The utilization of acid has been approved as a potential approach to enhance Stimulated Reservoir Volume (SRV) by creating secondary pores and microfractures in shale reservoirs. This paper proposed an acid soaking technique to quantify the generation of microfracturing behaviors. Two types of core samples from distinct shale depositional environments, namely Longmaxi carbonate-rich, and Yanchang clay-rich shale were emphasized. Hydrochloric acid (15%+ 3%KCL) was utilized to treat the shale samples for a period of 2 hours. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) experiments were performed to correlate the individual mineral phases. Inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray fluorescence tests (XRF) were utilized, to quantify the elemental analysis of the distinct mineral phases. For post acidizing test conditions, three different types of microfractures, namely stress-induced micro-fractures, acid dissolution micro-fractures, and acid shrinkage micro-fractures were observed. For the clay-rich shale, the stress-induced microfractures were more prominent within the Kaolinite and the boundary edges of the Chlorite/Biotite regions. Whereas, shrinkage micro-fractures dominated the chlorite regions. The Longmaxi carbonate-rich shale, on the other hand, revealed more evidence of the creation of acid dissolution microfractures within Anhydrite, calcite, illite, and organic matter regions. According to the ICP-OES and XRF test results, the clay-rich shale sample underwent excessive ionic imbibition, as well as an ion dislodgment mechanism. However, the carbonate-rich shale experienced only the ion dislodgment mechanism from the shale interface. No ions reverted to the shale sample as the electric equilibrium was established. This paper would contribute immensely to the classification of different micro-fracturing features, and their characteristics for the distinct shale mineralogies.

通过在页岩储层中形成次生孔隙和微裂缝，酸的利用已被批准为增加受激储层体积（SRV）的潜在方法。本文提出了一种酸浸技术来量化微断裂行为的产生。重点介绍了来自不同页岩沉积​​环境的两种岩心样品，即富含龙马溪的富碳酸盐岩和富含延长粘土的页岩。用盐酸（15％+ 3％KCL）处理页岩样品2小时。进行了扫描电子显微镜（SEM）和X射线衍射（XRD）实验，以关联各个矿物相。电感耦合等离子体发射光谱法（ICP-OES）和X射线荧光测试（XRF）用于量化不同矿物相的元素分析。对于后酸化测试条件，观察到三种不同类型的微裂缝，即应力诱导的微裂缝，酸溶解微裂缝和酸收缩微裂缝。对于富含粘土的页岩，应力诱导的微裂缝在高岭石内以及亚氯酸盐/黑云母区域的边界边缘内更为突出。而收缩微裂缝占主导地位的亚氯酸盐地区。另一方面，Longmaxi富含碳酸盐的页岩揭示了更多证据表明在硬石膏，方解石，伊利石和有机质区域内形成了酸溶微裂缝。根据ICP-OES和XRF测试结果，富含粘土的页岩样品经历了过多的离子吸收以及离子流失机理。然而，富含碳酸盐的页岩仅经历了页岩界面的离子驱离机理。建立电平衡后，没有离子还原为页岩样品。本文将为不同微裂缝特征的分类及其对不同页岩矿物学的特征做出巨大贡献。