复杂井筒条件下套管有效强度研究

发布时间：2017-12-31 17:35

本文关键词：复杂井筒条件下套管有效强度研究　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：常规套管强度设计没有考虑非均布外载和水泥环的影响,故论文提出了复杂井筒条件下套管有效强度的计算方法。利用该方法校核固井后套管有效强度,为后期压裂酸化和多级分段压裂等增产措施提供指导性技术指标,还能结合井下复杂情况分析套变井的套变机理,这些都是论文研究成果在现场的应用方向。特此说明,论文中的套管强度特指套管抗挤强度,有效抗挤强度就是套管在多种因素作用下的实际抗挤能力。由于目前套管强度研究缺少实验验证,论文采用自主设计的机械式套管受力模拟试验装置进行实验研究,与液压式装置相比,机械式套管受力模拟试验装置具有可以模拟多种非均布外载、实验操作简单和试验成本较低的优点。通过大量试验,将实验结果与理论计算、有限元分析相互印证,进一步完善复杂井筒条件下套管有效强度计算方法。套管受力模拟实验研究表明:非均布外载导致套管抗挤强度减少12.8%,局部外载条件下套管抗挤强度大幅度降低。水泥环保护套管的作用比较明显,套管100%居中条件下高强度韧性水泥环可以卸去27.4%的外载;套管偏心导致水泥环卸载作用降低,套管居中度为30%时和100%居中相比,水泥环卸载能力降低6.9%,这一数值在椭圆非均布外载下为2.9%,说明在现场非均布地应力条件下,套管偏心对水泥环的卸载作用影响不大;相比弹性模量,水泥石屈服强度对水泥环的卸载作用影响更大;套管和水泥环的胶结对水泥环的卸载作用几乎没有影响。另外,大主应力正对偏心窄间隙时水泥环的卸载能力更低。
[Abstract]:The conventional casing strength design does not consider the influence of non-uniform load and cement ring, so this paper puts forward a calculation method of casing effective strength under complex wellbore conditions. This method is used to check the casing effective strength after cementing. For the later fracturing acidification and multi-stage fracturing and other production measures to provide guidance technical indicators, but also can be combined with the downhole complex situation to analyze the casing variation mechanism. These are the application directions of the research results in the field. Here, the casing strength in the paper specifically refers to the casing anti-squeezing strength. Effective squeezing strength is the actual anti-squeezing ability of casing under the action of many factors. At present, the research of casing strength is lack of experimental verification. In this paper, the mechanical casing force simulation test device designed by ourselves is used to carry out experimental research. Compared with the hydraulic device, the mechanical casing force simulation test device can simulate a variety of non-uniform external loads. The advantages of simple operation and low test cost. Through a large number of experiments, the experimental results and theoretical calculation, finite element analysis mutually verified each other. Further improve the effective strength calculation method of casing under complex wellbore conditions. The experimental results of casing stress simulation show that the casing anti-squeezing strength is reduced by 12.8% due to non-uniform external load. Under the condition of local external load, the strength of casing collapsing is greatly reduced. The effect of cement environmental protection casing is obvious. Under the condition of casing 100%, the high strength and toughness cement sheath can remove 27.4% of external load. Casing eccentricity reduces the unloading effect of cement sheath. When the casing centrality is 30 and 100%, the unloading capacity of cement sheath is decreased by 6.9, which is 2.9% under elliptical non-uniform load. The results show that the eccentricity of casing has little effect on the unloading of cement sheath under the condition of non-uniform in-situ stress. Compared with the elastic modulus, the yield strength of cement stone has more influence on the unloading of cement ring. The cementation of casing and cement sheath has little effect on the unloading of cement sheath. In addition, the unloading capacity of cement sheath is lower when the large principal stress is being applied to the eccentric narrow gap.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE931.2

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