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| 固井界面微环隙产生机制及计算方法 |
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赵效锋1,2,管志川1,史玉才1,李涛1,廖华林1,蒋金兴1,孙宝江1
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(1.中国石油大学石油工程学院,山东青岛 266580;2.中国石化中原油田分公司石油工程技术研究院,河南濮阳 457001)
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| 摘要: |
| 针对油气井生产过程中固井界面微环隙的产生和发展规律进行仿真试验研究,并对套管-水泥环界面的黏结力进行测量,基于以上研究建立固井界面微环隙的理论计算方法。结果表明:套管内压过大导致水泥环产生塑性变形,套管内压减小时固井界面将受拉,实测固井界面存在数量级为0.1 MPa的黏结力,当界面拉力足以克服界面黏结力时,固井界面将会脱离产生微环隙;套管内压值越大,压力卸载后产生微环隙的机率越大,且微环隙尺寸越大;相同胶结质量下固井一界面比二界面更容易产生微环隙;理论计算结果与仿真试验结果具有较好的一致性。 |
| 关键词: 井筒完整性 微环隙 仿真试验 理论计算 黏结力 |
| DOI：10.3969/j.issn.1673-5005.2017.05.011 |
| 分类号::TE 21 |
| 文献标识码:A |
| 基金项目:国家自然科学基金项目(51674284);中央高校基本科研业务费专项(R1502039A, 16CX06035A) |
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| An assessment method for occurrence of micro-annular fractures on cementing interfaces of oil and gas well casing |
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ZHAO Xiaofeng1,2, GUAN Zhichuan1, SHI Yucai1, LI Tao1, LIAO Hualin1, JIANG Jinxing1, SUN Baojiang1
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(1.School of Petroleum Engineering in China University of Petroleum, Qingdao 266580, China;2.Research Institute of Petroleum Engineering, Zhongyuan Oilfield Company, SINOPEC, Puyang 457001, China)
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| Abstract: |
| The generation and development of micro-annular fractures on cementing interface of oil and gas well casing during long-term production were investigated via simulation experiments, and the bonding strength of cementing interface was measured in the experiments. Based on the experimental results, a theoretical assessment method of the micro-annular fracture was developed, and a good agreement between the experimental results and modeling was observed. The results show that an excessive inner casing pressure can lead to plastic deformation of cement sheath, while a tensile stress can be subjected on the cementing interface when the inner pressure is reduced during the casing pressure unloading process. The magnitude of the interfacial bonding strength is of 0.1 MPa as it was measured in the experiments, and micro-annular fractures can appear at the cementing interfaces when the tensile stress is sufficient high to overcome the bonding strength. The larger the inner casing pressure, the higher probability for the micro-annular fractures to occur during pressure surge, and the larger the fractures. Micro-annular fractures are more likely to appear at the first casing-cement interface due to a higher tensile stress even if the bonding strength at two interfaces is the same. |
| Key words: well integrity micro-annular fracture simulation experiment theoretical calculation bonding strength |
