A 125 ksi grade sulfur-resistant casing and induction heated method of manufacturing the same

Abstract

The present application relates to a kind of 125ksi steel grade sulfur-resistant casing and its induction heating manufacturing method, belong to sulfur-resistant casing technical field.The 125ksi steel grade sulfur-resistant casing induction heating manufacturing method, including the following steps: smelting, casting to get casting blank or cast ingot;The casting blank or cast ingot is heated to 1120~1150 ℃, and 0.5~2h is kept for high-temperature homogenization treatment, then again rolling, and raw pipe is prepared;The raw pipe is carried out on-line quenching, immediately water quenching to room temperature after heating, then again high-temperature tempering, and the sulfur-resistant casing with grain size below 10 μm is prepared.After high-temperature homogenization treatment, rolling is carried out, and then on-line quenching is carried out, is directly water quenched to room temperature after heating to temperature, without heat preservation treatment, then again tempering, and the sulfur-resistant casing containing tempering sorbite, residual austenite and second phase structure is obtained, with excellent strength and toughness match and higher SSCC performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anti-sulfur casing pipe, in particular to a 125ksi steel grade anti-sulfur casing pipe and an induction heating manufacturing method thereof. BACKGROUND

[0002] About half of the world's oil and gas fields contain H2S gas, with a maximum H2S partial pressure of 9 MPa and a formation temperature of 130℃. When ordinary steel materials are used for the exploitation of oil and gas resources containing hydrogen sulfide, under the action of service stress and hydrogen sulfide gas, hydrogen sulfide stress corrosion brittle fracture often occurs suddenly when the stress is far lower than the yield strength of the material itself, causing great damage.

[0003] At present, 110ksi high steel grade anti-sulfur casing pipes are relatively mature in China, but for deep well and ultra-deep well working conditions, neither the service strength nor the corresponding anti-SSCC performance can meet the use requirements by using 110 steel grade anti-sulfur oil well pipes. The existing high steel grade anti-sulfur casing pipes at home and abroad basically adopt Cr-Mo steel system. With the increase of pipe material steel grade, the SSCC sensitivity becomes more and more significant, and the requirements for organization and performance are higher.

[0004] Therefore, there is an urgent need for an anti-sulfur casing pipe with small grain size and high comprehensive performance to meet higher use requirements. SUMMARY

[0005] In view of the above analysis, the present application aims to provide a 125ksi steel grade anti-sulfur casing pipe and an induction heating manufacturing method thereof, to prepare an anti-sulfur casing pipe with high comprehensive performance and small grain size.

[0006] In one aspect, the present application provides an induction heating manufacturing method of a 125ksi steel grade anti-sulfur casing pipe, comprising the following steps:

[0007] S1: smelting and casting to obtain a casting blank or ingot;

[0008] S2: heating the casting blank or ingot to 1120-1150℃ and holding for 0.5-2h for high temperature homogenization treatment, and then rolling to obtain a rough pipe;

[0009] S3: on-line quenching the rough pipe, immediately water quenching to room temperature after heating, and then high temperature tempering to obtain an anti-sulfur casing pipe with a grain size of less than 10μm.

[0010] Further, the heating temperature of the on-line quenching is 900-950℃.

[0011] Preferably, the heating temperature of the on-line quenching is 910-930℃.

[0012] Further, the heating temperature of the tempering is 690-710 DEG C, the holding time of the tempering is 2-5h, and air cooling to room temperature.

[0013] Further, the grain size of the sulfur-resistant casing is 4-10um.

[0014] Further, the internal structure of the sulfur-resistant casing is tempered sorbite, residual austenite and dispersed and refined second phase distributed on the matrix.

[0015] Further, the volume fraction of the residual austenite is greater than or equal to 5%.

[0016] Further, the internal structure of the sulfur-resistant casing also contains a copper-rich phase.

[0017] Further, the second phase includes VC, V8C7, Cr 23 C6 and Mo7C3.

[0018] In another aspect, the application provides a 125ksi steel grade sulfur-resistant casing prepared by the manufacturing method of the 125ksi steel grade sulfur-resistant casing.

[0019] The components of the sulfur-resistant casing include, in mass percentage, C: 0.08-0.10%, Si: 0.1-0.2%, Mn: 3.0-3.6%, P: less than or equal to 0.010%, S: less than or equal to 0.005%, Mo: 0.30-0.50%, Cr: 1.0-1.2%, V: 0.30-0.40%, Ni: 1.0-2.0%, Cu: 1.0-2.0%, and the balance of Fe and inevitable impurities.

[0020] Compared with the prior art, the application can achieve at least one of the following beneficial effects:

[0021] 1. The application provides a preparation method of a sulfur-resistant casing, which comprises the following steps: after high-temperature homogenization treatment, rolling is performed, then on-line quenching is performed, the temperature is heated to a temperature, and then water quenching is directly performed to room temperature without holding treatment, and then tempering is performed, so that the sulfur-resistant casing containing tempered sorbite, residual austenite, a copper-rich phase and a second phase structure is obtained, and the grain size is less than 10um.

[0022] 2. The heating temperature of the on-line quenching is 900-950 DEG C, the heating temperature of the tempering is 690-710 DEG C, the holding time of the tempering is 2-5h, the volume fraction of the residual austenite in the obtained sulfur-resistant casing is greater than or equal to 5%, the obtained sulfur-resistant casing has excellent strength and toughness matching, and the delay crack propagation is improved, meanwhile, the austenite is FCC structure, the H solid solubility is much higher than that of the BCC structure of the matrix, more H can be adsorbed as hydrogen traps, and the matrix SSCC performance is improved.

[0023] 3. The anti-sulfur sleeve obtained by the induction heating manufacturing method has good comprehensive mechanics, and the yield strength of the anti-sulfur sleeve is greater than or equal to 875 MPa, the tensile strength is greater than or equal to 998 MPa, the elongation is greater than or equal to 18%, and the room temperature impact energy is greater than or equal to 130 J.

[0024] In the present application, the above technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification, or will be understood by implementing the present application. The purposes and other advantages of the present application can be achieved and obtained through the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application.

[0026] Figure 1 Metallographic structure (50 μm) of Example 1;

[0027] Figure 2 Metallographic structure (20 μm) of Example 1;

[0028] Figure 3 Metallographic structure (50 μm) of Example 3;

[0029] Figure 4 Metallographic structure (20 μm) of Example 3. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of the present application and are used together with the embodiments of the present application to explain the principles of the present application, but are not used to limit the scope of the present application.

[0031] The anti-sulfur sleeve is mainly used in oil and gas exploitation, and not only has to bear high pressure, but also has to resist the corrosion of H2S, Cl - Therefore, a 125 ksi steel grade anti-sulfur sleeve with high comprehensive performance is needed. Therefore, the present application provides an induction heating manufacturing method for a 125 ksi steel grade anti-sulfur sleeve, which comprises the following steps:

[0032] S1: smelting and casting to obtain a casting blank or a casting ingot;

[0033] S2: heating the casting blank or the casting ingot to 1120-1150 DEG C and keeping for 0.5-2 h for high-temperature homogenization treatment, and then rolling to obtain a rough pipe;

[0034] S3: the pipe is quenched on line, heated and immediately quenched in water to room temperature, and then tempered at high temperature to obtain the sulfur-resistant casing pipe with grain size below 10 microns.

[0035] Compared with the prior art, the preparation method provided by the application first performs high-temperature homogenization treatment, then performs rolling, and then performs on-line quenching, heating to a temperature and directly quenching in water to room temperature without heat preservation treatment, and then performs tempering, to obtain the sulfur-resistant casing pipe containing tempered sorbite, residual austenite, copper-rich phase and second phase structure. The sulfur-resistant casing pipe obtained has smaller grain size, can reach below 10 microns, and has higher comprehensive performance.

[0036] Specifically, in step S1, a converter, an electric furnace or an induction furnace can be used for smelting, and a continuous casting or a mold casting can be used for producing a casting blank or a casting ingot.

[0037] Specifically, in step S2, the casting blank or the casting ingot is heated to 1120-1150 DEG C in a heating furnace, and the heat preservation time is 0.5-2 h.

[0038] In the high-temperature homogenization treatment, it is ensured that all alloying elements are dissolved and exist in the form of solid solution in the matrix. However, when the heat preservation temperature is too high or the heat preservation time is too long, the austenite grains excessively grow or even overheat, which reduces the final performance of the sulfur-resistant casing pipe. When the heat preservation temperature is too low or the heat preservation time is too short, the sulfur-resistant casing pipe cannot be completely austenitized or the alloying elements are not fully solid-solved, the composition of the sulfur-resistant casing pipe is uneven, and the performance is affected.

[0039] Specifically, in step S2, water spraying cooling is used after rolling to form the pipe.

[0040] Specifically, in step S2, the finish rolling temperature of the rolling is 850-900 DEG C, to ensure that a certain amount of VC is precipitated during the rolling process.

[0041] Specifically, in step S3, the heating temperature of the on-line quenching is 900-950 DEG C.

[0042] Preferably, the heating temperature of the on-line quenching is 910-930 DEG C.

[0043] The on-line quenching is used to rapidly cool after heating to a predetermined temperature until cooling to room temperature, to obtain complete martensite structure, and the grain size is extremely fine in this process, and the second phase VC cannot be formed to pin the grain boundary.

[0044] Specifically, the heating temperature of the tempering is 690-710 DEG C, the heat preservation time of the tempering is 2-5 h, and air cooling is performed to room temperature.

[0045] Specifically, the anti-sulfur sleeve internal organization is tempered sorbite, residual austenite, copper-rich phase and matrix with dispersed and refined second phase.

[0046] After tempering, the quenched martensite organization is transformed into fine tempered sorbite organization, part of the martensite is reversely transformed into austenite, the reversely transformed austenite does not change after air cooling, the volume fraction of residual austenite is greater than or equal to 5%, and the comprehensive mechanical properties and SSCC performance are significantly improved.

[0047] Preferably, the volume fraction of residual austenite is 8% to 15%.

[0048] When the tempering temperature reaches 680 DEG C and the holding time is more than 3h, the copper-rich phase is formed, the copper-rich phase is FCC structure, and the residual austenite is dissolved H + The capacity is much higher than that of the BCC tempered sorbite matrix.

[0049] Specifically, the second phase mainly includes VC, V8C7, Cr 23 C6 and Mo7C3.

[0050] VC can be dispersed and precipitated in large quantities, and the VC second phase particles can be used as hydrogen traps to adsorb a large amount of H + , reduce the H + concentration in the matrix, and improve the SSCC performance. In addition, the size of the VC second phase particles is basically nanoscale, and is mainly spherical or short rod, so that a large amount of H + adsorbed on the VC particles is also difficult to use VC as a hydrogen-induced crack initiation point.

[0051] The application provides an anti-sulfur sleeve of 125ksi steel grade, which is prepared by the manufacturing method of the anti-sulfur sleeve of 125ksi steel grade.

[0052] The components of the obtained anti-sulfur sleeve include C: 0.08% to 0.10%, Si: 0.1% to 0.2%, Mn: 3.0% to 3.6%, P: less than or equal to 0.010%, S: less than or equal to 0.005%, Mo: 0.30% to 0.50%, Cr: 1.0% to 1.2%, V: 0.30% to 0.40%, Ni: 1.0% to 2.0%, Cu: 1.0% to 2.0%, and the balance of Fe and inevitable impurities.

[0053] The effects and dosage selection of the components contained in the application are specifically described as follows:

[0054] C: Carbon is a typical interstitial solid solution strengthening element, increasing the carbon content in the alloy is an effective way to improve the strength of the alloy, but too high C content will reduce the plasticity and toughness of the steel, and too much C and Mn will cause the appearance of banded structure in the steel. The banded structure is not conducive to the SSCC resistance of the anti-sulfur sleeve, and too high C content will cause too high strength, and the higher the strength, the higher the hydrogen-induced crack sensitivity, which is also not conducive to the SSCC resistance of the anti-sulfur sleeve.

[0055] Si: Silicon is a deoxidizer in steelmaking, but when the silicon content in the anti-sulfur sleeve is too high, the ability of the anti-sulfur sleeve to resist hydrogen sulfide corrosion is reduced.

[0056] Mn: Manganese can reduce the martensite transformation temperature Ms and increase the content of residual austenite, especially when the Mn content in the steel is ≥3%, it can also effectively improve the resistance of residual austenite decomposition. However, when the Mn content is too high, the volume fraction of residual austenite increases, which reduces the stability of residual austenite, and part of the residual austenite is transformed into martensite under certain conditions. The martensite has poor SSCC performance, high hardness and high hydrogen-induced crack sensitivity, which is not conducive to the SSCC performance of the pipe. C and Mn have a certain synergistic effect, which is easy to produce banded structure, which is not conducive to the SSCC performance of the anti-sulfur sleeve.

[0057] S: Sulfur element seriously deteriorates the corrosion resistance and toughness of the anti-sulfur sleeve, and easily forms MnS inclusions that deteriorate the SSCC performance, which needs to be controlled below 0.005%.

[0058] Cr and Mo: Chromium and molybdenum elements can improve the hardenability of the anti-sulfur sleeve to ensure that the pipe can obtain full martensite structure during quenching; at the same time, Mo element improves the tempering stability of the steel during high temperature tempering, avoids the rapid decrease of the strength of the anti-sulfur sleeve during high temperature tempering, which cannot meet the requirements of 125 steel grade, and ensures that the anti-sulfur sleeve has good comprehensive mechanical properties at high strength. Mo element and Cr element are also good uniform corrosion resistant elements, which reduce the H + The amount of penetration from the pitting surface into the anti-sulfur sleeve increases the anti-SSCC performance.

[0059] V: Vanadium element can precipitate VC during quenching, refine the grain by pinning the grain boundary, form carbide during heat treatment tempering to achieve precipitation strengthening effect, and also can improve the high temperature tempering resistance. In addition, due to the combination of V and C to precipitate carbide, the solid solution C content in the steel is reduced, the appearance of banded structure is reduced, and the SSCC sensitivity is also reduced. However, when the V content in the steel is too high, the toughness of the material will be significantly reduced.

[0060] Ni: Nickel element can expand the austenite phase region, is the main alloying element to form and stabilize austenite, improve the stability of residual austenite at room temperature. Ni can cooperate with Cr, Mo, improve the hardenability and corrosion resistance. At the same time, due to the Cu in the steel is easy to occur Cu brittle, need to add more than 1 / 2 content of Cu element of Ni element in the steel, therefore, the Ni element content is 1.0-2.0% in the application, and the content of Cu element is 1:1.

[0061] Cu: Copper element can form copper-rich phase in sulfur-resistant casing, which is a typical FCC structure, the solubility of H element in FCC structure is much higher than that of BCC structure of the matrix, so the copper-rich phase and the residual austenite can all dissolve a large amount of H + , improve the SSCC performance of the pipe.

[0062] In order to describe the application more clearly, the following examples and comparative examples are further illustrated.

[0063] Examples

[0064] Examples 1-4 of the application provide a preparation method of 125ksi high-grade sulfur-resistant casing, the components of the steel of examples 1-4 include: C: 0.08-0.10%, Si: 0.1-0.2%, Mn: 3.0-3.6%, P≤0.010%, S:≤0.005%, Mo: 0.30-0.50%, Cr: 1.0-1.2%, V: 0.30%-0.40%, Ni: 1.0-2.0%, Cu: 1.0-2.0%, the balance is Fe and inevitable impurities.

[0065] The preparation method of the steel of examples 1-4 and comparative examples 1-3 includes:

[0066] S1: adopting converter steelmaking, continuous casting to produce casting blank;

[0067] S2: heating the casting blank to homogenization temperature, keeping constant temperature for a period of time, then rolling, when the final rolling temperature reaches a certain temperature, using water cooling to form a rough pipe;

[0068] S3: on-line quenching the rough pipe, heating to a predetermined temperature and immediately water quenching to room temperature, then high temperature tempering, to obtain sulfur-resistant casing.

[0069] The specific preparation method of the steel of examples 1-4 and comparative examples 1-3 is shown in table 1, the corresponding components are shown in table 2, the microstructure is shown in table 3, the mechanical properties are shown in table 4, and the SSCC performance is shown in table 5. The microstructure of example 1 is shown in Figure 1 and 2 , the microstructure of example 3 is shown in Figure 3 and4 as shown.

[0070] Table 1 Preparation method of examples 1-4 and comparative examples 1-3

[0071]

[0072] Table 2 Chemical composition of examples 1-4 and comparative examples 1-3

[0073] Ingredients C Si Mn P S Cr Mo V Ni Cu Example 1 0.09 0.11 3.1 0.008 0.004 1.11 0.37 0.33 1.54 1.57 Example 2 0.08 0.20 3.0 0.007 0.004 1.20 0.32 0.35 1.91 1.85 Example 3 0.10 0.11 3.6 0.009 0.003 1.04 0.4 0.31 1.07 1.04 Example 4 0.10 0.15 3.4 0.006 0.004 1.13 0.31 0.37 1.43 1.48 Comparative Example 1 0.10 0.15 3.4 0.006 0.004 1.13 0.31 0.37 1.43 1.48 Comparative Example 2 0.10 0.15 3.4 0.006 0.004 1.13 0.31 0.37 1.43 1.48 Comparative Example 3 0.15 0.20 1.5 0.010 0.008 1.01 0.65 0.13 0.54 /

[0074] Table 3 Microstructure of examples 1-4 and comparative examples 1-3

[0075]

[0076]

[0077] Table 4 Mechanical properties of steel of examples 1-4 and comparative examples 1-3

[0078]

[0079] Table 5 SSCC resistance of examples 1-4 and comparative examples 1-3

[0080]

[0081] Referring to examples 1-4 and comparative examples 1-3 in combination with Tables 1-5 and Figures 1-4 It can be seen that the composition and preparation process of examples 1-4 provided by the present application, the obtained anti-sulfur pipe internal organization is tempering sorbite, the volume fraction of residual austenite is greater than 5%, and the grain size is less than 10 μm. The tensile strength, yield strength and impact energy of the obtained anti-sulfur pipe are higher, and the anti-SSCC performance test is passed, and the test time is 720h without breaking.

[0082] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for manufacturing a 125ksi grade sulfur-resistant sleeve using induction heating, characterized in that, Includes the following steps: S1: Smelting and casting to obtain billets or ingots; S2: The billet or ingot is heated to 1120-1150°C and held at that temperature for 0.5-2 hours for high-temperature homogenization treatment, and then rolled. The final rolling temperature is 850-900°C to obtain a rough tube. S3: The rough tube is subjected to online quenching. The online quenching heating temperature is 900~950℃. After heating, it is water quenched to room temperature and then tempered at high temperature. The tempering heating temperature is 690~710℃ and the tempering holding time is 2~5h. It is then air-cooled to room temperature to obtain a sulfur-resistant sleeve with a grain size of less than 10μm. The components of the anti-sulfur casing, by mass percentage, include C: 0.08~0.10%, Si: 0.1~0.2%, Mn: 3.0~3.6%, P≤0.010%, S: ≤0.005%, Mo: 0.30~0.50%, Cr: 1.0~1.2%, V: 0.30%~0.40%, Ni: 1.0~2.0%, Cu: 1.0~2.0%, with the balance being Fe and unavoidable impurities; the anti-sulfur casing has a yield strength ≥875MPa, tensile strength ≥998MPa, elongation ≥18%, room temperature impact energy ≥130J, and its resistance to SSCC was tested without breakage after 720h. The internal microstructure of the anti-sulfur casing consists of tempered sorbite, retained austenite, and a dispersed, refined second phase distributed on the matrix, wherein the volume fraction of the retained austenite is ≥5%.

2. The manufacturing method of the 125ksi grade sulfur-resistant sleeve with induction heating according to claim 1, characterized in that, The heating temperature for the online quenching is 910~930℃.

3. The manufacturing method of the 125ksi grade sulfur-resistant sleeve with induction heating according to claim 1, characterized in that, The grain size of the sulfur-resistant sleeve is 4-10 μm.

4. The manufacturing method of the 125ksi grade sulfur-resistant sleeve with induction heating according to claim 1, characterized in that, The internal structure of the sulfur-resistant casing also contains a copper-rich phase.

5. The manufacturing method of the 125ksi grade sulfur-resistant sleeve by induction heating according to claim 1, characterized in that, The second phase includes VC, V8C7, and Cr. 23 C6 and Mo7C3.

6. A 125ksi grade sulfur-resistant sleeve, characterized in that, It is prepared by the induction heating manufacturing method of the 125ksi steel grade anti-sulfur sleeve as described in any one of claims 1-5.

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