漂珠低密度水泥石力学性能分析和材料改性研究

发布时间：2018-04-22 21:31

本文选题：低密度水泥石 + 力学性能　；参考：《西南石油大学》2016年硕士论文

【摘要】：漂珠低密度水泥浆体系在低压、易漏地层的安全固井中发挥着重要作用,在我国西部高温深井和储气库井的固井中应用广泛。低密度水泥浆在井下凝固成水泥环后的封固能力直接关系到油气井的安全和生产寿命。目前国内对于漂珠低密度水泥浆体系的研究以满足工程应用为主,对水泥石长期力学性能的研究存在不足。因此,本文通过模拟现场工况对漂珠低密度水泥浆体系的力学性能进行深入的测试与分析,针对水泥石力学性能存在的不足,优选纤维材料进行力学改性,保障低密度水泥环在井下的长期封固能力。本文在对国内外研究现状进行充分调研的基础上,模拟现场工况对漂珠低密度水泥浆体系进行了全面、详细、深入的力学实验评价。测试了不同龄期、不同温度环境下水泥石的抗压强度、抗拉强度、单轴和三轴下水泥石的力学性能、循环载荷下水泥石的力学性能；对水泥石的孔径大小分布、微观形貌、孔隙度和渗透率大小进行了测试分析,从微观结构的角度分析了水泥石的宏观力学现象；通过水泥环力学模型、完整性实验和损伤理论等方法分析水泥环的失效机理；通过优选纤维材料来改善漂珠低密度水泥石的力学性能。本文在实验研究和理论研究的基础上,形成了如下结论：(1)漂珠低密度水泥石具有较好的抗压强度,而抗拉强度降低,抗拉与抗压强度之比较小；(2)通过循环加载实验发现,水泥石在第一周的循环加载中发生了较大的压实形变,在第二至第五周的加载中水泥石具有较好的弹性形变能力,在第六和第七周的加载中水泥石的塑性形变大幅增加,说明水泥石在多周加载之后内部结构产生破坏,丧失弹性形变的能力；(3)通过水泥环力学模型进行了计算,在高内压状态下水泥环主要表现为拉伸失效,水泥环上部和中部封固段的封固能力较好,下部封固段的封固能力不足,有待于提高；(4)通过完整性实验装置进行实验发现,漂珠低密度水泥环在高温养护环境下易发生本体开裂现象,而水泥浆体系在水化过程中产生的碱骨料反应是导致水泥环开裂的重要原因；(5)优选出FK纤维可以有效的提高低密度水泥石的抗拉强度和形变恢复能力,有效改善漂珠低密度水泥环在高温养护下的开裂现象；(6)掺入FK纤维后漂珠低密度水泥浆的流动性、API失水、稠化时间、沉降稳定性满足现场施工的要求。
[Abstract]:Bleach low density cement slurry system plays an important role in the safe cementing of low pressure and easy leakage formation and is widely used in high temperature deep wells and gas storage wells in western China. The sealing ability of low density cement slurry is directly related to the safety and production life of oil and gas wells. At present, the research on the low density cement slurry system is mainly to meet the engineering application, but the study on the long-term mechanical properties of cement stone is insufficient. Therefore, in this paper, the mechanical properties of the low density cement slurry system are tested and analyzed by simulating the field working conditions, aiming at the shortcomings of the mechanical properties of cement stone, the mechanical modification of the fiber material is selected. The long-term sealing ability of low density cement ring is guaranteed. Based on the investigation of the present research situation at home and abroad, this paper makes a comprehensive, detailed and in-depth mechanical experimental evaluation of the low density cement slurry system with drifted beads under simulated field conditions. The compressive strength, tensile strength, mechanical properties of uniaxial and triaxial sewers and the mechanical properties of cement stones under cyclic loading were tested under different ages and temperatures. The porosity and permeability are tested and analyzed, the macroscopic mechanical phenomena of cement stone are analyzed from the point of view of microstructure, the failure mechanism of cement ring is analyzed by means of cement ring mechanics model, integrity test and damage theory, etc. The mechanical properties of bleach low density cement stone were improved by optimizing the fiber material. Based on the experimental and theoretical studies, the following conclusions have been obtained in this paper: (1) the low density bleach cement stone has better compressive strength, while the tensile strength is lower, and the ratio of tensile strength to compressive strength is small. In the first week of cyclic loading, the cement stone has a large compaction deformation. During the second to fifth weeks of loading, the cement stone has a better elastic deformation ability, and the plastic deformation of the cement stone increases significantly during the sixth and seventh weeks of loading. It shows that the internal structure of cement stone is destroyed after multi-cycle loading, and the ability to lose elastic deformation is calculated by the mechanical model of cement ring. Under high internal pressure, the cement ring is mainly characterized by tensile failure. The sealing ability of the upper and middle parts of the cement ring is better than that of the lower part, which needs to be improved. Under the high temperature curing environment, the floating bead low density cement ring is prone to cracking. The alkali aggregate reaction in the hydration of cement slurry system is an important cause of cement ring cracking. FK fiber can effectively improve the tensile strength and deformation recovery ability of low density cement stone. It is effective to improve the cracking phenomenon of bleach low density cement ring under high temperature curing. After adding FK fiber, the flowing water loss, thickening time and settling stability of floating bead low density cement slurry can meet the requirements of site construction.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TE256

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