Development of Extra-high-strength Anti-collapse Casing

The salt bed stratum in Dongpu depression area of Zhongyuan Oilfield is developed so well that it is required that the uniaxial collapse strength of the casing must be no less than 103 MPa so as to cope with the severe geological conditions. A non-API Φ180 mm×11.51 mm casing is designed for easy connection with the API Φ177.8 mm×10.36 mm and Φ177.8 mm×11.51 mm casings as designed and used in both the upper and lower casing strings. Then the BG160TT extra-high-strength anti-collapse casing of the said non-API size is produced by means of the clean steel manufacturing technology. The preparation result shows that the said casing features such characteristics as yield strength ≥1 210 MPa,impact energy≥110 J,and collapse strength ≥110 MPa. Such extra-high-strength anticollapse casings have been successfully used in the well of Dongpu depression area of Zhongyuan Oilfield.