基于岩石细观力学的裂缝闭合机理研究

发布时间：2018-03-09 10:13

本文选题：裂缝　切入点：微凸体　出处：《西南石油大学》2016年硕士论文　论文类型：学位论文

【摘要】：在裂缝性地层中进行钻井和生产时,常由于裂缝开度的变化而引起堵漏失效、储层应力敏感等一系列工程问题。研究裂缝的闭合行为,建立裂缝闭合模型来预测其开度的变化能够有效解决以上问题。裂缝的宏观闭合变形来源于细观尺度下的微凸体变形,前人在对微凸体的力学行为进行假设后建立了众多的裂缝闭合模型。但目前尚未有针对岩石微凸体力学性质的实验研究,人们也并不清楚其实际变形过程。因此开展针对微凸体力学性质的研究,有助于进一步从细观角度认识裂缝的闭合变形机理,有利于降低裂缝性地层中的钻井成本和提升裂缝性油气藏的开采效果。本文以四川须家河组致密砂岩为研究对象,基于岩石细观力学,以CT扫描技术、力学实验、数值仿真为手段,对微凸体的细观非均质结构及其力学性质进行了系统地研究。本文完成的主要研究内容如下：(1)利用高精度显微CT机扫描重构了真实微凸体的细观非均质结构,并结合岩石薄片矿物分析结果,建立了真实微凸体的细观非均质模型。该模型直观地展示了微凸体的外表形貌和内部结构,为后期的数值仿真提供了基础。(2)进行了一系列的微凸体力学实验。在微凸体单调加载实验中,获得了微凸体受压变形的全程法向载荷—变形量曲线。对比后发现Hertz接触理论预测结果偏离了实验实测数据。在微凸体循环加载实验中,发现循环加载后微凸体的刚度会得到提升,但同时也在累积损伤。(3)将细观非均质模型与有限元仿真结合,发现微凸体的细观非均质结构对其变形造成了影响,从而表现出了尺寸效应。通过以上的研究,获得了真实微凸体的实际外表形貌和内部结构,了解了微凸体的实际变形过程。这有助于揭示工况变化下的地层裂缝空间动态变化与流动特征、井筒-地层耦合流动规律。同时还能为精细控压钻井、随钻堵漏、随钻储层评价、储层保护等多个领域的深入研究提供了理论依据。
[Abstract]:Drilling and production in fractured rocks, often due to the crack opening change caused by plugging failure, the reservoir should be sensitive to force a series of engineering problems. Study on crack closure behavior, the establishment of crack closure model to predict the opening change can effectively solve the above problems. The macro deformation of closed crack source in the micro asperity deformation scale, established crack closure model in many of the assumptions of the micro mechanical behavior of convex bodies. But there had been no experimental study on rock mechanical properties of the micro convex body, people do not know the actual deformation process. So the research of asperities on mechanical properties a closed, help to further understanding of the meso cracks deformation mechanism, to reduce the cost of drilling in the fractured formation and enhance the fractured oil and gas reservoir exploitation effect. Taking Sichuan to home The river was tight sandstone as the research object, the rock meso mechanics based on CT scanning technology, mechanics experiment, numerical simulation method of asperity micro inhomogeneous structure and its mechanical properties were systematically studied. The main contents of this paper are as follows: (1) the use of high precision micro CT scanning the reconstruction of the micro heterogeneous structure of micro convex body, and combined with the mineral rock thin section analysis, establish the real micro convex body micro heterogeneous model. The model visually shows the micro convex body surface morphology and internal structure, provides the basis for later simulation (2) of the numbers. The micro convex body mechanics experiment. In a series of micro convex monotonic loading experiment, obtained the whole method of asperity deformation to the load deformation curve. Compared with the theory of Hertz prediction results deviate from the experimental data. In the micro convex body Cyclic loading experiment, found after cyclic loading of micro convex body stiffness can be enhanced, but also the cumulative damage. (3) the micro heterogeneity model combined with the finite element simulation, micro convex body micro heterogeneous structure deformation caused by the impact, thus showing the size effect through the above research, the actual surface morphology and inner structure of real asperity, understand the asperity of the actual deformation. It is helpful to reveal the formation of cracks under the condition of spatial dynamic change and flow characteristics, flow regularity and wellbore formation coupling. But also for the fine controlled pressure drilling, with the plugging drilling drilling, reservoir evaluation, provides a theoretical basis for further research in many fields of reservoir protection.

【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】：TE21

【参考文献】