沥青基材料改善油井水泥环形变能力的研究

发布时间：2018-09-08 12:53

【摘要】：固井水泥石长期处于井下高温高压工作环境,还通常遭受来自钻采等工况带来的载荷冲击。然而,水泥石是一种天生硬、脆材料,形变能力差,因此容易在复杂应力作用下损伤失效,丧失层间封固的作用。因此,常规水泥石难以在井下环境中长期服役,对井筒完整性的安全和管理带来一定的隐患和潜在风险。面对这一矛盾问题,论文以对水泥石力学特性进行改造为出发点,引入沥青基材料到水泥浆体系中,对水泥石做韧性化改造,改善其变形协调能力,这项研究对保障油气井长期开采的安全和质量有一定的价值和意义。沥青基材料用于油井水泥石力学改性是国内首次尝试,有必要开展系统的研究。本文在对国内外研究现状进行充分调研的基础上结合实验室课题研究的条件,对石油沥青进行了改性处理,解决了沥青与水泥浆的相容性问题,并对改性沥青水泥浆体系的密度、流动性、API滤失量、稠化时间、收缩性等工程性能影响规律进行了测试,建议最佳掺量2%。本文对沥青水泥石抗压强度、劈裂抗拉强度测试,得出了不同改性沥青掺量的影响规律；对沥青水泥石单轴、三轴、三轴循环应力-应变规律展开了实验和分析,实验研究了2%改性沥青掺量下在软化点温度上下的应力一应变曲线变化规律,对实验参数弹性模量、泊松比、峰值应力、峰值应变等力学参数进行了讨论,定性分析了沥青水泥石在变形过程中的改善程度。为建立水泥石形变能力有效的评价方法,必须与水泥环层间封固性能相关。基于研究的需要,开发一种水泥环力学损伤失效模拟装置,探索了水泥环两种不同的失效方式,以此建立两个不同的力学形变参数来量化评价水泥环的层间封固能力。通过实验研究和理论分析,以脆性系数为基础的形变参数C和以本构方程为基础的形变参数H建立了力学参数与水泥环层间封固能力之间的关系,这种新的评价方法适用于油井水泥石的力学完整性评价,同时用C、H来评价沥青水泥石的力学性能,证明沥青水泥石的层间封固能力提高。最后,利用X射线衍射仪、孔渗仪、电子扫描显微镜等微观检测手段,对沥青材料改性水泥石的成分变化、孔渗特性、微观结构进行观察分析实验,并对水泥石力学改性机理进行了阐述。由此,论证结果表明沥青的掺入确有大幅改善油井水泥环形变能力的作用,论文最后也提出了相应的改进建议,为沥青水泥浆体系的进一步研究、改进和应用奠定了基础。
[Abstract]:Cementing cement stone is in the working environment of underground high temperature and high pressure for a long time, and it is usually subjected to load shock from drilling and production conditions. However, cement stone is a kind of natural hard, brittle material and poor deformation ability, so it is easy to damage and fail under complex stress and lose the effect of interlaminar sealing. Therefore, it is difficult for conventional cement stone to serve in underground environment for a long time, which brings some hidden trouble and potential risk to the safety and management of wellbore integrity. In the face of this contradiction, the paper takes the mechanical properties of cement stone as the starting point, introduces the asphalt base material into the cement slurry system, and improves the deformation coordination ability of the cement stone by making the toughness transformation of the cement stone. This study has certain value and significance to ensure the safety and quality of oil and gas wells. It is the first attempt to use asphalt base material in the modification of oil well cement stone, so it is necessary to carry out systematic research. In this paper, the petroleum asphalt was modified on the basis of the research status at home and abroad, and the compatibility between asphalt and cement slurry was solved. The effects of density, fluidity, API filtration, thickening time and shrinkage on the properties of modified asphalt cement slurry were tested, and the optimum dosage of 2 was suggested. In this paper, the compressive strength and splitting tensile strength of asphalt cement stone are tested, and the influence law of different modified asphalt content is obtained, and the uniaxial and triaxial cyclic stress-strain law of asphalt cement stone is tested and analyzed. The variation law of stress-strain curve at softening point temperature of 2% modified asphalt was studied experimentally. The experimental parameters such as elastic modulus, Poisson's ratio, peak stress, peak strain and other mechanical parameters were discussed, such as elastic modulus, Poisson's ratio, peak stress, peak strain and so on. The improvement degree of asphalt cement stone during deformation is analyzed qualitatively. In order to establish an effective evaluation method of cement stone deformation ability, it must be related to cement ring interlaminar sealing performance. Based on the need of research, a mechanical damage simulation device for cement ring is developed, two different failure modes of cement ring are explored, and two different mechanical deformation parameters are established to quantitatively evaluate the interlaminar sealing ability of cement ring. Through experimental study and theoretical analysis, the relationship between mechanical parameters and cementing ability of cement ring is established by means of deformation parameter C based on brittleness coefficient and deformation parameter H based on constitutive equation. The new evaluation method is suitable for evaluating the mechanical integrity of oil well cement stone, and the mechanical properties of asphalt cement stone are evaluated by Con H, which proves that the interlayer sealing ability of asphalt cement stone is improved. Finally, by means of X-ray diffractometer, poroosmograph and electron scanning microscope, the composition change, pore permeability characteristics and microstructure of asphalt modified cement stone were observed and analyzed. The mechanism of mechanical modification of cement stone is expounded. As a result, the results show that the mixing of asphalt can greatly improve the annular ability of oil well cement. At last, the corresponding suggestions are put forward, which will lay a foundation for the further study, improvement and application of asphalt cement slurry system.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE256

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