龙马溪组硬脆性页岩水化实验研究

发布时间：2018-02-08 20:09

本文关键词： 硬脆性页岩龙马溪组页岩水化作用自吸吸水率物理化学作用力学作用　出处：《西南石油大学学报(自然科学版)》2016年03期 　论文类型：期刊论文

【摘要】：硬脆性页岩水化对页岩气开发井壁稳定有重要的影响,为此,对龙马溪组硬脆性页岩进行水化实验研究,包括矿物组成、微观结构、水化应力、自吸吸水率及岩芯浸泡等方面实验研究,探讨分析了硬脆性页岩水化过程与机理。研究结果表明,页岩黏土矿物以伊利石为主,黏土矿物呈片状且定向排列,层理和微裂纹发育,为水化提供作用空间和流动通道;页岩水化应力和自吸吸水率随浸泡时间增加而先上升后趋于稳定,页岩组构对上升速率或幅度有重要影响;浸泡过程中,岩样表面主要形成平行层里面的裂缝,随着浸泡时间增加,岩样保持完整性或水化剥落成碎块,页岩组构和胶结程度对页岩水化程度有重要影响;页岩水化是物理化学作用和力学作用相互耦合结果,前者使岩石断裂韧性下降,后者使Ⅰ型裂纹应力强度因子增大,当应力强度因子大于岩石断裂韧性时,裂纹将扩展或增宽,逐渐形成宏观裂纹,可进一步扩展成裂缝。
[Abstract]:The hydration of hard brittle shale has an important effect on the stability of shale gas development wellbore. Therefore, the hydration experiments of hard brittle shale in Longmaxi formation are carried out, including mineral composition, microstructure, hydration stress, etc. In this paper, the hydration process and mechanism of hard brittle shale are discussed and analyzed. The results show that the shale clay is dominated by Illite, and the clay mineral is in the form of sheet and directional arrangement. Bedding and microcrack development provide space and flow channel for hydration, hydration stress and self-suction water absorption of shale increase first and then stabilize with the increase of soaking time, shale fabric has an important effect on the rising rate or amplitude. The fracture in parallel layer is mainly formed on the surface of rock sample. With the increase of soaking time, the rock sample remains intact or hydrated and spalling to pieces, and shale fabric and cementation degree have important influence on shale hydration degree. Shale hydration is the coupling result of physicochemical action and mechanical action. The former makes the fracture toughness of rock decrease, while the latter makes the stress intensity factor of mode I crack increase. When the stress intensity factor is larger than the fracture toughness of rock, the crack will expand or widen. A macroscopic crack is gradually formed, which can be further expanded into a crack.
【作者单位】： "油气藏地质及开发工程"国家重点实验室·西南石油大学;西南石油大学地球科学与技术学院;
【基金】：国家自然科学基金联合基金重点项目(U1262209);国家自然科学基金(51274172)
【分类号】：TE21

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