Development Of Q125 Steel Casing For Shale Gas

At the beginning of this century,the United States made a breakthrough in shale gas extraction technology,taking the lead in the commercial exploitation of shale gas,and profoundly affected the pattern of the world's energy supply and had a profound impact on politics,setting off a boom in the development of shale gas worldwide.China is rich in shale gas resources,and is the first country after the United States to enter the shale gas exploration and evaluation breakthrough and industrial development pilot stage.At present,relatively mature shale gas development areas in China are mainly concentrated in sichuan and chongqing,and a number of pilot areas have been established nationwide.With the support of national policies,China's shale gas exploitation technology continues to advance and the industry develops rapidly,generating a large number of oil well tubing demand and driving the rise of China's seamless pipe industry.By studying the service conditions and main failure modes of shale gas exploitation,this paper considers that only the special shale gas pipe with high strength and high toughness can meet the complicated service conditions of shale gas Wells in China,and designs and screens the 25CrMoBVRE material for the development of Q125 steel grade casing for shale gas exploitation.In the laboratory study,the CCT curve of 25CrMoBVRE experimental steel was measured by FORMASTOR-F automatic phase change analyzer.The A_C11 and A_C33 of the experimental steel were 683?and 805?respectively.The end quenching test method was used to determine the hardenability of the experimental steel.The results showed that the 25CrMoBVRE had good hardenability,and within 20.5mm90%martensite could be guaranteed.The study of heat treatment process shows that the experimental steel is heat-treated by quenching at 880?and tempering at 620?.The microstructure of the experimental steel is tempered sostenitic,the grain size is above grade 9,the strength to toughness ratio of the material is more than 10,and the performance indexes meet the design requirements.Articles at the same time the role of rare earth elements in the experimental steel was studied,the study found that25CrMoBVRE steel grade of rare earth elements on cast macrostructure of the billets have certain improvement effect,and rare earth elements on steel after heat treatment of the metallographic microstructure refinement effect to a certain extent,and rare earth for inclusion shape control,especially for sulfur,the role of oxygen in the form of inclusion of change is good,improve the transverse impact performance of the material,but the tensile properties of the rare earth elements on the experiment of steel hardenability and the effect is not obvious.On 25CrMoBVRE steel grade for laboratory research,for shale gas in baotou steel tube company dedicated Q125 grade of steel casing for phi?270 round billet production and specifications for the?177.8 x 9.19 mm tube body and?194.46 x 16mm collar of industrial development,trial production results conform to the technical requirements of shale gas is special grade steel Q125 casing,and through the third party evaluation experiment of Xi'an institute of tube...