CN203626622U - Structure for preventing corrosion damage of aluminum alloy-carbon steel pipe strings underground - Google Patents

Abstract

The utility model discloses a structure for preventing corrosion damage of aluminum alloy-carbon steel pipe strings underground, and belongs to the technical field of production pipe strings for oil field gas wells. The surface of an inner annular groove of an aluminum alloy jacket is octagonal, a correspondingly assembled inner aluminum alloy flange is also octagonal, and rotary bending and torsion unloosening between an upper pipe string and a lower pipe string can be effectively prevented after the aluminum alloy jacket and the inner aluminum alloy flange are assembled through an insulation sleeve, so that the insulating property of the connector is improved; a meshing plane, corresponding to the periphery of the inner carbon steel flange, of the aluminum alloy jacket is subjected to anodized oxidation treatment; a hook sleeve of the aluminum alloy jacket is connected with the jacket through straight threads; the insulating connector is assembled from bottom to top and filled with epoxy resin, the hook sleeve is tightened, and finally, a heat shrinking sleeve is taken as a connector protecting bush; centering devices and distribution of the centering devices: the centering device structures adopt plastic insulating pipes, four flanges are arranged on the periphery of a bone pipe, and every two flanges form one guide slot; and a plugging device is connected onto the bottommost end of the of the aluminum-alloy pipe.

Description

A kind of structure that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage

Technical field

The utility model relates to a kind of structure that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage, belongs to oil field gas well flow string technical field.

Background technology

Demand and the application proportion of China's natural gas exploitation are increasing, and oil gas Kai Chan enterprise, in order to reduce production costs, increases the benefit, and adopt the economy downhole tubular goods that is applicable to hole condition to become inevitable.

Long celebrating oil field belongs to typically (spy) hypotonic oil gas field, shows as the natural gas well and yields poorly, and well is more and more darker.It is domestic CT70 coiled tubing that water drainage-gas recovery technology adopts speed tubing string, it is with high costs, exploitation adopts the novel speed tubing string of down-hole " medium carbon steel+aluminium-alloy pipe " combination for this reason, this tubing string economic and practical is strong, particularly, in the face of the economical and effective exploitation in low yield super dark (more than 4000m) gas field, have more good cost advantage and potential application prospect.The carbon steel structure generally adopting for down-hole string, for the consideration of gas well safety in production, effective protection of aluminium-alloy pipe is the important topic facing simultaneously.

The outstanding problem that " medium carbon steel+aluminium-alloy pipe " combined string faces is, gas well oil casing is medium carbon steel, metallic aluminium is very active, its electrode potential is very negative, and the potential difference between carbon steel is large, both produce galvanic corrosion at the easily contact that exists together in narrow and small well, cause corrosion of aluminium alloy to damage, particularly for the high yield water gas well of water pumping gas production, the high salinity natural gas that is rich in hydrogen sulfide, carbon dioxide, sulfate reducing bacteria and chlorine root is taken liquid galvanic corrosion is played to great facilitation.

The known galvanic corrosion method that prevents, the one, avoid dissimilar metal directly to contact, the 2nd, corrosive medium processing, the 3rd, electrochemical protection, and corrosion resistant alloy adds coating, corrosion inhibiter measure.At floor surface engineering field, for the galvanic corrosion between aluminium alloys and dissimilar metal, application generally, comparatively ripe effective method is to adopt aluminium alloy anode oxide technique, form electrical insulating property, anti-corrosive properties are better and hardness is high alundum (Al2O3) thin layer in aluminum alloy surface, then carry out sealing of hole processing, can reach functional and ornamental all very high surface courses.

In oil drilling, under local circumstance, adopt aluminium drill pipe, although there is galvanic corrosion risk between drilling rod and steel pipe column structure, but because of drilling period shorter, and adopt Special Drilling Operation liquid, and only exist the short period to contact between steel pipe column, aluminium drill pipe corrosion damage degree is low, generally will not adopt special treatment measures.

For the complicated down-hole string of long-term production gas well, the galvanic corrosion between aluminium alloys-carbon steel bimetallic is very serious problem, if the aluminum alloy joint between bimetallic adopts anode oxidation process, this anodic oxidation joint is deposited subject matter both ways:

The one, gas well well depth reaches 4000m, and well temperature reaches 120 DEG C, and joint alumite will produce fire check under 80～100 DEG C of conditions.

The 2nd, alumite hardness is high, fragility is large, is not suitable for the environment of mechanism, and the high-strength impact power effect at joint screw thread place very easily causes micro-crack.

In the anaerobic environment of gas well at HTHP, the self-healing completely in time of aluminum alloy anode heat (micro-) crackle, being rich in chlorine root and multiple corrosive gas and high salinity at gas well produces under regimen condition, heat (micro-) crackle can directly cause joint to damage inefficacy, and gas well is produced will produce great security risk.

The pipe string combination that the interior employing of pit shaft has galvanic corrosion is always industry taboo, the common practice that prevents galvanic corrosion is as far as possible by the ad eundem tubing by high standard, for the careful consideration of better safe than sorry, this method is devoid of risk measure thoroughly to the exploitation of high yield corrosion gas well, but very uneconomical for gas stringer and the darker gas field of gas-bearing formation, seek economical and effective and prevent that reliably the method for aluminium-alloy pipe galvanic corrosion from being very necessary.

Summary of the invention

In order to overcome the deficiencies in the prior art, the utility model provides a kind of structure that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage.

For the aluminium-alloy pipe-carbon steel tube column combination adopting in Wellbore of Gas Wells, provide a kind of structure that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage.

A kind of structure that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage, the interior circular groove rooved face of aluminium alloys overcoat is octagon, correspondingly the profile of the carbon steel inward flange of assembling is also octagon, after assembling by insulation sleeve between the two, can effectively prevent that the rotation bending between lower tubular column from releasing, improve splice insulation performance; Aluminium alloys overcoat carries out anodization oxidation processes with the corresponding field of conjugate action of carbon steel inward flange periphery; The rhampotheca of aluminium alloys overcoat adopts straight thread to be connected with overcoat; Insulating joint by from lower toward assembled in sequence after, infusion epoxy resin, tightens rhampotheca, finally uses heat shrinking sleeve as connection protective cap;

Centralizer and distribution thereof: centralizer structure adopts plastic insulating tube, at four fins of peripheral zone of bone pipe, is guiding gutter between fin;

Plug device is connected to aluminium-alloy pipe bottom, and the blanking plug of gas in barrier wells is installed in reducing sleeve; The structure of plug device is made up of female joint, reducing sleeve and insulation sleeve; Reducing sleeve is connected with female joint by welding, and insulation sleeve is fixed in outside reducing sleeve by injection molded and is close to female joint lower end.

A kind of method that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage: contain following steps; Design by tubular column structure, realize between aluminium-alloy pipe and carbon steel tube and being electrically insulated, effectively avoid galvanic corrosion in gas well at HTHP to occur; The aluminium-alloy pipe top being connected with different kinds of metal tubes adopts insulation crossover sub, and aluminium-alloy pipe is connected with top tubing string by this joint; According to well track, at aluminium-alloy pipe, nonmetal centralizer is often installed across a certain distance, avoid aluminium-alloy pipe and carbon steel tube wall contact wear corrosion; At the Plastic cap of installation bottom of aluminium-alloy pipe, the blanking plug of gas well water pumping gas production is arranged in chamber, Plastic cap lower end, avoids touching of aluminium-alloy pipe and tubing and casing to damage corrosion;

Also contain three steps:

Step 1, at its topmost installing insulating crossover sub 1, this joint meets top carbon steel tubing string and is connected with the conversion of bottom aluminium alloys tubing string, adapt to operation and production environment in gas well at HTHP, do not occur circumferentially to rotate and lost efficacy, ensure being electrically insulated of aluminium-alloy pipe and top carbon steel tubing, avoid directly connecting the galvanic corrosion causing.

Step 2, according to gas well well track, at aluminium-alloy pipe pipe shaft, centralizer 2 is often installed across a certain distance, prevent aluminium-alloy pipe and the wear oxidation of carbon steel tubing string around.

Step 3, plug device 3 is installed in aluminium-alloy pipe lower end, is prevented touching to damage and corroding of lowest end and oil (cover) pipe carbon steel tube wall.

Second and third step plays the effect of protection oil (cover) pipe internal surface, particularly organic coating simultaneously.

Prevent a structure for down-hole aluminium alloys-carbon steel tubing string corrosion and damage, insulation crossover sub 1: formed by aluminium alloys overcoat 1.8, large felt pad 1.7, insulation sleeve 1.6, little felt pad 1.5 and insulating packing 1.2 and carbon steel inward flange 1.10.Wherein the interior circular groove rooved face of aluminium alloys overcoat 1.8 is octagon, correspondingly the profile of the carbon steel inward flange 1.10 of assembling is also octagon, by after insulation sleeve 1.6 assemblings, can effectively prevent that the rotation bending between lower tubular column from releasing between the two, improve splice insulation performance; The field of conjugate action that aluminium alloys overcoat 1.8 is corresponding with carbon steel inward flange 1.10 peripheries carries out anodization oxidation processes; The rhampotheca 1.3 of aluminium alloys overcoat 1.8 adopts straight thread to be connected with overcoat 1.8.Insulation crossover sub is by after assembled in sequence from the bottom up, and infusion epoxy resin, tightens rhampotheca 1.3, finally uses heat shrinking sleeve as connection protective cap.

Centralizer 2 and distribution thereof: centralizer 2 structures adopt plastic insulating tubes, at four fins 2.1 of peripheral zone of bone pipe 2.2, are guiding gutter 2.3 between fin 2.1; According to gas well well track and tubing parameter, the spacing of centralizer 2 on tubing string pressed following formula coding, calculates by software:

Suppose on aluminium-alloy pipe and only have centralizer place to contact with oil pipe (or sleeve pipe), between two centralizers, the maximum distortion of aluminium-alloy pipe is

$\mathrm{\δ}=\left(\frac{F_n{L_s}^3}{384\mathrm{EI}}\right)\left(\frac{24}{u^4}\right)\×(\frac{u^2}{2}-\frac{u\cosh u-u}{\sinh u})$

In formula:

wherein F is the axial force of aluminium alloys tubing string, N; L _sfor centralizer spacing, m; EI is the bending rigidity of aluminium-alloy pipe, Nm ².

Calculation criterion is

when

time, increase L _svalue, otherwise reduce L _s.Wherein f is proportion of deformation coefficient; d _tfor oil pipe (or sleeve pipe) external diameter, m; d _rfor aluminium-alloy pipe external diameter, m.

Plug device 3: plug device 3 is connected to aluminium-alloy pipe bottom, and in the interior installation barrier wells of reducing sleeve 3.2 blanking plug of gas.The structure of plug device 3 is made up of female joint 3.1, reducing sleeve 3.2 and insulation sleeve 3.4.Reducing sleeve 3.2 is connected with female joint 3.1 by welding, and insulation sleeve 3.4 is fixed in outside reducing sleeve 3.2 by injection molded and is close to female joint 3.1 lower ends.

The beneficial effects of the utility model:

(1) adopt insulation crossover sub 1 to design at carbon steel tubing string and aluminium-alloy pipe junction, effectively avoid topmost galvanic corrosion between two kinds of dissimilar metal joints, this joint meets top carbon steel tubing string and is connected with the conversion of bottom aluminium alloys tubing string, adapt to high temperature high voltage resistant gas well environment, meet workover treatment and working condition.Two intermetallic polygon Coupling Design guarantee that insulating joint torsional strength is high, convenient adopt engage thread fastening, avoid welding or the forged steel integral processing commonly used, significantly reduce costs; It is stressed that the Process on Aluminum Alloy Oxidation Film of the field of conjugate action of joint can effectively be born uniform face, aluminium alloy anodization processing can be used as and carbon steel between the second defence line of insulating, strengthen the joint effect of gas well high temperature and high pressure environment; Rhampotheca 1.3 adopts Screw assembly to ensure the detachable easily installation of joint, and maintainability is strong.

(2) at the pipe shaft of aluminium alloys tubing string by adopting the centralizer 2 of reasonable distance, effectively avoid the erosion corrosion between aluminium alloys tubing string and carbon steel oil (cover) pipe; For different well track gas wells, determine that rational centralizer spacing distributes, avoid the invalid installation of centralizer and affect operating efficiency and increase cost risk.

(3), at the plug of the installation bottom device 3 of aluminium-alloy pipe, prevent that aluminium alloys tubing string from damaging corrosion to touching of oil (cover) pipe.Plug device can prevent or reduce the intermetallic grazing damage level of lower end oil pipe to internal surface of sleeve pipe, the particularly damage of the larger position of dog-leg degree oil (cover) pipe; Can ensure internally coated integrality for organic internally coated oil (cover) pipe; Plug device is quick for installation, to the frequent underground work of directional well or adopt the underground work of organic undercoating oil (cover) pipe completion particularly applicable.

Adopt the utility model not only can overcome the great fatal problem of galvanic corrosion between down-hole aluminium alloys tubing string and carbon steel tubing string, and can effectively prevent aluminium-alloy pipe in pit shaft oil (cover) inside pipe wall friction touch wearing and tearing bad, especially take internally coated oil (cover) manage.Extend down-hole string service life, save development cost (gas well well repairing cost, indirect loss that tubing string damages are larger), produce 25 years by a bite well, individual well accumulation economic benefit more than 100,000 yuan, extends to a large amount of well depth gas stringers, and scale and benefit are remarkable.

The utility model, for the low cost speed tubing string water pumping gas production field of a large amount of gas wells of 3000～4500 meters of dark environment in long celebrating oil field, also can be applicable to the producing well of other oil gas field condition.

Brief description of the drawings

When considered in conjunction with the accompanying drawings, by the detailed description with reference to below, can more completely understand better the utility model and easily learn wherein many advantages of following, but accompanying drawing described herein is used to provide further understanding of the present utility model, form a part of the present utility model, schematic description and description of the present utility model is used for explaining the utility model, do not form improper restriction of the present utility model, as schemed wherein:

Fig. 1 is tactic pattern schematic diagram of the present utility model.

Fig. 2 is the structural representation of insulation crossover sub 1 of the present utility model.

Fig. 3 is insulation crossover sub 1 texture edge figure of the present utility model.

Fig. 4 is the structural representation of aluminium-alloy pipe centralizer 2 of the present utility model.

Fig. 5 is the texture edge figure of aluminium-alloy pipe centralizer 2 of the present utility model.

Fig. 6 is the structural representation of plug device 3 of the present utility model.

Below in conjunction with drawings and Examples, the utility model is further illustrated.

Detailed description of the invention

Obviously the many modifications and variations that, those skilled in the art do based on aim of the present utility model belong to protection domain of the present utility model.

Embodiment 1: as shown in Figure 1, Figure 2, shown in Fig. 3, Fig. 4, Fig. 5 and Fig. 6,

Prevent a structure for down-hole aluminium alloys-carbon steel tubing string corrosion and damage, particularly a kind of tactic pattern that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage.

A tactic pattern that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage, is mainly made up of three parts: the one, and at aluminium-alloy pipe top and carbon steel tube junction installing insulating crossover sub 1.The 2nd, at aluminium alloys tubing string, centralizer 2 is installed, on aluminium alloys tubing string, the spacing of centralizer 2 distribution calculating is axial force and the lateral force in conjunction with gas well space three-dimensional well track, centralizer place, progressively determines centralizer 2 spacing from the bottom to top by tentative calculation.The 3rd, plug device 3 is installed in aluminium-alloy pipe lower end.

Insulation crossover sub 1: formed by aluminium alloys overcoat 1.8, large felt pad 1.7, insulation sleeve 1.6, little felt pad 1.5 and insulating packing 1.2 and carbon steel inward flange 1.10.Wherein the interior circular groove rooved face of aluminium alloys overcoat 1.8 is octagon, and the profile of aluminium alloys inward flange 1.10 correspondingly is also octagon, assembles between the two by insulation sleeve 1.6, and rhampotheca 1.3 is connected with aluminium alloys overcoat 1.8 by screw thread.

Before joint assembling, carry out pretreatment and dry, pack successively insulated enclosure pad 1.7, insulated ring 1.6, top connection 1.1, O-ring seals 1.11, felt pad 1.5 into overcoat 1.8, then screw rhampotheca 1.3, to annular space infusion epoxy resin between rhampotheca 1.3 and top connection 1.1, finally use heat shrinking sleeve housed joint overcoat 1.8.

Insulated enclosure pad 1.7 and felt pad 1.5 PEEK material, insulated ring 1.6 and insulating packing 1.2 use epoxy resin, O shape circle fluorubber.Insulation materials part used can be cast and be processed or mold pressing injection mo(u)lding.Aluminium alloys overcoat 1.8 corresponding with carbon steel inward flange 1.10 the field of conjugate action carry out anodization oxidation processes.

Centralizer 2: centralizer structure adopts plastic insulating tube, at four fins 2.1 of peripheral zone of bone pipe 2.2, is guiding gutter 2.3 between fin 2.1.Centralizer 2 use polytetrafluoroethylene (PTFE), injection mo(u)lding processing.The design formulas that the spacing of centralizer 2 on tubing string distributes:

Suppose on aluminium-alloy pipe and only have centralizer place to contact with oil pipe (or sleeve pipe), between two centralizers, the maximum distortion of aluminium-alloy pipe is

$\mathrm{\δ}=\left(\frac{F_n{L_s}^3}{384\mathrm{EI}}\right)\left(\frac{24}{u^4}\right)(\frac{u^2}{2}-\frac{u\cosh u-u}{\sinh u})$

Calculation criterion is

when time, increase L _svalue, otherwise reduce L _s.

Write calculation procedure CQFZQ.EXE according to above-mentioned calculating formula, adopt that software obtains completion the DAT data file of three dimensional hole trajectory import, automatically draw well depth-spacing distribution map of centralizer.For example the well track of Long Dong gas field town AX-BY well is as follows:

Well depth: 4000m, kickoff point (KOP): 1980m, maximum hole deviation/well depth: 24.8 °/3000m, rate of over-all angle change <6 °/30m, aluminium-alloy pipe: Ф 38 × 4mm × 3900m, line density 1.20Kg/m, modulus of elasticity 70Gpa, oil pipe Ф 73.02 × 5.51mm × 3950m, sleeve pipe Ф 139.7 × 7.72mm × 4000m.

Computer run CQFZQ.EXE distance computation software, import the drilling data e-file " town AX-BY.DAT " that drilling crew submits to, calculating and plotting goes out the distribution map of well dog-leg degree-well depth curve and centralizer spacing-well depth, installs and is as short as 10m, grows to 100m spacing not etc. thereby obtain centralizer.

Plug device 3: plug device 3 is made up of female joint 3.1, reducing sleeve 3.2 and insulation sleeve 3.4.Insulation plug device 3 is connected on aluminium-alloy pipe bottom, and the blanking plug of natural gas in interim barrier wells can be installed by O shape ring recess 3.6 in reducing sleeve 3.2.Reducing sleeve 3.2 is connected with female joint 3.1 by welding, and insulation sleeve 3.4 is fixed in outside reducing sleeve 3.2 by annular groove 3.3 and is close to female joint 3.1 lower edge end faces by injection molded.

Above-described embodiment touches the mark: protection life-span >5; 150 DEG C of temperature, pressure 80Mpa; Insulating joint insulaion resistance >1G Ω; Torque resistant >10000Nm.Corrosion-free electric current and wearing and tearing harm between aluminium alloys tubing string and carbon steel tube.

A kind of structure that prevents down-hole aluminium alloys-carbon steel tubing string corrosion and damage; Aluminium-alloy pipe adopts insulation crossover sub 1 to be connected with carbon steel tube intercolumniation, and on aluminium alloys tubing string, set a distance suit centralizer 2, installs plug device 3 in aluminium-alloy pipe lower end; Insulation crossover sub 1 inner surface and the flange external surface of overcoat 1.8 be octagon; Rhampotheca 1.3 is threaded connection with overcoat 1.8; Felt pad 1.5 adopts PEEK material, and the field of conjugate action of aluminium alloys inward flange 1.10 peripheries and carbon steel overcoat 1.8 carries out anodization oxidation processes; According to gas well well track, determine that the spacing of centralizer 2 on aluminium alloys tubing string distributes, centralizer 2 is provided with guiding gutter 2.2; End at aluminium alloys tubing string is installed plug device 3, and plug device 3 is with O shape ring recess 3.6; Aluminium-alloy pipe top, down-hole is connected with carbon steel tubing string by insulation crossover sub 1, and insulation crossover sub 1 is realized top carbon steel tubing string and is connected with the conversion of bottom aluminium alloys tubing string, meets Temperature Deep high pressure production environment, does not affect normal rising in gas well and puts operation; According to gas well casing programme, at aluminium-alloy pipe tubing string, aluminium-alloy pipe centralizer 2 is installed, it is axial force and the lateral force in conjunction with gas well space three-dimensional well track, centralizer place that the spacing of aluminium-alloy pipe centralizer 2 distributes, and distributes from the bottom to top by the spacing of determining aluminium-alloy pipe centralizer 2; Plug device 3 is installed in aluminium-alloy pipe lower end.Above-mentioned three kinds of assemblies installation distribute and effectively prevent that galvanic corrosion and the friction of aluminium alloys tubing string and carbon steel tube intercolumniation from touching damage.This method protection life-span >10, insulating joint insulaion resistance >1G Ω, torque resistant >10000Nm, corrosion-free electric current and wearing and tearing harm between aluminium alloys tubing string and carbon steel tube.

As mentioned above, embodiment of the present utility model is explained, but as long as not departing from fact inventive point of the present utility model and effect can have a lot of distortion, this will be readily apparent to persons skilled in the art.Therefore, within such variation is also all included in protection domain of the present utility model.

Claims (1)

1. one kind prevents the structure of down-hole aluminium alloys-carbon steel tubing string corrosion and damage, the interior circular groove rooved face that it is characterized in that aluminium alloys overcoat is octagon, correspondingly the profile of the carbon steel inward flange of assembling is also octagon, after assembling by insulation sleeve between the two, can effectively prevent that the rotation bending between lower tubular column from releasing, improve splice insulation performance; Aluminium alloys overcoat carries out anodization oxidation processes with the corresponding field of conjugate action of carbon steel inward flange periphery; The rhampotheca of aluminium alloys overcoat adopts straight thread to be connected with overcoat; Insulating joint by from lower toward assembled in sequence after, infusion epoxy resin, tightens rhampotheca, finally uses heat shrinking sleeve as connection protective cap;

Centralizer and distribution thereof: centralizer structure adopts plastic insulating tube, at four fins of peripheral zone of bone pipe, is guiding gutter between fin;

Plug device is connected to aluminium-alloy pipe bottom, and the blanking plug of gas in barrier wells is installed in reducing sleeve; The structure of plug device is made up of female joint, reducing sleeve and insulation sleeve; Reducing sleeve is connected with female joint by welding, and insulation sleeve is fixed in outside reducing sleeve by injection molded and is close to female joint lower end.

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