摘要
API 5C3抗内压屈服设计的基本原理是管内壁屈服即失效,实际上,管内壁开始屈服并不会丧失密封和结构的完整性,内壁屈服在实际试验和现场应用中都体现不出来,爆裂能真实体现套管丧失密封的完整性。当裂纹深度大于管壁厚的5%时,失效形式是一种裂纹扩展失稳,应釆用基于断裂力学理论的裂纹失稳断裂公式来预测套管的断裂压力,并与ISO的韧性爆裂压力对比,以二者中小者为准。ISO10400:2007给出了油井套管的JIC值,由JIC和油井套管临界应力强度因子KIC的关系可求得油井套管的KIC值,根据KIC与预测断裂压力的失效评估图(failure assessment diagram,FAD)就可以预测出不同裂纹深度油井套管的抗内压断裂强度。FAD为油井套管的抗内压设计提供了一种重要的参考依据。
The basic principle of API 5C3 anti-pressure design is that casing yield is failure. Actually, casing yield does not result in the loss of internal pressure and structural integrity. Casing yield at the inner wall cannot be reflected in test and in field. Burst failure can truly represent the loss of internal pressure integrity and structural integrity. When the crack width is more than 5 % of the wall thickness, the failure is crack expansion instability. The burst failure pressure should be calculated using the theory of fracture mechanics, the calculated result should be compared with ISO ductile rupture value, and the smaller one should be used as casing fracture pressure. The casing and tubing Jic values were given in ISO 10400：2007 and the casing and tubing critical stress intensity factor（KIC）can be obtained by the correlation between JIC and KIC. The fracture pressure of casing with various crack width can be predicted by failure assessment diagram（FAD）. FAD provides an important reference for well casing anti-pressure safety design.
出处
《石油钻探技术》
CAS
北大核心
2009年第6期35-38,共4页
Petroleum Drilling Techniques
基金
国家新世纪优秀人才支持计划项目"高含H2S气藏完井管柱设计及其可靠性研究"(编号:NCET-08-0907)
四川省杰出青年学科带头人培养基金项目"石油膨胀管关键技术研究"(编号:06ZQ026-028)资助
关键词
油井
套管
抗压强度
破坏强度
预测
oil well
casing
compressive strength
collapse strength
prediction
