“巨型油气田”指在目前已知技术条件下，最终探明可采储量达到或超过0.68×10⁸t的油气田。本文在系统调研全球巨型油气田勘探与研究现状基础上，依托IHS、C&C数据库及国内外公开发表的相关文献资料，对截至2009年底的320个海相碳酸盐岩巨型油气田及其赋存的48个含油气盆地进行详细分析，重点探讨其发育的构造环境及其富集的盆地类型。构造环境主要包括伸展、挤压、走滑3种，应用Paul Mann提出的含油气盆地类型划分方案。研究表明，海相碳酸盐岩巨型油气田主要形成于伸展构造环境，包括大陆裂谷与上覆凹陷、面向大洋盆的被动大陆边缘2种类型盆地。伸展构造环境有利于优质烃源岩、有效储集层、良好盖层的形成及生储盖的有效配置。国外海相碳酸盐岩巨型油气田勘探带给我们的启示是:加强我国伸展构造环境下这2种类型原型盆地研究，尤其是盆地演化早期阶段裂谷的研究，这将对我国海相碳酸盐岩的油气勘探具有重要的指导意义。

<p>The giant fields are considered to be those with estimated ultimate recoverable hydrocarbons of equal or more than 680 million tons.On the basis of systematically surveying the status&nbsp; of the global giant field exploration and research,using the IHS and C&C databases and related literature on public publication,the paper analyses the 320 marine carbonate giant fields with their occurrence of 48 petroliferous basins by the end of 2009 in detail,with an emphasis on the plate tectonic setting and accumulation basin type.Plate tectonic setting includes divergent,convergent and transform,and the petroliferous basin classification of Paul Mann is used here.Research indicates that marine carbonate giant fields are formed mainly in divergent tectonic setting,including continental rifts and overlying sag,continental passive margins fronting major ocean basins.Divergent tectonic setting is favour of the forming of high quality source rocks,effective reservoir,good seal and effective assembly.The exploration inspiration is that enhancing the study of above-mentioned prototype basins in divergent tectonic setting,especially the rift&nbsp; at the early stage of basin evolution,which will guide our marine carbonate petroleum exploration.</p>

四川盆地天然气资源量居中国首位,目前探明率仅为18.8 %,勘探开发潜力巨大。近几年,四川盆地油气勘探相继在深层—超深层海相碳酸盐岩、海相非常规天然气、陆相致密气及陆相页岩油等新领域、新层系、新类型取得重大突破,展示出巨大的资源前景。川西—川中地区深层—超深层海相碳酸盐岩气藏多层系立体成藏,优质烃源岩供烃,多层系高能丘滩相储层垂向叠置、横向连片,源-储配置好,断裂输导体系发育,但勘探程度低,有望形成新的万亿立方米级规模增储区。川西—川中前陆坳陷—斜坡带为陆相致密气富集有利区,以须家河组为主力烃源岩,形成须家河组、侏罗系沙溪庙组两套成藏体系,已发现千亿立方米级大气田,累计提交地质储量超过1×10¹²m³,成为四川盆地天然气产量新的增长极。二叠系和侏罗系页岩、泥灰岩、煤岩等非常规含油气层系均连续稳定分布,油气大面积富集成藏,以川中—川东地区最为富集,已取得勘探突破。二叠系非常规天然气有利勘探区资源规模近8×10¹²m³,侏罗系页岩油有利勘探区资源量为16.96×10⁸t。川西—川中地区深层—超深层海相碳酸盐岩天然气以及陆相致密气已形成四川盆地新的规模增储主阵地,非常规天然气及陆相页岩油是重要的资源接替领域。

基于四川盆地海相大中型气田基本特征分析,结合海相克拉通阶段主要成藏地质单元划分及其对关键成藏要素的控制作用研究,探讨盆地海相碳酸盐岩大中型气田分布规律,指出勘探方向。通过周期性拉张-隆升背景的分析,提出四川海相克拉通阶段发育形成了5个大型古裂陷、3个大型古隆起、5个大型古侵蚀面等大型地质单元,这些地质单元控制了大中型气田的关键成藏要素：①大型古裂陷控制了优质烃源岩生烃中心展布;②大型古裂陷边缘、古隆起高部位、古侵蚀面控制了优质储集层的展布;③大型古裂陷、古隆起、古侵蚀面和现今构造背景联合控制了多类大中型圈闭的形成;④大型地质单元内圈闭继承性演化控制天然气规模聚集。通过大中型气田展布特征与大型成藏地质单元的对比分析,提出单个或多个成藏地质单元与现今构造的叠合关系控制了大中型气田的分布,“三古”叠合区最为有利。德阳—安岳古裂陷周缘、龙门山古裂陷东缘、开江—梁平海槽及城口—鄂西海槽边缘带、环川中水下古隆起高部位、川东—蜀南地区茅口组顶界古侵蚀面、川中—川西雷口坡组顶界古侵蚀面等,是四川盆地海相碳酸盐岩大中型气田勘探主要领域和方向。图6表2参59

Based on the analysis of the basic characteristics of medium- and large-sized marine gas fields in Sichuan Basin, combined with the division of major reservoir forming geological units in the marine craton stage and their control on key hydrocarbon accumulation factors, the distribution law of medium- and large-sized marine carbonate gas fields in the basin was examined and the exploration direction was pointed out. Through the analysis of the periodic stretching-uplifting background, it is concluded that five large scale paleo-rifts, three large scale paleo-uplifts, five large scale paleo erosion surfaces were formed in the marine craton stage of Sichuan Basin, and these geological units control the key reservoir forming factors of medium and large sized gas fields: (1) Large-scale paleo-rifts control the distribution of high-quality hydrocarbon generation centers. (2) The margin of large-scale paleo-rifts, high position of paleo-uplifts and paleo erosion surfaces control the distribution of high-quality reservoirs. (3) Large-scale paleo-rifts, paleo-uplifts, paleo erosion surfaces and present tectonic setting jointly control the formation of many types of large and medium-sized traps. (4) Natural gas accumulation is controlled by the inheritance evolution of traps in large geological units. Based on the comparative analysis of the distribution characteristics of medium- and large-sized gas fields and large geological units, it is proposed that the superimposition relationship between single or multiple geological units and the present structure controls the distribution of medium- and large-sized gas fields, and the "three paleo" superimposed area is the most advantageous. According to the above rules, the main exploration fields and directions of medium- and large-sized marine carbonate gas fields in Sichuan Basin include periphery of Deyang-Anyue paleo-rift, eastern margin of Longmenshan paleo-rift, margins of Kaijiang-Liangping oceanic trough and Chengkou-western Hubei oceanic trough, the high part of the subaqueous paleo-uplifts around Central Sichuan, paleo erosion surfaces of the top boundary of Maokou Formation in eastern and southern Sichuan Basin, paleo erosion surfaces of the top boundary of the Leikoupo Formation in central and western Sichuan Basin.

基于四川盆地海相油气勘探现状和进展，以主力烃源岩为核心，依据成藏要素组合关系划分四川盆地海相碳酸盐岩全油气系统，并分析各个含油气系统的成藏特征，总结常规-非常规一体化成藏规律，指明未来有利勘探方向。研究认为：①受多期伸展-聚敛构造旋回的控制，四川盆地海相发育3套区域性烃源岩和3套区域性盖层，可划分出寒武系、志留系和二叠系3个全油气系统。3个全油气系统以独立成藏为主，单一系统内天然气具有亲缘性。同时，局部地区大型断裂带贯穿多套全油气系统，形成断控复式全油气系统。②全油气系统内普遍发育“陆棚相页岩气聚集—台缘相控气藏—台内断-相共控型气藏”的成藏序列，具有立体成藏、有序分布的规律。③优质烃源岩是大气田形成的基础，全油气系统内天然气具有近源和源内富集的规律，规模性储层的发育与保持是天然气富集的保障，“多元生烃、油气转化、动态调整”是海相油气成藏的特色，良好的保存条件是天然气成藏的关键。④大型台缘带礁滩相带、深层页岩气与通源断裂相关的大型岩性复合体是未来四川盆地海相油气勘探的主要方向。

中国海相碳酸盐岩具有年代老、埋藏深、后期成岩改造强的特点,随着油气勘探逐渐走向“更老”、“更深”、“更复杂”的深层和超深层,碳酸盐岩储集层成因和分布规律成为影响油气勘探开发效益的关键因素。近年来,在塔里木、四川和鄂尔多斯三大海相盆地多个领域取得了一系列的勘探新突破,古老超深层碳酸盐岩储集层地质理论和相关技术取得显著进展。地质理论进展包括: (1)近地表环境成因孔隙构成超深层碳酸盐岩储集层的基础; (2)浅埋藏阶段的孔隙保持是决定超深层储集层质量的关键; (3)构造活动驱动深部流体运动对储集层质量具有重要改造作用。技术进展包括微量稀土元素面扫、激光U-Pb定年、团簇同位素和非传统稳定同位素等储集层地球化学实验分析技术和高温高压溶蚀模拟技术。勘探的深入和分析技术手段的进步,显著提升了对三大盆地重点领域规模优质储集层发育及分布规律的认识,为下步油田勘探取得重大突破奠定了基础。

Marine carbonate rocks in China are featured by old age,deep burial,and strongly diagenetic modification during the burial stage. As oil and gas exploration gradually extents towards “older”,“deeper”,and “more complex”deep and ultra-deep layers,the genesis and distribution patterns of carbonate reservoirs have become key factors affecting the efficiency of oil and gas exploration and development. In recent years,a series of exploration breakthroughs have been made in multiple exploration fields in the Tarim,Sichuan,and Ordos basins. Meanwhile,substantial progress has been made both in the geological theory and in the related technologies of ancient deep carbonate reservoirs. Advancements in geological theory include the following aspects: (1)porosity formecl under subaerial environment constitutes the basis of the deeply-buried carbonate reservoir size;(2)the preservation of porosity during shallow burial period is the key to the size and the quality of the deeply-buried dolomite reservoir;and(3)tectonic activity-driven deep fluid movements play an important role in modifying the quality of deeply-buried carbonate reservoir. Technological advancements include: (1)geochemically experimental analysis techniques such as surface scanning of trace rare earth elements,laser-ablation U-Pb dating,clumped isotopes and non-traditional stable isotopes;and(2)high-temperature and high-pressure dissolution simulation techniques. The deepening of exploration realm and the progress of analytical techniques have significantly improved the understanding of the development and distribution of large-scale high-quality reservoirs in deeply buried fields of the three major basins,and built the foundation for major breakthroughs in oil field exploration in the future.

在深层碳酸盐岩层系中,已陆续发现了塔河、普光、元坝、安岳等一系列大型油气田,并形成了碳酸盐岩“三元控储”等成储理论认识。近年来,四川和塔里木盆地相继在超过7 000 m甚至8 000 m的超深层中发现了优质碳酸盐岩储层。深层储层类型更加多样,控储因素中,相带、流体、压力和断裂,以及它们之间相互作用的内涵更为丰富。结合近期大量新的超深钻探资料,持续开展了深层-超深层碳酸盐岩成储机理的研究。通过塔里木盆地塔河-顺北地区奥陶系和四川盆地二叠系栖霞组、茅口组的深化研究,进一步揭示了构造破裂和多类型流体耦合改造储集体的成储机制;通过上震旦统四川盆地灯影组和塔里木盆地奇格布拉克组的系统分析,揭示了新元古代“白云石海”沉积环境、早期溶蚀和早期油气充注在成储与孔隙保持中的关键作用;通过开展含膏岩层系白云岩成储的物理模拟实验,揭示了膏盐岩封盖及超压、较为封闭的环境下,白云石重结晶作用显著改善了储集物性。深层-超深层储层发育机理新认识丰富了“三元控储”理论,有效引领了超深层,乃至特深层的油气勘探。断控和断-溶双控储集体、古老微生物丘滩相白云岩储层,尤其是寒武系厚层膏盐岩之下的微生物丘滩相白云岩储层,在中西部叠合盆地海相碳酸盐岩层系中广泛分布,有望成为万米特深层钻探的主要对象。

In deep carbonate strata of the Sichuan and Tarim Basins a series of large scale oil and gas fields have been discovered successively, including the Jingbian, Tahe, Puguang and Yuanba fields, and a “ternary reservoir control” theory for reef-shoal carbonate reservoirs has been developed. In recent years, high-quality carbonate reservoir rocks are discovered in ultra-deep layers at depths of greater than 7000 m or even 8000 m. The deep reservoirs show diverse rock types and complex interactions between the reservoir controlling factors such as facies belt, fluid, pressure, and fault. Using the newly obtained ultra-deep drilling data we carried out a systematic investigation into the formation mechanism of the ultra-deep carbonate reservoir rocks. In-depth studies of the Ordovician strata of Tahe-Shunbei-Shunnan area, Tarim Basin and the Permian Qixia and Maokou Formations in the Sichuan Basin provided further insights into reservoir formation by mechanisms of fault-related fracturing and coupled multi-type fluid alteration. Results for the Upper Sinian Dengying Formation in the Sichuan Basin and the Upper Sinian Qigebulake Formation in the Tarim Basin suggested that the Neoproterozoic “dolomite sea” depositional environment, early dissolution, and early hydrocarbon charging are the key factors for reservoir formation and preservation. Physical simulation experiment on dolomite reservoir formation in gypsum-bearing facies revealed that dolomite recrystallization can significantly improve reservoir properties under gypsum-salt capping and overpressure and relatively closed environment. The new insights enriched the “ternary reservoir control” theory and provided guidance for oil and gas exploration in ultra-deep and even extra-deep strata. In superimposed basins in central and western China, fault-controlled and fault/dissolution dual-controlled reservoirs, ancient microbial mound-shoal dolomite reservoirs, especially those with Cambrian thick gypsum-salt caprocks, are widely distributed in marine carbonate rocks and can be considered the main exploration targets at > 10000 m depths.

Many carbonate reservoirs in Sichuan Basin have been developed in multi-strata and accumulated in large thickness. These carbonate reservoirs play a great role in natural gas reserves and production in Sichuan-Chongqing region. Based on the analysis of basic characteristics such as rock types, physical properties and reservoir types, this study summarized the main controlling factors of development of carbonate reservoirs and the prediction of reservoir distribution in Sichuan Basin. The main types of reservoir rocks are granular dolomite, algal (reef) dolomite, and powder-fine crystal dolomite, followed by limestone. The reservoir rocks are generally characterized by low porosity and low permeability. High-quality reservoirs developed in local areas are the favorable exploration zones. The reservoirs can be divided into four types, i.e., fractured-porous reservoir, porous reservoir, fractured-vuggy reservoir, and fractured reservoir. The degree of reservoir development is mainly controlled by multi-factor such as the favorable sedimentary facies, dolomitization, and three-stage dissolution. Detailed depiction of sedimentary microfacies is an effective way for prediction of reservoir distribution in facies-controlled reservoirs such as organic reefs and grain shoals. As for the karst reservoirs associated with weathering, reconstruction of regional and local palaeogeomorphology will provide a basis for reservoir evaluation and prediction.

根据四川盆地海相碳酸盐岩储层的岩石学、地球化学等特征，结合储层发育分布规律，提出储层成因综合分类：指出四川盆地海相碳酸盐岩储层分为礁滩储集层、表生岩溶储集层、白云岩储集层三大类。三个大类进一步分为了7 个亚类。礁滩储集层发育的最主要控制因素是沉积相带，即礁、滩相沉积控制优质储层规模发育，也控制了后期的白云石化作用和岩溶作用；依据沉积特征，将礁、滩储集层分为台缘礁储集层、台缘颗粒滩储集层、台内颗粒滩储集层3 个亚类。岩溶作用的强度和对储层的改造效果受岩石成分和岩石组构控制，形成不同类型的表生岩溶储集层；依据储层特征，将表生岩溶储集层划分为白云岩风化壳储集层、石灰岩风化壳储集层2 个亚类。白云岩储集层主要受控于白云石化作用和与白云石化流体相关的溶蚀作用。储层成因及地质特征的认识对于四川盆地寻找规模碳酸盐岩储层的油气勘探具有重要借鉴作用。

According to the petrological and geochemical characteristics and the development distribution laws, the marine carbonate reservoirs in Sichuan Basin may be divided into three types from their genesis, including bioreef-shoal reservoirs, supergene karst reservoirs, and dolomite reservoirs. Moreover, these three types of reservoirs can be subdivided into seven subtypes. For the bioreefshoal reservoirs, the most important factor controlling their development is sedimentary facies belt, in other words, both bioreef- and shoal-facies sediments affect not only the large-scale development of quality reservoirs but also the later dolomitization and karstification. Based on sedimentary characteristics, this type of reservoirs may be subdivided into three subtypes, i.e. platform margin bioreef reservoirs, platform margin grain shoal reservoirs, and intraplatform grain shoal reservoirs. The karstification intensity and its effect on reservoir reformation are controlled by rock composition and framework to form different types of supergene karst reservoirs. In addition, on the basis of reservoir characteristics, the supergene karst reservoirs may be subdivided into two subtypes, i.e. dolomite weathering crust reservoirs and limestone weathering crust reservoirs. The former is mainly affected by dolomitization and dissolution associated with dolomitized fluid. These geological understandings on reservoir genesis and characteristics may provide important reference for seeking large-scale carbonate reservoirs in Sichuan Basin.

通过对塔里木和四川盆地礁滩、岩溶和白云岩储集层的实例解剖，深入分析碳酸盐岩储集层发育的物质基础，碳酸盐岩储集层孔隙发育、调整和保存的机理及环境，厘清不同类型碳酸盐岩储集层发育的主控因素。碳酸盐岩储集层发育受控于3个因素：①礁滩相沉积，其不仅是礁滩储集层发育的物质基础，同样是白云岩储集层和岩溶储集层发育非常重要的物质基础；②表生环境，碳酸盐岩储集层孔隙主要形成于表生环境，可以是沉积原生孔隙，也可以是早表生及晚表生期淡水溶蚀形成的次生溶孔（洞）；③埋藏环境，埋藏环境是碳酸盐岩储集层孔隙保存和调整的场所。没有单一成因的古老海相碳酸盐岩储集层，其成因为上述3个控制因素的叠加，储集层发育的主控因素分别为礁滩相沉积、表生岩溶作用、蒸发相带、埋藏-热液溶蚀作用时，分别形成礁滩储集层、岩溶储集层、沉积型白云岩储集层和埋藏-热液改造型白云岩储集层。图6表5参22

Through case study of reef-shoal, karst and dolostone reservoirs in the Tarim and Sichuan Basins, the material base and the mechanisms of porosity creation, modification and preservation of carbonate reservoirs were examined carefully in order to figure out the major factors controlling the development of various types of carbonate reservoirs. Three factors control the development of carbonate reservoirs: (1) carbonate sediments of reef-shoal facies are the material base for not only reef-shoal reservoirs, but also dolostone and karst reservoirs; (2) epigenetic environment is crucial for porosity creation, i.e. reservoir space in ancient carbonates includes primary depositional porosity and/or secondary dissolution pores caused by epigenetic, freshwater dissolution; and (3) burial environment is the setting for porosity modification and preservation. There is no carbonate reservoirs of solely one origin, carbonate reservoirs are all the products of the combined effect of the above three factors. The four main controlling factors, reef-shoal sediments, epigenetic karstification, evaporation facies belt and burial-thermal fluid dissolution give rise to the reef-shoal, karst, sedimentary dolostone and burial-hydrothermal alteration dolostone reservoirs respectively.

2013年四川盆地川中古隆起发现了安岳震旦系—寒武系特大型气田，磨溪区块龙王庙组探明含气面积779.9 km2，探明地质储量4 403.8×108 m3，气藏类型为构造岩性气藏，该领域具备形成万亿立方米级天然气储量规模。主要取得如下认识：①重新厘定了震旦系、寒武系地层沉积充填序列及划分对比依据。②晚震旦世—早寒武世早期继承性发育“德阳—安岳”古裂陷槽，控制下寒武统烃源层分布，源岩厚20～160 m、TOC值为1.7%～3.6%、Ro值为2.0%～3.5%。③灯影组发育碳酸盐镶边台地、龙王庙组发育碳酸盐缓坡台地，靠近同沉积古隆起发育大面积颗粒滩。④大面积发育震旦系灯影组碳酸盐岩缝洞型、寒武系龙王庙组白云岩孔隙型2套主要含气储集层，准同生白云石化和表生岩溶叠加改造形成相对高孔渗储集体，灯影组孔隙度3%～4%、渗透率（1～6）×10-3 μm2，龙王庙组孔隙度4%～5%、渗透率（1～5）×10-3 μm2。⑤古隆起核部在晚海西—印支期发育大型古油藏，分布面积超过5 000 km2，石油资源量（48～63）×108 t，燕山期发生原位原油裂解成气及斜坡深部分散液态烃裂解成气，提供充足气源。⑥震旦系—寒武系特大型气田形成和留存主要受“古裂陷槽、古台地、古油裂解气、古隆起”“四古”共同控制。⑦初步预测震旦系—寒武系天然气资源量总量可达5×1012 m3左右，古隆起及其斜坡带、蜀南坳陷带、川东高陡构造带深层是该层系重点勘探区带。四川盆地深部安岳震旦系—寒武系原生原油裂解气特大型气田重大发现，在全球古老地层天然气勘探中尚属首次，对开拓全球中深层下古生界—中上元古界古老地层油气领域具有重大科学与实践意义。图15表4参20

The Anyue Sinian-Cambrian giant gas field was discovered in central paleo-uplift in the Sichuan Basin in 2013, which is a structural-lithological gas reservoir, with 779.9 km2 proven gas-bearing area and 4 403.8×108 m3 proven geological reserves in the Cambrian Longwangmiao Formation in Moxi Block, and the discovery implies it possesses trillion-cubic-meter reserves in the Sinian-Cambrian Formations in Sichuan Basin. The main understandings achieved are as follows: (1) Sinian-Cambrian sedimentary filling sequences and division evidence are redetermined; (2) During Late Sinian and Early Cambrian, “Deyang-Anyue” paleo-taphrogenic trough was successively developed and controlled the distribution of source rocks in the Lower-Cambrian, characterized by 20-160 m source rock thickness, TOC 1.7%-3.6% and Ro 2.0%-3.5%; (3) Carbonate edge platform occurred in the Sinian Dengying Formation, and carbonate gentle slope platform occurred in the Longwangmiao Formation, with large-scale grain beach near the synsedimentary paleo-uplift; (4) Two types of gas-bearing reservoir, i.e. carbonate fracture-vug type in the Sinian Dengying Formation and dolomite pore type in the Cambrian Longwangmiao Formation, and superposition transformation of penecontemporaneous dolomitization and supergene karst formed high porosity-permeability reservoirs, with 3%-4% porosity and (1-6)×10-3 μm2 permeability in the Sinian Dengying Formation, and 4%-5% porosity and (1-5)×10-3 μm2 permeability in the Cambrian Longwangmiao Formation; (5) Giant paleo-oil pool occurred in the core of the paleo-uplift during late Hercynian—Indosinian, with over 5 000 km2 and (48-63)×108 t oil resources, and then in the Yanshanian period, in-situ crude oil cracked to generate gas and dispersive liquid hydrocarbons in deep slope cracked to generate gas, both of which provide sufficient gas for the giant gas field; (6) The formation and retention of the giant gas field is mainly controlled by paleo-taphrogenic trough, paleo-platform, paleo-oil pool cracking gas and paleo-uplift jointly; (7) Total gas resources of the Sinian-Cambrian giant gas field are preliminarily predicted to be about 5×1012 m3, and the paleo-uplift and its slope, southern Sichuan Basin depression and deep formations of the high and steep structure belt in east Sichuan, are key exploration plays. The discovery of deep Anyue Sinian-Cambrian giant primay oil-cracking gas field in the Sichuan Basin, is the first in global ancient strata exploration, which is of great inspiration for extension of oil & gas discoveries for global middle-deep formations from Lower Paleozoic to Middle-Upper Proterozoic strata.

2011年以来，在四川盆地川中古隆起磨溪—高石梯地区发现震旦系、寒武系特大型气田，主力含气层系包括震旦系灯影组灯二段、灯四段及寒武系龙王庙组，地质储量规模超过万亿立方米。在简要回顾川中古隆起大气区战略发现历程的基础上，系统阐述川中古隆起龙王庙组特大型气田的形成条件及油气富集规律，指出大型古隆起背景、大型网状供烃系统、规模化的颗粒滩储集层以及区域性的储盖组合是特大型气田形成的重要条件；针对龙王庙组超深、高温、高压等复杂地层条件，分别在测井、地震、钻井、储集层改造等方面进行了技术攻关，并形成了相应的配套成果，应用效果良好，展示了四川盆地震旦系—寒武系巨大的油气勘探潜力。图13参13

Since 2011, a giant gas field has been discovered in the Sinian and Cambrian strata in Moxi–Gaoshiti region, central Sichuan paleo-uplift, with the geological reserves reaching more than one trillion cubic meters. The main gas-bearing layers include Deng 2 Member, Deng 4 Member of Sinian Dengying Formation and Cambrian Longwangmiao Formation. Based on brief review of the exploration history of large gas province in central Sichuan paleo-uplift, the paper systematically describes the formation conditions and petroleum accumulation patterns of the giant gas field, and points out the large ancient uplift background, huge net of hydrocarbon supply system, large-scale particle shoal reservoirs and regional reservoir-cap combinations are important material conditions for the formation of the giant gas field. In view of the huge depth, high temperature, high pressure and some other complex formation conditions, a lot of efforts have been put into the research on logging, seismic, drilling, reservoir stimulation etc, and a series of accomplishments have been achieved, which work well in the exploration and development of gas in Sichuan Basin. The Sinian and Cambrian strata in the Sichuan Basin have a great potential for petroleum exploration.

蓬探1井是部署在四川盆地德阳&mdash;安岳裂陷内以震旦系灯影组为主要目的层的风险探井，探索裂陷主力 烃源灶区灯影组储层及含气性。利用蓬探1井钻井资料，结合地震资料，分析了蓬探1井地层与沉积序列，探讨裂陷 内灯二段台缘丘滩分布控制因素，指出下一步有利勘探区域。研究结果表明：①德阳&mdash;安岳裂陷北段灯影组地层序列 表现为灯四段缺失，灯三段与下寒武统麦地坪组假整合接触；②德阳&mdash;安岳裂陷内灯二段发育受同沉积断层控制的丘 滩体，微生物碳酸盐岩发育；③灯二段储层以藻砂屑云岩、藻凝块云岩为主，溶蚀孔洞发育，储层储集物性良好； ④灯二段含气性良好，测井解释气层厚度为119.26m，气水界面为-5550m。研究认为裂陷内灯二段发育多排断阶控 制的台缘丘滩带，与寒武系筇竹寺组烃源岩直接接触，近源成藏条件优越，是规模勘探的重要领域。2020年5月4日 蓬探1井在灯二段测试获天然气121.98&times;104m3/d，展示裂陷内灯二段具有较大勘探潜力。

Research of Tongwan Movement gradually became popular for its multi-episode tectonics in Sinian-Early Cambrian.It arrived at a common view that the Tongwan Movement was closely related to the karst reservoirs in Dengying Formation of Sinian.However,it is still controversial on the relationship between the Tongwan Movement and Sinian-Early Cambrian paleo-tectonics.Therefore,a study on the Tongwan Movement is meaningful for its tight connection with hydrocarbon geological conditions.Based on drilling core,outcrop and seismic data in central Sichuan area and combined with geological materials,the stages,the motion of Tongwan Movement and its impact on the Sinian-Early Cambrian paleo-tectonics were studied,leading to the results as follows:(1)The 3-episode Tongwan Movement appeared episodic uplift as a whole.Tongwan Ⅰ and Ⅱ episode influenced the whole of Yangzi Plate,while the effect of Tongwan Ⅲ episode was restricted in limited areas.Even the same episode of Tongwan Movement showed different magnitudes in different areas,which reflected the existence of differential vertical motion in some areas.(2)Tongwan episodic uplifting resulted in differential elevation and subsidence,which accelerated the formation of uplift-depression patterns.The Sinian-Early Cambrian tectonic evolution of Sichuan Basin could thus be divided into 7 stages,including uplift-depression differentiation embryonic stage,uplift-depression differentiation stage,intense uplift-depression differentiation stage,uplift-depression forming stage,uplift-depression adjusting stage and uplift-depression filling-up stage.(3)The interaction of paleohighs and Tongwan episodic uplifting motivated the uplifting and exposure of sedimentary mound-beach in uplifting area,which was beneficial for the development of karst reservoirs.The unconformity of Tongwan Movement could act as dominant channels for migration of ancient oil reservoirs in Sinian and present gas reservoirs.In conclusion,Tongwan multi-episode movement has a great influence on the tectonic evolution,reservoir formation and migration and accumulation of hydrocarbon in Sinian-Early Cambrian.

华南板块新元古代的兴凯地裂运动始于晋宁运动后（800 Ma B. P.），强烈活动于新元古代中期的苏雄—开建桥组火山岩喷发期（700 Ma B. P.），结束于中奥陶世的郁南运动（458 Ma B. P.）。演化历程大体相当于Rodinia（罗迪尼亚）超大陆解体时，应为Rodinia 超大陆裂解期的组成部分。兴凯地裂运动在新元古代形成扬子板块的基底，对中上扬子区后期构造变形有重要的影响，为后兴凯期（加里东运动）形成大型古隆起和大形拗陷提供了基础；产生的基底断裂对四川盆地后期构造活动有控制作用；形成的稳定大陆边缘为下组合烃源岩发育提供了条件。

利用钻井和地震资料,在上扬子克拉通德阳-安岳地区发现晚震旦世-早寒武世克拉通内裂陷,受张性断裂控制,呈NNW向展布,南北长320 km、东西宽50~300 km。裂陷演化经历了形成期、发展期、消亡期3个阶段,形成有利的近源成藏组合。研究结果表明:1晚震旦世灯影组沉积期为裂陷形成期,裂陷内发育槽盆相沉积,两侧发育台地边缘相丘滩体,控制了灯影组优质储层的形成与分布;2早寒武世梅树村组沉积期-筇竹寺组沉积期为裂陷发展期,充填500~1000 m的深水陆棚相泥质岩,是优质烃源岩沉积期;3沧浪铺组沉积期为裂陷消亡期,经填平补齐,结束了克拉通内裂陷的演化历史。克拉通内裂陷是安岳特大型气田形成的关键因素,裂陷内优质烃源岩为特大型气田提供了充足的气源,在晚燕山期-喜马拉雅期川中古隆起西部快速隆升过程中形成区域性侧向封堵,有利于裂陷东翼的高石梯-磨溪地区特大型气田的保存。克拉通内裂陷及其大气田成藏作用对古老克拉通盆地深层油气勘探有重要的参考价值。

According to the drilling and seismic data,the Late Sinian-Early Cambrian intra-cratonic rift was found in Deyang-Anyue area of the Upper Yangtze craton.This rift is controlled by tensional fault and distributed in NNW trending with the NS length of 320 km and EW width of 50-300 km.After three stages of rift evolution,i.e.,the forming stage,developing stage and dying stage,a favorable near-source accumulation assemblage was formed.The research results indicate that:(1) the sedimentary stage of Late Sinian Dengying Formation is the rift forming stage,during which trough-basin facies sedimentation is developed in the rift,while platform marginal facies mounds and shoals are developed on both side,controlling the formation and distribution of high-quality reservoirs in Dengying Formation;(2) the sedimentation stage of Early Cambrian Meishucun-Qiongzhusi Formation is the rift development stage,during which deep-water continental shelf facies argillaceous rocks are filled in the rift with a thickness of 500-1000 m,indicating the sedimentation stage of high-quality source rocks;(3) the sedimentation stage of Canglangpu Formation is the rift dying stage,terminating the evolution history of intra-cratonic rift by gap filling.The intra-cratonic rift is a key factor for the formation of Anyue giant gas field,where the high-quality source rocks provide abundant gases for the giant gas field.A regional lateral sealing occurred during the rapid rising of the western paleo-uplift in Central Sichuan during the Late Yanshan-Himalayan period,favorable to the preservation of the Gaoshiti-Moxi giant gas field on the east wing of the rift.The intra-cratonic rift and its role in giant gas accumulation provides a significant reference for deep oil and gas exploration in paleo-craton basins.

Based on the observation of typical outcrops, cores and petrographic thin sections, combined with the experimental analysis data, the lithofacies palaeogeography, reservoir characteristics and their main controlling factors of the Cambrian Xixiangchi Formation in Sichuan Basin were studied. The results show that: (1) The Xixiangchi Formation is developed in the rimmed carbonate platform, and the Sichuan Basin is located in the interior of the limited platform as a whole, with the high-energy shoal facies developing on both sides of the Liangping-Chongqing platform depression; (2) The effective reservoirs are mainly developed in the middle and upper part of Xixiangchi Formation, dominated by grain dolomite, crystalline dolomite and algae dolomite. The reservoir spaces are consisted of dissolution pore, intergranular pore, intercrystalline pore and fracture, with porosity mostly at the range of 2,～5, and the average of 3.46,. (3) The formation and distribution of reservoirs are controlled by sedimentary facies, penecontemporaneous dissolution and supergene karstification. Reservoirs are mainly developed in the higher part of paleogeomorphology, and in the upper part of upward-shallowing cycle of sea water, and near the pinchout line of Ordovician. It is predicted that the areas of Hechuan-Guang'an and Nanchuan-Shizhu, as the high parts of palaeogeomorphology at the both sides of Liangping-Chongqing platform depression, are the favorable shoal reservoir zones, and Xichong-Guang'an-Tongnan area is the favorable karst reservoir zone. It is concluded that the Xichong-Guang'an area is the main target zone of natural gas exploration in the future.

综合利用野外露头、岩心、钻测井等资料，对四川盆地及周缘地区晚奥陶世岩相古地理演化过程进行了描述和对比，并探讨了其主控因素。研究结果表明： ①加里东运动早期拉张—伸展作用导致四川盆地周缘坳陷加深，其后扬子板块和华夏地块碰撞挤压，形成了晚奥陶世以上扬子地区为中心，西北、西部、南部三面环隆的古地理格局。②四川盆地及周缘地区晚奥陶世可划分出（混积）滨岸、碳酸盐缓坡、（混积）陆棚相等沉积相类型。宝塔组—临湘组主要发育碳酸盐缓坡相；五峰组沉积期海侵达到高峰，碳酸盐缓坡被淹没，发育（混积）陆棚相深水黑色页岩；观音桥组沉积期发生的海退导致大部分地区由深水陆棚转为浅海陆棚亚相；各时期古隆起周缘均有（混积）滨岸相发育，受物源影响部分地区具有混合沉积特征。③研究区晚奥陶世岩相古地理格局受构造运动、海平面变化和古气候等因素综合控制，在沉积相平面展布和垂向演化上均有体现。

Based on outcrops, cores, drilling and logging data, the evolution process of Lithofacies paleogeography of Late Ordovician in Sichuan Basin and its surrounding areas was described and compared, and the main controlling factors were discussed. The results show that:(1) The early Caledonian tension-extension led to the deepening of the depression around the study area, and then the collision and extrusion of the Yangtze plate and Cathaysia block formed the paleogeographic pattern of the upper Late Ordovician Yangtze region as the center, surrounded by uplifts on the northwest, west and south sides.(2) The Late Ordovician in Sichuan Basin and its surrounding areas can be divided into(mixed) shore, carbonate gentle slope and(mixed) shelf sedimentary facies. The Baota Formation-Linxiang Formation mainly developed carbonate gentle slope facies. At the transgressive peak of Wufeng Formation, the carbonate gentle slope was submerged and developed(mixed) shelf deep water black shale. The regressions of Guanyinqiao Formation led to the transition from deep shelf to shallow shelf subfacies in most areas. There are(mixed) shore facies developed in the periphery of paleo-uplift in all periods, and some areas affected by provenance have mixed sedimentary characteristics.(3) The lithofacies paleogeographic pattern of the Late Ordovician in the study area is controlled by multiple factors such as tectonic movement, sea level change and paleoclimate, which is reflected in the plane distribution and vertical evolution of sedimentary facies.

Based on the data of drilling, outcrop, logging, seismic and micro -area multi-parameter experimental analysis obtained in recent years, the key geological problems of the Permian Qixia Formation in sichuan basin are systematically analyzed and the following recognitions is obtained: (1) The sedimentation of Qixia Formation is controlled by the residual geomorphology of Middle Sichuan paleouplift, in which the shallow ramp is developed in most areas of paleouplift. The eastern margin of the paleouplift appears as a shape of"S", and gradually evolves into a medium-deep ramp towards the southeast. The geomorphology of the western margin of the paleouplift is relatively the highest, which is the basis for the development of the platform margin. (2)In the middle-late Qixia period, there exists a right-leaning "L" type slightly rimmed platform margin in western Sichuan, which extends to Guangyuan area in northeast and Emeishan area in southwest. The platform margin transforms into a broad sea sharply in the west and a carbonate ramp gradually in the east. (3) As the main reservoir rock of Qixia Formation, crystalline dolomite is formed gradually under the penecontemporaneous magnesium-rich fluid infiltration and reflux, and is finalized after adjustment and transformation in a buried environment.(4)High quality dolomite reservoirs are controlled by sedimentary facies, sequence interfaces, micro-paleogeomorphology and other factors, among which the thick crystalline dolomite layers are mainly distributed in the Guangyuan-Jiangyou and Ya'an-Leshan areas in western Sichuan Basin, and the medium-thin crystalline dolomite layers are mainly distributed in the Nanchong-Moxi-Gaoshiti areas in central Sichuan Basin.

Based on data of outcrop, drilling core, logging, thin section and other macro and micro data, the characteristics of sedimentary facies, reservoir types, reservoir-controlling factors and reservoir distribution patterns of the Perimian Maokou Formation are systematically studied in Sichuan Basin. The author obtains the understanding as follows: (1) The sedimentary pattern of Maokou Formation is influenced by the NW-SE faults formed by Emei taphrogenesis, but not by Caledonian paleo-uplift. (2) Carbonate ramp, slope and basin are three main facies in Maokou Formation. The high-energy shoal of high-stand system tract developed in shallow ramp in the middle-late period of Maokou is the most favorable reservoir sedimentary facies. (3) Two types of reservoir such as hole-pore dolomite reservoir and karst fractured-vuggy limestone reservoir are developed in Maokou Formation. The high-energy bioclastic shoal is the material basis for reservoirs of Maokou Formation. Early dolomization is the key factor for the preserving of dolomite reservoir, tectonic movement and paleo-karstification are important conditions of reservoir development. (4) Dolomite reservoir is mainly distributed in the Ya'an-Leshan and the Yanting-Guang'an areas. Karst fractured-vuggy limestone reservoirs are distributed in the whole basin, but the Luzhou-Kaijiang uplift is the most developed area.

四川盆地中三叠统雷口坡组近年取得重要的勘探发现，规模储集体是控制成藏的关键因素之一。通过野外露头、探井、测井和地震等资料，编制雷口坡组岩相古地理图，分析规模储集体特征，得到3点新认识：①雷口坡期四川盆地南、东、北3个方向较封闭、海水从西侧进入，为较封闭碳酸盐岩台地；雷一、二段沉积期为弱镶边碳酸盐岩台地，雷三、四段沉积期为镶边碳酸盐岩台地。②雷口坡组发育台地边缘、开阔台地、局限台地和蒸发台地等沉积相，以局限台地相为主，包括潟湖、台内滩和潮坪等亚相，发育台地边缘滩和台内滩2类油气储集体。③雷口坡组发育2套规模颗粒滩储集体：一是川西北地区雷三、四段台地边缘滩，厚度大（一般大于50 m）；二是川中地区雷一段下部的台内滩，厚度小、分布稳定、面积大（大于20 000 km²）、成规模，这2类规模储集体经多期岩溶作用改造，形成质量较好的储层，为规模油气成藏提供物质基础。

In recent years， important exploration findings have been made in the Middle Triassic Leikoupo Formation in Sichuan Basin， and the large-scale reservoir is one of the key factors to control the hydrocarbon accumulation. Based on the data of outcrops， exploration wells， logging and seismic data， the lithofacies paleogeographic map of Leikoupo Formation is compiled and the characteristics of large-scale reservoirs are analyzed， and the following three understandings are obtained. （1） In Leikoupo stage， Sichuan Basin was a relatively closed carbonate platform， the south， east and north directions of Sichuan Basin were relatively closed， and seawater entered from the west. The first and second members of Leikoupo Formation are weakly rimmed carbonate platform， and the third and fourth members of Leikoupo Formation are rimmed carbonate platform. （2） The Leikoupo Formation can be divided into platform margin， open platform， restricted platform and evaporate platform， and the restricted platform is the main one， including lagoon， intra-platform shoal and tidal flat. There are two types of hydrocarbon reservoirs in Leikoupo Formation： Platform margin shoal and intra-platform shoal. （3） The Leikoupo Formation develops two sets of large-scale mound shoal reservoirs. One is the platform margin mound shoal of the third and fourth members of Leikoupo Formation in Northwest Sichuan， with large thickness （generally more than 50 m）. And the other is the intra-platform shoal in the lower part of the first member of Leikoupo Formation in Central Sichuan， which has the characteristics of small thickness， stable distribution， large area （more than 20 000 km²） and large scale. These two types of large-scale reservoirs are reformed by multi-stage karstification to form good quality reservoirs， which provide material basis for large-scale hydrocarbon accumulation. The results of this paper improve the understanding of the deposits and reservoirs of Leikoupo Formation in Sichuan Basin， and guide the hydrocarbon exploration in this field， which has important theoretical and practical significance.

2022年，风险探井充探1井在中三叠统雷口坡组雷三²亚段海相泥灰岩段测试获工业油气流，发现新的产油气层段和新类型油气资源，勘探取得重大发现，但对泥灰岩油气成藏认识尚不清楚，制约了勘探选区与部署。以充探1井为重点，研究剖析了雷三²亚段泥灰岩油气成藏特征。研究表明：①油气及烃源岩地球化学分析数据显示充探1井雷三²亚段泥灰岩油气来源于自身泥灰岩烃源，泥灰岩既是烃源岩、又是储集层，源-储一体；②雷三²亚段泥灰岩在川中地区为潟湖相沉积，厚40~130 m，面积约40 000 km²，生烃强度为（4~12）×10⁸ m³/km²，估算生烃量为25×10¹² m³；③川中潟湖相区泥灰岩储集层大面积分布，西充—仪陇、资阳—简阳和磨溪南等3个地区储集层厚20~60 m，分布面积为7 500 km²；④潟湖相泥灰岩油气具有“源-储一体、膏盐岩封盖、超压”成藏特征，属于海相非常规油气新类型，油气在生烃中心、储集层厚值区和裂缝发育复合区富集，是一个值得勘探重视的非常规油气新领域。⑤依据川中二维地震并结合三维地震解释分析，优选西充和遂宁2个有利区带，估算区带天然气资源量为（2 000~3 000）×10⁸ m³，是近期值得重视的勘探有利区。

Based on the detailed analysis of the lithologic characteristics, sedimentary structure, sedimentary assemblage and facies sequence of field outcrops and drilling data, six types of sedimentary facies can be identified in Guanwushan Formation of Middle Devonian in Western Sichuan. From west to east, basin-slope facies, platform margin facies, open-confined platform facies, and tidal flat facies are developed successively. The distribution of sedimentary facies in northwest Sichuan is obviously controlled by Devonian syndepositional faults, with the characteristics of migration from west to east, and the evolution of platform margin from reef to shoal. Influenced by paleo-island, the distribution and evolution of sedimentary facies in southwest Sichuan is controlled by both syndepositional faults and barrier islands. Sedimentation controls the development of carbonate reservoirs of Guanwushan Formation obviously, which is mainly manifested in that sedimentation controls the type of carbonate reservoirs and the development degree of primary pores, the facies-controlled penecontemporaneous dissolution controlled by sedimentary cycles improves the primary pores, and facies distribution controlled by sedimentary evolution controls the plane distribution of carbonate reservoirs.

The Permian Qixia and Moukou formations in Sichuan Basin have been the key targets for natural gas exploration since 1950s.With the continuous deepening of the exploration and development,it has been different of the exploration ideas and directions.In order to clarify the next direction of natural gas exploration,based on a combination of drilling,outcrop,logging,seismic and geochemical data,this paper systematically analyses the geological questions and explorational domains of Qixia and Moukou formations.The results indicate that:(1)The Qixia Formation-Maokou Formation in the Sichuan Basin is mainly a platform depositional system,which can be divided into three stratigraphic sequences(SQ1,SQ2,and SQ3 from bottom to top).In addition to the western Sichuan platform margin,the Qixia Formation-Maukou Formation in the central and eastern Sichuan Basin developed a number of high-energy shoals in the highstand system,encompassing an area of over 40,000 km2.This has laid a solid foundation for the development of shoal reservoirs.(2)The primary reservoirs of the Qixia Formation-Maukou Formation are pore-cavity dolomite,karst fractured-vuggy limestone,and microporous-microfractured marlite of which,pore-cavity dolomite is the main reservoir of recently explored.The dolomite of the Qixia Formation is primarily developed in the Guanyuan-Beichuan-Ya'an-E'mei area in the west of the Sichuan Basin,while the main deposits of the Maokou Formation are distributed in Xuanhan-Wanzhou,Guanyuan-Jiange,and Jiange-Guangan-Fengdu area.Karst fractured-vuggy limestone reservoirs are mainly developed in the central Sichuan to southern Sichuan region.Microporous-microfractured marlite reservoirs are mainly distributed in local areas of northern and eastern Sichuan,and the research level is relatively low.(3)Four realistic fields and two potential fields can be distinguished in the Qixia-Maokou formations natural gas exploration in the Sichuan Basin.The dolomitized shoal zone of the Maokou Member 2 in the northern-central-eastern Sichuan Basin is the most significant realistic exploration field for the Middle Permian natural gas storage and production.We need to accelerate the comprehensive evaluation of reservoirs and submit or upgrade natural gas reserves.The isolated dolomited shoal in the lower sub-member of the Maokou Member 2 in the eastern Sichuan Basin is anticipated to be one of the most significant potential exploration field in the future.We need to deepen the research and finely characterize the distribution range of reservoirs,striving to achieve a breakthrough in this field as soon as possible and promote it becoming a replacement field for natural gas exploration.

四川盆地中部龙女寺地区二叠系中统茅口组是该区近年来天然气勘探开发的重要层系之一，但受制于储层非均质性强、成因机制不明等因素，延缓了其天然气高效勘探开发进程。为了解决上述问题，采用岩心观察、薄片鉴定、测井资料分析等手段和方法，研究了该区茅口组沉积特征、储层岩石学特征、储集空间类型及储层类型，探讨了储层成因机制及控制储层演化的主要地质过程，建立了储层演化模式。研究结果表明：①该区茅口组储层主要发育在茅二下亚段细—中晶白云岩中，白云岩普遍具有残余颗粒幻影特征，属于低孔隙度、特低渗透率储层；②储集空间类型包括晶间孔、晶间溶孔、针状孔、连通缝洞及裂缝，储层类型可划分为裂缝—孔洞型、孔洞型以及孔隙型，其中前两者为优势储层类型；③白云岩储层发育区域与颗粒滩体分布范围高度重合，砂屑滩相带和生屑滩相带的孔隙度显著高于滩间海相带和台坪相带；④准同生期大气淡水溶蚀形成初始孔隙，白云岩化作用保存储集空间，早期热液流体沿断裂侵入引发水力压裂并形成鞍形白云石充填，最终构建了“砂屑滩为基础，准同生溶蚀成储，白云岩化保储，热液改造优储”的储层演化模式。结论认为，该区茅口组储层非均质性受沉积相带与多期成岩作用的共同控制，准同生期溶蚀作用奠定储层基础，热液改造扩大储集空间，滩体结构与断裂体系是优质储层发育的主控因素。

The Middle Permian Maokou Formation has recently emerged as one of vital reservoirs for natural-gas exploitation in Longnvsi area. However, Maokou reservoirs are characterized by strong heterogeneity resulting in uncertain forming mechanisms, which may retard their efficient exploration and development. Thus, the depositional and petrological characteristics, and reservoir space and types were analyzed for this formation after core observation, thin-section identification, and logging-data analysis. Moreover, reservoir-forming mechanisms and the main geological process controlling reservoir evolution were discussed to create an evolution model. Results show that (i) Maokou reservoirs in the study area are dominantly developed with fine- to medium- crystalline dolomite in the lower part of the second member of Maokou Formation (Maokou 2 Member). Generally, unreal images of residual grain are visible in the dolomite. And such reservoirs belong to low porosity and ultra-low permeability ones; (ii) their space consists of intercrystalline pores, intercrystalline dissolution pores, needle-like pores, contiguous fractures and vugs, and fractures. And they can be classified into three types, such as fractured-vuggy, vuggy, and porous reservoirs, with the first two as the predominant; (iii) dolomite reservoirs are mostly extended into grain-beach bodies. And not only fragmental shoal but bioclastic beach facies belts exhibit remarkably higher porosity than that in inter-beach sea and platform-flat facies belts; and (iv) initial pores are stemmed from meteoric freshwater of penecontemporaneous dissolution. Dolomitization preserves reservoir space. Early hydrothermal fluid invasion along faults induces hydraulic fractures to generate saddle-shaped dolomite filling. Accordingly, the created model is in line with the fragmental shoal as the basis, the penecontemporaneous dissolution for forming reservoirs, the dolomitization for reservoir preservation, and the hydrothermal alteration for making reservoirs better. In conclusion, strong heterogeneity in these Maokou reservoirs is jointly conditioned by sedimentary facies belts and multiepisodic diagenesis, with the dissolution attributing to reservoir basis, the expanded space due to the alteration, and beach bodies’ structure and fault system as the major controls on the development of quality reservoirs.

2023年11月1日,威寒1井上奥陶统宝塔组获产气量为9.02×10⁴m³/d,展示出四川盆地奥陶系白云岩岩溶孔隙型储层较大的勘探潜力。以此为契机,基于威远气田上奥陶统宝塔组沉积相、储层岩性和物性等综合分析,研究了宝塔组天然气的特点及展布特征,立足生、储、盖等多方面条件,总结分析了四川盆地威远地区宝塔组的成藏优势。3大古隆起和3期构造运动控制了四川盆地奥陶系的沉积充填特征,盆地内宝塔组高能滩体环绕川中古隆起呈规模展布。宝塔组发育3类储层,即白云岩岩溶型储层、灰岩岩溶型储层和弱白云石化区断溶体,其中,威寒1井宝塔组主要为白云岩岩溶型储层。奥陶系发育两套成藏组合:威远地区是以斜坡背景为主的上组合成藏富集区块,由志留系、五峰组供烃;而威寒1井缺失上覆盖层,生-储-盖组合类型主要为"下生上储",气源均来自寒武系筇竹寺组。威远地区宝塔组经历了"先油后气"的成藏过程,生油高峰期在晚二叠世,生气高峰期在早侏罗世。受潮缘滩体、构造背景和地层控制,威远气区宝塔组潮缘滩发育大型背斜构造背景下的构造-地层复合气藏。

On November 1, 2023, the gas yield from the Ordovician Baota Formation in Well Weihan1 was 9.02×10⁴m³/d, demonstrating the great exploration potential of Ordovician dolomite karst porous reservoir in Sichuan Basin. Taking this opportunity, based on comprehensively analyzing the sedimentary facies, reservoir lithology and physical properties of the Upper Ordovician Baota Formation in Weiyuan gas field, the study deeply analyzes the natural gas characteristics and distribution characteristics of Baota Formation. Moreover, the advantageous hydrocarbon accumulation conditions of Baota Formation in Weiyuan area of Sichuan Basin are summarized and analyzed in terms of source, reservoir and cap. Three paleo-uplifts and three stages of tectonic movements controlled the Ordovician sedimentary filling in Sichuan Basin, and large-scale distribution of high energy beaches in Baota Formation around the central uplift of Sichuan Basin. Three types of reservoirs are developed in Baota Formation, i.e., dolomite karst reservoir, limestone karst reservoir and fault-karst reservoir in weak dolomitization area, among them, Baota Formation in Well Weihan1 is dominated by dolomite karst reservoir. There are two sets of Ordovician accumulation assemblages. Weiyuan area is the upper hydrocarbon accumulation block developed on the slope background, and the source rocks are Silurian and Wufeng Formation. The caprocks are absent in Well Weihan1, the source-reservoir-cap assemblage is mainly characterized by "lower generation and upper reservoir", and the gas source is from the Cambrian Qiongzhusi Formation. Baota Formation in Weiyuan area experienced the process of "oil accumulation followed by gas enrichment". The peak oil generation occurred in Late Permian, and the peak gas generation was in Early Jurassic. Controlled by the peritidal beach body, tectonic setting and strata, the structural-stratigraphic composite gas reservoir in the peritidal beaches of Baota Formation was developed under the background of large anticline structure in Weiyuan gas area.