This study identifies the following three key factors controlling shale gas reservoirs in the lower Cambrian Niutitang Formation, northern Guizhou, China: sedimentary features, diagenetic modification, and stable tectonic conditions. This research addresses gaps in previous studies by investigating how tectonic and diagenetic conditions contribute to the unique characteristics of shale gas enrichment in tectonically complex areas with high thermal maturity (Ro > 2.5%). Sedimentary conditions revealed a positive correlation between total organic carbon (TOC) content and gas adsorption capacity, with higher TOC enhancing adsorption. Experimental data indicate that the TOC content (2.33%–9.07%) significantly correlates with methane adsorption capacity (Langmuir volume VL = 1.87–8.78 cm3/g at 30 °C and 10 MPa), as evidenced by the linear relationship between TOC and VL in shale samples. Clay mineral content exhibited a dual role as moderate levels (15%–25%) improved adsorption, while excessive amounts (>30%) reduced efficiency due to pore occlusion. Diagenesis, including compaction, cementation, and thermal evolution of organic matter, significantly reshaped reservoir porosity. Quantitative analysis of core samples demonstrates that compaction caused a porosity reduction of 18%–25% in samples with burial depths exceeding 1500 m, thereby influencing gas retention capacity. The reservoir has entered the anchizone (average vitrinite reflectance Ro = 2.54%), characterized by advanced organic matter maturation and widespread organic porosity development. Tectonic activity was critical for gas retention; intense tectonic activity led to shallower burial depths and gas loss, whereas structurally stable areas favored preservation. This study emphasizes the significance of tectonic conditions and their role in maintaining gas reservoirs in the anchizone, reconciling discrepancies in gas storage mechanisms observed in basins with similar TOC and thermal maturity. In summary, deep marine shale gas enrichment relies on the synergistic effects of high-quality sedimentary foundations (TOC > 4%, quartz > 30%), diagenetic evolution optimizing pore structures, and stable tectonic conditions ensuring gas retention. These findings provide new insights into the exploration of shale gas in complex tectonic regions and offer a framework for improving prediction models in shale gas enrichment by integrating micro-scale organic–inorganic interactions with macro-scale tectonic controls.

Drawing on extensive geological surveys, as well as systematic mineralogical, petrological, and geochemical analyses, the study evaluates the provenance, tectonic setting, paleo-redox conditions, and paleoclimate characteristics of the Wufeng Formation black shale in the Fenggang area. The analysis of mineral components reveals that quartz content is notably the highest, suggesting that the shale is primarily siliceous. The TOC content was highest in the YI Outcrop, ranging from 2.19 to 5.56, with an average of 3.23, followed by the SX Outcrop. Redox-sensitive indices including MoEF, UEF, V/Cr, and U/Th exhibit considerable variability, indicating significant heterogeneity of the redox conditions, which is primarily characterized as a restricted marine shelf setting. The bottom water of YI Outcrop has the strongest reducing property, and mainly deposited in an anoxic environment. Organic-rich siliceous mudstone is widely distributed across the region. The provenance analysis indicates that the study area is predominantly sourced from felsic igneous rocks. Additionally, paleoclimate and paleo-weathering analyses suggest that the region underwent intense chemical weathering under warm climatic conditions. We found that the sedimentary environment exhibits pronounced spatial variability. In the northern part of the study area, water conditions were deeper, anoxic, and reducing. Toward the east, water depth gradually decreased, transitioning to weakly oxidizing and suboxic conditions. Furthermore, significant tectonic activity in the region led to the formation of multiple underwater highs, indicative of an active continental margin likely associated with the rapid uplift of paleo-uplifts. The formation of organic-rich shale was primarily influenced by two factors: favorable preservation conditions in reducing water bodies and high primary productivity driven by biological activity in weakly oxic environments.

Upper Ordovician-Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China.Due to the complex sedimentary environment adjacent to the Kangdian Uplift,the favorable area for organic-rich shale development is still undetermined.The authors,therefore,focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin.Multiple methods were applied in this study,including thin section identification,scanning electron microscopy(SEM)observations and X-ray diffraction(XRD),and elemental analysis on outcrop samples.Five lithofacies have been defined according to the mineralogical and petrological analyses,including mudstone,bioclastic limestone,silty shale,dolomitic shale,and carbonaceous siliceous shale.The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity.The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization.High dolomite content in the study area is accompanied by high TOC,which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water.And for the area close to the Kangdian Uplift,the shale gas generation capability is comparatively favorable.The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted,and more shale gas resources in the mountain-basin transitional zone might be identified in the future.

The Permian Capitanian-Changhsingian black shale formed in intra-platform basins are the major source rocks in Southwest China. However, the depositional conditions and organic matter accumulation of these black shales are not well understood. In this study, geochemical characteristics comprise TOC, major, trace and REEs from sixty-two samples from the studied outcrop in Northern Nanpanjiang Basin, Southwest China are systematically investigated to determine silicon source, paleo-ocean productivity, and paleo-redox conditions to reveal their influence on organic matter enrichment under 3rd-order sequence. The Capitanian-Changhsingian black shale in the study area is the result of the combined effects of active extensional activity, high paleo-productivity maintained by volcanic activity, and dysoxic and anoxic conditions represented by biological extinction events. There are differences in the factors controlling organic matter accumulation in black shale at different stages. The controlling factors for the organic enrichment during Capitanian (SQ2) are the rapidly deepening water mass of extensional rifts and the high productivity induced by volcanic ash in the igneous provinces, as well as the global anoxic event represented by “negative carbon isotope shift.” The controlling factors during Changhsingian are the deepening of water mass under the reactivation of extensional rifts, resulting in a dysoxic environment, and the high productivity maintained by volcanic activity in South China. The Wuchiapingian black shale was formed under dysoxic conditions under the stagnation of extensional activity, and intermittent volcanic activity in South China maintained the high paleo-productivity level of the Wuchiapingian stage.

为了探索贵州上二叠统富有机质页岩时空分布规律,以孤峰阶、吴家坪阶、长兴阶早期、长兴阶晚期为研究单元,精细刻画不同时期古地理特征,开展古地理特征和富有机质页岩分布研究.通过研究区沉积充填特征分析,识别出"宣威型""龙潭型""吴家坪型"和"领薅型"四种沉积转换面,代表了不同地区沉积充填差异性.研究结果显示,海陆过渡型富有机质页岩层段纵向上分布在吴家坪阶—长兴阶,平面上分布在遵义—安顺—兴义以西地区,岩性由煤岩、炭质泥岩、粉砂岩、砂岩组成,构成单独的含气系统.海相富有机质页岩纵向上分布在孤峰阶—长兴阶台棚—台盆相带内.孤峰阶分布在遵义—晴隆—罗甸地区,岩性由炭质泥岩、硅质泥岩夹硅质岩组成,厚度 10～30m.吴家坪阶分布在册亨—紫云—罗甸以南地区,岩性由炭质粉砂质泥岩、粉砂岩、灰岩组成,厚达百米.长兴阶晚期分布在凤岗—贵阳—紫云—罗甸地区,岩性由炭质泥岩、硅质泥岩、硅质岩组成,厚度 10～30m.

Dark mudstones and shales of the Carboniferous Jiusi Formation are widely developed in northern Guizhou and Yunnan provinces, SW China. However, the distribution, reservoir characterization, and exploration potential of organic-rich shales in this area are yet to be quantified, thus limiting the prospect of shale gas in this area. This study investigates the basic geological conditions of Jiusi shale gas, using core data, well-logs, and some other test data, obtaining the following results. The organic-rich shales are mainly composed of deltaic-to-shallow-shelf deposits, with thickness ranging from 0 to 450 m, and above 350 m around the subsidence center. The organic matter is mainly type II kerogen with TOC content of mostly 1%e2%, indicating a moderate maturity. The argillaceous shale reservoirs are indicative of strong heterogeneity, high clay minerals content, low porosity, low permeability, high specific surface area, and relatively developed secondary porosity. The gas-log anomaly intervals obtained from the survey wells have a cumulative thickness that is apparently greater than 200 m, and a few shale intervals showing high desorbed and adsorbed gas contents. Due to complex structures in the study area, conditions responsible for shale gas occurrence and trapping are generally moderate. However, areas having wide and gentle folds with moderate depth of burial reveals relatively favorable conditions of hydrocarbon traps. In contrast with typical marine-continental transitional shales, the Jiusi shale have better geological conditions for shale gas preservation. The analysis of the geological framework and hydrocarbon potential of Carboniferous Jiusi Formation provide more insight for the exploration of Carboniferous shale gas in southern China. (c) 2023 Sinopec Petroleum Exploration and Production Research Institute. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

This study investigates the provenance and tectonic background of the lower Silurian Longmaxi Formation black shale of the Yanyuan Basin in the western Kangdian ancient land and provides guidance for shale gas exploration and development in the area. The mineral petrological and geochemical characteristics of the Longmaxi Formation black shale in this area have been studied in detail. The study area is mainly a passive continental margin environment, but also has the attributes of an active continental margin and island arc environment due to the collision between the western oceanic crust and the Yangtze continental crust. The source rocks are mainly felsic igneous rocks, with a small contribution of intermediate–basic rocks. It is inferred that the Kangdian ancient land in the eastern part of the area could be the main provenance area, but with the contribution of sediments derived from oceanic island arc located in the west. During the whole Longmaxi period, the tectonic movement was intense, the climate was cold, the degree of chemical weathering was low, and it was a highly volatile geological sedimentary basin. Therefore, the highly siliceous organic-rich mudstone, which was different from the Sichuan Basin, was deposited.

Abstract The Late Ordovician-Early Silurian period witnessed the second largest Phanerozoic mass extinction, Hirnantian glaciation and volcanic events. Wufeng, Guanyinqiao and Longmaxi formations were developed in South China across the Ordovician-Silurian transition.To infer the weathering conditions, provenance, tectonic setting of the source area in western South China during this period, we measured the mineralogical and geochemical characteristics of 42 samples of Wufeng-Longmaxi formations taken from Xindi No. 1 well, south west of Sichuan Basin. These shales and argillaceous limestones mainly consist of quartz, clay mineral, carbonate, feldspar, and minor amounts of pyrite. Geochemically, the rocks from three formations are enriched in CaO and MgO and slightly depleted in SiO2, Al2O3 and K2O. Chondrite-normalized rare earth elements (REE) patterns display a negative Eu anomaly, a slight enrichment in LREE and a flat HREE. Paleoweathering indices (CIA and PIA) and Th/U ratios indicate that the sediments experienced moderate-intense to weak chemical weathering in the source area. CIA values of the lower Wufeng Formation range from 64.88 to 70.88, indicating a warm and humid climate. Upward the CIA values on the top of Wufeng Formation decrease from 62.56 to 62.93, the CIA values of the Guanyinqiao and lowest Longmaxi formation are consistently low values (58.48-67.12) , suggesting a cold and dry climate which is consistent with Gondwana glaciation in Hirnantian period. Geochemical discrimination diagrams revealed that the rocks of the three formations were derived from felsic igneous source rocks and deposited in an active continental margin setting.

To further study the sedimentary environment of the black mudstone in the early Carboniferous Dawuba Formation in the Middle and Upper Yangtze regions and support regional shale gas exploration and related research, the major and trace elements of the Dawuba Formation in Well CY1, located in deep water shelf facies, were tested and analyzed. The results show that the study area contains mainly continental margin deposits affected by hydrothermal deposition, and they are rich in organic matter and have high primary productivity. The parent rocks are mainly acidic rocks, such as felsic igneous rocks, granites and some sedimentary rocks. And the provenance is mainly provided by acidic igneous rocks of the Jiangnan Paleouplift. An ICV<1 and high CIA and Th/U values indicate a warm and humid climate and under stong chemical weathering conditions. The values of V/(V+Ni), Cu/Zn and Ce/La suggest that organic-rich intervals of the Dawuba Formation accumulated under predominantly dysoxic conditions. The warm and humid climate is conducive to the flourishing of micropaleontology, and the high primary paleoproductivity and weakly reducing environment are conducive to the formation of organic-rich shale, forming high-quality reservoir source rock in the Dawuba Formation.

The permeability characteristics of natural fracture systems are crucial to the production potential of shale gas wells. To investigate the permeability behavior of a regional fault that is located within the Wufeng Formation, China, the gas permeability of shale samples with natural micro-fractures was measured at different confining pressures and complemented with helium pycnometry for porosity, computed micro-tomographic (µCT) imaging, and a comparison with well testing data. The cores originated from a shale gas well (HD-1) drilled at the Huayingshan anticline in the eastern Sichuan Basin. The measured Klinkenberg permeabilities are in the range between 0.059 and 5.9 mD, which roughly agrees with the permeability of the regional fault (0.96 mD) as estimated from well HD-1 productivity data. An extrapolation of the measured permeability to reservoir pressures in combination with the µCT images shows that the stress sensitivity of the permeability is closely correlated to the micro-fracture distribution and orientation. Here, the permeability of the samples in which the micro-fractures are predominantly oriented along the flow direction is the least stress sensitive. This implies that tectonic zones with a large fluid potential gradient can define favorable areas for shale gas exploitation, potentially even without requirements for hydraulic fracture treatments.

AbstractShale gas resources in mainland China and its commercial exploitation has been widely focused on the Wufeng–Longmaxi Formation organic-matter-rich shale in the Sichuan Basin. However, whether southwestern margin of the Sichuan Basin can produce high-quality shale gas has not been well resolved, which might be related to the poor understanding of the relationship between Cenozoic tectonic deformation and shale gas preservation. To answer the aforementioned scientific question, we conducted a detailed work in the Mugan area to show geologic structures and gas contents in the area through seismic profiles and geochemistry analysis. Specifically, the stable Mugan syncline shows a high gas content (>2.6 m3/t measured at three boreholes D1, D2, and D3), whereas its periphery presents a poor gas content (about 0.6 m3/t measured at two boreholes X1 and Y1). Moreover, oblique fracture density and dissolved pores are much higher at boreholes X1 and Y1 than that at the other three boreholes. We propose an opposite-verging thrust fault model to explain the different gas contents and tectonic features in the Mugan area, which might indicate that regions in the southwestern Sichuan Basin with similar tectonic and stratigraphic characteristics as those in the Mugan syncline are likely to produce high-yield shale gas. This finding provides new insights into the exploration theory of shale gas in the Tibetan Plateau.

通过对康滇古陆东侧彝良洪沟和西侧盐源小高山晚二叠世沉积充填序列和沉积环境分析,认为古陆两侧沉积时限和富有机质页岩空间展布存在差异.古陆西侧小高山地区黑泥哨组自下至上沉积环境为滨岸-火山溢流-沼泽-三角洲,下部玄武岩显示峨眉山玄武岩第四次喷发溢流特征,向西至泸沽湖地区出现三套玄武岩夹层,说明西部沉积时间早,向东超覆于康滇古陆.富有机质页岩分布在黑泥哨组下部沼泽环境中,累计厚度大,具有较好的资源潜力.古陆东侧昭通彝良洪沟宣威组自下至上沉积环境为河流-三角洲-沼泽,无玄武岩夹层表明该地区沉积时限晚于西部小高山地区.富有机质页岩分布在宣威组上部沼泽环境中,累计厚度薄,资源潜力有限.

The petrology, mineralogy, elemental geochemistry, biology and PGEs characteristics of the black shale of the Wufeng and Longmaxi Formations in the CN outcrop of the Sichuan Basin are studied in this paper. The distribution and change in PGEs at different horizons are summarized, and the reasons for PGEs enrichment are discussed. The results show that the PGEs in the organic-rich shale segment are obviously enriched, which is positively correlated with the Total Organic Carbon (TOC) content and has a Pt–Pd distribution characteristic. δEuN, Pd/Pt, (Pt + Pd)/(Os + Ru + Ir), etc., and SiO2–Al2O3 and It/Pt–Pd/Pt discrimination diagrams, indicate that they are not extraterrestrial sources, nor are they the origins of normal seawater deposition but they are related to hydrothermal deposition. The enrichment process of PGEs is relatively complicated and is controlled by the impact of the sedimentary environment in the restricted basin. The anoxic water environment and organic-rich environment are the main factors of PGEs enrichment. PGEs and TOC have a good positive correlation and can be used as index parameters for sedimentary environments and organic matter enrichment.

二叠系龙潭组是四川盆地最主要的海陆过渡相页岩气勘探层位.通过钻井岩芯和薄片观察、X射线衍射、扫描电镜、有机地球化学分析、孔渗测试、现场解吸和等温吸附等手段,以SD1井为例,对川东南石宝矿区龙潭组烃源岩特征和页岩气潜力进行研究.结果表明:1)研究区SD1井龙潭组泥页岩累计厚度约47.74 m,与煤层及粉-细砂岩交互出现,主要为分流间湾和沼泽微相沉积;2)泥页岩总体黏土矿物含量高(平均值为49.7％),富菱铁矿、黄铁矿和锐钛矿,缺乏长石和其他碳酸盐矿物;3)有机质主要由镜质组构成,干酪根δ13C集中分布在–22.8‰ ～ –24.2‰之间,以Ⅲ型干酪根为主,有机质丰度高(TOC平均值为7.37％),处于过成熟生干气阶段,生烃潜力大;4)储集空间主要包括微裂缝、有机质孔、溶蚀孔和晶间孔,孔隙度变化在3.05％～4.35％之间,平均值为3.79％;渗透率约为0.486μD,远小于0.1 mD,具超低孔超低渗特征;5)现场解吸泥页岩含气量为0.61～4.70 m3/t,平均值为2.16 m3/t,含气性相对较好,饱和吸附气含量均大于2.00 m3/t,显示出良好的吸附性能.综合研究认为,川东南石宝矿区龙潭组页岩气开发潜力较大,龙潭组上段中部C14–C17碳质泥岩夹煤层组合和龙潭组中段上部C20–C24碳质泥岩夹煤层组合为主力勘查层段.

奥陶—志留交替时期是地球历史时期中的关键时期,该时期华南地区沉积的五峰组—龙马溪组黑色页岩是现阶段我国页岩气勘探的重点层位,多套斑脱岩存在于黑色页岩内,指示该时期研究区经历过多期连续的火山活动.本文选取了四川盆地东部华地1井和武隆黄莺乡五峰组—龙马溪组剖面,以黑色页岩和斑脱岩为研究对象,通过野外考察、元素地球化学等分析方法,系统地分析了有机质富集的主控因素(陆源输入、古生产力、古氧化还原条件),并在此基础上分析斑脱岩与页岩有机质富集间的关系.结果显示,研究区五峰组—龙马溪组黑色页岩TOC呈高-低-高模式,氧化还原指标(V/V+Ni、V/Cr、Ni/Co)表明水体经历了厌氧-富氧-厌氧的过程,生产力指标(Cu、Babio、Sibio)、陆源输入指标(Ti/Al、Zr/Al、Th/Al)表明五峰和龙马溪组具较高的生产力和陆源输入,观音桥组较两者均低,三者与有机碳的相关关系反映氧化还原条件对有机质富集作用最大,生产力次之,陆源输入最弱.从斑脱岩发育特征与有机碳、生产力和氧化还原条件的关系看,频繁的火山活动可能对五峰和龙马溪组有机质的保存产生双促作用,一是为海洋提供营养物质,提升其生物生产力;二是火山灰飘落至海水表面阻止了部分光照进入,海底缺氧环境加剧,造成生物大量死亡并落入海底,作为有机质埋藏.

本文以四川盆地及其周缘五峰组—龙马溪组页岩气评价为例,总结了页岩气有利区优选的储层参数、保存参数和压力系数等参数,量化了各关键参数平面分布,运用多元线性回归分析方法计算了参数权重,通过多参数加权叠加公式建立了多元线性回归模型:有利区=-0.317+0.75×埋深+0.285×TOC+0.148×RO+0.093×孔隙度-0.128×渗透率+0.201×脆性矿物-0.199×压力系数,并开展了定量化优选评价页岩气有利区工作.分析结果表明,各参数权重由大到小排序为:埋深、TOC、脆性矿物和压力系数、RO、孔隙度、渗透率,代表对含气性的影响作用依次减小.经过量化优选的有利区主要集中于四川盆地内,包括威远—自贡一线、宜宾—泸州—涪陵一线和川东区域为主,盆外的昭通、金沙、道真和黔江区域为相对有利区.该预测评价结果与四川盆地页岩气勘探实际基本相符,有利区表现形式较传统综合地质方法更清晰、直观.

保存条件是我国南方构造复杂区页岩气地质评价中的关键,本文通过对四川盆地周缘断裂展布、地层产状、目的层埋深以及地层接触情况等多项参数进行分析,评价构造复杂区海相页岩气保存条件影响因素,建立保存条件参数体系,并通过模糊识别数学方法对各项参数赋予权重并进行排序,确定保存条件主控因素的重要性.其中,断裂分布、埋藏深度、压力系数及地层产状是最重要控制因素,上覆泥岩厚度、目的层地层接触关系及底部古岩溶等也具有一定影响.最后,本文以黔北长顺区域作为研究对象,对其保存条件参数指标的平面分布图进行量化叠加,获得保存条件有利区域量化评价图.通过对比,认为该方法与常规方法评价保存条件具有一定的一致性,但在清晰直观性方面以及有利区内的量化可对比性上具有更明显的优势.

奥陶纪—志留纪之交是华南被动大陆边缘盆地向前陆盆地演化的重要转折时期,形成广泛分布的五峰组—龙马溪组黑色页岩。为进一步探讨该套黑色页岩的形成背景,以黔北地区道页1井为例,开展沉积序列和地球化学研究。研究结果表明:五峰组及龙马溪组底部主要为硅质碳质页岩,夹多层斑脱岩,U/Th为0.2～2.90,V/Cr为1.18～14.34,Ni/Co为2.31～11.59,TOC为0.68%～5.91%,平均3.76%,稀土配分曲线为平坦型,δEu以弱正异常为主、个别为弱负异常;龙马溪上部及新滩组主要由泥岩及钙质泥岩组成,U/Th为0.16～0.23,V/Cr为0.88～1.79,Ni/Co为1.77～3.91,TOC为0.1%～0.84%,δEu以明显负异常为主,表现出低斜率右倾型稀土配分曲线。以上特征表明五峰组及龙马溪组底部形成于间歇性缺氧的还原环境,龙马溪组上部及新滩组为富氧环境。结合斑脱岩的分布特征综合分析认为,五峰组及龙马溪组底部页岩是汇聚背景下前陆盆地早期沉积的产物,强烈火山作用给大陆边缘海带来营养元素,刺激初级生产力的增加,造成水体迅速缺氧,可能是造成同期海底缺氧的主要诱因。

扬子地台内晚奥陶世末—早志留世初五峰—龙马溪组内沉积了多层钾质斑脱岩,但对于该时期扬子地台西缘钾质斑脱岩的研究报道相对较少.本文旨在通过对云南大关地区新地2井五峰—龙马溪组内沉积的钾质斑脱岩进行矿物学及地球化学分析,进一步确定扬子西缘该时期钾质斑脱岩原始岩浆类型及其所产生的构造环境.矿物学特征表明,钾质斑脱岩主要由黏土矿物和非黏土矿物组成,其中黏土矿物由伊利石和伊蒙混层组成,非黏土矿物以石英、长石、方解石、白云石和黄铁矿等为主.钾质斑脱岩主量元素以高K2O,低TiO2为特征,微量元素特征表现为富集Rb、Ba、Th、U等元素,Ti、P元素相对亏损,Ti/Th值指示了酸性火山灰的性质;ΣREE在(49.86～209.43)×10-6;与球粒陨石相比,轻稀土轻微富集、具Eu负异常,无Ce异常;在Nb/Y-Zr/TiO2图解中,数据点主要落在安山岩和粗面英安岩之间,表明钾质斑脱岩源岩浆性质为中酸性岩浆;依据微量元素特征和构造环境判别结果,初步认为原始岩浆可能形成于岛弧环境,其火山灰来源可能与扬子北缘早古生代秦岭洋闭合过程中的板块碰撞有关.

Marine shale gas in the southern Sichuan Basin is the most successful area of shale gas exploration and development in China. In order to open up new shale gas fields and search for new shale gas reserves and production replacement blocks, it is necessary to continuously establish and complete the standards on shale gas reservoir evaluation and area selection under different structural settings. The early exploration practice shows that shale in the mountainous complex structural area along the southwestern margin of the Sichuan Basin varies greatly in the gas bearing property, so systematical analysis and study on the shale gas enrichment mechanisms in this area is of great significance to searching for new shale gas exploration areas. Based on drilling data of 5 wells in the mountainous complex structural area along the southwestern margin of the Sichuan Basin, the main factors controlling the shale gas bearing property and the shale gas enrichment model were discussed based on the systematical experiments and analysis of the outcrops, cores and cuttings of Longmaxi Formation shale from the aspects of organic geochemistry, physical property, gas content, hydrocarbon generation history and pore evolution history, so as to lay a solid geological basis for the birth of a new shale gas area. And the following research results were obtained. First, the shale of the first submember of first Member of Longmaxi Formation (S1l11) in the mountainous complex structural area along the southwestern margin of the Sichuan Basin has an average TOC of 3.02%–4.97% and Ro of 2.38%–3.37%, and the average total gas content in local enrichment zones is up to 4.62 m3/t, so it is classified as quality shale. Second, the detailed studies on hydrocarbon generation history indicate that the shale has the characteristics of “low thermal evolution rate and low maturity”. It is characterized by late hydrocarbon generation, low thermal evolution rate, low current maturity and short late diffusion time, which are favorable for shale gas enrichment. Third, the pore evolution history reveals that shale pore evolution can be divided into six stages, i.e., sharp pore reduction, pore reduction, organic pore formation, pore preservation, organic pore dissipation and karstification, and organic pore and TOC are the most direct control factors of shale gas content. Fourth, favorable shelf facies belt is conducive to the formation of large-scale reservoir space and effective pores, and diversities of preservation conditions under different structural styles and at different structural positions control different pore evolution stages. The shale gas in the mountainous complex structural area is characterized by horizontal zoning and differential enrichment. “Low thermal evolution rate and low maturity” and “slow structural uplifting” are beneficial to the long-term enrichment and preservation of shale gas. In conclusion, the mountainous complex structural area along the southwestern margin of the Sichuan Basin has a shale gas enrichment model of “sedimentation controlling source rocks, diagenesis controlling reservoirs and structure controlling preservation”. This research result provides idea and reference for searching for new shale gas areas and fields.