基于KT模型的椭圆度对套管抗挤强度的影响

Effect of ovality on casing collapse strength based on KT model

 范森¹ 陈顶峰² 冯雷³ 冯福平¹ 雷扬¹ 韩旭¹

东北石油大学石油工程学院，黑龙江 大庆 163318 中国石油吉林油田扶余采油厂，吉林 松原 138000 中海油能源发展股份有限公司工程技术分公司，天津 300452）

College of Petroleum Engineering, Northeast Petroleum University, Daqing 163318, China Fuyu Oil Production Plant, Jilin Oilfield Company, Songyuan 138000, China Engineering Technology Company, CNOOC Energy Technology ＆ Services Limited, Tanggu 300452, China)

 椭圆度会降低套管的抗挤强度，但对其影响程度及规律并未得到统一认识。文中以考虑因素较为全面的KT抗挤强度计算模型为基础，建立了椭圆度与套管抗挤强度关系模型。研究结果认为：套管的抗挤强度随椭圆度的增大而降低，但降低趋势逐渐变缓；套管的抗挤强度降低值随径厚比（D/t）的增大呈先增大后减小的趋势，存在一个临界D/t值，可使椭圆形套管的抗挤强度降低值最大；钢级越高，椭圆形套管的抗挤强度降低值最大的临界D/t值越小。文中较为全面地揭示了椭圆度对套管抗挤强度的影响程度及规律，进一步深化了椭圆度对套管抗挤强度影响的认识。

 The ovality can reduce the casing collapse strength, but the effect of ovality on casing collapse strength is uncertain. Based on the collapse strength of KT model and calculation of the average outer diameter of the casing, the calculation model of ovality and casing collapse strength was established. The conclusions are obtained: the casing collapse strength decreases with the increase of ovality, but the trend slows down gradually; the lost of casing collapse strength increases with the increase of D/t at first and then decreases, there is a critical value of D/t which can get the maximum lost of collapse strength; the critical value of D/t is small when the grade of casing is high, it means that the maximum lost of collapse strength in high grade of casing with ovality happens when D/t is small. The result reveals the degree and rule of the effect of ovality on casing collapse strength, which can further deepen the understanding of the effect of ovality on casing collapse strength.

10.6056/dkyqt201703029