| 摘要: |
| 针对目前油井水泥混合料配比设计困难、缺乏合理颗粒级配模型的现状，基于分形几何理论建立了颗粒群分 形连续级配模型。利用激光粒度测试仪分析了级配原材料的粒径分布状况，并将分形级配模型与Andreasen方程进 行对比,得到实现最紧密堆积的分形维数范围。结合塔里木现场要求取分形维数为2. 561,优化设计出浆体密度为 1-40 g/cm3的三元体低密度水泥浆体系，并对体系性能进行了室内评价。结果表明，该体系水泥石抗压强度(24 h) 大于18.4 MPa,养护压力对强度影响很小,水泥浆失水量和游离液含量较低,稠化和流变性能满足要求,体系稳定性 好,验证了体系粒径分布的合理性和分形级配模型的可行性。 |
| 关键词: 颗粒级配 分形级配模型 固井 低密度水泥 试验评价 |
| DOI： |
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| 基金项目:国家“863”高技术研究发展计划项目(2006AA09Z340) |
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| Design and evaluation of oil well cement system based on fractal grading theory |
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CHENG Rong-chao, WANG Rui-he, WANG Cheng-wen, BU Yu-huan
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(College of Petroleum Engineering in China University of Petroleum，Dongying 257061, China)
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| Abstract: |
| In view of the present situation of oil well cement for the difficulty in solid mixture proportion design and the lack of appropriate particle size distribution model，a fractal successive grading model for particle group was established based on the fractal geometry theory. The particle size distribution for grading raw materials was analyzed by the particle size laser test machine, and the fractal grading model was compared with Andreasen equation to obtain the fractal dimension range for the closest packing effect. In accordance with the field requirements of Tarim Oilfield, the fractal dimension was set as 2. 561, and a ternary light weight cement slurry system with slurry density of 1. 40 g/cm3 was optimized and designed. Meanwhile, in-house evaluation was conducted on the properties of the developed cement system. The results show that the compressive strength of ternary system was improved larger than 18. 4 MPa(24 h) for set cement, and the curing pressure has negligible effect on the strength. The system also shows lower fluid loss and free water content, favorable consistence development, rheological property and stability for cement slurry. Hence，the rationality of particle size distribution for the developed system and the feasibility for the proposed fractal grading model are both validated. |
| Key words: particle size distribution fractal grading model cementing light weight cement experimental evaluation |
