CN216240484U

CN216240484U - Erodible underground centralizer

Info

Publication number: CN216240484U
Application number: CN202121943042.0U
Authority: CN
Inventors: 黄建生; 卢云霄; 范玉斌; 张学政; 孙毅然; 杨钊; 李文杰
Original assignee: Sinopec Oilfield Service Corp; Sinopec Shengli Petroleum Engineering Corp; Downhole Operation Co Sinopec of Shengli Petroleum Engineering Corp
Current assignee: Sinopec Oilfield Service Corp; Sinopec Shengli Petroleum Engineering Corp; Downhole Operation Co Sinopec of Shengli Petroleum Engineering Corp
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2022-04-08
Anticipated expiration: 2031-08-18

Abstract

The utility model discloses an erodible underground centralizer, which is provided with an upper joint and a central pipe, wherein the upper joint is connected with the central pipe, a fixing sleeve and a pressing ring are sequentially fixed outside the central pipe from top to bottom, and a soluble metal centralizing body is clamped between the fixing sleeve and the pressing ring. The downhole tool is suitable for various downhole tubular columns and downhole tools of oil-gas-water wells, and is used for righting the downhole tools and the downhole tubular columns. The soluble metal centralizing body used in the utility model is processed by a soluble metal material and is fixed by a fixing sleeve and a pressing ring. The soluble metal centralizer dissolves and disappears under the action of temperature, medium and time, and the diameter of the centralizer is restored to be the same as that of a pipe column or a downhole tool connected with the centralizer. The drilling tool can not be jammed due to the fact that the centralizer is large in size, the underground pipe column can be smoothly pulled out, the construction period is obviously shortened, and production cost is reduced.

Description

Erodible underground centralizer

Technical Field

The utility model relates to a centralizer for oil, gas and water well underground pipe columns and underground tools in the petroleum industry, in particular to an erodible underground centralizer.

Background

The centralizer is a common downhole tool in oil, gas and water wells in the petroleum industry, and can be put into a tubular column and a tool string which are put into the well according to different operation requirements in the production and operation of the oil, gas and water wells so as to realize specific process requirements. The downhole centralizer is usually made of steel and is machined by metal, the diameter of the downhole centralizer is much larger than that of a production pipe column, and the downhole centralizer plays a role in centralizing a downhole pipe column or a tool connected in the downhole pipe column so that the downhole pipe column and the downhole tool are positioned in the center of a shaft.

The traditional centralizer mainly has two structural forms:

one is to weld a plurality of righting pieces in the circumferential direction of the central tube to realize righting of the tubular column;

the other method is to directly mill the large-diameter material to form a plurality of centralizing devices so as to realize the centralizing of the underground pipe column or the underground tool.

The centralizer of two kinds of structures is from going into the well to being played out to ground, and its diameter can not change, has following problem in the use:

(1) the traditional underground centralizer is characterized in that a centralizing block is directly welded on an oil pipe short section body, so that the traditional underground centralizer is high in processing difficulty, high in welding cost and free of unified standards, and does not meet the construction requirements of on-site standardized well entry;

(2) in the process of underground operation or production, under the influence of underground complex factors such as sand production or scaling of oil, gas and water wells, the annular space is blocked or the inner diameter of the casing pipe is reduced due to sand production, casing pipe scaling or other reasons, and the situation that the centralizer is blocked when the centralizer is lifted out of a downhole pipe column can be caused. When the pipe string needs to be lifted out of the well, the centralizing body connected in the pipe string is often buried, so that the pipe string cannot be normally lifted out. The light person can get out of the pipe column by moving the pipe column to be unlocked, and the heavy person needs to get out of the pipe column by adopting the modes of sleeve milling, grinding milling and the like.

(3) In the above situation, in order to lift the pipe string out of the well, a working pipe string with a milling tool needs to be put in first, and the buried centralizer is milled; because the centralizers connected in the underground pipe column and the underground tool are usually made of metal materials, the centralizers are high in welding hardness and difficult to mill, so that a plurality of difficulties are caused to normal pipe column pulling-out operation and fishing construction, and the extra operation cost is greatly increased while the construction period is influenced.

Currently, there are many centralizers for downhole strings and tools, but they are made of metal, such as the following:

CN201721659422.5 discloses a downhole tool centralizer, including centralizer body, holding ring, electronic equipment, right the bush, right the body, clearance district, recess, fixed rotating shaft and runner, the internally mounted of long section casing one end has the holding ring, electronic equipment is installed to one side of first spring shim, the drilling fluid runner hole has been seted up to the inboard of fourth spacing ring, the mid-mounting of long section casing has the bush of righting, the body of righting has been cup jointed in the outside of bush of righting, it is provided with clearance district to right the bush and right between the body, the both ends of lining of righting all are seted up flutedly, the runner is installed through fixed rotating shaft in the inside of recess, have the reducing wear, protect data acquisition equipment's function, improve life, can carry out autogyration and reciprocate simultaneously, are applicable to more circumstances, convenient to use.

However, if the above-mentioned patent technologies are affected by complex factors such as sand production or scaling of oil, gas and water wells, when the underground pipe string needs to be pulled out, the centralizer is buried, the pipe string cannot be normally pulled out, and milling is still needed. The problem that the underground pipe column cannot be pulled out due to the fact that the centralizing body is clamped cannot be solved.

The utility model discloses a centralizer in pit belongs to the oilfield equipment field. This downhole centralizer includes: rigidity body, buffering support, lubricating oil box have on the rigidity body and right the chamber, and seted up the dashpot on the outer wall of rigidity body. The buffer support is positioned outside the rigid body and can radially extend and retract along the buffer groove. The lubricating oil box is located on the outer side wall of the upper end of the rigid body, the lubricating oil box is provided with an elastic switch capable of radially stretching, when the elastic switch is compressed by a well wall, the lubricating oil box is opened, and when the elastic switch resets, the lubricating oil box is closed. Utilize the rigidity body to right the operation, guarantee the work rigidity, elasticity when utilizing the buffering to support and provide the reply friction, the weakening friction utilizes the lubricating oil box to lubricate simultaneously, further weakening friction to under the prerequisite of guaranteeing to right the operation and go on smoothly, reduce the wearing and tearing of working string and centralizer in the pit, improve its life-span.

Above-mentioned utility model guarantees under the smooth prerequisite of going on of rightting operation, has reduced the wearing and tearing of working string and centralizer in the pit, improves its life. However, if the pipe string is influenced by complex factors such as sand production or scaling of oil, gas and water wells, the centralizing body is buried when the pipe string needs to be pulled out of the well, the pipe string cannot be normally pulled out, and milling is still needed. The problem that the underground pipe column cannot be pulled out due to the fact that the centralizing body is clamped cannot be solved.

To reduce the cost of operations and shorten construction periods, there is still a need for improvements in centralizers for downhole strings and tools.

Disclosure of Invention

The utility model aims to provide an erodible underground centralizer, which overcomes the defect that the existing underground centralizer is difficult to mill, drill and remove after being stuck, and enables a centralizer body in the centralizer to be dissolved and disappear automatically in a natural state in a well. The milling, drilling and removing processes after the centralizer is blocked are avoided, and the production cost is reduced.

The technical solution of the utility model is as follows:

implementation mode one

An erodable downhole centralizer provided with an upper joint and a central pipe, the upper joint being connected with the central pipe, wherein: the fixed sleeve and the compression ring are sequentially fixed outside the central tube from top to bottom; the soluble metal centralizing body is clamped between the fixing sleeve and the compression ring.

Preferably, the fixing sleeve is a cylindrical body, the central hole is provided with an internal thread, and the internal thread of the fixing sleeve can be in threaded connection with the central pipe; the cylinder wall at the lower end of the fixing sleeve is a wedge-shaped cylinder wall which inclines downwards, and the degree of the downward inclination of the wedge-shaped cylinder wall is set to be 35-55 degrees.

Preferably, the compression ring is a cylindrical body, an internal thread is arranged in a central hole, and the internal thread of the compression ring can be connected with the central pipe; the upper end cylinder wall of the compression ring is an upward inclined wedge-shaped cylinder wall, and the upward inclination degree of the wedge-shaped cylinder wall is set to be 35-55 degrees.

Preferably, the soluble metal centralizing body clamped between the fixed sleeve and the compression ring is a cylindrical body which can be sleeved outside the central tube; the upper end face and the lower end face of the cylinder wall of the soluble metal righting body are respectively provided with a groove-shaped structure which is matched with the wedge-shaped cylinder walls of the fixing sleeve and the pressing ring, and chamfers are also arranged in the upper end face and the lower end face.

Preferably, a fixing screw is further connected between the fixing sleeve and the central tube, and between the pressing ring and the central tube.

Second embodiment

An erodable downhole centralizer provided with an upper joint and a central pipe, the upper joint being connected with the central pipe, wherein: the fixed sleeve and the compression ring are sequentially fixed outside the central tube from top to bottom; the soluble metal centralizing body is clamped in a centralizing body clamping groove between the fixing sleeve and the compression ring. Preferably, the excircle of the lower part of the fixed sleeve is smaller than the excircle of the upper part, the excircle of the upper part is provided with an internal thread to be connected with the central pipe, and the excircle of the lower part is provided with an external thread to be connected with the clamp ring; the middle part of the cylinder body of the fixed sleeve is provided with righting body clamping grooves, and the number of the righting body clamping grooves is consistent with that of the soluble metal righting bodies; the groove wall at the upper end of the righting body clamping groove in the middle barrel of the fixed sleeve is a downward-inclined wedge-shaped groove wall, and the downward inclination degree of the wedge-shaped groove wall is set to be between 35 and 55 degrees.

Preferably, the longitudinal section of the compression ring is U-shaped, the inner wall of the upper body is provided with an internal thread, and the internal thread can be connected with an external thread at the lower part of the fixing sleeve; a centering body clamping groove with the same number as that of the fixed sleeve is machined in the upper body of the compression ring; the groove wall at the upper end of the righting body clamping groove in the pressing ring is an upward inclined wedge-shaped groove wall, and the upward inclined degree of the wedge-shaped groove wall is set between 35 degrees and 55 degrees.

Preferably, the upper end face and the lower end face of the soluble metal centralizing body clamped in the clamping grooves of the centralizing bodies of the fixing sleeve and the compression ring are respectively provided with a groove-shaped structure which is consistent with the wedge-shaped groove walls of the clamping grooves of the centralizing bodies of the fixing sleeve and the compression ring.

Preferably, the soluble metal centralizing body is a block-shaped body, groove-shaped structures which are matched with the wedge-shaped groove walls of the fixing sleeve and the compression ring are arranged in the upper end surface and the lower end surface of the soluble metal centralizing body, and chamfers are also arranged in the upper end surface and the lower end surface; and fixing screws are arranged between the fixing sleeve and the central pipe, and the fixing screws arranged in the fixing sleeve and the pressing ring are arranged in a staggered manner.

Compared with the existing steel structure centralizer, the centralizer has the remarkable using effects that:

the utility model is suitable for various underground pipe columns and underground tools of oil-gas-water wells, and is used for righting the underground tools and the underground pipe columns.

The soluble metal centralizing body used in the utility model is processed by a soluble metal material and is fixed by a fixing sleeve and a pressing ring. In normal construction operation, the soluble metal righting body has a righting effect on a downhole tool or a pipe column; after construction, the soluble metal centralizer dissolves and disappears under the action of temperature, medium and time, and the diameter of the centralizer is restored to be the same as that of a pipe column or a downhole tool connected with the centralizer. In the process of lifting the pipe column in subsequent construction operation, the drill pipe clamping accident caused by the large size of the centralizer can be avoided, the underground pipe column can be smoothly lifted out, the underground accident caused by the drill pipe clamping of the centralizer and the operation cost caused by solving the underground accident caused by the drill pipe clamping of the centralizer are avoided, the construction period is obviously shortened, and the production cost is reduced.

The soluble metal centralizers in the utility model have two embodiments, and the soluble metal centralizers in each embodiment can be processed and manufactured by configuring different soluble metal material formulas according to the working time and temperature of the downhole tubular column in the well.

The two implementation structures of the utility model have fewer parts, all the parts can be processed in a standardized way, and the utility model has simple structure and convenient processing.

In conclusion, the utility model has obvious use effect, can generate better economic benefit and social benefit and has good application value.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the principles of the utility model and not to limit the utility model. In the drawings:

fig. 1 is a schematic structural view of a first embodiment of the present invention.

FIG. 2 is a schematic structural view of a second embodiment of the present invention.

Fig. 3 is a schematic view of the pouch of fig. 2.

In the figure: the device comprises an upper joint 1, a fixing sleeve 2, a soluble metal centralizing body 3, a compression ring 4, a fixing screw 5 and a central pipe 6.

Detailed Description

The drawings are for reference and illustration purposes only and are not intended to limit the scope of the present disclosure. The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the utility model, and not restrictive of the full scope of the utility model. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.

In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships illustrated in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention. Further, in the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The utility model has the following two embodiments:

implementation mode one

Referring to fig. 1, an erodable downhole centralizer is provided with an upper joint 1 and a central pipe 6, the upper joint 1 being connected to the central pipe 6, wherein: the fixed sleeve 2 and the compression ring 4 are fixed outside the central tube 6 from top to bottom in sequence;

the soluble metal centralizing body 3 is clamped between the fixed sleeve 2 and the pressing ring 4.

The soluble metal centralizing body 3 is made of soluble metal materials, and the soluble metal centralizing body 3 can be prepared by different soluble metal material formula configurations according to the working time and temperature of the pipe column in the well. The defect that the existing steel structure underground centralizer is difficult to mill, drill and remove after being blocked is overcome, the soluble metal centralizing body 3 in the centralizer can be dissolved and disappear automatically in the natural state in the well, the milling, drilling and removing process after the centralizer is blocked is avoided, the construction period is shortened, and the operation cost is reduced.

On the basis of the above-described examples, the present embodiment also has the following examples:

a preferred embodiment: the fixing sleeve 2 is a cylindrical body, an internal thread is arranged in a central hole, and the internal thread of the fixing sleeve 2 can be in threaded connection with the central pipe 6; the cylinder wall at the lower end of the fixed sleeve 2 is a wedge-shaped cylinder wall which inclines downwards, and the degree of the downward inclination of the wedge-shaped cylinder wall is set between 35 degrees and 55 degrees.

A preferred embodiment: the compression ring 4 is a cylindrical body, an internal thread is arranged in a central hole, and the internal thread of the compression ring 4 can be connected with the central pipe 6; the upper end cylinder wall of the compression ring 4 is an upward inclined wedge-shaped cylinder wall, and the upward inclined degree of the wedge-shaped cylinder wall is set to be 35-55 degrees.

A preferred embodiment: the soluble metal centralizing body 3 clamped between the fixed sleeve 2 and the compression ring 4 is a cylindrical body which can be sleeved outside the central tube 6; the upper end face and the lower end face of the cylinder wall of the soluble metal righting body 3 are both provided with groove-shaped structures which are matched with the wedge-shaped cylinder walls of the fixed sleeve 2 and the pressing ring 4, and chamfers are also arranged in the upper end face and the lower end face. The soluble metal centralizing body 3 in the embodiment is a cylindrical body and is clamped between the fixed sleeve 2 fixed outside the central tube 6 and the compression ring 4. The soluble metal centralizing body 3 of the cylindrical body, the fixing sleeve 2 and the compression ring 4 are easy to manufacture and process and convenient to assemble, and the manufacturing cost of the soluble metal centralizing body 3 of the cylindrical body is slightly higher than that of the block body.

A preferred embodiment: and a fixing screw 5 is also connected between the fixing sleeve 2, the compression ring 4 and the central pipe 6, so that the connection strength between the fixing sleeve 2, the compression ring 4 and the central pipe 6 can be further enhanced.

Embodiment two of the present invention:

referring to fig. 2 and 3, an erodable downhole centralizer is provided with an upper sub 1 and a central pipe 6, the upper sub 1 being connected to the central pipe 6, wherein: the fixed sleeve 2 and the compression ring 4 are fixed outside the central tube 6 from top to bottom in sequence;

the soluble metal centralizing body 3 is clamped in a centralizing body clamping groove between the fixed sleeve 2 and the compression ring 4.

The soluble metal centralizing body 3 in the embodiment is made of soluble metal materials, and the soluble metal centralizing body 3 can be prepared by different soluble metal material formula configurations according to the working time and temperature of the pipe column in the well. The defect that the existing steel structure underground centralizer is difficult to mill, drill and remove after being blocked is overcome, the soluble metal centralizing body 3 in the centralizer can be dissolved and disappear automatically in the natural state in the well, the milling, drilling and removing process after the centralizer is blocked is avoided, the construction period is shortened, and the operation cost is reduced. The soluble metal centralizing body 3 in the embodiment is a block-shaped body, a centralizing body clamping groove is also processed between the fixing sleeve 2 and the pressing ring 4, the manufacturing cost of the soluble metal centralizing body 3 is low, but the processing of the fixing sleeve 2 and the pressing ring 4 in the first embodiment is complex.

a preferred embodiment: the lower excircle of the fixed sleeve 2 is smaller than the upper excircle, the upper excircle is provided with an internal thread to be connected with the central tube 6, and the lower excircle is provided with an external thread to be connected with the clamp ring 4; the middle part of the cylinder body of the fixed sleeve 2 is provided with righting body clamping grooves, and the number of the righting body clamping grooves is consistent with that of the soluble metal righting bodies 3; the upper end groove wall of the centralizing body clamping groove in the middle barrel of the fixed sleeve 2 is a downward inclined wedge-shaped groove wall, and the downward inclination degree of the wedge-shaped groove wall is set between 35 degrees and 55 degrees.

A preferred embodiment: the longitudinal section of the compression ring 4 is U-shaped, the inner wall of the upper body is provided with internal threads, and the internal threads can be connected with external threads at the lower part of the fixed sleeve 2; the upper body of the compression ring 4 is provided with righting body slots with the same number as the fixed sleeve 2; the groove wall at the upper end of the righting body clamping groove in the compression ring 4 is an upward inclined wedge-shaped groove wall, and the upward inclined degree of the wedge-shaped groove wall is set between 35 degrees and 55 degrees.

A preferred embodiment: the upper end surface and the lower end surface of the soluble metal centralizing body 3 clamped in the centralizing body clamping grooves of the fixed sleeve 2 and the compression ring 4 are respectively provided with a groove-shaped structure which is matched with the wedge-shaped groove walls of the centralizing body clamping grooves of the fixed sleeve 2 and the compression ring 4.

A preferred embodiment: the soluble metal centralizing body 3 is a block-shaped body, groove-shaped structures which are matched with the wedge-shaped groove walls of the fixed sleeve 2 and the compression ring 4 are arranged in the upper end surface and the lower end surface of the block-shaped body of the soluble metal centralizing body 3, and chamfers are also arranged in the upper end surface and the lower end surface; and fixing screws 5 are respectively arranged between the fixing sleeve 2 and the central pipe 6 and between the pressing ring 4 and the central pipe 6, and the fixing sleeve 2 and the fixing screws 5 arranged in the pressing ring 4 are installed in a staggered manner. The fixing screw 5 arranged in the fixing sleeve 2 is arranged in the upper body of the fixing sleeve 2 between the righting body clamping grooves; set screw 5 of installation in clamp ring 4 sets up in the body of clamp ring 4 of righting body draw-in groove below, the fixed cover 2 is installed with the dislocation of set screw 5 of installation in clamp ring 4, further strengthens the joint strength between fixed cover 2 and clamp ring 4 and center tube 6.

The working principle and the using method of the utility model are as follows:

connecting the erodible underground centralizer to a required position in an underground pipe column according to the design requirement of an underground construction process, and putting the erodible underground centralizer into a well along with the underground pipe column;

after the pipe column at the well is put into the well, various constructions such as fracturing, sand prevention or other constructions can be normally carried out, and the soluble metal righting body 3 in the centralizer plays a righting role in the construction process;

after the construction is finished, under the combined action of time, medium in the well, temperature and the like, closing the well according to the dissolving time of the formula in the soluble metal centralizing body 3 and waiting for dissolving;

after the soluble metal centralizer 3 is corroded, the diameter of the centralizer can be matched with that of the underground pipe column, the underground pipe column can be smoothly lifted out, and the pipe column can not be jammed due to the fact that the size of the centralizer in the well is large.

The embodiments described above are merely exemplary embodiments, but the present invention is not limited to these embodiments, and those skilled in the art can make modifications without departing from the spirit and teaching of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof. Any modification, equivalent replacement, improvement and the like made within the spirit and inventive concept of the present invention should be included in the protection scope of the present invention. The scope of protection is therefore not limited to the description above.

Claims

1. The utility model provides an erosion-soluble underground centralizer, is equipped with top connection and center tube, and the top connection is connected characterized by with the center tube: the fixed sleeve and the compression ring are sequentially fixed outside the central tube from top to bottom; the soluble metal centralizing body is clamped between the fixing sleeve and the compression ring.

2. An erodable downhole centralizer according to claim 1, wherein the retaining sleeve is cylindrical and the central bore is provided with internal threads, the internal threads of the retaining sleeve being threadably connectable to the central tube; the cylinder wall at the lower end of the fixing sleeve is a wedge-shaped cylinder wall which inclines downwards, and the degree of the downward inclination of the wedge-shaped cylinder wall is set to be 35-55 degrees.

3. An erodable downhole centralizer according to claim 1 wherein the clamp ring is cylindrical and the central bore is internally threaded, the internal threads of the clamp ring being connectable to the base pipe; the upper end cylinder wall of the compression ring is an upward inclined wedge-shaped cylinder wall, and the upward inclination degree of the wedge-shaped cylinder wall is set to be 35-55 degrees.

4. An erodible downhole centralizer according to claim 2 or 3 wherein the soluble metal centralizer captured between the retaining sleeve and the compression ring is a cylinder that can be fitted over the central tube; the upper end face and the lower end face of the cylinder wall of the soluble metal righting body are respectively provided with a groove-shaped structure which is matched with the wedge-shaped cylinder walls of the fixing sleeve and the pressing ring, and chamfers are also arranged in the upper end face and the lower end face.

5. An erodable downhole centralizer according to claim 4 wherein a set screw is connected between the retaining sleeve and the clamp ring and the base pipe.

6. The utility model provides an erosion-soluble underground centralizer, is equipped with top connection and center tube, and the top connection is connected characterized by with the center tube: the fixed sleeve and the compression ring are sequentially fixed outside the central tube from top to bottom; the soluble metal centralizing body is clamped in a centralizing body clamping groove between the fixing sleeve and the compression ring.

7. An erodable downhole centralizer according to claim 6, wherein the outer circle of the lower part of the fixing sleeve is smaller than the outer circle of the upper part, the outer circle of the upper part is provided with internal threads to be connected with the central pipe, and the outer circle of the lower part is provided with external threads to be connected with the compression ring; the middle part of the cylinder body of the fixed sleeve is provided with righting body clamping grooves, and the number of the righting body clamping grooves is consistent with that of the soluble metal righting bodies; the groove wall at the upper end of the righting body clamping groove in the middle barrel of the fixed sleeve is a downward-inclined wedge-shaped groove wall, and the downward inclination degree of the wedge-shaped groove wall is set to be between 35 and 55 degrees.

8. An erodable downhole centralizer according to claim 7, wherein the longitudinal section of the compression ring is U-shaped and the inner wall of the upper body is provided with internal threads which can be connected with external threads on the lower part of the fixing sleeve; a centering body clamping groove with the same number as that of the fixed sleeve is machined in the upper body of the compression ring; the groove wall at the upper end of the righting body clamping groove in the pressing ring is an upward inclined wedge-shaped groove wall, and the upward inclined degree of the wedge-shaped groove wall is set between 35 degrees and 55 degrees.

9. An erodible downhole centralizer according to claim 7 or 8 wherein the upper and lower faces of the soluble metal centralizers retained in the retaining sleeve and the retaining ring centralizer slots are each provided with a grooved formation conforming to the wedge-shaped groove walls of the retaining sleeve and the retaining ring centralizer slots.

10. An erodible downhole centralizer according to claim 9 wherein the soluble metal centralizer is a block, the block of soluble metal centralizer having grooved features in both its upper and lower faces that conform to the wedge-shaped walls of the retaining sleeve and the hold-down ring and chamfers in both the upper and lower faces; and fixing screws are arranged between the fixing sleeve and the central pipe, and the fixing screws arranged in the fixing sleeve and the pressing ring are arranged in a staggered manner.