Sample surface grinding method for detecting hydrogen sulfide cracking resistance of petroleum drilling tool

Abstract

The invention discloses a sample surface grinding method for hydrogen sulfide cracking resistance detection of a petroleum drilling tool, which belongs to the technical field of metal component surface grinding, and comprises the working procedures of sample clamping, sample surface rough grinding, sample surface fine grinding, detection, grinding for removing detection traces and sample surface polishing. According to the method, operation is carried out strictly according to set procedures, and abrasive paper applied in the rough grinding procedure and the fine grinding procedure is required to move relative to the surface of the sample. The sample surface polishing procedure is the core technology of the method and is an important technical means for achieving the standard reaching of the surface phase roughness of the sample, and in the polishing process, water plays a role of a polishing agent, so that the mirror surface effect is easily formed on the surface of the sample. Equipment applied to the method is a common horizontal lathe, small and medium-sized enterprises in the industry are configured, and equipment obstacles and technical obstacles do not exist when the method is implemented. In addition, consumables used in the method are easy to obtain and low in cost, so that the application cost is low, and the matching requirements of batch production are completely met.

Description

Technical Field

[0001] The present invention belongs to a technical solution in the technical field of metal component surface grinding. Specifically, the present invention relates to a sample surface grinding method for detecting hydrogen sulfide cracking resistance of petroleum drilling tools. Background Art

[0002] Oil drilling tools are one of the main tools for oil drilling. They are subjected to huge mechanical stress and corrosive environment during the drilling process. During the drilling stage, they have to transmit torque and bear the accumulated weight of many drill pipe sections. With the increase of drilling depth, the well conditions have become more complicated. The complex conditions of the underground formations have put forward higher requirements on the performance of drilling tools. In particular, the hydrogen sulfide contained in the underground formations has strong corrosiveness on the surface of the drill pipe, which may cause stress corrosion cracking and seriously affect the service life and safety of the drilling tools. This problem has become the main reason for the failure of special drill pipes. In view of the above situation, ensuring the reliability of drilling tools and ensuring that the drilling tools have good resistance to hydrogen sulfide cracking has become a core issue that must be solved in drilling engineering.

[0003] The drill pipe in oil drilling tools is usually made of high-strength alloy steel (such as 26CrMo48VN6), which has excellent strength and toughness. However, despite the excellent mechanical properties of this material, its resistance to hydrogen sulfide corrosion is still poor, and it is prone to cracking and corrosion. Therefore, during the production process of drilling tools, hydrogen sulfide cracking resistance must be tested to ensure that they meet safety and reliability standards. To this end, the American Petroleum Institute (API) has specially formulated relevant industry standards, which require drilling tools to be tested for hydrogen sulfide cracking resistance during production.

[0004] Existing methods for detecting hydrogen sulfide cracking usually require high-precision grinding of the sample surface in order to effectively detect microscopic cracks. This detection method has extremely strict requirements on the roughness of the sample surface, especially in the early stage of hydrogen sulfide cracking, when the cracks are extremely small and microscopic in the early stage of the cracking. Therefore, the surface of the sample to be detected is required to be nearly mirror-like flat. In order to meet this requirement, traditional grinding processes still rely on high-precision and expensive imported grinding equipment in some cases. In recent years, some high-end equipment composed of a combination of grinders and polishers has appeared on the market, which can efficiently and finely process the surface of the sample. However, the high cost of these equipment makes it difficult for small and medium-sized enterprises to afford them, and due to technical barriers and government trade policy restrictions, these equipment are also very difficult to obtain domestically. Therefore, there is an urgent need for a grinding technology that can reduce costs and is efficient so that small and medium-sized enterprises can achieve high-quality hydrogen sulfide cracking detection in production.

[0005] In addition, the prior art also involves a portable hydrogen sulfide detection device and a detection method for oil drilling sites. Patent CN101737040A discloses a hydrogen sulfide detection device and a detection method for oil drilling sites. The device includes a detection instrument and a pre-treatment separation box, wherein the pre-treatment separation box is provided with an air flow distribution device for separating and pre-treating samples for subsequent detection. This portable device is mainly aimed at hydrogen sulfide detection under field conditions, and can achieve rapid detection of hydrogen sulfide to a certain extent. However, the device mainly focuses on on-site gas detection, and does not involve a detection method for the resistance of the drill tool surface to hydrogen sulfide cracking. Therefore, this technology cannot directly solve the problem of precision machining of the drill tool surface and high-precision surface roughness requirements, nor can it meet the high-standard detection requirements for the resistance of the drill tool to hydrogen sulfide cracking.

[0006] In summary, although the existing technology involves hydrogen sulfide detection and surface treatment, it still has obvious deficiencies in meeting the requirements of high-precision surface roughness and reducing the cost of equipment and consumables. In particular, the high cost, operation complexity and technical requirements of existing grinding technology and equipment have become the main obstacles for small and medium-sized enterprises in realizing anti-hydrogen sulfide cracking detection. Therefore, the development of a low-cost, easy-to-operate grinding method that can achieve high-precision surface quality is a technical problem that needs to be solved urgently in the current technical field. Summary of the invention

[0007] The present invention aims to solve the problems of high cost, technical difficulty and operation complexity, surface quality that cannot meet the requirements, low production efficiency and high equipment requirements in the existing detection technology, and proposes a sample grinding method for oil drilling tool anti-hydrogen sulfide cracking detection, which is simple and easy to operate, has a significant polishing process effect, guarantees high-precision surface quality, has low equipment requirements, strong adaptability, stable processing quality, high production efficiency and low application cost.

[0008] The present invention achieves the technical objectives through the following technical solutions.

[0009] A sample surface grinding method for detecting hydrogen sulfide cracking of petroleum drilling tools, characterized in that it comprises the following steps: S1. Clamping the sample: Clamp the tube-shaped oil drill pipe sample through the three-jaw chuck configured on the horizontal lathe, adjust the lathe spindle speed to control it within the range of 1700-1900 rpm, and after correction, the coaxiality error of the clamped sample and the lathe spindle coaxiality error is ≤0.05mm; S2, rough grinding of sample surface: the rough grinding of sample surface is implemented in four steps. The first step is to use 400 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 12-18 minutes. After rough grinding, the surface roughness of the sample reaches Ra3.2μm; the second step is to use 600 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 8-12 minutes. After rough grinding, the surface roughness of the sample reaches Ra1.6μm; the third step is to use 800 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 4-6 minutes. After rough grinding, the surface roughness of the sample reaches Ra0.8μm; the fourth step is to use 1000 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 4-6 minutes. After rough ring grinding, the surface roughness of the sample reaches Ra0.4μm; S3, sample surface fine grinding: the sample surface fine grinding is completed in two steps. The first step is to use 1200 mesh fine steel sandpaper for sample surface fine grinding. This stage of grinding takes 4-6 minutes. After fine grinding, the surface roughness reaches Ra0.2μm. The second step is to use 1600 mesh ultra-fine steel sandpaper for sample surface fine grinding. This stage of grinding takes 1-2 minutes. After fine grinding, the surface roughness reaches Ra0.1μm. S4, testing process: geometric dimensions and hardness testing of the finely ground tube-shaped oil drill pipe specimens; S5. Grinding to remove detection marks: Use 1200 mesh fine steel sandpaper to grind the residual detection marks on the surface of the sample for 1 to 2 minutes, and then use 1600 mesh ultra-fine steel sandpaper to finely grind the residual detection marks on the surface of the sample for 1 to 2 minutes. After fine grinding, the surface roughness of the sample reaches Ra0.1μm; S6. Sample surface polishing: Sample surface polishing is a composite process, including conventional polishing, water polishing and fine polishing. In the conventional polishing, the sample surface is polished with a diamond sand polishing agent with a particle size of 3.5 μm. After the conventional polishing is performed for 18-22 seconds, the water polishing is performed. The water polishing lasts for 20-30 seconds, and the operation is performed alternately at least three times. Finally, a clean cotton flannel cloth is soaked in water and fine polished for 30 to 40 seconds. After fine polishing, the surface roughness of the sample reaches Ra0.05 μm.

[0010] As a further improvement, during the polishing process of the sample surface, polishing agent or water is used alternately, and the switching time between water polishing and conventional polishing does not exceed 3 seconds each time.

[0011] As a further improvement scheme, the water used in the process of polishing the sample surface is distilled water at room temperature. In the polishing process, the water used is distilled water at room temperature, and water and polishing agent are used alternately in the polishing process, which reduces the use of chemical polishing agents, reduces the impact on the environment, and also reduces the cost of chemical consumables in production, which is in line with the concept of sustainable development.

[0012] As a further improvement, the cotton linter cloth used in the fine polishing process is a long cotton linter product.

[0013] As a further improvement, the cotton flannel cloth used in the fine polishing process needs to be soaked in water for ≥10 minutes until it is saturated with water before use for fine polishing the sample surface.

[0014] As a further improvement, in the rough grinding process and the fine grinding process, there is relative movement between the sandpaper and the sample surface, including sequentially implemented circumferential movement and axial forward and backward movement. The relative movement between the sandpaper and the sample surface ensures the uniformity of grinding.

[0015] As a further improvement, during the polishing of the sample surface, the particle size of the polishing agent used in the conventional polishing process is 1-5 μm.

[0016] As a further improvement plan, during the rough grinding and fine grinding of the sample surface, the contact pressure between the sandpaper and the sample surface is controlled within the range of 0.5-1.5N / cm², and during the polishing of the sample surface, the amount of polishing agent used is 0.05-0.1g / cm², and the polishing agent is evenly distributed on the sample surface to ensure the grinding uniformity and surface quality. To ensure the consistency of the polishing effect, the consistency of the surface quality in each process is effectively guaranteed, thereby greatly improving the stability of the product and the pass rate of sample inspection.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention uses fine graded grinding and polishing processes to ensure that the surface roughness meets the standard while ensuring that the sample surface reaches a mirror-like effect, and the surface roughness can reach Ra0.05μm. This technical solution can meet the strict requirements of hydrogen sulfide cracking resistance detection for high-precision surface quality, and effectively solves the problem that the surface roughness in the prior art cannot meet the detection requirements.

[0018] The grinding method of the present invention shortens the overall processing time through reasonable process arrangement, and each step of the operation has clear time control (the time range of each grinding step), ensuring the consistency and efficiency of the processing. Compared with the high-precision equipment in the prior art, the present invention can not only maintain good processing quality, but also greatly improve production efficiency and meet the needs of large-scale production.

[0019] The present invention adopts a composite method of conventional polishing, water polishing and fine polishing in the polishing process, and the particle size of the polishing agent is moderate. The alternating use of water polishing and conventional polishing ensures that the sample surface achieves a mirror effect and removes residual detection traces. The long cotton flannel used in the fine polishing process can more efficiently remove surface unevenness after being soaked in water, and finally the sample surface achieves an ultra-fine effect of Ra0.05μm, which meets the requirements of hydrogen sulfide cracking resistance detection.

[0020] The present invention uses low-cost, easily available grinding consumables such as sandpaper and polishing agent. Compared with the prior art that needs to rely on high-precision imported equipment (such as a combination of a grinder and a polisher), the present invention significantly reduces the procurement cost of equipment and consumables, and does not require high supporting equipment, and small and medium-sized enterprises have supporting capabilities. This has great economic advantages for small and medium-sized enterprises, can effectively reduce production costs, does not require expensive equipment to be invested, reduces technical barriers, and enhances market competitiveness. The grinding method of the present invention has clear steps, simple operation, and is easy to implement. Unlike traditional high-precision equipment that requires complex operations and professional training of technicians, the present invention can be completed on relatively simple equipment, and the operator can get started without excessively high technical barriers. This makes the method suitable for production lines of various sizes, especially small and medium-sized enterprises, with greater operability and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a 50-fold magnification of the surface roughness of the sample R after grinding.

[0022] Figure 2 This is a 50-fold magnification of the surface roughness of the parallel section of the sample after grinding. DETAILED DESCRIPTION

[0023] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments.

[0024] The present invention discloses a sample surface grinding method for testing hydrogen sulfide cracking resistance of petroleum drilling tools, which comprises the steps of clamping the sample, rough grinding of the sample surface, fine grinding of the sample surface, testing, grinding to remove the testing traces, and polishing the sample surface. The method uses a step-by-step approach to achieve fine processing of the sample surface, and the steps are arranged as follows: ① The sample clamping process is a positioning process. This embodiment is a sample of an 8-inch oil drill pipe. The pipe segment sample is clamped by a three-jaw chuck configured on a horizontal lathe, and its rotation speed is controlled within the range of 1700 to 1900 rpm. The rotation speed in this embodiment is set to 1800 rpm. The clamped sample must be calibrated before processing, and the coaxiality error between the sample and the lathe spindle is required to be ≤0.05mm.

[0025] ② The rough grinding process of the sample surface is implemented in four steps. The first step is to use 400 mesh ordinary diamond sandpaper for rough grinding. The grinding time at this stage is 15 minutes. After rough grinding, the surface roughness of the sample reaches Ra3.2μm. The second step is to use 600 mesh ordinary diamond sandpaper for rough grinding of the sample surface. The grinding time at this stage is 10 minutes. After rough grinding, the surface roughness of the sample reaches Ra1.6μm. The third step is to use 800 mesh ordinary diamond sandpaper for rough grinding of the sample surface. The grinding time at this stage is 5 minutes. After rough grinding, the surface roughness of the sample reaches Ra0.8μm. The fourth step is to use 1000 mesh ordinary diamond sandpaper for rough grinding of the sample surface. The grinding time at this stage is 5 minutes. After rough grinding, the surface roughness of the sample reaches Ra0.4μm.

[0026] ③ The sample surface fine grinding process is still a basic process, which is arranged after the surface rough grinding process. The surface fine grinding process is divided into two steps. The first step uses 1200 mesh fine diamond sandpaper for sample surface fine grinding. This grinding time is 5 minutes. After fine grinding, the sample surface roughness reaches Ra0.2μm. The second step uses 1600 mesh ultra-fine diamond sandpaper for sample surface fine grinding. This stage of grinding takes 2 minutes. After fine grinding, the sample surface roughness reaches Ra0.1μm.

[0027] ④ The detection process is an auxiliary process, which is arranged after the fine grinding process and is used to detect the geometric size and hardness of the sample.

[0028] ⑤ The grinding process for removing traces is a supplement to the detection process. When implemented, first use 1200 mesh fine diamond sandpaper to grind the residual detection traces on the sample surface for 2 minutes, and then use 1600 mesh ultra-fine diamond sandpaper to finely grind the residual detection traces on the sample surface for at least 1 minute. After fine grinding, the surface roughness of the sample reaches Ra0.1μm.

[0029] ⑥ The sample surface polishing process is a composite process and is also the last process of the method. It includes a conventional polishing process, a water polishing process and a fine polishing process. The conventional polishing process uses a diamond sand polishing agent with a particle size of 3.5μm to polish the sample surface. After the conventional polishing process is implemented for 20 seconds, it is changed to a water polishing process. The water polishing lasts for a total of 25 seconds. This alternating operation is performed at least three times, and the switching time between the polishing agent and water does not exceed 3 seconds each time. The water used in the polishing process of the present invention is room temperature distilled water, which must be kept clean. The last process is the fine polishing process. The purpose of implementing this process is to achieve a sample surface roughness that meets or exceeds the industry standard Ra0.25μm requirement. This process clearly requires the use of clean cotton flannel cloth, and the cotton flannel cloth is a high-quality long cotton flannel product. The cotton flannel cloth must be immersed in water before fine polishing. The immersion process lasts at least 10 minutes. The cotton flannel cloth saturated with water can be used for fine polishing. The fine polishing process takes a very short time. In this embodiment, the surface roughness level of the sample is significantly improved in only 30 seconds. Its Ra is only 0.05μm, which exceeds the industry standard requirement of Ra0.25μm for the surface roughness of the sample.

[0030] In addition to strictly following the established procedures, the implementation of this method also requires that the sandpaper used in the rough grinding process and the fine grinding process have relative movement with the sample surface. The relative movement includes sequentially implemented circumferential movement and axial forward and backward movement. The implementation of this technical measure is aimed at further improving the quality and efficiency of grinding and polishing. It only takes four hours to produce a set of three samples that fully meet the requirements of industry standards, and the annual qualified rate of samples is more than 95%.

[0031] The sample surface polishing process is the core technology of the method and an important technical means to achieve the standard surface roughness of the sample. During the polishing process, water plays the role of a polishing agent because water molecules are ultra-fine and have a good polishing effect, making it easy for the sample surface to form a mirror effect.

[0032] Compared with the existing high-end grinding equipment, the present invention has lower requirements for supporting equipment. The grinding method uses an ordinary horizontal lathe and simple grinding and polishing equipment to complete the entire process. Small and medium-sized enterprises do not need to invest in expensive equipment, which reduces technical barriers and enhances the universality and adaptability of the method. Ordinary horizontal lathes are equipped in small and medium-sized enterprises in this industry. There are no equipment barriers or technical barriers to the implementation of this method. In addition, the consumables used in this method are easy to obtain and cheap, so the application cost is low, which fully meets the supporting needs of mass production. The surface roughness of the sample after grinding reaches a mirror effect, far exceeding the maximum roughness requirement of Ra0.25μm, and the test pass rate is increased in a leap. Before the invention of this method, the pass rate of the samples of the same material and the same performance against hydrogen sulfide cracking was less than 10%; the pass rate of the samples made using the present invention reached more than 95%. At the same time, the previous grinding time was shortened. It took more than 2 days to grind three samples before, and the pass rate of the sample test was very low. After adopting the grinding method of the invention, all production and grinding of three samples can be completed within 4 hours; 3 Break the monopoly of foreign equipment and use a simple method to achieve the sample roughness effect of foreign confidential equipment.

[0033] In summary, the present invention has significant advantages in reducing production costs, improving processing quality and production efficiency, and enhancing the adaptability and operability of the method. It not only solves the contradiction between surface roughness and detection requirements in the prior art, but also provides a low-cost and high-efficiency solution for small and medium-sized enterprises, which helps to promote the development of oil drilling tool anti-hydrogen sulfide cracking detection technology.

[0034] It should be noted that, in the present invention, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0035] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features of the invention described herein.

Claims

1. A sample surface grinding method for detecting hydrogen sulfide cracking of petroleum drilling tools, characterized in that: The following steps are involved: S1. Clamping the sample: Clamp the tube-shaped oil drill pipe sample through the three-jaw chuck configured on the horizontal lathe, adjust the lathe spindle speed to control it within the range of 1700-1900 rpm, and after correction, the coaxiality error of the clamped sample and the lathe spindle coaxiality error is ≤0.05mm; S2, rough grinding of sample surface: the rough grinding of sample surface is implemented in four steps. The first step is to use 400 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 12-18 minutes. After rough grinding, the surface roughness of the sample reaches Ra3.2μm; the second step is to use 600 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 8-12 minutes. After rough grinding, the surface roughness of the sample reaches Ra1.6μm; the third step is to use 800 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 4-6 minutes. After rough grinding, the surface roughness of the sample reaches Ra0.8μm; the fourth step is to use 1000 mesh ordinary diamond sandpaper for rough grinding of sample surface. The grinding time at this stage is 4-6 minutes. After rough ring grinding, the surface roughness of the sample reaches Ra0.4μm; S3, sample surface fine grinding: the sample surface fine grinding is completed in two steps. The first step is to use 1200 mesh fine steel sandpaper for sample surface fine grinding. This stage of grinding takes 4-6 minutes. After fine grinding, the surface roughness reaches Ra0.2μm. The second step is to use 1600 mesh ultra-fine steel sandpaper for sample surface fine grinding. This stage of grinding takes 1-2 minutes. After fine grinding, the surface roughness reaches Ra0.1μm. S4, testing process: geometric dimensions and hardness testing of the finely ground tube-shaped oil drill pipe specimens; S5. Grinding to remove detection marks: Use 1200 mesh fine steel sandpaper to grind the residual detection marks on the surface of the sample for 1 to 2 minutes, and then use 1600 mesh ultra-fine steel sandpaper to finely grind the residual detection marks on the surface of the sample for 1 to 2 minutes. After fine grinding, the surface roughness of the sample reaches Ra0.1μm; S6. Sample surface polishing: Sample surface polishing is a composite process, including conventional polishing, water polishing and fine polishing. In the conventional polishing, the sample surface is polished with a diamond sand polishing agent with a particle size of 3.5 μm. After the conventional polishing is performed for 18-22 seconds, the water polishing is performed. The water polishing lasts for 20-30 seconds, and the operation is performed alternately at least three times. Finally, a clean cotton flannel cloth is soaked in water and fine polished for 30 to 40 seconds. After fine polishing, the surface roughness of the sample reaches Ra0.05 μm.

2. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 is characterized in that: During the polishing process of the sample surface, polishing agent or water is used alternately, and the switching time between water polishing and conventional polishing does not exceed 3 seconds each time.

3. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 is characterized in that: The water used in the sample surface polishing process is distilled water at room temperature.

4. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 is characterized in that: The cotton linter cloth in the fine polishing process is made of long cotton linter.

5. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 or 4, characterized in that: The cotton flannel cloth used in the fine polishing process needs to be soaked in water for ≥10 minutes until it is saturated with water before use, and is used for fine polishing of the sample surface.

6. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 is characterized in that: In the rough grinding process and the fine grinding process, there is relative movement between the sandpaper and the sample surface, including circumferential movement and axial forward and backward movement implemented sequentially.

7. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 or 2, characterized in that: During the polishing process of the sample surface, the particle size of the polishing agent used in the conventional polishing process is 1-5 μm.

8. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 is characterized in that: During the rough grinding and fine grinding of the sample surface, the contact pressure between the sandpaper and the sample surface is controlled within the range of 0.5 to 1.5 N / cm² to ensure grinding uniformity and surface quality.

9. The sample surface grinding method for oil drilling tool anti-hydrogen sulfide cracking detection according to claim 1 is characterized in that: During the sample surface polishing process, the amount of polishing agent used is 0.05-0.1 g / cm², and the polishing agent is evenly distributed on the sample surface to ensure the consistency of the polishing effect.

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