二叠系龙潭组是目前四川盆地页岩气勘探开发的新热点层位.通过偏光显微镜鉴定、场发射扫描电镜分析、X射线衍射测试、有机碳含量测定及高压压汞分析、现场解析气实验等手段和方法,对川南地区二叠系龙潭组页岩储层进行了综合研究.研究结果表明:①川南地区二叠系龙潭组为一套陆相曲流河沉积,河漫沉积的页岩发育,其矿物成分主要为石英和黏土矿物,含少量碳酸盐矿物.②研究区页岩储层主要发育粒间(缘)孔与微裂缝,局部发育粒内孔与溶蚀孔,偶见有机质孔隙,其中黏土矿物层间微裂缝最为发育.孔隙结构表现为以微孔为主,介孔(孔径为2～50 nm)次之,孔径普遍较小,分选较差,孔隙和喉道半径差异较大,非均质性强.③研究区页岩储层中煤岩含气量最高,炭质泥岩与泥岩次之,泥质粉砂岩、粉砂岩与细砂岩含气量最低.与龙马溪组页岩储层相比,龙潭组泥岩孔隙度与总含气量更好,渗透率较差,其中炭质泥岩的孔隙度和总含气量最佳.④研究区二叠系龙潭组勘探潜力较大,烃源岩中有机质类型主要为Ⅲ型,其次为Ⅱ2型;其Ro值平均约为2.8％,达到高熟阶段;TOC含量变化范围大,炭质泥岩中的TOC一般大于15％.⑤川南地区二叠系龙潭组发育河漫平原沉积,富有机质泥页岩分布稳定,具备良好的页岩气形成条件,估算其天然气资源量约为2.4×1012 m3,有利勘探区主要位于川南古蔺—叙永地区.

The Lower Jurassic Da’anzhai Member in the Sichuan Basin is one of the important distribution series of strata of shale oil and gas （tight oil and gas）,but its drilling and test results are worse,so it is in urgent need to research the geological characteristics of favorable intervals and select the favorable exploration areas.Based on field outcrop,core,logging,and geophysical data,this paper studies the geological characteristic of the Da’anzhai Member shale oil and gas,analyzes the control factors of shale oil and gas enrichment,and selects the favorable exploration areas.And the following research results are obtained.First,the Da’anzhai Member is a set of mixed strata of shell limestone and black shale.The shale mineral is mainly composed of clay,followed by quartz and calcite,with a small amount of feldspar and pyrite,and the content of brittle minerals is medium.Second,the pore type is mainly inorganic pore,with a small number of organic pores,and multi-scale fractures such as shell edge fracture and joint fracture are developed.The physical properties decrease with the increase of shell content.Third,the abundance of organic matter in shale is moderate to good with average TOC of 1.34%.The organic matter is mainly of mixed type with a small amount of sapropel type and humic type.R o averages 1.11%,the degree of thermal evolution is low in the south and high in the north,and it is overall in the stage of maturity to high maturity.The oil content is moderate with chloroform asphalt"A"content averaging 0.26%.Fourth,the average S 1 value of pyrolysis free hydrocarbons is 1.27 mg/g,and the average OSI is 84.35mg/g.The lower limit of hydrocarbon source for shale oil and gas enrichment is TOC＞1.5% and R o ＞0.9%.The hydrocarbon expulsion efficiency is lower vertically,and the sections with higher oil content index （OSI＞100 mg/g） are mainly distributed in the middle of thick shale.Fifth,the movable oil saturation is generally less than 20%.Due to the influence of texture fractures and shale bedding fractures,the oil mobility in the samples of limestone interbedded with shale and shale with interbedded limestone is better than that in limestone and shale.In conclusion,the Da’anzhai Member shale has great potential in shale oil and gas exploration and development,high hydrocarbon generation quality,multi-scale fractures,and high formation pressure are the key factors for the enrichment and high production of shale oil and gas in the basin,and the favorable exploration areas are mainly distributed in the Santai-Yilong and Nanchong areas of central Sichuan Basin.

Reconstructing karst palaeogeomorphology is a useful approach to identifying target areas for oil and gas exploration. This study used the elevation method to reconstruct the karst palaeogeomorphology at the top of the 4th member (Z 2 dn 4 ) of the Dengying Formation (Z 2 dn) in the Central Sichuan Basin based on 2D and 3D seismic and drilling data. The bottom of the Longwangmiao Formation and the top of the 2nd member (Z 2 dn 2 ) of the Z 2 dn were optimized as the upper and lower base levels, respectively. The reconstructed palaeogeomorphology was divided into five types – slopes, erosional peneplains, monadnocks, domes and depressions – according to their morphology, scope and gradient, allowing inference of the palaeohydrological conditions. Slopes were subdivided into gentle (<1.2°) and steep (≥ 1.2°; maximum gradient around 16°). Reservoirs on steep slopes and monadnocks are the most developed, owing to their considerable hydraulic head differences, strong palaeohydrodynamics, and intense erosion and incision. Steep slopes with more developed karst porosities are banded and immediately adjoin a regional hydrocarbon generation centre. Hydrocarbons generated in this centre tend to migrate laterally and become entrapped in porous slopes and their vicinities. Consequently, hydrocarbons move upward along steep slopes and, preferentially, slopes and monadnocks. Thus, the steep slope zone and its vicinity (including some monadnocks, gentle slopes and peneplains) are the most favourable areas for exploration of hydrocarbon reservoirs and should be the primary targets.

为精细评价陆相页岩储层特征,有效指导页岩油勘探开发,以四川盆地中部侏罗系自流井组大安寨段页岩层系为例,综合应用岩心精描、薄片鉴定、扫描电镜观察、核磁共振、氮气吸附和测井解释等定性和定量的分析方法,对页岩层系岩相和储层微观特征进行研究.提出了页岩层系岩相划分方案,认为大安寨段页岩层系具有以裂缝和溶蚀宏孔为主的微米级储集空间和纳米级孔、缝构成的双重介质,明确了纹层状含介壳页岩及薄层状介壳灰质页岩/泥质介壳灰岩为有利储集岩类,岩相类型和成岩作用是造成储集性能差异的主要因素,富有机质页岩与介壳灰质夹层形成源储一体的有利配置.研究结果表明:大安寨段页岩层系主要包括纹层状长英质页岩、纹层状含介壳页岩、层状—块状黏土质粉砂岩、薄层状介壳灰质页岩、薄层状泥质介壳灰岩和块状介壳灰岩6种岩相类型;块状介壳灰岩孔隙度平均为1.01％,其他(含介壳)页岩孔隙度平均为1.12％～4.85％,页岩层系储集空间以纳米级孔隙为主,形态以狭缝状为主,孔径主要分布为10～5×103 nm,介孔和宏孔发育.大安寨段湖相页岩层系含油气性较好,有机质发育的纹层状或薄层状(含介壳)页岩受有机酸溶蚀增孔的作用,形成大量次生孔隙,从而形成了源储一体的富有机质页岩与介壳灰质夹层有利配置,夹层中(微)裂缝和溶蚀宏孔为游离烃提供主要的储集空间,页岩基质内广泛发育的纳米孔,孔径小、连通性较差,两者形成的微纳米级孔-缝双重介质,使大安寨段油气稳产成为可能,对于四川盆地的陆相页岩油气勘探开发具有重要的意义.

四川盆地侏罗系沙溪庙组是致密气勘探的重点领域,但其沉积体系和砂体发育特征研究薄弱,制约了天然气的勘探开发.为进一步弄清沙溪庙组沉积体系演化和砂体发育特征,以四川盆地中部地区(以下简称川中地区)沙溪庙组为研究对象,综合利用岩心、薄片、测录井和地震资料,系统研究沙溪庙组沉积相微相和砂体成因类型.研究结果表明:①受东北部大巴山和米仓山逐渐隆升影响,四川盆地沙溪庙组沉积时期为北东—南西向的前陆盆地,盆地内地势宽缓,古水系主要呈北东—南西向,北部的大巴山和南部物源联合控制川中地区沙溪庙组沉积格局;②川中地区砂岩多见海绿石矿物,表明沙溪庙组沉积中心位于盆地中部,沙溪庙组气候干湿交替频繁,湖盆水体较浅且动荡,地形较为宽缓,具备形成浅水三角洲的沉积背景;③沙一段半干旱气候条件下发育的浅水三角洲多呈朵叶状,沉积相带展布宽广,平面表现为多个朵叶体叠合而成的复合体,砂体叠置连片发育,单期河道砂体宽度大,常见河口砂坝;④沙二段干旱气候条件下主要发育枝状分流河道型浅水三角洲,多呈鸟足状或树枝状,砂体顺河道呈条带状分布,河道较窄且相互切割,河口砂坝仅仅分布于河道的末端,单个规模较小.结论 认为,系统分析了川中地区沙溪庙组沉积相的演化与分布规律,总结了沙溪庙组的沉积特征及砂体发育模式,对下步川中地区沙溪庙组致密气勘探具有重要指导意义.

继2011年高石1井在四川盆地川中古隆起核部高石梯—磨溪地区上震旦统灯影组获得天然气勘探重大突破之后,近期角探1井又在该古隆起斜坡区获得天然气勘探重大新发现.为了进一步明确后者灯影组油气勘探的目标和方向,分析了灯影组的沉积演化过程、储层特征与油气成藏模式,探讨了该斜坡区巨厚微生物碳酸盐岩储层油气成藏的关键要素.研究结果表明:①该区灯影组沉积分异作用强,区域构造运动奠定了该区南高北低的沉积古地貌,川中至川北沉积环境由局限向开阔转变,沉积水动力条件较高石梯—磨溪地区更强,其次,在拉张背景下发育的大量同沉积断层控制该区微古地貌,在缓坡背景上形成似阶梯状沉积古地貌,进一步加剧了该区的沉积分异;②储层纵向跨度大,横向受古地貌或同沉积断层控制,蓝藻菌的趋光性促使微古地貌高部位的碳酸盐岩具有更高的沉积速率,古地貌高地的丘滩体厚度更大,低洼区以沉积低能细粒碳酸盐岩为主,其次,沉积期内海平面周期性短暂下降,为丘滩体早期溶蚀作用创造了有利条件;③晚期台地大范围暴露,在低洼区形成汇水区,侵蚀掉低洼区顶部的储层,残留下致密层,为低部位的丘滩相储层提供了良好的遮挡条件,形成岩性圈闭;④生烃高峰期,该区处于古构造高部位,断裂系统发育,是古油藏聚集的有利区.结论 认为,该区较强的沉积分异作用是岩性圈闭发育的主控因素;该古隆起斜坡区在四川盆地生烃高峰期处于古构造高部位,是天然气规模成藏的关键.

Since the Anyue Gasfield, located in the central Sichuan paleo-uplift of the Sichuan Basin, was discovered, great efforts have been made to work on natural gas exploration and discovery in the Sinian–Lower Paleozoic in the north slope of present paleo-uplift which has similar depositional settings. It is verified by the breakthrough of natural gas exploration in the second Member of Upper Sinian Dengying Formation in the north slope of central Sichuan paleo-uplift by wildcat well PT1 and the new sign of natural gas exploration in the Canglangpu Formation of Lower Cambrian and the fourth Member of Dengying Formation by Well JT1 that there are also favorable conditions for the formation of large-scale gas province in the north slope. In order to determine the natural gas exploration potential of Sinian–Lower Paleozoic in the central Sichuan paleo-uplift and provide the guidance for the following exploration deployment, this paper analyzed the petroleum geological conditions of Sinian–Lower Paleozoic in the north slope. And the following research results were obtained. First, the marginal platform belts in the second and the fourth Member of Sinian Dengying Formation in the north slope are basically separated areally, and they are superior to the Gaoshiti–Moxi area in terms of marginal platform width and sedimentary thickness and are intrinsically advantageous in sedimentation. Second, compared with the Gaoshiti–Moxi area, the reservoirs of Sinian Dengying Formation in the north slope are better in reservoir conditions, and many sets of quality reservoirs are developed vertically in Sinian–Cambrian. Third, hydrocarbon accumulation elements of Sinian Dengying Formation are better allocated in the north slope. Lithological traps are developed with a larger cumulative area. Wells JT1 and PT1 verify that there is gas in the lithological trap of the fourth and the second Member of Dengying Formation and large-scale lithological gas reservoirs are developed in the slope setting. In conclusion, compared with the Gaoshiti–Moxi area, the Sinian–Lower Paleozoic in the north slope is superior in petroleum geological conditions and has the advantage of multi-layer stereoscopic exploration vertically, presenting a great natural gas exploration potential and promising exploration prospects, so it is a new important strategic zone of conventional natural gas exploration in the Sichuan Basin.

历经10余年的探索与发展,中国南方地区已全面进入中浅层海相页岩气规模效益开发阶段,综合评价四川盆地及其周缘页岩气勘探开发潜力和发展前景,是关乎四川盆地能否建成"天然气大庆"的关键.为了给下一步的页岩气勘探开发提供理论支持,通过系统总结四川盆地上奥陶统五峰组-下志留统龙马溪组页岩气勘探开发理论和成效,分析了中国南方页岩气勘探开发现状与潜力,预判了未来的发展前景.研究结果表明:①川南地区4 500 m 以浅五峰组-龙马溪组海相页岩的页岩气资源量为3.7×1012 m3,其中可采储量超过2×1012 m3,具备建成1 000×108 m3页岩气年产规模并稳产10年以上的开发潜力,中国石油天然气股份有限公司迄今已累计提交页岩气探明地质储量1.061×1 012 m3,并建成百亿立方米年产量页岩气大气区;②渝东北-鄂西地区、川西南-滇东北复杂构造区五峰组-龙马溪组海相页岩的页岩气资源潜力较好,亦具有良好的勘探开发前景;③四川盆地及其周缘具有三套后备页岩气层系,即下寒武统筇竹寺组海相页岩、上二叠统龙潭组海陆过渡相页岩和下侏罗统自流井组陆相页岩,其中筇竹寺组海相页岩在绵阳-长宁拉张槽内优质页岩厚度较大、压力较高、孔隙较发育,是下一步页岩气勘探开发的重点,而川中-川东北地区自流井组大安寨段陆相页岩也具有一定的页岩油气勘探开发潜力.

In recent years, natural gas exploration in the deep marine carbonates of the Sichuan Basin has been strengthened continuously. And based on the research results in the regional geological setting, a great number of new geological understandings are obtained in terms of lithofacies palaogeography, reservoir genesis and hydrocarbon accumulation evolution. What's more, new progress of natural gas exploration is achieved in many strata and domains in the Sichuan Basin, e.g. Qixia Fm of Middle Permian, Maokou Fm and Emeishan basalt, and the prospect of natural gas exploration is promising. In this paper, the recent exploration achievements of Middle Permian natural gas in the Sichuan Basin were summarized. First, under the control of palaeogeomorphology of late Caledonian, marginal platform shoal and girdle intra-platform shoal that are distributed in a large scale were developed at the edge of western Sichuan sea basin and in the periphery of central Sichuan paleo-uplift during the sedimentation of Qixia Fm, and they are large in scale and extensive in distribution range. Dolomite reservoirs are developed with good gas bearing property. Second, two kinds of reservoir bodies are mainly developed in the Maokou Fm of the Sichuan Basin. One is the shoal body which is developed along the marginal platform and the intra-platform high belt under the control of facies belt superimposed with late dolomitization, and the other is the effective karst reservoir which is distributed at the karst slope belt under the action of large-scale erosion in the late Maokou period. Third, volcanic gas reservoirs are discovered in the areas of Chengdu and Jianyang, and their quality reservoirs are of volcanic eruption facies and characterized by great thickness, good physical properties and extensive distribution. The discovery of this new type of gas reservoir expands the exploration domain of Middle Permian natural gas in the Sichuan Basin. In conclusion, the improvement of the large-scale natural gas exploration potential in many strata and domains of Middle Permian in the Sichuan Basin promotes it to be one important replacement domain of the further increase of natural gas production and reserves in the Sichuan Basin.

Based on analysis of outcrop, drilling, logging and seismic data, and geotectonic background, the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan Basin were reconstructed, and the petroleum geological significance of the lithofacies paleogeography and paleokarst geomorphology were discussed. The Maokou Formation is divided into 3 long-term cycles, namely LSC1, LSC2 and LSC3, which correspond to the Member 1, Member 2 and Member 3 of the Maokou Formation, respectively. Controlled by the extensional structure caused by opening of the Mianlue Ocean in the north margin of the upper Yangtze blocks and basement faults produced by mantle plume uplifting, the area had tectonic differentiation in NWW and NE, and sedimentary basement took on episodic settlement from north to south, as a result, the sedimentary systems of Member 1 to Member 3 gradually evolved from carbonate platform to platform-slope-continental shelf. According to the residual thickness, paleokarst geomorphologic units such as karst highland, karst slope and karst depression at different stages were reconstructed. The karst geomorphological units were developed successively on the basis of sedimentary geomorphology. Sedimentary facies and paleokarst geomorphology are of great significance for oil and gas accumulation. The Maokou Formation in northwestern Sichuan has two kinds of most favorable reservoir zone combinations: high energy grain shoal and karst monadnock, platform margin slope and karst slope. Based on this understanding, the planar distribution of the two kinds of reservoir zones were predicted by overlapping the favorable reservoir facies belt with paleokarst geomorphology. The study results provide a new idea and reference for the exploration deployment of the Middle Permian Maokou Formation in the Sichuan Basin.

自2018年YT1井首次在四川盆地西部发现孔隙型火山碎屑岩储层以来,2019年TF2井又在川西地区钻揭79 m厚的孔隙型火山碎屑岩储层,取得了该盆地火山岩碎屑岩气藏勘探的重大突破和勘探新进展.为了进一步明确川西地区二叠系火山岩气藏的勘探前景,综合运用地质、地球物理和地球化学等技术方法,基于二叠系火山碎屑岩岩石学和岩相学分析成果,根据最新的物性等资料,对该区火山碎屑岩储层特征及其主控因素等进行了系统研究;进而结合油气成藏要素的匹配关系,探讨了该区天然气勘探的潜力.研究结果表明:①四川盆地二叠系火山岩形成于板块内部地幔柱活动,川西地区主要发育爆发相火山碎屑岩储层,储集空间以弥散状脱玻化溶蚀微孔为主,孔喉分选较好;②火山机构和喷发旋回是控制规模储层发育的主要因素——火山活动早期能量强,形成厚层爆发相储层,是最有利于储层发育的相带,距离火山作用中心越近,爆发相厚度越大、旋回越完整;③二叠系火山碎屑岩气藏下伏发育裂陷槽控下寒武统筇竹寺组优质烃源岩,油气沿高角度断裂运移至优质爆发相储层中,上覆上二叠统龙潭组提供了优质盖层,为天然气大规模运聚提供了有利的成藏组合.结论 认为,川西地区二叠系火山碎屑岩具备发育大规模优质储层的地质条件,并且该区油气成藏组合条件良好,天然气资源丰度大,展现出巨大的天然气勘探开发潜力,是四川盆地天然气增储上产的重要领域之一.

As an important exploration target in the Sichuan Basin, the Lower Triassic Feixianguan Formation has been previously interpreted to be deposited in the trough-platform margin system according to the genetic model of classic lithofacies paleogeography. However, this model does not apply to the northwestern Sichuan Basin. Accordingly, this study proposed a new genetic model that highlighted the carbonate ramp based on the outcrop sections, drilling and logging data, and seismic sections. A large-scale regional regression was found to occur in Sichuan Basin at the end of the Late Permian, leading to the evolution of the original Kaijiang-Liangping Trough into a very shallow tidal flat/lagoon environment at the beginning of the Early Triassic. The sedimentary pattern during the Early Triassic was different from that during the Late Permian. A total of six long-term cycles (LSC1-LSC6) were identified within the Feixianguan Formation. The deposition of LSC1-LSC3 witnessed the filling of the trough to a large extent, and the depositional periods of LSC4 and LSC5 were the main shoal-forming periods. The Feixianguan Formation in the study area was speculated to be deposited in the continuous continental carbonate ramp. With the intensified uplifting of the Longmenshan island chain and the Kangdian ancient land on the northwestern margin of the Upper Yangtze Platform, a large number of terrigenous materials were input into the study area from west to east, leading to the continuous eastward migration of the carbonate facies belt during the deposition of the Fei 1 and Fei 2 Members. Meanwhile, large-area inner-ramp shoal bodies were formed during the deposition of LSC5. It became possible to find a giant gas reservoir belt in the Feixianguan Formation of the northwestern Sichuan Basin and the results of this study provide a new complement to the existing classic trough-platform margin shoal-forming model.

Based on field observation, core description and well logging analysis, the tectonic-sedimentary framework of the Liangshan and Qixia Formations in the northwestern Sichuan Basin, China is deeply discussed. Two long-term sequence cycles were identified, denoted as LSC1 and LSC2, respectively. The sequence stratigraphic framework was established, suggesting the Liangshan Formation to be not isochronously deposited. Paleogeomorphy before deposition of LSC1 was reconstructed by the impression method. LSC1 was featured by thin, low-energy shoal deposits in the high topography, and thick inter-shoal sea and open sea deposits in the low topography. Meanwhile, paleogeomorphy before deposition of LSC2 was reconstructed using the residual thickness method, which was demonstrated to have primary high-energy, thick shoal deposits in the high topography, and thin inter-shoal and open sea deposits in the low topography. The results show that differential tectonic subsidence has already taken place during the Qixia Period, and thus the Dongwu Movement should occur earlier than previously expected. Meanwhile, pre-depositional paleogeomorphy has obvious controlling effects on the sequence stratigraphic filling and sedimentary facies distribution. Results of this study were expected to provide practical guidance to fine characterization of the sedimentary evolution process and prediction of high-quality reservoir distribution.

近年来,中石油、中石化、壳牌等国内外能源公司相继对四川盆地侏罗系自流井组大安寨段湖相页岩开展了油气勘探工作.为了有效地指导湖相页岩油气的相关勘探开发工作,针对该盆地侏罗系湖相油气资源量与储量不匹配、致密储层物性与油气产量不匹配等矛盾,综合岩心、露头、钻井、测井、试油、分析化验等资料,对侏罗系湖相油气系统开展了页岩油气地质特征、勘探开发对象等方面的研究工作.研究结果表明:①四川盆地侏罗系发育自流井组东岳庙段、大安寨段以及凉高山组上段共计3套优质页岩层系,具有源储一体、源储紧邻的特点,是典型的页岩油气发育层系,其中又以大安寨段为典型代表;②大安寨段页岩层系具有有机质含量高、有机质类型好、热演化程度适中、生烃能力强、页岩物性好、储集性能优、脆性矿物含量高、源储配置关系好、页岩厚度大、含油气性好等特征,是典型的页岩油气藏;③通过对大安寨段万吨井的解剖以及页岩有机质含量、热解参数、储层物性等试验数据揭示,该页岩油气藏存在着页岩与介壳灰岩两类储层的油气补给,并且前者的补给能力可能更强,故而页岩层系是侏罗系湖相页岩油气储量有效动用的主要对象;④基于目前的新认识,以页岩油气为勘探对象,通过非常规油气的技术手段,采用水平井+体积压裂技术,该层系一定会取得新的油气勘探突破.结论 认为,该项研究成果可以为四川盆地侏罗系湖相页岩油气的资源发现以及储量有效动用等提供理论和技术支撑.

以岩心观察和薄片鉴定为基础,结合沉积学、储层地质学等相关理论为指导,针对磨溪地区下寒武统龙王庙组晶粒白云岩开展了较精细的储层特征及成因研究.研究结果表明,川中地区龙王庙组晶粒白云岩储层储集性能良好,其主要的储集岩类型为粉晶白云岩及具残余颗粒结构的粉晶白云岩;储集空间包括晶间孔、晶间溶孔、溶洞与裂缝,总体上表现为“中低孔低渗”的孔隙型和孔隙-裂缝型储层.研究区晶粒白云岩储层的发育及演化受到沉积作用和成岩作用的共同控制:位于古地貌高地的台坪相及颗粒滩相为储层的形成奠定了物质基础;白云岩化和重结晶作用是形成现今粉晶白云岩及具残余颗粒结构粉晶白云岩的最直接原因;而多期溶蚀改造是研究区晶粒白云岩储层次生孔隙和溶洞形成的关键.综合以上研究认识建立了龙王庙组粉晶白云岩储层成因演化模式,并将其演化划分为同生沉积成岩阶段、埋藏阶段及构造破裂阶段.

随着认识的不断深入和工程技术的进步,页岩油气已经正式进入我国储量序列,正在有序开发.通过岩心、露头、钻井、测井以及大量的分析化验资料,对四川盆地侏罗系大安寨段湖相页岩油气的形成地质条件和资源潜力进行系统分析和评价.研究结果表明:①大安寨段湖相页岩主要发育在大一三亚段浅湖、半深湖泥,有机碳含量平均为1.15％,有机质类型均以Ⅱ型干酪根为主,镜质体反射率介于0.8％～1.4％,处于成熟—高成熟阶段,页岩厚度大,生烃能力强,具备形成页岩油气的物质基础.②大安寨段页岩以黑色、灰黑色页岩与生物介壳灰岩不等厚互层为主,脆性矿物平均含量为63.4％含量较高;页岩孔隙度平均为5.92％,储集条件好,储层发育微米—纳米级孔隙,具备储集页岩油气的储集空间,有利于页岩储层的改造.③大安寨段湖相页岩油气具有埋藏浅、保存条件好、压力系数高等优越条件,按照有机碳含量大于1.5％的范围,计算页岩油资源量为70×108t,页岩气的资源量为3.5×1012 m3,结合大安寨段页岩油气评价指标,优选出射洪—遂宁—南充—蓬安—仪陇—南部页岩油气勘探有利区近1×104km2,并建议在公山庙、龙岗地区开展先导试验工作.

Since 2014, great gas discoveries have been achieved in the Upper Paleozoic Shuangyushi zone in the piedmont zone of the Longmenshan mountains, northwestern Sichuan Basin, where multiple gas wells with industrial flows have been drilled and completed successively in the Middle Permian Qixia Fm and Middle Devonian Guanwushan Fm, etc. Along with the steady progress of exploration there, to make a further in-depth study on the characteristics of the frontal–piedmont zones in the Longmenshan thrust–nappe structures will be of great significance to both a better understanding of Upper Paleozoic gas reservoirs in this study area and the expansion of oil and gas exploration field. In view of this, based on the newly deployed 3D seismic surveys, gravity–magnetic–electronic data, and practical drilling information from exploration wells like Well ST 9, the characteristics of the frontal–piedmont zones in the Longmenshan thrust–nappe structures are analyzed as well as the features of the buried structures, gas reservoir forming conditions and exploration prospect there. The following findings were obtained: (1) A huge buried structure belt is developed underlying the Longmenshan front fault belt No. 1 (LSFFB 1) and marine strata are thus formed below the Lower Triassic Jialingjiang Fm due to the roles of compressive folding, extrusion and deformation; (2) The detachment horizons from LSFFB 1 go from shallower in the south to deeper in the north, turning from Cambrian slipping in the south to basement-involved in the north. The Paleozoic and its overlying strata were overall uplifted with a higher degree northward and so did the strata between the up-thrown and down-thrown sides of the faults with a greater displacement distance and higher folding degree, resulting in that the Paleozoic strata in the north are 1500 higher uplifted than those in the south; (3) In the western Jiange and Guangyuan areas, the eastern LSFFB 1 presents a tectonic pattern of “three steps” as a whole. In conclusion, there are good gas reservoir forming conditions in LSFFB 1, the down-thrown sides of which cover an area of 1800 km2, where the Guanwushan Fm and Qixia Fm provide good accumulation and preservation conditions for gas reservoirs, which will become favorable gas exploration targets in the deep marine strata in NW Sichuan Basin.

Many significant breakthroughs have been made in regards to deep oil and gas exploration and development in recent years. However, a systematic analysis has not been carried out on the progress, challenges, and development trend of exploration and development of onshore deep oil and gas resources in China. This paper summarizes five main points of deep oil and gas resources: (1) more gas, less oil, and complicated phases; (2) high temperature and pressure, as well as profoundly different basins or formations; (3) multiple hydrocarbon sources and accumulations; (4) relatively tight but effective large-scale reservoirs; and (5) complicated accumulation process and multi-stage reconstructions. Based on the exploration and development history of deep oil and gas, this paper points out China's take on it is at the “large-scale discovery stage during which significant achievements have been obtained in carbonate, clastic, and volcanic reservoirs. Nonetheless, there are still four challenges, namely: (1) complex hydrocarbon generation, reservoir evolution, and accumulation restriction on how to determine exploration orientation and targets; (2) long well drilling and completion period, as well as high well construction cost delay petroleum discovery and efficient development; (3) undeveloped logging technology for HPHT slim holes that cannot ensure accurate identification of hydrocarbon reservoir; and (4) effective development and large-scale utilization of unspecific recovery technique and equipment limit. Finally, by the comprehensive analysis, it is concluded that onshore deep oil and gas resources are mainly distributed in three areas of six basins in China. The areas have a vast exploration potential and have strategically successive resources. It is suggested that petroleum companies and universities, as well as research institutes, should work together to overcome difficulties in theory and practical technology for deep oil and gas exploration and development. Such partnership could develop fit-for-purpose theories and technical systems to support deep oil and gas development.

Exploration of the Sinian-Lower Paleozoic formations in the Sichuan Basin starts from the 1950s, and is tortuous and complex. To summarize the exploration experiences is of great significance of reference for exploration of oil and gas in deep carbonate rocks of the Sichuan Basin. Gas accumulation in the Anyue oversize gasfield is chiefly controlled by the Deyang-Anyue intra-platform rift and central Sichuan paleouplift. The intra-platform rift controls the scale hydrocarbon generation center and effective hydrocarbon plays. The Anyue gasfield is characterized by near-source hydrocarbon accumulation. The marginal zone of intra-platform rift and high part of the paleouplift control the scale distribution of favorable facies belts of reservoir development, and overlapped by paleokarstic reformation, the reservoirs are widely distributed. The intra-platform rift and paleouplift jointly control formation of the scale traps and hydrocarbon enrichment. Gas reservoir features and major controlling factors for hydrocarbon accumulation have some differences in the main play strata, such as Longwangmiao Formation, and Member 4 and Member 2 of Dengying Formation. The gas reservoir in the Longwangmiao Formation is a lithologic gas reservoir under the tectonic setting, and the inherited paleouplift is a key for reservoir formation and hydrocarbon accumulation. The gas reservoir in the Member 4 of Dengying Formation is mainly controlled by large structural-stratigraphic composite traps, and the gas reservoir in the Member 2 of Dengying Formation is the structural trap. Distribution of the large gasfields in the Dengying Formation is controlled by the intra-platform rift, near-source hydrocarbon-reservoir configuration controlled by the ancient erosion plane and stratigraphic sealing in the updip direction. For exploration and development of the Anyue gasfield, four series of technologies are developed, namely, reservoir seismic fine description technology, well logging fine evaluation technology of gas layers, fast drilling technology of complex strata, and stimulation technology for high temperature and high pressure gas layers. Technical progresses provide powerful guarantee for efficient exploration and development of the oversize gasfields.

The exploration and development of tight oil in the Jurassic has a long history in the Sichuan Basin.Many new developments and recognitions have been made during the 12th Five Year Plan based on tight oil geological theory and modern exploration and development techniques.However, tight oil exploration is still in beginning stages, facing the challenges of deepening theoretical knowledge, innovating key technology, improving management, and promoting development methodically.Due to complex geological conditions and the unforeseeable international crude oil supply situation, some advice was proposed to realize development efficiencies of the Jurassic tight oil in the Sichuan Basin.Target selection should be optimized to identify "sweet spots".New techniques are necessary for breaking bottlenecks.Improved management helps reduce costs.Scientific organizations can promote tight oil development systematically.