Steel for heat-resistant high-strength sleeve and preparation process of steel

Abstract

The invention discloses steel for a heat-resistant high-strength sleeve and a preparation process of the steel. The steel consists of the following chemical components in percentage by weight: 0.10-0.25% of C, 0.10-0.30% of Si, 0.70-1.30% of Mn, 0.05-0.30% of Hf, 0.001-0.006% of B, 0-0.20% of Mo, 0-0.25% of W, 0-0.15% of Nb, 0-0.20% of Ta, 0-0.18% of Ti, 0-0.18% of Zr, 0.01-0.20% of RE, not greater than 0.008% of P, not greater than 0.004% of S and the balance of Fe. According to the steel for the heat-resistant high-strength sleeve and the preparation method of the steel, a high-temperature deformation quenching process is adopted for the whole sleeve, so that a relatively high dislocation density and other deformation defects are kept to obtain the sleeve with uniform tissue and high toughness; a medium-temperature section long-time thermal insulation process and a high-temperature section short-time thermal insulation process are adopted, so that relatively high strength is kept and the toughness is remarkably improved; elements such as Nb, W, Hf, Mo, Re and the like are added and quickly cooled to a temperature lower than 260 DEG C to preserve the heat for a long time, so that heat resistance, high strength, high toughness and high impact resistance of the sleeve are effectively guaranteed.

Description

technical field [0001] The invention relates to a casing for high-temperature, high-pressure oil and gas wells or thermal recovery wells, in particular to a heat-resistant high-strength casing steel and a preparation process thereof, belonging to the field of ferrous metal smelting and pipe making. Background technique [0002] With the expansion of the onshore exploration field and the development of deep layers, the temperature and pressure in the well will increase accordingly. In China, Tarim Oilfield is the representative. The reservoir burial depth is generally 5000m, the deepest can reach 7830m, and the formation pressure is generally 105MPa, the highest can reach 184MPa, The highest formation temperature is generally 130°C, and the highest can reach 176°C. High temperature reduces the yield strength and elastic modulus of the casing, and high pressure increases the external pressure on the casing, both of which increase the service risk of the pipe. Offshore oil and...

AI Technical Summary

Problems solved by technology

The average temperature of steam injection in thermal recovery wells is about 320°C, and some of them exceed 350°C. At the same time, due to the loose cementation of the formation of heavy oil, sand is easy to produce during the oil recovery process, causing the formation to move, thereby causing the casing to collapse, deform, and dislocate. Breakage and other casing damage

Moreover, during the injection-production and recovery processes, the casing undergoes repeated cold and heat deformation, resulting in periodic tensile and compressive stresses, which can easily lead to fatigue failure of ordinary casings. Therefore, it is necessary to develop heat-resistant high-strength casings.