Category: Dates of. Web site: Materials. Design. nssmc.com/

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1 Title of Innovation: ULTRA HIGH STRENGTH CRA SM TM Nominee(s) Masayuki SAGARA, Nippon Steel & Sumitomo Metal Corporation Yohei OTOME, Nippon Steel & Sumitomo Metal Corporation Naoki SAWAWATARI, Nippon Steel & Sumitomo Metal Corporation Hisashi AMAYA, Nippon Steel & Sumitomo Metal Corporation Masaaki IGARASHI, Nippon Steel & Sumitomo Metal Corporation Category: Materials Design Dates of Innovation Development: From Apr.2005 to Jan Web site: nssmc.com/ Summary Description: Exploration for extreme High Pressure High Temperature (x HPHT) of thesee types of reservoirs requires usage of high hydrocarbon reserves with corrosive environments has been increasing. The development value CRA (Corrosion Resistant Alloy) seamless oil country tubular goods (OCTG) that contain large amounts of noble elements such as chromium and nickel. NSSMC s conventional CRA (e.g. SM and 125, type 4c material defined in NACE MR0175/ISO ) is one of most popular grades in oil & gas industry. However, the industry needs more high strength gradess for x HPHT corrosive deeper well applications. The higher nitrogen contents in the austenitic alloy are positive to enhance the strength, especially after cold working but negative in the hott workability and also corrosion resistance 1

2 in the harsh environments. NSSMC has developed the ultra high strength CRA OCTG (140ksi grade, SM ) meant for high pressure, high temperature gass well development applications by raising the nitrogen content to strengthen the material. In addition, rare earth micro alloying resulted in enhancing the corrosion resistance, as well as improving the hot workability. The key technology for breakthrough in the consistent of the strength, productivity and corrosion resistance is the appropriate alloying of rare earth metal. The mechanism of the positive effect of rare earth micro alloying is resolved. Shipments of such OCTG have already begun. 2

3 Full Description: How does the innovation work? Exploration for extreme High Pressure High Temperature (x HPHT) hydrocarbon reservoir with corrosive environments has been increasing. The development of these types of reservoirs requires usage of high value CRA seamless oil country tubular goods (OCTG) that contain large amounts of noble elements such as chromium and nickel. NSSMC s conventional CRA (e.g. SM and 125, type 4c material defined in NACE MR0175/ISO ) is one of most popular grades in oil & gas industry. However, the industry needs more high strength grades for x HPHT corrosive deeper well applications. NSSMC has developed the ultra high strength CRA OCTG (140ksi grade, SM ) meant for high pressure, high temperature gas well development applications by raising the nitrogen content to strengthen the material. In addition, rare earth micro alloying resulted in enhancing the corrosion resistance, as well as improving the hot workability. SM is suitable for the usage in x HPHT deeper wells with corrosive media condition. When and how was the innovation developed? From Apr.2005 to Jan How or why is the innovation unique? The conventional SM2535 in type 4c material is 110ksi or 125ksi, but the innovated grade is 140ksi, which can be most suitable for the deeper well application in x HPHT exploration. What type of corrosion problem does the innovation address? Stress Corrosion Cracking in severe sour environment is addressed. What is the need that sparked the development of the innovation? Industrial needs for developing x HPHT wells motive the development of high strength CRA. Are there technological challenges or limitations that the innovation overcomes? The most challengeable technological barrier was the consistent of the strength, productivity and corrosion resistance. 3

4 What are the potential applications of the innovation?? The usage for the hydrocarbon developmen t in x HPHT deeper wells. Figure 1 Regional Conceptual Model Ultra Deep Playy Onshore to Shelf to Deepwater. 1) 1) Nakamizu, Oil & Gas Review,Vol.44,No.7,P.73,(2010) How does the innovation provide an improvement over existing methods, techniques, and technologies? Regarding chemical composition, the nitrogen content of the CRA increases the strength of material. In addition, rare earth micro alloying resulted in enhancing the corrosion resistance, as well as improving the hot workability. Table 1 Mechanical properties of SM TM Grade SM SM New grade SM YS, ksi TS, ksi Elongation, % Figure 2 shows the change in the ratio of reduction in area at SSRT 2) for two alloys (REM free and REM added). Adding REM improves SCCC resistance.. REM free REM added Ratio of reduction in area Figure 2 Effect of REM on SCC resistance evaluated with SSRT. (0.7MPaH 2 S, 25%NaCl+ +0.5%CH 3 COOH) 4

5 2) NACE Standard TM Item No , NACE International (2004). Figure 3 shows typical TEM microstructuress of thin foilss for two alloys in tension. As shown in this figure, the dislocations in REM free alloy arranges inn a planar configuration. On the other hand, REM added alloy has a cellular dislocation structure. Figure 3 The effect of REM on dislocation structure. Figure 4 shows schematic illustrations showing how thee dislocation substructures affect on the SCC resistance of the alloys. It is considered that the alloys with the planar dislocation substructure produce a large slip step at surface caused by the consecutive dislocation slipss on the same slip plane. This leads to a break out of the passive film on the surface and thus corrosion takes place very easily there. It is also considered that the large slip causes a stress concentration to the surface and grain boundary which may also initiate SCC. To reduce the susceptibility to SCC of the alloys in sour environments, one can change the dislocation substructure by changing the elements such as REM. It is found that a small amount of REM changes the dislocation substructure very effectively from planar to cellular one which does not generatee large slip steps at surface, resulting in less susceptibility to SCC in the sour environment. (a)planar Structure Passive Film (b)cellular Structure Dislocation Slip Line Metal Surface Small Strain Corrosion Area Corrosion Area : Large Stresss Concentration : Large Poor SCC Resistance Large Corrosion Area : Small Stress Concentrationn : Small Richh SCC Resistance Figure 4 Schematic image of relationshipp with dislocation and SCC. 5

6 What type of impact does the innovation have on the industry/industries it serves? For x HPHT deeper wells, it was impossible to design the well structure using 110 or 125ksi CRAs. The innovationn makes to be possible to design thee well with cost effectivee solutions. Does the innovationn fill a technology gap? If so, please explain the technological need and how it was addressed prior to the development of the innovation.. Conventional CRA such as 110 or 125 ksi grades with heavy wall is needed for x HPHT deeper wells. But developedd material can make the productionn efficient for oil & gas and the well design reasonable. Has the innovation been tested in the laboratory or in the field? If f so, please describe any tests or field demonstrations and the results that support the capability and feasibility of the innovation. Evaluation test for SCC susceptibility of newly developed alloy shown in table 2 was carried out in sour environment. Table 3 provides long term 4PBB test results for developed alloy and referencee sample. After corrosion test, samples were investigated by means of observation on cross sectional microstructure. Any test samples even high strength material (A, B) did not suffer from SCC. Through the evaluation test by constant strain method, it is cleared that the developed material has sufficient SCC resistance in sourr environment. Table 2 Chemical composition of tested material. Mark Cu Ni A B C Cr Mo N REM yes yes none Yield Strength (ksi) Elongation(%) Hardness(HRC) Notation 34.0 Developed alloy 36.3 Developed alloy 31.0 Referenced alloy Table 3 Long term four point bend test results of developed alloy. (100psi H 2 S, 25%NaCl with 0.5%CH 3 COOH, 6 month duration) 6

7 Is the innovation commercially available? If yes, how long has it been utilized? If not, what is the next step in making the innovation commercially available? Yes. The 1 st shipment was 2011 Are you aware of other organizations that have introduced similar innovations? If so, how is this innovation different? No. Are there any patents related to this work? If yes, please provide the patent title, number, and inventor. Yes. PUBLICATION_NUMBER; WO TITLE_OF_INVENTION: HIGH STRENGTH Cr Ni ALLOY PRODUCT AND SEAMLESS OIL WELL PIPES INVENTOR: OTOME YOHEI [JP]; IGARASHI MASAAKI [JP]; AMAYA HISASHI [JP]; OKADA HIROKAZU [JP] 7