally realizes external pipe setting;

[0085] The completion string is cemented, or the screen completion is carried out;

[0086] As time goes by, the centralizer 3 hardens permanently;

[0087] The heavy oil well starts to produce, or the geothermal well starts to produce.

[0088] When applying the above operation method to the completion string of a high-temperature and high-pressure well, the centralizing tool is lowered together with the completion string. After being lowered, there is no need for manual intervention. The centralizing tool will automatically absorb water and undergo self-expansion and self-hardening processes according to the well diameter, and finally realize the permanent centralization and straightening of the completion string. It solves the technical problems that are prone to occur when completing the well string in high-temperature and high-pressure wells such as dry hot rocks and heavy oils, such as large changes in wellbore size, non-centralization of the well string, and difficulty in realizing self-variable diameter of conventional centralizers. By replacing the material of the centralizer 3, a centralizer 3 that can self-expand and self-adjust according to temperature and wellbore diameter is designed, realizing the straightening of the completion string under irregular high-temperature conditions.

[0089] Embodiment 2

[0090] Refer to Figures 3 to 7 This application also provides a centralizing tool, including a central pipe 1 and two retaining rings 2 sleeved on the central pipe 1. A plurality of centralizers 3 are sleeved on the central pipe 1 and located between the two retaining rings 2, and a spacer ring 4 is clamped between adjacent two centralizers 3; the centralizer 3 includes a central ring 31 and a plurality of centralizing blocks 32 circumferentially spaced on the outer wall of the central ring 31; the centralizing tool is configured to be able to be connected in series in the steam injection string applied to a heavy oil well and can gradually expand and become larger by heating to set on the completion string, and can also gradually dissolve under the action of water vapor; or the centralizing tool is configured to be able to be connected in series in the completion string applied to a high-temperature and high-pressure well and can absorb water and gradually expand and become larger to set on the well wall.

[0091] Among them, the function of the central pipe 1 is to provide support for the centralizer 3, spacer ring 4 and retaining ring 2. The main function of the retaining ring 2 is to block the centralizer 3 and play a limiting role. The centralizer 3 is made of a material resistant to high temperature and high pressure. The centralizer 3 is the core component of the whole tool. Relying on multiple centralizing blocks 32 protruding outward circumferentially on the centralizer 3, the centralizing of the pipe string can be realized. In order to enhance the centralizing effect, a multi-stage combined centralizing design is adopted. The centralizer 3 is designed as multiple ones and can be increased according to specific conditions such as the bottom-hole temperature, pressure, wellbore diameter, etc., so as to achieve a sufficient centralizing effect. The function of the spacer ring 4 is to separate different centralizers 3 from each other.

[0092] When this centralizing tool is applied to a heavy oil well to centralize the steam injection pipe string, the centralizer 3 should adopt a soluble centralizer that can dissolve. Before steam injection, the centralizing tool is lowered together with the steam injection pipe string. Since the steam injection pipe string is inside the completion pipe string (such as casing), after the steam injection pipe string is lowered to the preset position, the expansion of the soluble centralizer will centralize inside the completion pipe string. It is supported on the inner wall of the completion pipe string through the protruding centralizing blocks 32 to make the steam injection pipe string centered; at the same time, since the protruding centralizing blocks 32 protrude on the basis of the central ring 31 (the central ring 31 and the centralizing blocks 32 can be integrally formed), therefore, under high-temperature conditions, the annular central ring 31 can expand circumferentially when heated, providing an expansion thrust. This thrust can push the protruding centralizing blocks 32 to tightly adhere to the inner wall of the completion pipe string, and finally the entire centralizer 3 is seated on the inner wall of the completion pipe string to prevent the pipe string from sliding during the steam injection process and losing its fixing function.

[0093] During the steam injection and soaking process, due to the action of high-temperature steam, the protruding centralizing blocks 32 will slowly shrink and dissolve, and at the same time, the central ring 31 will also slowly dissolve, and the tight adhesion force to the pipe string will slowly become smaller and gradually separate from the inner wall of the completion pipe string. By the end of the soaking, the soluble centralizer has completely separated from the inner wall of the completion pipe string, and at the same time, the remaining undissolved soluble centralizer will spontaneously contract due to the temperature drop, which also fully ensures that the soluble centralizer 3 can completely separate from the completion pipe string and be smoothly retrieved.

[0094] When this centralizing tool is applied to high-temperature and high-pressure wells such as hot dry rock or heavy oil wells to centralize the completion pipe string, since when centralizing the casing completion pipe string or screen completion pipe string in a high-temperature and high-pressure well, the main function of the centralizer 3 is to centralize the pipe string, a material that is easy to expand needs to be used to achieve centralization outside the pipe. When in use, when this centralizing tool is part of the completion pipe string, the centralizer 3 can absorb water and expand until it expands to a state of tightly adhering to the wellbore wall to complete the tool centralization. At this time, the centralizing requirements of the wellbore wall with different wellbore diameters can be met.

[0095] The centralizing tool in the operation method of the first embodiment above specifically adopts the centralizing tool in the second embodiment. The specific operation method of the centralizing tool in the second embodiment applied to the steam injection string or the completion string has been described in detail in the first embodiment above and will not be elaborated here.

[0096] Therefore, the centralizing tool of the present application has a simple structure. By setting a centralizing ring 3 that can gradually expand, and designing the centralizing ring 3 in the form of a central ring 31 and a plurality of centralizing blocks 32, when heated or absorbing water, the central ring 3 expands circumferentially and pushes each centralizing block 32 outwards. Each centralizing block 32 first supports and clings to the corresponding wellbore wall or pipe wall. During the continuous expansion of the centralizing ring 3, each centralizing block 32 can achieve adaptive adjustment and centralization of the pipe string, and thus can achieve a tighter seal when the entire centralizing ring 3 is set. The entire centralizing ring 3 is an expandable type for centralization, which can automatically adjust the centralizing height according to the inner diameter size of the external wellbore wall or pipe wall, with stronger adaptability. It can be applied to the centralization of steam injection strings such as heavy oil, and also to the centralization of completion strings in high-temperature and high-pressure wells such as hot dry rock.

[0097] In practical applications, the material of the centralizing ring 3 is selected according to the actual formation conditions and working conditions of the application. When the centralizing tool is applied to the steam injection string of a heavy oil well, the centralizing ring 3 includes fluorine, silicon, sodium, and polyethylene, and the mass ratio is (5 - 7):(1 - 3):(1 - 2):(0.5 - 1.5). It can not only withstand high temperature and high pressure, but also expand when heated, and can self-dissolve under the action of high-temperature steam.

[0098] When the centralizing tool is applied to the completion string of a high-temperature and high-pressure well, the centralizing ring 3 includes oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent, and cross-linking agent, and the mass ratio is 12:(4 - 3):(30 - 52):(20 - 32):(4 - 8). It can not only withstand high temperature and high pressure, but also absorb water and expand, and can permanently harden over time.

[0099] Furthermore, generally, the longitudinal section of the centralizing block 32 along the axial direction of the centralizing ring 3 is an isosceles trapezoid to achieve better centralization and facilitate ensuring a better setting effect. The outer wall of each retaining ring 2 away from the centralizing ring 3 is a conical surface with an outer diameter gradually decreasing in the direction away from the centralizing ring 3 to play a guiding role.

[0100] Refer to Figure 3 At both ends of the central pipe 1, two connectors 5 are respectively connected. The two retaining rings 2 can be axially limited between the two connectors 5. The main function of the connector 5 is to connect downhole steam injection strings such as steam injection packers and steam injection valves, or to connect casing or screen pipes during high-temperature and high-pressure well completion, playing a role of connecting the upper and the lower.

[0101] Preferably, the spacing length between the two joints 5 is greater than the total axial length of the two retaining rings 2, the plurality of straightening rings 3 and the plurality of spacer rings 4. In this way, the position of the whole formed by the retaining ring 2, the straightening ring 3 and the spacer ring 4 on the central pipe 1 can be fine-tuned between the two joints 5, which can assist in adjusting the position of the straightening ring 3, making the operation more convenient, especially when applied to horizontal wells.

[0102] The straightening tool of the present embodiment, when applied to the steam injection string of a heavy oil well, can realize that the steam injection string is in a centered state during the steam injection process, can realize balanced steam injection, and improve the final recovery rate of the heavy oil, solving the problems of lack of an effective high-temperature and high-pressure straightening tool during heavy oil steam injection, the steam injection string is not centered, the steam injection effect is poor, and the later recovery rate is low. By designing a soluble straightening ring, during the heavy oil steam injection process, under the action of high-temperature steam, the straightening ring 3 is heated and expanded to continuously increase its diameter, and is closely attached to the inner wall of the completion string. , and then set on the completion string to ensure a good steam injection effect; in the well-simmering stage after steam injection, the material of the straightening ring 3 reacts with water vapor to self-dissolve, and the diameter is continuously reduced until the straightening ring 3 is separated from the completion string after the steam injection is completed, and the sealing is achieved. This can ensure that the steam injection string will not be stuck, and the steam injection string can be smoothly and safely pulled out to complete the steam injection construction, preventing safety accidents, and solving the problem that the steam injection string can be lowered but the seal is not tight during heavy oil steam injection, and the steam injection string cannot be pulled out after the steam injection is completed.

[0103] When applied to completion strings of high-temperature and high-pressure wells, the straightening ring 3 is designed to self-expand and self-adjust according to the temperature and borehole diameter. The straightening of the completion string under irregular high-temperature conditions is achieved through the selected material of the straightening ring 3. The water in the annulus is absorbed to self-expand, and the volume expands to achieve straightening of the completion string, and then it is sealed on the well wall and finally hardened. This solves the technical problem that the borehole size changes easily when completing the string in high-temperature and high-pressure wells such as dry hot rock and heavy oil, the string is not centered, and the conventional straightener is difficult to achieve self-diameter change.

[0104] It should be noted that in the general petroleum field, high temperature and high pressure wells refer to wells with a temperature greater than 150°C and a pressure greater than 30MPa. The high temperature and high pressure wells mentioned in this embodiment mainly refer to heavy oil wells with a temperature greater than 320°C and geothermal wells with a temperature greater than 150°C.

[0105] In summary, the operation method and centralizing tool for centralizing the pipe string in this embodiment are mostly applied to horizontal wells and are suitable for operations that require steam injection into the pipe to improve the recovery rate during the completion of heavy oil thermal recovery, or operations that require centralizing the completion pipe string under working conditions such as high-temperature and high-pressure geothermal wells. By centralizing the steam injection pipe string inside the pipe during steam injection, the steam injection effect is improved, and finally the recovery rate is increased, which has broad market application prospects. By setting a plurality of centralizing rings 3 on the central pipe 1 to achieve centralizing inside the pipe (centralizing inside the completion pipe string) or centralizing outside the pipe (centralizing in the open hole well), the centralizing height can be automatically adjusted according to the wellbore size, and the technical problems of being able to lower, lift, and seal the steam injection centralizing tool during heavy oil steam injection can be solved, which has important engineering value for heavy oil high-temperature steam injection and hot dry rock completion.

[0106] The above is only a schematic specific embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for straightening a pipe string, characterized in that: The steps include: S1. Determine the number and material of the righting rings; wherein the righting rings include a center ring and a plurality of righting blocks circumferentially spaced apart on the outer wall of the center ring; S2, sleeve a plurality of the straightening rings on the central tube, and install a spacer ring between two adjacent straightening rings to assemble a straightening tool; S3. Connect multiple straightening tools in series in the straightening string and lower them into the well together with the straightening string; after the straightening string is lowered to a preset position, the straightening ring gradually expands and becomes larger, and the center ring expands circumferentially and pushes each straightening block outward, so that the straightening ring is seated on the corresponding well wall or corresponding pipe wall outside the straightening string.

2. The method for straightening a pipe string according to claim 1, characterized in that: The uprighting string is a steam injection string used in heavy oil wells, and step S3 includes: Connecting a plurality of the straightening tools in series in the steam injection string and lowering them into the completion string together with the steam injection string; During the lowering of the steam injection pipe string, as the downhole temperature continues to increase, the straightening ring is heated and gradually expands; After the steam injection string is lowered to a preset position, high-temperature steam is injected into the steam injection string, and the righting ring continues to expand due to the heat, so that the righting ring is seated on the wall of the completion string.

3. The method for straightening a pipe string according to claim 2, characterized in that: In step S1, the number of the righting rings is determined according to the well section that needs to be righted, and the material of the righting rings is determined according to the temperature, pressure and amount of steam injection; the righting rings include fluorine, silicon, sodium and polyethylene, and the mass ratio is (5-7):(1-3):(1-2):(0.5-1.5).

4. The method for centralizing a pipe string according to claim 2, characterized in that: After step S3, the method further includes: The well is soaked for a preset time, and during the process of injecting high-temperature steam into the steam injection pipe column and soaking the well, the righting ring is gradually dissolved under the action of the high-temperature steam; After the well soaking is completed, the self-dissolution of the straightening ring is completed, and the straightening tool is unsealed; Lift out the steam injection pipe column.

5. The method for straightening a pipe string according to claim 1, characterized in that: The uprighting string is a completion string used in high temperature and high pressure wells. Step S3 includes: Connecting a plurality of the straightening tools in series in the completion string and lowering them into the open hole together with the completion string; During the running of the completion string, the straightening ring continuously absorbs water in the open hole and gradually expands; After the completion string is lowered to a preset position, the stabilizing ring absorbs water in the open hole and continues to expand, so that the stabilizing ring is seated on the well wall of the open hole.

6. The method for centralizing a pipe string according to claim 5, characterized in that: In step S1, the number of the righting rings is determined according to the righting position calculated based on the wellbore size after completion, and the material of the righting ring is determined according to the temperature and pressure of the high-temperature and high-pressure well; the righting ring includes oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent and cross-linking agent, and the mass ratio is 12:(4-3):(30-52):(20-32):(4-8).

7. The method for centralizing a pipe string according to claim 5, characterized in that: After step S3, the method further includes: The centralizing ring is permanently hardened within the open hole.

8. A straightening tool, characterized in that: It comprises a central tube and two retaining rings sleeved on the central tube, a plurality of straightening rings sleeved on the central tube and located between the two retaining rings, and a spacer ring is sandwiched between two adjacent straightening rings; The straightening ring includes a center ring and a plurality of straightening blocks circumferentially spaced on the outer wall of the center ring; the straightening tool is configured to be connected in series to a steam injection string used in a heavy oil well and to gradually expand and enlarge by heat to be seated on a completion string, and to gradually dissolve under the action of water vapor; or the straightening tool is configured to be connected in series to a completion string used in a high-temperature and high-pressure well and to gradually expand and enlarge by absorbing water to be seated on a well wall.

9. The straightening tool according to claim 8, characterized in that: The straightening ring includes fluorine, silicon, sodium and polyethylene, and the mass ratio is (5-7):(1-3):(1-2):(0.5-1.5); or the straightening ring includes oil-absorbing resin, rubber, water-absorbing resin, reinforcing agent and cross-linking agent, and the mass ratio is 12:(4-3):(30-52):(20-32):(4-8).

10. The straightening tool according to claim 8, characterized in that: The longitudinal section of the straightening block along the axial direction of the straightening ring is an isosceles trapezoid; the outer wall of each retaining ring away from the straightening ring is a conical surface whose outer diameter gradually decreases in the direction away from the straightening ring.

11. The straightening tool according to claim 8, characterized in that: Two joints are respectively connected to the two ends of the central tube, and the two retaining rings can be axially limited between the two joints; the interval length between the two joints is greater than the total axial length of the two retaining rings, multiple straightening rings and multiple spacer rings.

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