Different role of oil casing and processing technology
The oil casing pipe is a kind of large diameter pipe, which has the function of fixing the wall of oil and gas well or well. The casing is inserted into the well hole and fixed with cement to prevent the borehole from separating the rock formation and the borehole collapse, and ensuring the circulation of the drilling mud to be used for drilling. Different types of casing pipes used in the oil production process: surface layer oil casing protection drilling to avoid contamination of shallow water and shallow gas reservoirs, support the wellhead equipment and maintain the weight of the other layers of the casing. Technical oil casing - separate the different levels of pressure, so that the normal circulation of drilling fluid and protect the production casing. Oil casing - the oil and natural gas from the ground under the storage layer is derived, for the protection of drilling, drilling mud layer. When the oil casing is produced, the outside diameter is usually 114.3 mm to 508 mm.
27MnCrV steel AC1=736 C AC3=810 C, when the heating temperature of Subcritical Quenching selected at 740-810 DEG C. Select the quenching heating temperature of 780 DEG C, soaking time 15min quenching; tempering after quenching from 630 degrees Celsius temperature, tempering holding time 50min. Because of Subcritical Quenching heating in the alpha + gamma quenching in the two-phase region, retain some undissolved ferrite state, while maintaining high strength and toughness is improved.
At present, the technology has been applied in the steel processing factory, quality assurance data show that the yield strength of steel after heat treatment at Rt0.6 820-860MPa Rm in 910-940MPa, the tensile strength and impact toughness of Akv in 65-85J, the survivability of 100% qualified. The data show that 27MnCrV steel is high grade oil casing is quite good, on the other hand also shows that the Intercritical Hardening Process is an excellent method to avoid the high temperature brittle steel products.
At the same time, low temperature lower tempering temperature, reducing stress hardening, thus reducing the quenching deformation, so as to ensure the smooth operation of heat treatment production, provides a good material for the follow-up and thread machining etc..
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