CT150ksi continuous oil well pipe and preparation method thereof

Abstract

The invention discloses a CT150ksi continuous oil well pipe and a preparation method thereof, belongs to the technical field of oil well pipes, and solves the problems of low strength and toughness of continuous oil well pipes in the prior art. The CT150ksi continuous oil well pipe comprises the following components in percentage by mass: 0.21 percent to 0.26 percent of C, 0.18 percent to 0.28 percent of Si, 1.2 percent to 1.6 percent of Mn, 0.35 percent to 0.55 percent of Mo, 0.45 percent to 0.52 percent of Cr, 0.25 percent to 0.3 percent of Ni, 0.03 percent to 0.06 percent of Al, 0.02 percent to 0.03 percent of Nb, 0.01 percent to 0.02 percent of Ti, 0.0012 percent to 0.002 percent of B, less than or equal to 0.005 percent of P, less than or equal to 0.005 percent of S and the balance of Fe and inevitable impurities. The CT150ksi continuous oil well pipe disclosed by the invention is high in strength and good in toughness.

Description

Technical Field

[0001] The invention relates to the technical field of oil well pipes, and in particular to a CT150ksi continuous oil well pipe and a preparation method thereof. Background Art

[0002] Continuous oil well pipes have the advantages of strong mobility, high efficiency, low cost and reusability, and have been widely used in various operations such as small wellhead drilling, completion, oil testing, oil production, well repair and gathering and transportation. At present, with the continuous increase in the depth of oil wells, the high temperature and high pressure environment in deep wells will put forward more stringent requirements on the strength and resistance to sulfide stress corrosion cracking of oil well pipes. The existing steel grade oil well pipes on the market can no longer meet the service requirements, and it is urgent to develop higher strength steel grade continuous oil well pipe steel. Summary of the invention

[0003] In view of the above situation, the present invention aims to provide a CT150ksi continuous oil well tubular and a preparation method thereof, so as to solve the problem of low strength and toughness of existing continuous oil well tubulars.

[0004] The purpose of the present invention is mainly achieved through the following technical solutions:

[0005] The invention provides a CT150ksi continuous oil well pipe. The components of the CT150ksi continuous oil well pipe include, by mass percentage, C: 0.21%-0.26%, Si: 0.18%-0.28%, Mn: 1.2%-1.6%, Mo: 0.35%-0.55%, Cr: 0.45%-0.52%, Ni: 0.25%-0.3%, Al: 0.03%-0.06%, Nb: 0.02%-0.03%, Ti: 0.01%-0.02%, B: 0.0012%-0.002%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities.

[0006] Furthermore, in the components of CT150ksi continuous oil well tubing, the C+Mn content is between 1.4% and 1.8%.

[0007] Furthermore, in the components of CT150ksi continuous oil well tubing, the content of Ti+Nb is between 0.03% and 0.045%.

[0008] Furthermore, in the composition of CT150ksi continuous oil well tubing, Cr / Ni is between 1.5 and 1.9.

[0009] Furthermore, the components of CT150ksi continuous oil well pipe include, by mass percentage: C: 0.22% ~ 0.26%, Si: 0.18% ~ 0.28%, Mn: 1.2% ~ 1.57%, Mo: 0.35% ~ 0.55%, Cr: 0.45% ~ 0.52%, Ni: 0.25% ~ 0.3%, Al: 0.035% ~ 0.06%, Nb: 0.02% ~ 0.029%, Ti: 0.01% ~ 0.02%, B: 0.0012% ~ 0.002%, P: ≤ 0.005%, S: ≤ 0.005%, and the balance is Fe and unavoidable impurities.

[0010] Furthermore, the room temperature microstructure of the CT150ksi continuous oil well pipe includes tempered troostite + dispersed precipitated cementite + a small amount of precipitated phase.

[0011] Furthermore, in the room temperature microstructure of the CT150ksi continuous oil well tubular, the volume percentage of cementite is 1.0% to 2.5%.

[0012] The present invention also provides a method for preparing a CT150ksi continuous oil well pipe, which is used to prepare the above-mentioned CT150ksi continuous oil well pipe. The preparation method comprises the following steps:

[0013] Step 1: smelting and pouring to obtain a billet or ingot;

[0014] Step 2: rolling the billet or ingot after high temperature homogenization treatment, and coiling after laminar cooling to obtain a rough tube; the rough tube structure includes more than 90% bainite structure, or the rough tube structure is martensite;

[0015] Step 3: After the rough pipe is subjected to rapid quenching and tempering treatment, a CT150ksi continuous oil well tubular is obtained; wherein the rapid quenching and tempering treatment includes induction quenching + induction high temperature tempering.

[0016] Furthermore, in step 3, the induction quenching step includes: induction heating the rough pipe to a complete austenitizing temperature at a heating rate of more than 20°C / s, keeping the temperature for a short time, and then quenching to room temperature.

[0017] Furthermore, in step 3, the step of induction high temperature tempering includes: induction heating the rough pipe to 590-625°C at a heating rate of more than 20°C / s, keeping warm for a short time and then air cooling to room temperature.

[0018] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0019] The CT150ksi continuous oil well pipe of the present invention can obtain a CT150ksi continuous oil well pipe with high strength and excellent toughness by accurately controlling the mass percentages of elements such as C, Si, Mn, Cr, Mo, Ni, Ti, and Nb.

[0020] In the preparation method of the CT150ksi continuous oil well pipe of the present invention, the initial structure before quenching and tempering is precisely controlled, and the double induction quenching and tempering process is combined to ensure that the structure of the continuous oil well pipe includes tempered troostite + dispersed cementite + a small amount of precipitation phase, thereby ensuring that it has a high strength level and a high toughness.

[0021] In the preparation method of the CT150ksi continuous oil well pipe of the present invention, a structure of tempered troostite + dispersed cementite + a small amount of precipitated phase is obtained through a rapid heat treatment process. The tempered troostite as a matrix structure has a good match of strength, toughness and plasticity, and can ensure good SSCC resistance. A small amount of (Ti, Nb) C precipitated phase hinders dislocation recovery and ensures the strength of the steel during tempering. Finally, the strength and toughness of the continuous oil well pipe of the composition of the present invention can be matched, and all meet the required range.

[0022] The CT150ksi continuous oil well pipe of the present invention has high strength and good toughness, with a yield strength of ≥1150Pa, such as 1180-1250MPa; a tensile strength of ≥1250MPa, such as 1280-1330MPa; an elongation of ≥14%, such as 14.5%-16%; and an impact energy of ≥120J at -40°C, such as 135-150J; and fully meets the requirements of 150ksi steel grade oil well pipe.

[0023] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the contents particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0025] Figure 1 This is a microstructure diagram of the coiled oil well tubular after tempering according to Example 1 of the present invention;

[0026] Figure 2 This is a microstructure diagram of the coiled oil well tubular after tempering according to Example 2 of the present invention;

[0027] Figure 3 This is a microstructure diagram of the coiled oil well tubular after tempering according to Example 3 of the present invention.

[0028] Figure 4 This is a microstructure diagram of the coiled oil well tubular after tempering according to Example 4 of the present invention.

[0029] Figure 5 This is a microstructure diagram of the coiled oil well tubular after tempering according to Example 5 of the present invention. DETAILED DESCRIPTION

[0030] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0031] The present invention provides a CT150ksi continuous oil well pipe. The components of the CT150ksi continuous oil well pipe include, by mass percentage, C: 0.21%-0.26%, Si: 0.18%-0.28%, Mn: 1.2%-1.6%, Mo: 0.35%-0.55%, Cr: 0.45%-0.52%, Ni: 0.25%-0.3%, Al: 0.03%-0.06%, Nb: 0.02%-0.03%, Ti: 0.01%-0.02%, B: 0.0012%-0.002%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities.

[0032] Specifically, in the components of the CT150ksi continuous oil well tubular, the C+Mn content is between 1.4% and 1.8%, for example, the C+Mn content is between 1.42% and 1.79%.

[0033] Specifically, in the components of the CT150ksi continuous oil well tubular, the content of Ti+Nb is between 0.03% and 0.045%.

[0034] Specifically, in the composition of the CT150ksi continuous oil well pipe, the Cr / Ni ratio should be between 1.5 and 1.9, for example, Cr / Ni should be between 1.55 and 1.9.

[0035] Specifically, in the composition of the CT150ksi continuous oil well pipe, Cr+Ni+Mo+Al≥1.2%, for example, Cr+Ni+Mo+Al is 1.2% to 1.4%.

[0036] The functions and dosages of the components in the present invention are described in detail below.

[0037] C: Increasing the carbon content in steel is an effective way to improve the strength of coiled oil well pipes, but too high a C content will reduce the plastic toughness of the steel. At the same time, too much C and Mn will cause banded structure in the steel, making the subsequent induction heating less than ideal performance. The C+Mn content must be guaranteed to be between 1.4% and 1.8%, and the Mn content must be controlled when the C content is increased. Therefore, the C content of the present invention is controlled between 0.21% and 0.26%.

[0038] Si: Si is a deoxidizer in steelmaking, but excessive silicon is not good for the steel's resistance to hydrogen sulfide corrosion. Therefore, the content of Si in the present invention is controlled at 0.18% to 0.28%.

[0039] Mn: Mn is a strong austenite forming element, which is beneficial to increase the hardenability of the material and is a significant strengthening element. However, increasing the Mn content will reduce the material's resistance to sulfide stress cracking. Therefore, the Mn content is controlled at 1.2% to 1.6%.

[0040] P, S: P and S are impurities in steel and are not conducive to toughness. In the present invention, the content of P and S is controlled to be ≤0.005%.

[0041] Mo: Mo can significantly improve hardenability and ensure that the steel can obtain martensite structure during quenching; at the same time, adding Mo element can improve tempering resistance, ensure that when tempering at a higher temperature, the dislocation density of the steel is reduced, hydrogen diffusion aggregation is reduced, and the resistance to sulfide stress cracking is improved. In the present invention, the content of Mo is controlled to be 0.35% to 0.55%.

[0042] Al: Aluminum is a commonly used deoxidizer in steel. Adding a small amount of aluminum to steel can refine the grains, improve hardenability and impact toughness, but excessive aluminum will reduce welding performance and cutting performance. Therefore, the Al content is controlled at 0.03% to 0.06%.

[0043] Cr: Cr is also an element that improves the hardenability of the pipe. It works together with Mo to improve the hardenability and ensure that the martensite structure is obtained during quenching. At the same time, Cr plays a role in resisting sulfide stress corrosion. Therefore, the Cr content is controlled at 0.45% to 0.52%.

[0044] Ni: Ni expands the austenite phase region. Ni can work synergistically with Cr, Mo, etc. The Cr / Ni ratio is guaranteed to be between 1.5 and 1.9. The total amount of Cr+Ni+Mo+Al is more than 1.2%. The hardenability and corrosion resistance are improved. The low-temperature toughness of the steel is improved by the Ni content. In the present invention, the Ni content is controlled to be 0.25% to 0.3%.

[0045] Ti, Nb: Ti and Nb can precipitate (Ti, Nb) C during rolling, which can refine the grains by pinning the grain boundaries, and form carbides during the heat treatment and tempering process to achieve precipitation strengthening. It can also improve the high temperature tempering resistance and improve the strength by fine grain strengthening and second phase strengthening. In the present invention, the Nb content is controlled to be 0.02% to 0.03%, the Ti content is 0.01% to 0.02%, and the Ti+Nb content is guaranteed to be between 0.03% and 0.045%.

[0046] Specifically, in order to further improve the comprehensive performance of the above-mentioned CT150ksi continuous oil well pipe, the components of the above-mentioned CT150ksi continuous oil well pipe include, by mass percentage: C: 0.22%-0.26%, Si: 0.18%-0.28%, Mn: 1.2%-1.57%, Mo: 0.35%-0.55%, Cr: 0.45%-0.52%, Ni: 0.25%-0.3%, Al: 0.035%-0.06%, Nb: 0.02%-0.029%, Ti: 0.01%-0.02%, B: 0.0012%-0.002%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities.

[0047] Specifically, the room temperature microstructure of the CT150ksi continuous oil well pipe includes tempered troostite + dispersed precipitated cementite + a small amount of precipitated phase, and the grain size is about 3-5 μm.

[0048] Specifically, in the room temperature microstructure of the CT150ksi continuous oil well tubular, the volume percentage of cementite is about 1.0% to 2.5%.

[0049] Specifically, in the room temperature microstructure of the CT150ksi continuous oil well pipe, the precipitated phase mainly includes (Ti, Nb) C. The size of the precipitated phase is about 2 to 40 nm.

[0050] On the other hand, the present invention also provides a method for preparing the above-mentioned CT150ksi continuous oil well tubular, comprising the following steps:

[0051] Step 1: smelting and pouring to obtain a billet or ingot;

[0052] Step 2: After high-temperature homogenization treatment of the billet or ingot, rolling is performed, and after rolling is completed, laminar cooling is performed and coiling is performed to obtain a rough pipe;

[0053] Step 3: After the rough pipe is subjected to rapid quenching and tempering treatment, a CT150ksi continuous oil well tubular is obtained; wherein the rapid quenching and tempering treatment includes induction quenching + induction high temperature tempering.

[0054] Specifically, in the above step 1, a converter, an electric furnace or an induction furnace may be used for smelting, and continuous casting may be used to produce billets, or mold casting may be used to produce ingots.

[0055] Specifically, the function of the above step 2 is to obtain a specific bainite-based (greater than 90%) or martensite structure by controlling rolling and coiling, and then significantly refine the grains through rapid heat treatment to improve the final performance of the material. Therefore, the specific steps of controlling the above step 2 include: heating the billet or ingot to 1150-1200°C in a heating furnace, and keeping it at 1150-1200°C for 1.5-2.5h, and rolling after taking it out of the furnace, and the rolling includes rough rolling and finish rolling.

[0056] Considering that too much reduction will lead to poor material quality and uneven surface, too little reduction will make the rolled piece difficult to control during the rolling process and prone to thickness fluctuations; therefore, the reduction of each rolling pass is controlled between 20% and 30%.

[0057] Considering that too high a start rolling temperature of finishing rolling will affect the dimensional accuracy and shape stability of the product, and increase the grain size, and too low a temperature will lead to a decrease in the mechanical properties of the steel, the start rolling temperature of finishing rolling is therefore controlled at 970-990°C.

[0058] Considering that if the final rolling temperature of fine rolling is too high, the grains in the steel will grow; if the final rolling temperature is too low, it will easily form oxide scale, hardening phenomenon and burrs of steel, further affecting the performance of steel. Therefore, the final rolling temperature is controlled at 850-900℃ to ensure that a certain amount of (Ti, Nb)C is precipitated during the rolling process.

[0059] Specifically, in the above step 2, after exiting the rolling mill, the steel is cooled to 600° C. by spraying water and then coiled to form a rough tube, ensuring that a structure mainly composed of bainite (greater than 90%) or martensite is formed.

[0060] Specifically, in the above step 2, the structure of the rough pipe includes more than 90% of bainite structure + a small amount of precipitation phase, and the precipitation phase mainly includes (Ti, Nb) C. Or the structure of the rough pipe is martensite.

[0061] Specifically, the specific steps of the above step 3 include:

[0062] S31, induction quenching: the rough pipe is induction heated to the complete austenitization temperature of 880-900℃ at a heating rate of more than 20℃ / s, and then quenched to room temperature after a short-term heat preservation of about 3-5s;

[0063] S32, induction high temperature tempering: heat the rough pipe to 590-625℃ at a heating rate of more than 20℃ / s, keep it warm for 3-5s and then air cool it to room temperature.

[0064] Specifically, in the above S31, induction quenching is to heat the rough pipe to the complete austenitizing temperature at a fast heating rate and keep it warm for a short time to obtain a grain size with significantly refined grains, while ensuring that the (Ti, Nb)C precipitated during the rolling process is not completely dissolved, further pinning the grain boundaries to prevent the grain boundaries from growing and preventing rapid coarsening, and then quenching to room temperature to obtain a complete martensitic structure.

[0065] Specifically, in the above S31, the heating rate is 20 to 50°C / s.

[0066] Specifically, in the above S32, the rough pipe is heated to 590-625°C at a heating rate of more than 20°C / s (e.g., 20-50°C / s), kept at this temperature for 3-5s, and then air-cooled to room temperature. The quenched martensite structure is transformed into a fine tempered troostite structure. By increasing the heating rate, dispersed and finely precipitated cementite can be obtained, and rapid heating increases the precipitation position of cementite. Dispersed cementite ensures good strength and toughness.

[0067] Specifically, in the above S32, rapid high-temperature tempering suppresses a large amount of dislocation recovery, while fine (Ti, Nb)C further hinders dislocation recovery, ensuring high strength, while dispersed cementite particles ensure good toughness.

[0068] Specifically, the grain size of the room temperature microstructure of the 130 ksi steel grade continuous oil well tubular product is about 4.5 μm, for example, 3 to 5 μm.

[0069] Specifically, the room temperature microstructure of the CT150ksi continuous oil well pipe includes tempered troostite + dispersed precipitated cementite + a small amount of precipitated phase, and the grain size is about 3-5 μm.

[0070] Specifically, in the room temperature microstructure of the CT150ksi continuous oil well tubular, the volume percentage of cementite is about 1.0% to 2.5%.

[0071] Specifically, in the room temperature microstructure of the CT150ksi continuous oil well pipe, the precipitated phase mainly includes (Ti, Nb) C. The size of the precipitated phase is about 2 to 40 nm.

[0072] Specifically, the above-mentioned CT150ksi continuous oil well pipe has high strength and good toughness, with a yield strength of ≥1150Pa, such as 1180-1250MPa; a tensile strength of ≥1250MPa, such as 1280-1330MPa; an elongation of ≥14%, such as 14.5%-16%; and an impact energy of ≥120J at -40°C, such as 135-150J; and fully meets the requirements of 150ksi steel grade oil well pipe.

[0073] The CT150ksi continuous oil well pipe of the present invention can obtain a CT150ksi continuous oil well pipe with high strength and excellent toughness by accurately controlling the mass percentages of elements such as C, Si, Mn, Cr, Mo, Ni, Ti, and Nb in steel.

[0074] In the preparation method of the CT150ksi continuous oil well pipe of the present invention, the initial structure before quenching and tempering is precisely controlled, and the double induction quenching and tempering process is combined to ensure that the structure of the continuous oil well pipe includes tempered troostite + dispersed cementite + a small amount of precipitation phase, thereby ensuring that it has a high strength level and a high toughness.

[0075] In the preparation method of the CT150ksi continuous oil well pipe of the present invention, a structure of tempered troostite + dispersed cementite + a small amount of precipitated phase is obtained through a rapid heat treatment process. The tempered troostite as a matrix structure has a good match of strength, toughness and plasticity, and can ensure good SSCC resistance. A small amount of (Ti, Nb) C precipitated phase hinders dislocation recovery and ensures the strength of the steel during tempering. Finally, the strength and toughness of the continuous oil well pipe of the composition of the present invention can be matched, and all meet the required range.

[0076] The CT150ksi continuous oil well pipe of the present invention has high strength and good toughness, with a yield strength of ≥1150Pa, such as 1180-1250MPa; a tensile strength of ≥1250MPa, such as 1280-1330MPa; an elongation of ≥14%, such as 14.5%-16%; and an impact energy of ≥120J at -40°C, such as 135-150J; and fully meets the requirements of 150ksi steel grade oil well pipe.

[0077] The advantages of precise control of the composition and process parameters of the continuous oil well tubing of the present invention are demonstrated below with specific examples and comparative examples.

[0078] Embodiments 1-5 of the present invention provide a CT150ksi continuous oil well tubular and a preparation method thereof. The chemical compositions of Embodiments 1-5 are shown in Table 1.

[0079] The preparation method of Examples 1-5 comprises:

[0080] (1) Using converter steelmaking and continuous casting to produce ingots;

[0081] (2) heating the above-mentioned ingot to a homogenization temperature, keeping the temperature in a constant temperature section for a period of time, then taking it out of the furnace, piercing and rolling it, and using water spray cooling to form a rough pipe at an appropriate final rolling temperature; the reduction amount of each rolling pass is between 20% and 30%; the start rolling temperature of the finishing rolling is controlled at 970-990°C; the final rolling temperature is 850-900°C; the structure of the rough pipe includes more than 90% bainite structure + a small amount of precipitation phase; or the structure of the rough pipe is martensite;

[0082] (3) The cooled rough pipe is subjected to double induction heating treatment (induction quenching + induction tempering) to obtain CT150ksi continuous oil well tubing.

[0083] The thickness of the ingots of Examples 1 to 3 is 350 mm, and the thickness of the ingots of Examples 4 and 5 is 400 mm. The specific preparation process parameters of Examples 1-5 are shown in Table 2 below, the final microstructures are shown in Table 3, and the mechanical properties are shown in Table 4. The microstructure of Example 1 after tempering is shown in Table 3. Figure 1 As shown, the microstructure of Example 2 after tempering is as follows Figure 2 As shown, the microstructure of Example 3 after tempering is as follows Figure 3 As shown, the microstructure of Example 4 after tempering is as follows Figure 4 As shown, the microstructure of Example 5 after tempering is as follows Figure 5 shown.

[0084] Table 1 Chemical composition wt%

[0085]

[0086]

[0087] Table 2 Process parameters

[0088]

[0089] Table 3 Microstructure

[0090] Serial number Microstructure Grain size Cementite content Size of precipitated phase Example 1 Tempered troostite + cementite + (Ti, Nb) C About 4.5μm 1.2％ About 5~30nm Example 2 Tempered troostite + cementite + (Ti, Nb) C About 3.8μm 1.5％ About 5~25nm Example 3 Tempered troostite + cementite + (Ti, Nb) C About 4.8μm 1.3％ About 10~30nm Example 4 Tempered troostite + cementite + (Ti, Nb) C About 5.0μm 1.1％ About 5~30nm Example 5 Tempered troostite + cementite + (Ti, Nb) C About 3.9μm 1.2％ About 10~30nm

[0091] Table 4 Mechanical properties

[0092]

[0093] The inventor has conducted a large number of experimental studies during the research process, and now uses some solutions with poor performance as comparative examples.

[0094] Comparative Example 1

[0095] This comparative example provides a steel material for continuous oil well pipes, the preparation method and components of which are shown in Tables 1 and 2 above, and the remaining methods are the same as those in Example 1, which will not be described in detail. Among them, the initial structure before quenching and tempering is ferrite + bainite. The initial structure requirements are not met, and the heating rates during quenching and tempering do not meet the requirements. C, Cr, Nb, Ni, Ti + Nb, Cr / Ni do not meet the design composition range, and its strength and toughness do not meet the design requirements.

[0096] Comparative Example 2

[0097] This comparative example provides a steel material for continuous oil well pipes, the preparation method and components of which are shown in Tables 1 and 2 above, and the remaining methods are the same as those in Example 1, which will not be described in detail. Among them, the heating rates during quenching and tempering do not meet the requirements, the total amounts of Si, Mn, Cr, Nb, Ti+Nb, C+Mn, Cr / Ni, Cr+Ni+Mo+Al do not meet the designed composition range, and its strength and toughness do not meet the designed requirements.

[0098] Comparative Example 3

[0099] This comparative example provides a steel material for continuous oil well pipes, the preparation method and components of which are shown in Tables 1 and 2 above, and the remaining methods are the same as those in Example 1, which will not be described in detail. Among them, the heating rate and quenching temperature during quenching do not meet the requirements, C, Si, Cr / Ni do not meet the design composition range, and its strength and toughness do not meet the design requirements.

[0100] The main performance test results of the comparative example are shown in Table 4 above.

[0101] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A CT150ksi continuous oil well tubular, characterized in that: The components of the CT150ksi continuous oil well pipe include, by mass percentage, C: 0.21%-0.26%, Si: 0.18%-0.28%, Mn: 1.2%-1.6%, Mo: 0.35%-0.55%, Cr: 0.45%-0.52%, Ni: 0.25%-0.3%, Al: 0.03%-0.06%, Nb: 0.02%-0.03%, Ti: 0.01%-0.02%, B: 0.0012%-0.002%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities.

2. The CT150ksi coiled oil well tubular according to claim 1, characterized in that: In the components of the CT150ksi continuous oil well pipe, the content of C+Mn is between 1.4% and 1.8%.

3. The CT150ksi coiled oil well tubular according to claim 1, characterized in that: In the components of the CT150ksi continuous oil well pipe, the content of Ti+Nb is between 0.03% and 0.045%.

4. The CT150ksi coiled oil well tubular according to claim 1, characterized in that: In the components of the CT150ksi continuous oil well pipe, Cr / Ni is between 1.5 and 1.

9.

5. The CT150ksi coiled oil well tubular according to any one of claims 1 to 4, characterized in that: The components of the CT150ksi continuous oil well pipe include, by mass percentage, C: 0.22% to 0.26%, Si: 0.18% to 0.28%, Mn: 1.2% to 1.57%, Mo: 0.35% to 0.55%, Cr: 0.45% to 0.52%, Ni: 0.25% to 0.3%, Al: 0.035% to 0.06%, Nb: 0.02% to 0.029%, Ti: 0.01% to 0.02%, B: 0.0012% to 0.002%, P: ≤0.005%, S: ≤0.005%, and the balance is Fe and unavoidable impurities.

6. The CT150ksi coiled oil well tubular according to any one of claims 1 to 5, characterized in that: The room temperature microstructure of the CT150ksi continuous oil well pipe includes tempered troostite+dispersed precipitated cementite+a small amount of precipitated phase.

7. The CT150ksi coiled oil well tubular according to claim 6, characterized in that: In the room temperature microstructure of the CT150ksi continuous oil well pipe, the volume percentage of cementite is 1.0% to 2.5%.

8. A method for preparing CT150ksi continuous oil well tubular goods, characterized in that: The preparation method is used to prepare the CT150ksi continuous oil well tubular according to any one of claims 1 to 7, and the preparation method comprises the following steps: Step 1: smelting and pouring to obtain a billet or ingot; Step 2: rolling the billet or ingot after high temperature homogenization treatment, and coiling after laminar cooling to obtain a rough tube; the rough tube structure includes more than 90% bainite structure, or the rough tube structure is martensite; Step 3: After rapid quenching and tempering treatment of the rough pipe, a CT150ksi continuous oil well tubular is obtained; wherein the rapid quenching and tempering treatment includes induction quenching + induction high temperature tempering.

9. The preparation method according to claim 8, characterized in that: In step 3, the induction quenching step includes: induction heating the rough pipe to a complete austenitizing temperature at a heating rate of more than 20°C / s, keeping the temperature for a short time, and then quenching to room temperature.

10. The preparation method according to claim 8 or 9, characterized in that: In step 3, the step of induction high temperature tempering includes: induction heating the rough pipe to 590-625°C at a heating rate of more than 20°C / s, keeping the temperature for a short time and then air cooling to room temperature.

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