Shale components affect organic–inorganic diagenesis, control the formation and evolution of pore structure, and lead to heterogeneity of shale reservoirs. Therefore, revealing the coupling control of shale components on the porosity and pore structure is crucial for selecting the dominant lithofacies. In this study, the lacustrine shale with medium maturity in the first member of the Qingshankou Formation (Qing1 Member) in the Changling Sag, southern Songliao Basin, China, was analyzed. Using pressurized sealed original shale samples and 2-D nuclear magnetic resonance (2D-NMR) analysis, the effective porosity of shale was accurately determined. The pore structure was characterized via experiments such as low-temperature nitrogen adsorption, NMR, and scanning electron microscope (SEM) analyses. In addition, the joint influences of the shale rock components, sedimentary structure, and maturity on the porosity and pore structure were investigated. Finally, the favorable reservoirs in the lacustrine shale with medium maturity and their formation conditions were identified. Studies have shown that for lacustrine shale with medium maturity: (1) a moderate total organic carbon (TOC) content (between 1% and 2.5%) is a key factor for improving the effective porosity and the proportions of mesopores (100–1000 nm) and small-pores (30–100 nm). This is related to the generation of organic acids and the cracking of organic matter into pores. An excessive TOC content can lead to increased plasticity of the rock and filling of the pores by bitumen. (2) The porosity and pore structure are controlled by the organic matter and inorganic minerals as well as sedimentary structure. Organic matter has dual impacts on the porosity improvement related to clay minerals, promotion of clay conversion and filling of clay-related pores, and the ratio of the clay content to the TOC (Vsh/TOC) can reflect the degree of influence of organic matter, the greater the Vsh/TOC ratio is, the greater the effective porosity and proportion of micropores are. (3) Organic matter and felsic minerals jointly effect the improvement of the effective porosity and larger pores (>30 nm), which is related to their good compression resistance, organic pore retention, and dissolution-enhanced porosity effect. The product of the TOC and felsic mineral content (Vsi*TOC) can reflect the degree of their coupled effect. For moderate TOC contents, a higher felsic mineral content, and moderate shell laminae (Vca>10%) are conducive to the development of the effective porosity and larger pores. (4) The organic medium-rich argillaceous laminated felsic shale and organic-medium argillaceous laminated clayey shale have a higher effective porosity and higher proportion of larger pores, making them the dominant lithofacies for shale oil sweet spots.

中文翻译：

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有机无机岩石组分对中熟湖相页岩孔隙度及孔隙结构的耦合控制——以松辽盆地南部青山口组为例

页岩组分影响有机-无机成岩作用，控制孔隙结构的形成和演化，导致页岩储层的非均质性。因此，揭示页岩组分对孔隙度和孔隙结构的耦合控制对于选择优势岩相至关重要。本研究以松辽盆地南部长岭凹陷青山口组一段（青一段）中成熟度湖相页岩为研究对象。利用加压密封的原始页岩样品和二维核磁共振（2D-NMR）分析，准确测定了页岩的有效孔隙度。通过低温氮气吸附、核磁共振和扫描电子显微镜（SEM）分析等实验对孔结构进行了表征。此外，还研究了页岩组分、沉积结构和成熟度对孔隙度和孔隙结构的共同影响。最后，识别了湖相中熟页岩有利储集层及其形成条件。研究表明，对于中成熟度湖相页岩：（1）适度的总有机碳（TOC）含量（1%~2.5%）是提高有效孔隙度和中孔（100~1000 nm）比例的关键因素。 ）和小孔（30–100 nm）。这与有机酸的生成以及有机质裂解成孔隙有关。 TOC 含量过高会导致岩石的塑性增加以及沥青填充孔隙。 (2)孔隙度和孔隙结构受有机质、无机矿物和沉积结构的控制。有机质对粘土矿物相关的孔隙度改善、促进粘土转化和粘土相关孔隙的充填具有双重影响，粘土含量与TOC的比值（Vsh/TOC）可以反映有机质的影响程度，Vsh/TOC比值越大，有效孔隙率和微孔比例越大。 （3）有机质和长英质矿物共同提高了有效孔隙度和较大孔隙（>30 nm），这与它们良好的抗压、有机质孔隙保留和溶蚀增孔作用有关。 TOC与长英质矿物含量的乘积(Vsi*TOC)可以反映二者耦合作用的程度。 TOC含量适中、长英质矿物含量较高、壳纹层适中（Vca>10%）有利于有效孔隙度和较大孔隙的发育。 （4）富含有机介质泥质层状长英质页岩和有机质介质泥质层状粘土质页岩有效孔隙度较高，大孔隙比例较高，是页岩油甜点区的优势岩相。