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对于套管挤毁问题较为严重的油气水井，采用非API标准的特厚壁套管来提高其抗挤强度，是今后预防套管挤毁的重要发展方向。目前，特厚壁套管的抗挤强度计算和尺寸系列尚未形成工业标准，文章提出特厚壁套管的抗挤强度计算方法和尺寸系列，供设计者和厂家参考。API/ISO套管挤毁工作组曾对本文公式进行了测评，结果曼示具有较高的计算精度。大量计算表明，特厚壁套管的抗挤强度大大提高，约为加厚前原套管抗挤强度的1．5～4倍，甚至6倍。最后还介绍了特厚壁套管在中原油田的现场应用情况。

Collapsing Strength Calculation and On-Site Application of Extra-Heavy Wall Casing

??In regard to the oil/gas/water well with seriously collapsed casing,it is an importantly developing trend for preventing casing from being collapsed to apply non API extra heavy wall casing to raising collapsing strength.Th industrial standard of the collapsing strength calculation and size series of extra heavy wall casing hasn't yet formed at present.In the paper,the collapsing strength calculation method and size series of the extra heavy wall casing are put forward,thus giving a reference to designers and production units.The formulas proposed in the paper were evaluated by API/ISO casing collapsing work team and the results indicate that these formulas are of relatively high accuracy.Through a lot of calculation it is shown that the collapsing strength of the extra heavy casing is greatly increased,being larger than that of the original casing (before thickening) by 1.5??4 times,even by 6 times.Finally,the on site application of the extra heavy wall casing in Zhongyuan Oil Field is also preliminarily introduced in the paper.