湘西北页岩气储层的物理力学特性试验研究及脆性评价

发布时间：2018-07-03 09:32

本文选题：页岩气储层 + 牛蹄塘组　；参考：《湖南科技大学》2017年硕士论文

【摘要】：全球经济快速发展,各国对能源的需求不断攀升。页岩气作为一种分布广泛的新型清洁能源,它的开发受到了各国的重视。当前,页岩气的主要开采方式是对页岩气储层进行压裂增产改造;而页岩气储层的物理力学特性对增产改造有着重要影响,储层的脆性评价又是其可压裂性评价的重要内容之一,因此开展对页岩气储层的物理力学特性研究和脆性评价对页岩储层的可压裂性评价及我国页岩气开发技术瓶颈的突破具有重要理论价值和实践意义。本文以湘西北某地区寒武系牛蹄塘组的页岩为研究对象,通过调研地质资料、踏勘现场了解了页岩储层所在地区的基本地层特征;通过称量法测得并分析了页岩在干燥、自然和饱和状态下的密度、含水率等基本物理特征;利用X粉末衍射仪进行X衍射实验,分析了页岩储层的矿物组分;利用扫描电镜观察和分析了页岩的矿物晶体相貌和孔隙结构特征;利用RYL-600剪切流变仪和RMT-150B岩石力学试验机对岩样开展了单轴压缩、三轴压缩和劈裂试验,获得并分析了页岩在单轴压缩条件下不同含水状态时的强度与变形特征、在三轴压缩条件下(围压分别为10MPa、25MPa和40MPa)的强度与变形特征以及在劈裂条件下的强度与变形特征;在调研分析国内外岩石脆性评价方法的基础上,结合本文实验所得数据运用不同脆性指数对页岩储层进行了脆性评价,并对评价结果进行了对比分析。研究结果表明本文页岩储层:(1)结构致密,天然含水率低且饱和含水率低于1%;脆性矿物含量较高,粘土矿物含量相对较低;微孔隙及微裂缝较为发育。(2)单轴抗压强度平均为102.54MPa,杨氏模量平均为27.85GPa,泊松比平均为0.23;随着含水率的增加,单轴压缩强度降低,泊松比提高;单轴压缩破坏时的应变为0.32%~0.74%,页岩在达到峰值强度后迅速炸裂破坏。随着围压的增加,页岩的抗压强度增加,杨氏模量也增加;三轴压缩条件下的破坏模式主要有单剪切破坏与劈裂破坏,破坏后残余强度与峰值强度比值低。劈裂时抗拉强度平均为11.07MPa,页岩达到峰值强度后迅速破坏,无残余强度。(3)不同脆性评价方法得出的评价结果不一致,综合对比分析后得:湘西北牛蹄塘组页岩脆性良好,适合压裂增产改造。
[Abstract]:With the rapid development of global economy, the demand for energy is rising. Shale gas is widely distributed as a new clean energy, its development has been paid attention to. At present, the main way of producing shale gas is fracturing and improving shale gas reservoir, and the physical and mechanical characteristics of shale gas reservoir have an important influence on the production increase and transformation. The evaluation of reservoir brittleness is one of the important contents of fracturing evaluation. Therefore, it is of great theoretical value and practical significance to study the physical and mechanical properties of shale gas reservoir and evaluate its brittleness for the fracturing evaluation of shale reservoir and the breakthrough of technical bottleneck of shale gas development in China. In this paper, the shale of Cambrian Niutetang formation in a certain area of northwest Hunan Province is taken as the research object, the basic stratigraphic characteristics of the area where the shale reservoir is located are understood on the spot by investigation and geological data, and the dryness of the shale is obtained and analyzed by the weighing method. The basic physical characteristics of natural and saturated state, such as density, water cut and so on, are analyzed by X powder diffractometer, and the mineral components of shale reservoir are analyzed by X powder diffractometer. The mineral crystal appearance and pore structure characteristics of shale were observed and analyzed by scanning electron microscope, uniaxial compression, triaxial compression and splitting tests were carried out by RYL-600 shear rheometer and RMT-150B rock mechanics tester. The strength and deformation characteristics of shale under uniaxial compression are obtained and analyzed. The strength and deformation characteristics of shale under triaxial compression (10 MPA and 40 MPA, respectively) and under splitting condition are obtained and analyzed. On the basis of investigation and analysis of rock brittleness evaluation methods at home and abroad, different brittleness indices are used to evaluate shale reservoir brittleness in combination with the experimental data in this paper, and the evaluation results are compared and analyzed. The results show that the shale reservoirs in this paper are: (1) the structure is compact, the natural water content is low and the saturated water content is lower than 1%, the brittle mineral content is high, the clay mineral content is relatively low; The average uniaxial compressive strength, Young's modulus and Poisson's ratio are 102.54 MPA, 27.85 GPA and 0.23 respectively, and the uniaxial compressive strength decreases and Poisson's ratio increases with the increase of moisture content. The strain of uniaxial compression failure is 0.32 and 0.74, and the shale burst quickly after reaching the peak strength. With the increase of confining pressure, the compressive strength and Young's modulus of shale increase, and the failure mode under triaxial compression mainly includes single shear failure and split failure, and the ratio of residual strength to peak strength is low. The average tensile strength during splitting is 11.07 MPA, and the shale is destroyed rapidly after reaching the peak strength without residual strength. (3) the evaluation results obtained by different brittleness evaluation methods are not consistent. The comprehensive comparative analysis shows that the shale brittleness of Niutetang formation in northwest Hunan is good. It is suitable for fracturing and increasing production.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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