Marine carbonate rocks in China are characterized by aging, developing in small-scale cratons and locating in the lower tectonic layer of superimposed basins. Reservoir genesis and distribution are among the many scientific problems in hydrocarbon exploration. This paper summarizes three innovative achievements made by the project team of the Key Laboratory of Carbonate Reservoir in the past five years in the field of marine carbonate sedimentary reservoir research in China as follows: (1) based on the analysis of tectonic-lithophase paleogeography of the Sinian-Cambrian, Changxing Formation-Feixianguan Formation in Sichuan Basin, it is found that the intra-platform rifts in small-scale craton were generally developed, and thus the carbonate platform sedimentary models of bi-margin ＆ bi-shoal were established. This discovery reveals that the source rocks and large-scale reservoirs can also develop in the intra-platform, which provides a theoretical basis for the exploration field expansion from the margin to the internal of the platform, and it was confirmed by the discovery of the Anyue gas field; (2) based on the exploration practice of karst reservoirs in the Tarim Basin, innovations in the genesis of karst reservoirs and the type ＆ distribution of karst reservoirs of intra-carbonate rocks broke the traditional view that the karst reservoirs mainly develope in the buried hills. This view extends the exploration realm from the buried hill areas to intra-carbonate rocks areas, and it was confirmed by the discovery of Harahatang and Shunbei oilfield on the south slope of North Tarim Basin; (3) the old and deep-buried marine carbonate reservoirs are still facie-controlled and the pores are more inherited from pre-buried stage than modificated in buried stage, which laid the foundation for the scale and predicatability for deep-buried and ancient marine carbonate reservoirs, which promote the exploration values of these reservoirs. This view was confirmed by the hydrocarbon exploration practice in Tarim and Sichuan Basins. Reef-shoal(mound) facies, evaporite tidal flats, sequence boundaries, exposure surfaces and unconformities, paleo-uplifts and fault systems control the distribution of high-quality and large-scale reservoirs of deep-buried and ancient marine carbonates. These understandings not only have important theoretical significance for the development of carbonate sedimentary reservoir discipline, but also provide basis for the expansion of exploration field.

Based on structural and tectonic geology, this paper discussed the distribution characteristics and their structural/tectonic controlling factors of the marine carbonate oil and gas accumulation around/on the intracratonic sags, paleo-uplifts and basin-mountain systems across the Sichuan superimposed basin. During the early stage of hydrocarbon accumulation formation, the intracratonic sags controlled the formation of high-quality source rocks, reservoir rocks and their assemblage, whilst the paleo-uplifts controlled the hydrocarbon migration and accumulation to form paleo oil reservoir and paleo gas reservoir. Subsequently, the basin?mountain systems changed the structural geology and adjusted the hydrocarbon accumulations to accommodate gas-fields across the basin. It is considered that the intracratonic sags are the essential factors for hydrocarbon accumulation in early stage, paleo-uplifts are the best places for hydrocarbon migration and accumulation, and the basin-mountain systems are the most important factor for hydrocarbon accumulation and adjustment in late stage. The coupling relationships accounted for hydrocarbon distri?bution in carbonates across the Sichuan basin. Therefore, it is suggested that the prospect areas of deep to super-deep reservoir in carbonates are in the middle and northern segments of the western Sichuan Basin, where could be dominant with large?scale primary and secondary gas reservoirs. There are four favorable factors as following: （1） wide-spread high-quality source rocks of Lower Cambrain black shale, （2） high-quality multi reservoir rocks, （3） good carrier or conducting network composed of faults and unconformities for hydrocarbon migration and accumulation, and （4） multi cap rocks composed of low?porosity and low-permeability carbonate, mudstone and gypsum-salt strata.

深入总结中国石油化工股份有限公司（简称中国石化）“十三五”期间在不同勘探领域取得的各项成 果，梳理和分析油气成藏理论新认识和技术新进展，以期为“十四五”发展规划编制提供依据。5 年来，中国石化大 力推进高质量勘探，通过攻关中西部三大盆地海相碳酸盐岩、四川盆地致密气及深层—常压页岩气、东部成熟探区复 杂隐蔽油气藏、中西部碎屑岩致密油气等领域的油气富集理论、甜点预测技术及低成本工程工艺技术，发现并培育了 塔里木盆地顺北油田、四川盆地涪陵页岩气田两个10×108t 级大油气田，拓展了6 个亿吨级规模效益增储阵地。通 过中国石化矿权区油气资源赋存状况研究，明确了“十四五”发展思路及措施：立足长期低油价下高质量发展，加大 勘探力度，拓展资源类型、突出区带整体、注重低品位盘活，加快推进勘探大突破大发现，预计新增探明石油地质储 量9.6×108t、天然气地质储量1.16×1012m3。为确保发展目标顺利实现，提出了持续加大勘探投入、加大地震勘探、 加强风险勘探、加强科技创新、提升工程技术5 项保障措施。

Over the past five years, Sinopec has vigorously promoted high-quality exploration. This paper explains the basis for<br>development planning for the 14th Five-Year Plan period, summarizes the achievements of China Petroleum and Chemical Corporation (Sinopec) in different exploration fields during the 13th Five-Year Plan period and analyzes new understandings of hydrocarbon accumulation theories and new technological progress. The 13th Five-Year Plan period has been marked by the discovery and cultivation of two 100-million-ton-level oil and gas fields, in carbonate rocks in the Tarim Shunbei oilfield and the Fuling shale gas field in the Sichuan Basin. Six large-scale oil and gas reserves increase positions with billion-ton-levels have also been proved. These achievements have largely been the results of developments in hydrocarbon accumulation theories, ‘sweet-spot’ prediction technology, and low-cost engineering technology in the fields of marine carbonate rocks in the three giant basins of the central and western regions, tight gas and deep (greater than 3500 m in depth) and normal pressure shale gas in the Sichuan Basin, complex and subtle oil and gas reservoirs in the eastern mature exploration areas, and tight oil and gas in clastic rocks in the central and western regions. By comprehensively studying the current status of oil and gas resources, the company has defined development ideas and measures for the 14th Five-Year Plan period. The principal objectives are high-quality development under long-term low oil prices, enhancing exploration efforts, expanding resource types, highlighting exploration across whole plays, invigorating low-grade resources, and accelerating major breakthroughs and discoveries. The goal is to increase proven oil and gas geological reserves by 9.6×108 t and 1.16×1012 m3, respectively. To ensure this goal is achieved, five basic measures are proposed: continuously increasing exploration investment, increasing seismic exploration, strengthening risk exploration, enhancing scientific and technological innovation, and improving engineering technology.<br>

四川盆地是一个高度富气的盆地,在四川盆地已发现的海相大中型气田多以孔隙型储层为主,普遍含有硫化氢(一般占天然气体积的0.2%~17%),烃类主要以原油裂解气为主.充足的气源是四川盆地海相油气富集的重要条件,古隆起为海相油气的聚集提供了圈闭条件,富含膏盐的白云岩储层为硫化氢的形成提供了硫源和催化条件.海相层系大多经历过较大的埋深,这为硫酸盐热化学还原反应的发生提供了热动力条件,而硫酸盐热化学还原反应过程更为原油裂解提供了催化条件,导致气藏中既富含硫化氢又富含甲烷气.研究表明,川东北地区飞仙关组和长兴组成藏条件优越,是最现实的勘探目的层系;四川盆地邻近膏盐层上下的大量薄层席状分布的孔隙型白云岩储层为潜在的勘探目的层;川东地区是四川盆地勘探潜力最大的地区.

Some giant gas fields recently discovered in the Lower Triassic Feixianguan Formation at the northeast part of Sichuan Basin proved that this basin is very rich in natural gas.Gas is mainly stored in the porous reservoir with high proportion of hydrogen sulfide normally being from 0.2% to 17% of the total gas volume.The hydrocarbon gas components were derived from thermal cracking of crude oil.Plenty of gas sources provided basic materials,and palaeo-uplift provided the traps for oil and gas accumulation.Gypsiferous-rich dolostone reservoir offered sulfur and catalyst conditions for the formation of hydrogen sulfide gas.The most deeply buried marine sediments provided the thermal conditions for thermochemical sulfate reduction (TSR),which leads to the formation of hydrogen sulfide.TSR provided catalysts for oil cracking,which leads to rich methane and hydrogen sulfate in gas reservoir.The Feixianguan and Changxing formations are the most practical exploration targets due to good accumulation conditions.Potential targets exist in the thin and sheet-like porous dolostones near gypsum,particularly in the Triassic Leikoupo and Jialingjiang formations.The best exploration potential is in the east parts of Sichuan Basin.

近年来四川盆地蓬深10、合深9、潼深17和正阳1等井钻探证实深层上二叠统长兴组发育一套孔隙型礁滩复合体灰岩储层，突破了深层碳酸盐岩大油气田主要分布于孔隙型白云岩储层和岩溶缝洞型灰岩储层的传统认识。基于岩心和薄片观察、储层地球化学特征分析、井震联合的储层识别和追踪，开展深层礁滩灰岩孔隙形成机理研究，取得4个方面认识：①深层长兴组孔隙型礁滩复合体灰岩储集空间以粒间孔、格架孔、生物体腔孔、铸模孔和溶孔为主，形成于沉积和早表生环境；②断续分布的多孔礁滩复合体被相对致密的泥晶灰岩包裹，在复合体持续增温条件下导致局部异常高压的形成；③长兴组储层的底板为上二叠统吴家坪组互层的致密泥岩和灰岩，顶板为下三叠统飞仙关组一段致密泥晶灰岩夹泥岩，在致密顶底板的夹持下，导致长兴组区域异常高压的形成；异常高压（超压封存箱）是沉积和早表生环境形成的孔隙在深层得以保持的关键；④在顶底板和礁滩复合体识别基础上，通过井震联合预测有利礁滩灰岩储层分布面积达10.3×10⁴ km²。上述认识奠定了深层孔隙型灰岩储层发育的理论基础，拓展了四川盆地深层灰岩储层勘探新领域。

栖霞组是四川盆地中二叠统海相碳酸盐岩的主要产层。古构造高点通常是油气长期运聚的有利低势区，其研究对油气勘探尤为重要。基于钻井、测井、地震及野外地质等资料，开展川南地区中二叠统栖霞组关键构造期古构造演化及油气关系研究。结果表明：川南地区栖霞组台内滩发育，寒武系及志留系烃源岩在研究区内广泛分布；晚二叠世栖霞组顶面古构造呈现NW—SE向低幅隆起；早三叠世在古蔺—泸县—荣昌呈北西向倾伏隆起；中三叠世倾伏隆起发展壮大成穹隆构造隆起带，古构造高点迁移，面积增大；晚三叠世构造隆起带继承性发展但隆起范围略有缩小；早—中侏罗世，构造格局基本继承晚三叠世末的穹窿构造隆起带，隆起带内出现多个规模不等的古构造圈闭；后经喜马拉雅运动调整为呈帚状向南展布的侏罗山式褶皱。流体包裹体均一温度分析表明，栖霞组存在4期油气运移。结合古构造演化特征，认为栖霞组台内环古隆起边缘高带是原油运移的有利区，早—中三叠世形成的古圈闭能够较好地捕获油气，早—中侏罗世天然气主要向穹隆状隆起带内的圈闭运移，喜马拉雅期古气藏进一步调整形成现今气藏格局。根据栖霞组油气成藏要素及古构造特征，认为帚状构造北部斜坡区①号储层内江—泸县地区烃源岩与古构造匹配关系好，具有较大的天然气勘探潜力。

Qixia Formation of Middle Permian is the main reservoir of marine carbonate rocks in Sichuan Basin. The Paleostructural high point is usually a favorable low-potential area for long-term migration and accumulation of oil and gas， so the study of paleostructure is particularly important for oil and gas exploration. Based on the data of drilling， logging， seismic and field geology， this paper studies the paleostructural evolution and oil-gas relationship of the key tectonic periods of the Middle Permian Qixia Formation in southern Sichuan. The results show that the intra-platform shoals of Qixia Formation in southern Sichuan is developed， and the Cambrian and Silurian source rocks are widely distributed in the area. Paleostructure of the top of Qixia Formation in Late Permian showed a NW-SE low-amplitude uplift. In the Early Triassic， there was a NW plunging uplift in Gulin-Luxian-Rongchang. In the Middle Triassic， the plunging uplift developed into a dome tectonic uplift zone， and the paleotectonic peak migrated and its area increased. In the Late Triassic， the tectonic uplift zone developed inheritingly. In the Early-Middle Jurassic， the tectonic pattern basically inherited the dome tectonic uplift belt at the end of the Late Triassic， and several palaeotectonic traps of different sizes appeared in the uplift belt. Later， it was extruded into the Jura-type folds by the tectonic stress of Himalayan movement， spreading southward in a broom-like shape. The homogenization temperature analysis of fluid inclusions shows that there are four stages of oil and gas migration in Qixia Formation. Combined with the characteristics of palaeotectonic evolution， it is considered that the upper belt of the inner ring palaeouplift of Qixia Formation is a favorable area for crude oil migration， and the palaeotrap formed in the Early and Middle Triassic can capture oil and gas well. The palaeogas migrated to the trap in the dome uplift belt in the Early and Middle Jurassic. The palaeogas reservoir in the Himalayan period further adjusted to form the present gas reservoir pattern. According to the hydrocarbon accumulation factors and paleostructural characteristics of Qixia Formation， it is considered that the source rocks in Neijiang-Luxian area in the No. 1 reservoir in the Northern Slope area of the broom-like structure have a good matching relationship with the paleostructure， and have great potential for natural gas exploration.

The development pattern of the high-quality reservoir in the Changxing Formation in the Wolonghe-Yangduxi area of southeastern Sichuan is complex. To clarify its evolution, genetic mechanisms, and distribution patterns, this study integrates data from profiles, cores, thin sections, and well logs. It reveals the distribution mechanisms of the bio-reef and shoal reservoirs in the Changxing Formation and discusses the controlling effects of tectonic, sedimentary, and diagenetic processes on reservoir development. The results show the following: (1) The Changxing Formation mainly develops open platform facies, platform margin facies, and slope-basin facies, which can be further subdivided into subfacies of platforms, intra-platform depressions, intra-platform depressions marginal reefs, and intra-platform depressions marginal shoals. The intra-platform margin reefs and the reefs at the edge of the platforms are favorable microfacies for reservoir development. (2) The high-quality reservoirs of the Changxing Formation are dominated by medium-thick-layered biogenic reef limestone and bioclastic limestone, with secondary porosity as the main reservoir space. (3) Sedimentary conditions, sea level fluctuations, and diagenesis are crucial factors for reservoir development. Paleogeomorphological conditions provide the foundation for reservoir development, while sea level fluctuations control the internal structure of the reef–shoal and the cyclical variations in the reservoir.

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.

对四川盆地二叠系和三叠系接触关系的认识长期存在较大分歧。通过对钻井、岩心等资料的研究发现，蜀南地区长兴组钻进过程中出现大量钻具放空现象，岩心上见大量的溶沟、溶缝、溶洞及岩溶角砾。综合分析认为蜀南地区长兴组与飞仙关组并非连续沉积，其间存在沉积间断，长兴组古岩溶作用发育，形成了长兴组顶部古岩溶不整合。泸州古隆起的持续发展和二叠纪末期一次重大海退引起的长时期暴露溶蚀是蜀南地区长兴组古岩溶形成的关键。古岩溶对碳酸盐岩的储集性能具有较强的优化改造能力，古岩溶不整合面可以作为油气长距离运移的优质通道，岩溶斜坡带是油气成藏的有利区带。长兴组顶部古岩溶不整合的发现为区内二叠系和三叠系非整合接触找到了直接证据，对今后蜀南地区乃至四川盆地长兴组的油气勘探具有指导意义。

There exists a long-time dispute for the contact relation between the Permian and the Triassic in Shunan area of Sichuan Basin. The drilling break phenomenon commonly occurred during the drilling process, and a great quantity of karrens, dissolved fractures, caves and karst breccia were found in the rock cores. The comprehensive analysis shows that there is not the successive sedimentation between Changxing Formation and Feixianguan Formation in the Shunan area of Sichuan Basin. The paleokarst in Changxing Formation is highly-developed and causes the paleokarst unconformity at the top of Changxing Formation. The Luzhou palaeo-high embryo and the exposed corrosion due to a major regression at the end of the Permian are the key factors to form and develop paleokarst. Actually, the paleokarst can optimize the hydrocarbon accumulation capacity in carbonate rocks. The uncomfortable surface can be taken as the high-quality channel of the long-distance hydrocarbon migration. The discovery of the paleokarst unconformity at the top of Changxing Formation proved the existence of the uncomfortable contact relation between the Permian and the Triassic. The further exploration of biothermal limestone in Changxing Formation of Sichuan Basin was presented.

<p>Based on the sedimentological analysis of outcrops and drilling cores with seismic facies analysis, this study divided the Permian in Sichuan Basin and adjacent areas into five 3rd-order sequences, and prepared four maps of the Permian lithofacies paleogeography of Sichuan Basin and adjacent areas in the 3rd-order sequence stratigraphic framework, i.e., PSQ1(Guadalupian or Middle Permian Qixia Formation), PSQ2-PSQ3(Guadalupian Maokou Formation), PSQ4(Longtan/Wujiaping Formation, Wuchiapingian&nbsp; Stage of Lopingian or Upper Permian), and PSQ5(Changxing/Dalong Formation, Changhsingian Stage of Lopingian). These showed that the evolution of Permian lithofacies paleogeography in Sichuan Basin and adjacent areas was mainly controlled by the background of regional rifting tectonics and the activities of syndepositional normal faults with an overall increasing trend in the rifting activity. Carbonate ramps mainly occurred in the Guadalupian and evolved into rimmed platform in the Lopingian. The Emei mantle plume activity and basalt eruptions in the end of Guadalupian led to the formation of Kangdian oldland, which became the provenance of terrigenous clastic sediments in the southwestern Sichuan. Through the compilation of lithofacies paleogeography maps, a series of intra-platform reefs and shoals as well as intra-platform depressions was discovered. It further clarified the distribution of middle ramp facies and platform margin facies in the northern Sichuan Basin, and provided guidance for exploration of natural gas in the Permian in Sichuan Basin and adjacent areas. Based on the distribution of main hydrocarbon source rocks and the accumulation conditions, it was proposed that the favorable natural gas exploration zones of Permian carbonate reservoirs in Sichuan Basin included:(1) the dolomitized platform-margin reefs and shoals of the Lopingian around Kaijiang-Liangping basin facies;(2) the dolomitized platform margin reefs and shoals of the Lopingian along the southwest margin of Chengkou-E&rsquo;xi basin facies;(3) the dolomitized middle-ramp reefs and shoals of the Guadalupian in the northern Sichuan Basin;(4) the weathering crust karst reservoirs of Maokou Formation;(5) the dolomitized intra-platform reefs and shoals of the Lopingian in Changxing Formation; and(6) the fractured hydrothermal dolomite reservoirs of the Guadalupian.</p>