CN113216870A - Straight wing type resin casing centralizer and installation method thereof - Google Patents

Abstract

The invention relates to a straight-wing resin casing centralizer and an installation method thereof, wherein the straight-wing resin casing centralizer comprises a first centralizing strip, a second centralizing strip, a third centralizing strip and a fourth centralizing strip which are sequentially adhered to the outer wall of a casing from left to right at intervals, and the first centralizing strip, the second centralizing strip, the third centralizing strip and the fourth centralizing strip are arranged in a staggered mode at an included angle of 90 degrees on the circumference. The invention develops and is matched with a special casing centralizing process for reconstructing a shaft of an old shale gas well in China, a resin centralizer can be manually adhered to a 3.5 ' casing, the process requirement of re-inserting the 3.5 ' casing in a 5.5 ' casing horizontal well is met, and the special casing centralizing process has the characteristics of good adhesion stability, high centering degree, low friction resistance, good perforating bullet penetrability and the like, is simple to operate, high in accuracy, small in error, safe and reliable, and can be directly applied to field operation construction.

Description

Straight wing type resin casing centralizer and installation method thereof

Technical Field

The invention relates to the field of centering and centering of small-size casings of shale gas reconstruction shafts, in particular to a straight wing type resin casing centralizer and an installation method thereof.

Background

The existing shale gas well generally adopts a pressurization and intermittent development mode, the yield is quickly decreased, and the difficulty of increasing and stabilizing the yield of the gas field is high. The conventional shale gas well repeated fracturing generally adopts a whole-shaft temporary plugging steering process, but is influenced by factors such as serious reservoir leakage, reinforced heterogeneity, local excessive transformation and the like, and has poor effect. The reconstruction shaft repeated fracturing technology recovers the integrity of the shaft and reduces leakage through sleeve fixing in a sleeve, a bridge plug is adopted for segmenting and uniformly reconstructing a horizontal segment, the reconstruction scale is improved, accurate excavation and maximum excavation are realized, the life cycle of the shale gas well is prolonged, and the gas reservoir recovery ratio is effectively improved.

Existing casing centralizers mainly include: the spring type centralizer, the rigid centralizer and the semi-rigid centralizer are mainly supported by machinery, and are large in friction resistance and high in resistance risk in a casing running stage, and the technical requirements of high centering degree and small friction resistance coefficient of a small casing in casing-in-casing-fixing small-gap operation are not met.

Disclosure of Invention

The invention aims to provide a straight wing type resin casing centralizer with good adhesion stability, high centering degree, low friction resistance and good perforating bullet penetrability and an installation method thereof.

The technical scheme adopted by the invention for solving the technical problems is as follows: the straight-wing resin casing centralizer is characterized by comprising a first centralizing strip, a second centralizing strip, a third centralizing strip and a fourth centralizing strip which are sequentially adhered to the outer wall of a casing from left to right at intervals, wherein the first centralizing strip, the second centralizing strip, the third centralizing strip and the fourth centralizing strip are arranged in a staggered mode at an included angle of 90 degrees on the circumference.

In the above scheme, the distance between the first centralizing strip and the casing box section is 4m, the distance between the second centralizing strip and the first centralizing strip is 30cm, the distance between the third centralizing strip and the second centralizing strip is 2.6m, the distance between the fourth centralizing strip and the third centralizing strip is 30cm, and the distance between the fourth centralizing strip and the casing box section is 2.05 m.

In the scheme, the first righting strip, the second righting strip, the third righting strip and the fourth righting strip are made of resin and are of three-dimensional right trapezoidal structures, the overall thickness is 11.5mm, the lower end surface of each righting strip is arc-shaped, the length of each righting strip is 30cm, the width of each righting strip is 12cm, the upper end surface of each righting strip is arc-shaped, and the length of each righting strip is 27cm and the width of each righting strip is 10 cm.

In the above scheme, the first righting strip, the second righting strip, the third righting strip and the fourth righting strip are of straight wing type structures.

In the scheme, the first centering strip, the second centering strip, the third centering strip and the fourth centering strip are bonded to the casing through adhesives, the adhesives are prepared by mixing epoxy resin adhesives and polyamide curing agents, and the ratio of the epoxy resin adhesives to the polyamide curing agents is 6.5: 3.5.

In the scheme, the epoxy resin adhesive is a thermoplastic high polymer with a linear structure, which is formed by condensation polymerization of epoxy chloropropane and diphenol propane under the action of alkali.

The invention also provides an installation method of the straight wing type resin casing centralizer, which comprises the following steps:

s1, grinding the sleeve;

s2, manufacturing a resin centralizer installation mould; preferred rigid plastic is as the mould material, wholly is three-dimensional regular trapezium structure, whole thickness 3.5mm, 5 round holes of even preparation of upper surface: wherein the centre round hole is the filling hole, diameter 8mm, and the round hole all around is bleeder vent, diameter 5mm, and the mould internal volume is strict according to the centralizer shape preparation: the thickness is 11.5mm, the lower end surface is arc-shaped, the length is 30cm, the width is 12cm, the upper end surface is arc-shaped, the length is 27cm, and the width is 10 cm;

s3, a resin centralizer installation method; (1) the periphery of the manufactured hard die is stably and uniformly stressed and bound at the corresponding polished position of the sleeve by using a strong adhesive tape, and the moving condition cannot occur; (2) the special high-temperature glue is uniformly sprayed on the surface of the sleeve, and is a 300 ℃ resistant high-temperature adhesive prepared from E-51 epoxy adhesive, dibutyl phthalate and tetraethylenepentamine according to the components of 100:15: 13; (3) mixing the agent A and the agent B in a ratio of 6.5:3.5 by using special mixing pump injection equipment, and injecting the mixture into a middle round hole of a mould by using an adjustable injection pump; (4) in the injection process, the continuity and the failure of equipment are ensured, if the equipment is interrupted, the equipment is disposed in time, if the equipment can not be recovered after more than 30min, the equipment is determined to be unqualified, and the equipment is manufactured again; (5) after the manufacture of the single centralizer is finished, the distance and the angle of the adjacent centralizer are checked again; (6) completing the manufacture of the 4-piece centralizer of the single casing according to the methods (1) to (5); (7) after the resin centralizer of a single casing pipe is installed, the centralizer is placed on a pipe frame in a standing and suspending way for more than 8 hours, cannot be moved and impacted, and the external environment is ensured not to be changed obviously in the process;

s4, preprocessing after the resin centralizer is molded; (1) performing micro-processing on the surface of the centralizer by using a file, and particularly polishing and grinding the edges and corners at the periphery; (2) wrapping the centralizer by a specially-made ventilated rubber anti-abrasion layer to protect the centralizer; (3) in the process of transferring and transporting, the anti-abrasion layer cannot be damaged until the sleeve is disassembled before being put into a sleeve.

The straight wing type resin casing centralizer and the installation method thereof have the following beneficial effects:

1. the invention develops and matches a small-size casing centralizing process for reconstructing a shaft of an old shale gas well in China, can manually stick a resin centralizer on a 3.5 ' casing on site, meets the technical requirement of re-putting a 3.5 ' casing in a 5.5 ' casing horizontal well, has the characteristics of good sticking stability, high centering degree, low friction resistance, good perforating bullet penetrability and the like, is simple to operate, high in accuracy, small in error, safe and reliable, and can be directly applied to site operation construction.

2. The invention develops and matches a small-size casing centered and centered in an outer large casing in the process of rebuilding a shaft of an old shale gas well, can ensure the centering degree of the small-size casing by more than 70 percent, has simple operation, high precision, small error, safety, reliability and convenient maintenance, and can be directly applied to field operation construction; the straight wing type resin casing centralizer solves the technical problem of large friction resistance between the inner small casing and the outer large casing in the casing-in-casing fixing process, is safe and reliable, and greatly reduces the construction risk of midway resistance of the casing-in-casing stage and cement slurry loss return in the well cementation stage in the casing-in-casing fixing process.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a schematic structural view of a straight wing resin casing centralizer of the present invention;

FIG. 2 is a side view of FIG. 1;

FIG. 3 is a front view of a centralizer strip;

FIG. 4 is a top view of a centralizer strip;

fig. 5 is a schematic view of the installation mold.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

As shown in figures 1-5, the straight wing type resin casing centralizer comprises 2 pieces of resin casing centralizers which are respectively arranged at the left end and the right end of a 3.5' casing, are distributed at 90 degrees on the circumference, and are staggered to have no influence on the annular flow area and reduce the friction resistance. 2 pieces of the male buckle are arranged at a distance of 2.05m from the male buckle section, and are oppositely arranged at a distance of 30 cm; 2 pieces are arranged 4m away from the female buckle section, are arranged relatively at a distance of 30cm, and are arranged in the middle at all angles. The first centralizing strip, the second centralizing strip, the third centralizing strip and the fourth centralizing strip are oppositely distributed around the single sleeve, wherein two left-end sleeves are relatively 180 degrees, two right-end sleeves are relatively 180 degrees, the left ends and the right ends are correspondingly 90 degrees, the single sleeve is integrally and uniformly distributed for 360 degrees, and the centering degree of the inner-layer small sleeve in the outer-layer large sleeve is more than or equal to 70 percent.

Besides the arrangement requirements of the centralizer, the centralizer has the following two technical characteristics: (1) the distance between the two centralizers in the middle of a single sleeve is 260 cm; (2) the distance between the two adjacent centralizers at the left end and the right end is 30 cm. The advantage of arranging like this can ensure that the small casing pipe of inlayer all presents the central state at horizontal well full horizontal section.

Centralizer geometric structure design aspect. The whole single-piece centralizer is in a three-dimensional regular trapezoid structure and is effectively adhered to the sleeve, the whole thickness is 11.5mm, the lower end surface is in an arc shape, the length is 30cm, the width is 12cm, the upper end surface is in an arc shape, and the length is 27cm, and the width is 10 cm. The outer surface of the centralizer is polished smoothly and smoothly without grooves, and the edges and corners at the periphery are subjected to arc transition treatment, so that stress concentration is avoided when the centralizer is in contact with an outer-layer casing pipe, and the integral structure of the casing pipe is damaged.

The resin centralizer adheres materials and components. In the invention, two chemical materials of an agent A and an agent B are preferably used as the pasting raw materials of the resin centralizer, wherein the chemical component of the agent A is an epoxy resin adhesive, and the chemical component of the agent B is a polyamide curing agent. The agent A and the agent B are uniformly and fully mixed, the effect comparison analysis of the adhesive strength and the friction coefficient is carried out according to different component combinations of 7:3, 6.5:3.5, 6:4, 5:5, 4:6 and the like, and a destructive test is carried out by an acting force of more than 3000psi, and the optimal mixing ratio of the agent A to the agent B is preferably 6.5: 3.5.

The main technical challenges of the casing fixing process in the shale gas old well casing include: (1) small clearance, long horizontal section, scaling and other impurities in the old well, and difficult casing running; (2) the stratum is produced for several years, the deficit is serious, the pressure bearing capacity is low, small-gap well cementation is realized, the ECD is high, and the leakage risk is large; (3) a casing without a coupling is selected, the design difficulty of the centralizer is high, and the casing is not easy to center; (4) the annular space is small, and the cement paste is required to be low in viscosity and small in flow resistance; (5) the later stage fracturing pressure is large, and the requirement on the elastic modulus of the set cement is high. Therefore, the structural design and material preference of the centralizer are related to the success or failure of the whole project.

Regarding the shape of the resin stabilizer, preference is given. At present, the straight wing type centralizer and the spiral type centralizer are mainly used, the supporting centering degree of the spiral type centralizer is more than or equal to 80% in a sleeve-in-sleeve fixing environment, the centralizing performance is good, but later-period cement slurry flows in a gap between two layers of sleeves, the loss and return risk is large, and the well cementation quality cannot be guaranteed. In the fixed sleeve environment of the straight wing type resin centralizer sleeve, the support centering degree is more than or equal to 70 percent, the centralizing performance is reduced, but the friction coefficient can be controlled to be 0.15-0.18, and the small-size casing can be effectively ensured to be lowered to the bottom of the artificial well. In addition, the straight wing type resin centralizer is adopted, so that when well cementation cement slurry flows between two layers of casings, the resistance is small, the difficulty of well cementation operation is effectively reduced, and the well cementation quality is improved.

The design relates to a well cementation tubular column structure. (1) A centralizer is arranged on the two sleeves below the disjointing device to assist the disjointing device to be centered; (2) a centralizer is installed from 300m above the target point A of the horizontal section to the bottom of the well, and good centering and cement covering which are long enough above the target point A are guaranteed.

The invention also provides an installation method of the straight wing type resin casing centralizer, which comprises the following steps:

1. the resin centralizer mounts equipment to be prepared. (1) Sander, performance requirement: 1MPa, and the requirement of the air source discharge capacity is more than or equal to 14m³Min; (2) a portable roughness detector; (3) a double-channel grease injection machine, wherein the grease injection pressure is more than or equal to 1.5 MPa; (4) three-phase power, 120psi air supply, crane and other auxiliary equipment.

2. And (6) polishing the sleeve. Preferably, the sleeve with high compressive strength is used as a sticking carrier of the centralizer, the mounting position and the periphery of the centralizer are polished step by a special steel tube grinding wheel polisher, and the sleeve is qualified when the surface roughness Ra of the sleeve is detected to be more than or equal to 80 mu m by a portable surface roughness meter.

3. And manufacturing a centralizer installation mould. Preferred rigid plastic is as the mould material, wholly is three-dimensional regular trapezium structure, whole thickness 3.5mm, 5 round holes of even preparation of upper surface: wherein the centre round hole is the filling hole, diameter 8mm, and the round hole all around is bleeder vent, diameter 5mm, and the mould internal volume is strict according to the centralizer shape preparation: the thickness is 11.5mm, the lower end surface is arc-shaped, the length is 30cm, the width is 12cm, the upper end surface is arc-shaped, the length is 27cm, and the width is 10 cm.

4. The installation environment of the resin centralizer is required. (1) The centralizer pasting and mounting environment is carried out in a relatively closed environment with light shielding and rain shielding functions; (2) the humidity of the installation environment is preferably 40 to 50 percent measured by a hygrometer; (3) the temperature of the installation environment is kept above 20 ℃, and if the natural environment cannot be met, measures such as artificial heating and the like are adopted.

5. Provided is a resin centralizer installation method. (1) The periphery of the manufactured hard die is stably and uniformly stressed and bound at the corresponding polished position of the sleeve by using a strong adhesive tape, and the moving condition cannot occur; (2) the special high-temperature glue is uniformly sprayed on the surface of the sleeve, and is a 300 ℃ resistant high-temperature adhesive prepared from E-51 epoxy adhesive, dibutyl phthalate and tetraethylenepentamine according to the components of 100:15: 13; (3) mixing the agent A and the agent B in a ratio of 6.5:3.5 by using special mixing pump injection equipment, and injecting the mixture into a middle round hole of a mould by using an adjustable injection pump; (4) in the injection process, the continuity and the failure of equipment are ensured, if the equipment is interrupted, the equipment is disposed in time, if the equipment can not be recovered after more than 30min, the equipment is determined to be unqualified, and the equipment is manufactured again; (5) after the manufacture of the single centralizer is finished, the distance and the angle of the adjacent centralizer are checked again; (6) completing the manufacture of the 4-piece centralizer of the single casing according to the methods (1) to (5); (7) after the single casing pipe resin centralizer is installed, the centralizer is placed on the pipe frame in a standing and suspending mode for more than 8 hours, cannot be moved and impacted, and the external environment is guaranteed not to change obviously in the process.

6. And (4) preprocessing the molded resin centralizer. (1) Performing micro-processing on the surface of the centralizer by using a file, and particularly polishing and grinding the diamond corners at the periphery; (2) wrapping the centralizer by a specially-made ventilated rubber anti-abrasion layer to protect the centralizer; (3) in the process of transferring and transporting, the anti-abrasion layer cannot be damaged until the sleeve is disassembled before being put into a sleeve.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (7)

1. The straight-wing resin casing centralizer is characterized by comprising a first centralizing strip, a second centralizing strip, a third centralizing strip and a fourth centralizing strip which are sequentially adhered to the outer wall of a casing from left to right at intervals, wherein the first centralizing strip, the second centralizing strip, the third centralizing strip and the fourth centralizing strip are arranged in a 90-degree included angle staggered mode on the circumference.

2. The straight wing resin casing centralizer of claim 1, wherein the distance between the first centralizing strip and the casing box section is 4m, the distance between the second centralizing strip and the first centralizing strip is 30cm, the distance between the third centralizing strip and the second centralizing strip is 2.6m, the distance between the fourth centralizing strip and the third centralizing strip is 30cm, and the distance between the fourth centralizing strip and the casing pin section is 2.05 m.

3. The straight-wing resin casing centralizer of claim 1, wherein the first centralizing strip, the second centralizing strip, the third centralizing strip and the fourth centralizing strip are made of resin and are of three-dimensional right-trapezoid structures, the overall thickness is 11.5mm, the lower end surface is arc-shaped, the length is 30cm, the width is 12cm, the upper end surface is arc-shaped, and the length is 27cm and the width is 10 cm.

4. The straight-wing resin casing centralizer of claim 1, wherein the first, second, third, and fourth centralizing bars are straight-wing structures.

5. The straight wing type resin casing centralizer of claim 1, wherein the first centralizing strip, the second centralizing strip, the third centralizing strip and the fourth centralizing strip are bonded on the casing through adhesives, and the adhesives are prepared by mixing epoxy resin adhesives and polyamide curing agents in a mixing ratio of 6.5: 3.5.

6. The straight-wing resin casing centralizer of claim 5, wherein the epoxy resin adhesive is a thermoplastic high polymer with a linear structure formed by condensation polymerization of epichlorohydrin and diphenol propane under the action of alkali.

7. A method of installing the straight-wing resin casing centralizer of claim 1, comprising the steps of:

s1, grinding the sleeve;

s2, manufacturing a resin centralizer installation mould; preferred rigid plastic is as the mould material, wholly is three-dimensional regular trapezium structure, whole thickness 3.5mm, 5 round holes of even preparation of upper surface: wherein the centre round hole is the filling hole, diameter 8mm, and the round hole all around is bleeder vent, diameter 5mm, and the mould internal volume is strict according to the centralizer shape preparation: the thickness is 11.5mm, the lower end surface is arc-shaped, the length is 30cm, the width is 12cm, the upper end surface is arc-shaped, the length is 27cm, and the width is 10 cm;

s3, a resin centralizer installation method; (1) the periphery of the manufactured hard die is stably and uniformly stressed and bound at the corresponding polished position of the sleeve by using a strong adhesive tape, and the moving condition cannot occur; (2) the special high-temperature glue is uniformly sprayed on the surface of the sleeve, and is a 300 ℃ resistant high-temperature adhesive prepared from E-51 epoxy adhesive, dibutyl phthalate and tetraethylenepentamine according to the components of 100:15: 13; (3) mixing the agent A and the agent B in a ratio of 6.5:3.5 by using special mixing pump injection equipment, and injecting the mixture into a middle round hole of a mould by using an adjustable injection pump; (4) in the injection process, the continuity and the failure of equipment are ensured, if the equipment is interrupted, the equipment is disposed in time, if the equipment can not be recovered after more than 30min, the equipment is determined to be unqualified, and the equipment is manufactured again; (5) after the manufacture of the single centralizer is finished, the distance and the angle of the adjacent centralizer are checked again; (6) completing the manufacture of the 4-piece centralizer of the single casing according to the methods (1) to (5); (7) after the resin centralizer of a single casing pipe is installed, the centralizer is placed on a pipe frame in a standing and suspending way for more than 8 hours, cannot be moved and impacted, and the external environment is ensured not to be changed obviously in the process;

s4, preprocessing after the resin centralizer is molded; (1) performing micro-processing on the surface of the centralizer by using a file, and particularly polishing and grinding the edges and corners at the periphery; (2) wrapping the centralizer by a specially-made ventilated rubber anti-abrasion layer to protect the centralizer; (3) in the process of transferring and transporting, the anti-abrasion layer cannot be damaged until the sleeve is disassembled before being put into a sleeve.

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