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| Research on the Mechanical and Anti-corrosion Properties of a New Type of Oil Well Pipe |
| Received:September 29, 2020 Revised:November 19, 2020 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.01.013 |
| KeyWord:00Cr9 9Cr oil well pipe mechanical properties corrosion resistance properties |
| Author | Institution |
| GU Lin |
CNOOC Research Institute Co., Ltd., Beijing , China |
| FENG Huan-zhi |
CNOOC Research Institute Co., Ltd., Beijing , China |
| ZHOU Ding-zhao |
CNOOC Research Institute Co., Ltd., Beijing , China |
| HE Song |
CNOOC Research Institute Co., Ltd., Beijing , China |
| XING Xi-jin |
CNOOC Research Institute Co., Ltd., Beijing , China |
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| Abstract: |
| This article aims to evaluate the tensile strength, impact toughness, hardness and threaded connection and other mechanical properties and anti-corrosion properties of a new type of oil well pipe steel 00Cr9, which provides a theoretical basis for the use of the new material. In terms of mechanical properties, according to GB/T228-2002 Metallic Material - Tensile Testing at Room Temperature, the 00Cr9-110 grade steel samples (2) were tested for tensile strength and yield strength; referring to API SPEC 5CT (2011 ), the materials (2 samples) were tested for the Charpy V-notch impact toughness (CVN absorption energy); and 00Cr9 pipe (00Cr9-110 grade) and martensitic stainless steel 13Cr were conducted for microscopy Vickers hardness comparison test. At the same time, an experimental analysis on the threaded connection performance of 00Cr9 pipe was carried out with the National Supervision and Inspection Center for Petroleum Pipe Quality. In terms of anti-corrosion properties, the corrosion resistance against carbon dioxide (CO2) and hydrogen sulfide (H2S) was evaluated through the corrosion weight loss test and anti-stress corrosion cracking (SCC) test under hydrogen sulfide environment. During the corrosion simulation experiment, a magnetic drive reactor is used to simulate the actual corrosion environment. During the experiment, the speed of the kettle is adjusted to drive the test piece to simulate the flow rate; the designed conditions for SCC test under normal temperature and pressure are as follows:the solution is NACE A solution, the load is 80% of the actual yield strength, the temperature is 24 ℃, the test gas is 0.1 MPa H2S, the test period is 30 days, and the method of loading strength includes C-ring and uniaxial stretching. The research results show that compared with the conventional 13Cr pipe material, 00Cr9 material reduces the carbon content in the metal, refines the grain structure, homogenizes the impurities in the steel, and reduces the structural defects in the metallography, such improving the mechanical strength and corrosion resistance properties of the oil well pipe, and greatly enhancing the efficiency of on-site work. The tensile strength and impact toughness of this material meet the requirements, the Vickers hardness (HV1=256) has slightly exceeded the standard hardness (specified as HV1<250), and the threaded connection performance reaches the standard. The pitting corrosion rate in the low-temperature environment with CO2 is very small, mainly uniform corrosion, and the corrosion weight loss meets the requirements. The stress corrosion cracking sensitivity is high, and sulfide stress corrosion cracking is prone to occur, so it does not meet the NACE MR0175 sulfur resistance requirements. It is recommended to be used in downhole environment below 90 ℃, with CO2 and without H2S. At present, the price of 00Cr9 oil well pipe is lower than ordinary 13Cr pipe. With large-scale application in the Bohai Sea area, the oilfield development costs can be reduced. It is expected to replace the currently commonly used 13Cr oil well pipe in the Bohai Sea in the future. |
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