鄂尔多斯盆地是中国第二大沉积盆地，油气资源丰富，中国石油长庆油田公司经过50余年勘探实践，创新形成了内陆坳陷湖盆大型三角洲、陆相致密砂岩气、奥陶系岩溶古地貌等成藏地质理论，2022年油气产量跨越6 500×10⁴ t油气当量，其中天然气年产量首次突破500×10⁸ m³，建成了中国第一大油气生产基地和第一大天然气产区。近年来，长庆油田公司为进一步夯实油气持续稳产上产的资源基础，不断深化地质综合研究，强化技术攻关，加大新区新领域风险勘探力度，油气勘探取得丰硕成果。通过创新中生界延长组长7₃纹层型页岩油和新层系长8₂滩坝型致密油成藏理论认识，新增石油规模储量为4×10⁸ t；创新盆地奥陶系盐下、太原组致密灰岩和盆地西缘乌拉力克页岩油气成藏理论，新增天然气规模储量超4 000×10⁸ m³；同时攻关形成了地球物理、压裂等一系列非常规油气勘探新技术，油气勘探取得重大发现，预计盆地新增石油资源潜力（20~40）×10⁸t、天然气资源潜力（2~3）×10¹² m³，为保障长庆油田公司6 500×10⁴ t以上油气当量稳产奠定了坚实的资源基础。

Ordos Basin is the second largest sedimentary basin in China with abundant oil and gas resources. After more than 50 years of exploration practice， PetroChina Changqing Oilfield Company has innovated reservoir-forming geological theories such as large delta of inland depression lake basin， continental tight sandstone gas and Ordovician karst paleo-landform. In 2022， the oil and gas equivalent has exceeded 65 million tons， and the China's largest oil and gas production base and largest natural gas production area have been built. In recent years， in order to further consolidate the resource base for continuous and stable production of oil and gas， Changqing Oilfield Company has continuously deepened comprehensive geological research， strengthened technical research， and increased risk exploration efforts in new areas. Oil and gas exploration has achieved fruitful results. Through innovative theoretical understanding of the formation of the Mesozoic Chang 7₃ laminated shale oil and the new series Chang 8₂ beach bar tight oil reservoir， the new oil reserves increased by 400 million tons； Natural gas exploration has innovated the theory of oil and gas accumulation in Ordovician undersalt， Taiyuan Formation biolimestones and Ulalik shale in the western margin of the basin， increased the scale of reserves by more than 400 billion cubic meters. At the same time， a series of new unconventional oil and gas exploration technologies such as geophysics and fracturing have been formed， and major discoveries have been made in oil and gas exploration. It is estimated that the new oil resource potential of the basin is 2-4 billion tons， and the natural gas resource potential is 2-3 trillion cubic meters. It has laid a solid resource foundation for ensuring long-term stable production of more than 60 million tons of Changqing Oilfield Company.

Ordos Basin is the second largest sedimentary basin in China, which has abundant oil and gas resources and broad exploration prospect. In recent two decades, growth in oil and gas reserves and production is the fastest in Ordos Basin, and now it is the largest oil and gas producing basin and the largest natural gas producing region in China. Through more than 50 years of research, Changqing Oilfield has innovated five petroleum geological understandings, including “shale oil of continental freshwater lake basin, large delta of inland depression lake basin, Jurassic paleogeomorphic oil reservoir group, continental tight sandstone gas, and Ordovician karst paleogeomorphic natural gas”. Moreover, three technology series have been developed in terms of “3D seismic exploration in loess plateau, logging identification and evaluation technology of low-permeability tight oil and gas layers, and volume fracturing of low-permeability tight reservoir”. As a result, four billion-ton-level large oil regions and three trillion-cubic-meter-level large gas regions have been discovered, contributing a lot to the national energy and resource security and providing important experience and reference for the exploration of similar basins at home and abroad.

The Majiagou Middle Assemblage refers to the whole gas-bearing reservoir beds from Submember-5 to Submember-10 of Lower Ordovician Majiagou Member-5 in Ordos Basin. Intercrystalline pore, intercrystalline dissolved pores and dissolved vugs are predominating in the Middle Assemblage dolostone reservoirs that are widely distributed on the east side of the Ordovician Central Paleouplift, Ordos Basin. The Ordovician Middle Assemblage dolostone reservoirs experienced a long process of hydrocarbon accumulation and reservoir evolution. The good source-reservoir-cap assemblage consists of the Middle Assemblage karst dolostone as reservoirs and the overlying thick Carboniferous-Permian coal measure strata as cap and source rock. Attributed to the upper Paleozoic source rock that had reached to the peak of hydrocarbon generation and expulsion during late Jurassic to early Cretaceous period, the "source in the upper and reservoir in the lower" styled gas reservoirs formed widely in the Middle Assemblage. Because of modulation of the earlier gas reservoirs caused by structural evolution since early Cretaceous, nowaday gas reservoirs commonly formed in the laterally-sealling locations within Middle Assemblage. It is suggested that lithologic traps are the favorable exploration targets.

鄂尔多斯盆地蕴藏多种类型天然气资源。随着勘探领域由常规到非常规、浅层到深层深入，鄂尔多斯盆地逐渐展现出一批新领域、新类型天然气藏。基于近年来的勘探成果，梳理出深部煤层气、太原组灰岩气和铝土岩气、奥陶系盐下气、海相页岩气和深层元古界气等新类型气藏，并从沉积构造背景、源-储配置、封盖保存条件等方面进行了深入分析。通过分析其生-储-盖配置关系，总结不同类型天然气的成藏特征与差异，认为这些气藏整体上具有近源成藏、自生自储的成藏模式。在落实气藏富集特征的基础上，评价了各领域天然气藏的有利勘探区，明确了其资源潜力和储量规模。深部煤层气的有利含气区面积为6.9×10⁴km²，资源量预计为13.80×10¹²m³，预计可落实万亿立方米储量规模；太原组灰岩气藏的有利含气区面积为1.5×10⁴km²，初步估算资源量为1.6× 10¹²m³，储量规模达5 000×10⁸m³；太原组铝土岩气藏的勘探面积为7 000 km²，天然气资源量超过5 000×10⁸m³；奥陶系盐下马家沟组四段天然气的有利勘探面积为2.5×10⁴km²，预计储量规模超过7 000×10⁸m³；乌拉力克组海相页岩的有利含气区面积为9 000 km²，天然气资源量预计为1×10¹²m³，并落实了含气富集区2个；深层元古界优选出2个天然气有利区，勘探面积为5.71×10⁴km²。鄂尔多斯盆地天然气资源仍具有较大的勘探潜力。

Ordos Basin is rich in various types of natural gas resources. With the deep exploration from conventional to unconventional hydrocarbons and from shallow to deep strata, a set of natural gas reservoirs of new fields and new types are discovered in Ordos Basin. Based on exploration achievements in recent years, the paper summarizes the new types of gas reservoirs, including deep coalbed methane, Taiyuan Formation limestone gas and bauxite gas, Ordovician presalt gas, marine shale gas, and deep Proterozoic gas, and further performs an in-depth analysis from the perspectives of sedimentary-tectonic background, source-reservoir configuration, and sealing-preservation condition. By analyzing the deployment relationship of source-reservoir-cap assemblage and summarizing the differences of accumulation characteristics and various natural gas, it is believed that these gas reservoirs generally have the accumulation model of near-source, self-generation and self-reservoiring. Based on determining the enrichment characteristics of gas reservoirs, the paper evaluates the favorable exploration areas for natural gas reservoirs in various fields and clarifies their resource potentials and reserve scales. The favorable gas-bearing area of deep coal bed methane is 6.9×10⁴km²; the resources are estimated to be 13.80×10¹²m³, expected to achieve a reserve of trillions of cubic meters. The favorable gas bearing area of Taiyuan Formation limestone gas reservoir is 1.5×10⁴km², with preliminary estimated resources of 1.6×10¹²m³, and a reserve scale of 5 000×10⁸m³. The exploration area of Taiyuan Formation bauxite is 7 000 km², with natural gas resources exceeding 5 000×10⁸m³. The favorable exploration area for presalt natural gas in the Member 4 of Ordovician Majiagou Formation is 2.5×10⁴km², with an estimated reserve exceeding 7 000×10⁸m³. The favorable gas-bearing area of Wulalik Formation marine shale is 9 000 km²; the natural gas resources are estimated to be 1×10¹²m³, and two gas abundance zones have been identified. Two favorable areas of natural gas in the deep Proterozoic are optimized, with an exploration area of 5.71×10⁴km². The natural gas resources in Ordos Basin still have large exploration potential.

鄂尔多斯盆地奥陶系马家沟组四段首次发现了工业性聚集的天然气藏，揭示出盆地深层盐下含气系统也具有良好的勘探前景，但目前对该套含气系统的基本成藏条件及天然气富集规律的认识不清，严重制约了勘探进程。综合利用地震、测井、钻井岩心、岩石薄片及天然气同位素等资料，以含气系统的方法对其成藏条件及富集规律进行了整体研究。结果表明：盐下含气系统主要表现为断层输导型的自生自储天然气成藏模式，晶间孔和溶孔是滩、丘体白云岩储层主要储集空间，广泛分布的膏盐岩是优质盖层，断裂及相关裂隙系统构成自身海相碳酸盐岩烃源岩与有效储集体之间的疏导介质，局部构造、断裂与白云岩储层的叠加有利于形成高产富集区。盆地东部的米脂—神木区域是盐下马四段目前最有利的勘探区带，马三段、马二段是未来勘探的有利目标层系。

The first industrial accumulation of natural gas reservoirs has been discovered in the fourth member of Majiagou Formation （Ma 4 Member） in the Ordos Basin， indicating the subsalt gas-bearing system also has good exploration prospects， but the poor understanding of the basic reservoir forming conditions and natural gas enrichment laws restricts the exploration process seriously. A comprehensive study about the accumulation conditions and enrichment rules of the reservoir were studied by means of gas-bearing system based on seismic， logging， drilling core， rock thin sections， and natural gas isotope data. The results showed that the subsalt gas-bearing system exhibits a self generated and self stored natural gas reservoir formation mode of fault transport type， and intergranular pores and dissolution pores are the main storage spaces of beach and hill dolomite reservoirs. The widely distributed gypsum salt rock is a high-quality cap rock， with faults and related fracture systems forming the guiding medium between its own source rock and effective reservoir. The superposition of local structures， faults， and dolomite reservoirs is conducive to the formation of high-yield enrichment zones. The Mizhi-Shenmu area in the eastern part of the basin is currently the most favorable exploration zone for the Ma 4 Member， while the Ma 2 and Ma 3 members are favorable target layers for future exploration.

为了查明鄂尔多斯盆地奥陶系克里摩里组—乌拉力克组构造—沉积响应特征，为该区有利勘探区带预测与目标优选提供技术支撑，依据地震、测井、钻井岩心、微观薄片及野外剖面等资料，在构造控沉积思想指导下，对鄂尔多斯盆地西缘奥陶纪克里摩里期—乌拉力克期古构造格局及沉积特征进行了系统研究。结果表明：①克里摩里期—乌拉力克期古构造格局整体体现出“一陆一隆一坳、过渡带北东向凸—凹相间”的分异特征；②克里摩里期—乌拉力克期为镶边台地沉积模式，沉积相类型包括台地边缘、斜坡、深水陆棚和盆地；③古构造格局控制沉积相平面展布，台地边缘沿中央古隆起及隆坳过渡带上的北东向凸起分布；斜坡相主要沿隆坳过渡带上的北东向凹陷分布；深水陆棚相和盆地相主要沿西部坳陷分布。

In order to find out the tectonic-sedimentary characteristics of the Ordovician Kelimoli-Wulalike formations in the Ordos Basin， and provide technical support for the prediction and target optimization of favorable exploration zones in this area， the paleotectonic pattern and sedimentary characteristics of the Ordovician Kelimoli-Wulalike stages in the western edge of the Ordos Basin are studied systematically under the guiding ideology of tectonic controlling deposition， based on seismic， well logging， drilling cores， microscopic thin section and outcrops. The results indicate that： （1）The paleotectonic pattern of the Kelimoli-Wulalike stages reflects the characteristics of “one land， one uplift and one depression， and high and sag alternate with each other along the northeast direction of transition zone”； （2）The deposition pattern of the Kelimoli-Wulalike stages is rimmed shelf and the types of sedimentary facies include platform edge， slope， deep-water shelf and basin； （3）The paleotectonic pattern controls the plane distribution of sedimentary facies. The platform margins are distributed along the central paleo-uplift and the NE-trending bulge on the uplift transition zone， the slope facies are mainly distributed along the NE-trending sag on the uplift transition zone； the deep-water shelf facies and basin facies are mainly distributed along the western depression.

鄂尔多斯地区在奥陶纪处于华北克拉通板块的西南边缘地区。由于受秦岭—祁连—贺兰三叉裂谷系开裂—聚合作用的影响,奥陶纪鄂尔多斯地区与华北克拉通已开始出现明显构造与沉积作用的分异,突出表现为奥陶纪沉积期鄂尔多斯东部大规模膏盐岩沉积层的发育。古构造分析表明鄂尔多斯地区奥陶纪总体呈现为“三隆—两坳—一古陆”的古构造分布格局;奥陶纪经历了冶里—亮甲山期的早期边部海侵、马家沟期振荡性的整体沉降海侵以及平凉—背锅山期的西南边缘快速沉陷的古地理演化过程,表现出较强的阶段性演化特征。鄂尔多斯地区奥陶纪整体的沉积充填作用具有以下重要特征: 一是受中央古隆起控制、东西向沉积分异明显;二是随时代演进,早中期以内源沉积为主,晚期则以混源或陆源碎屑沉积为主;三是西南边缘沉积巨厚,是奥陶纪最为活跃的构造沉降区。

MT1井的战略突破揭示鄂尔多斯盆地马家沟组四段（简称马四段）具有良好的勘探前景，然而对马四段沉积期岩相古地理及储层认识的不足制约了天然气勘探与部署。利用地质与地球物理相结合的方法，对马四段沉积期岩相古地理进行恢复并开展岩相古地理对储层发育的控制研究，结果表明：（1）马四段沉积前鄂尔多斯盆地具有三隆一坳的古地理格局，三隆即伊盟古陆、中央古隆起和吕梁隆起，一坳即台内坳陷，又可进一步分为两凸两凹，即榆林—横山凸起、神木—米脂凸起、桃利庙凹陷和米脂凹陷。隆坳相间、坳中有凸的古地理格局控制了马四段储集相带的展布；（2）马四段沉积期由3个四级旋回组成，马四3亚段沉积期主体为海侵旋回，中央古隆起演化为弱镶边台地边缘，盆地东部整体表现为半局限台地，以石灰岩和云质石灰岩沉积为特点；马四₂ 亚段沉积期为海退早期，随着台缘滩的加积和海平面下降，台缘滩障壁作用凸显，盆地东部表现为局限台地沉积特点，在凸起区开始发育丘滩并沉积薄层白云岩和硬石膏岩；马四₁ 亚段沉积期为海退中期，台缘滩障壁作用加剧，盆地东部局限台地水体持续变浅，凸起以丘滩坪沉积为主，白云岩和硬石膏岩厚度增加、范围扩大。（3）岩相古地理控制了马四段储层发育的类型与分布，主要发育了颗粒白云岩储层、微生物白云岩储层和斑状（灰质）白云岩储层，颗粒白云岩储层和微生物白云岩储层受颗粒（丘）滩微相控制，沿古隆起和凸起区发育，而斑状（灰质）白云岩储层则分布于潟湖相。研究认为，榆林—横山凸起及神木—米脂凸起地区有利于马四段储层发育，是有利勘探区带。

The strategic breakthrough in Well MT 1 indicates promising prospects of the fourth member of Majiagou Formation (Ma 4 Member) in Ordos Basin. However, the lack of understanding on lithofacies paleogeography and reservoir development of Ma 4 Member restricts the further gas exploration and deployment. By integrating geological and geophysical methods, the lithofacies paleogeography restoration of Ma 4 member and its control on reservoir development are analyzed. The study results show that: (1) The paleogeography before the deposition of Ma 4 member had a pattern of “three uplifts and one depression”, i.e., Yimeng Ancient Land, Central Paleo Uplift, Lvliang Uplift, and Intra Platform Depression. Among them, the depression was further divided into two bulges and two sags, namely Yulin-Hengshan Bulge, Shenmu-Mizhi Bulge, Taolimiao Sag and Mizhi Sag. The paleogeographic pattern of alternating uplift and depression and bulge in depression controlled the distribution of favorable reservoir development zone of Ma 4 member; (2) Three fourth-order cycles were developed in the deposition period of Ma 4 member, including the third, second, and first submembers of Ma 4 member (i.e., Ma 4₃, Ma 4₂ and Ma 4₁) from bottom to top. Ma 4₃ submember was dominated by transgression cycle, in which the Central Uplift evolved into a weakly rimmed platform margin and the eastern basin presented a semi-restricted platform, with the main deposits of limestone and dolomitic limestone. Ma 4₂ submember was developed in the early-stage regression. With the accretion of platform marginal beach and the fall of sea level, the barrier effect of platform margin was prominent. The eastern basin was characterized by the restricted platform environment, and thin layers of dolomite and gypsum rocks of mound beach facies were deposited in bulge areas. Ma 4₁ submember was mainly deposited in the middle stage of regression. The barrier effect of the platform margin enhanced, and water depth in the restricted platform in the eastern basin continued to be shallower.The mound beach was dominated in bulge areas, with a larger thickness and wider distribution range of dolomite and gypsum rock; (3) The lithofacies paleogeography controlled the type and distribution of Ma 4 member reservoir, with the grain dolomite, microbial dolomite and porphyritic (limy) dolomite reservoirs developed. Controlled by the grain (mound) beach microfacies, the grain dolomite and microbial dolomite reservoirs were developed at the paleo uplift and bulge area. While the porphyritic (limy) dolomite reservoir was mainly developed in lagoon environments. In conclusion, Yulin-Hengshan and Shenmu-Mizhi bulges are favorable areas for reservoir development and gas exploration practice.

The exploration targets for marine oil and gas in the Ordos Basin have gradually shifted from the early weathering crust reservoirs of the Majiagou Formation to the inner carbonate reservoirs below the unconformity at the top of Ordovician.However,the research level of deep Cambrian and Ordovician in the basin is relatively low,and the overall characteristics and configuration relationship of the source,reservoir,and cap rock are unclear.Based on the latest drilling and seismic data,combined with basic geological work such as field outcrop investigation,laboratory analysis,core and thin section observation,the author has compiled a series of maps of tectonics-lithofacies paleogeography,maps of hydrocarbon source rocks and favorable sedimentary facies zones,to clarify the development characteristics and configuration relationship of source,reservoir,and cap rocks of the Cambrian-Ordovician.The Cambrian system in the Ordos Basin has a structural pattern of inherited uplifts developing within the platform and inherited rifts developing at the platform edge.The southwestern and northeastern rifts of the basin control the development of Middle and Lower Cambrian source rocks mainly in the sea troughs and bays,while the Wushenqi and Qingyang ancient uplifts control the development of granular shoals and weathered crust reservoirs mainly in the periphery and platform edge zones of the ancient uplifts.The Ordovician has a sedimentary pattern of multiple uplifts and depressions developing within the platform,and the differential distribution of sedimentary facies is jointly controlled by sedimentary paleogeomorphology and sea level changes.The three uplift zones within the platform control the distribution of favorable microfacies such as granular shoal and gypsum dolomite tidal flat,while the two depression zones within the platform control the distribution of marine source rocks.Tectonic-sedimentary models of the platform margin rift in Cambrian and the platform inner depression in Ordovician control the development of source rocks and reservoirs,and form three sets of excellent source-storage-cap combinations,which have great potential for natural gas accumulation and are important areas for future risk exploration in the Ordos Basin.

基于最新钻井与地震资料，对鄂尔多斯盆地乌审旗古隆起的分布进行刻画，同时采用Bischke曲线、平衡剖面方法分析其形成演化。结果表明，乌审旗古隆起为加里东早期形成的挤压型古隆起，平面呈南北向展布的椭圆状，长轴约194 km，短轴近东西向，长55~94 km，核部寒武系被剥蚀的厚度与面积分别为170~196 m和11 298 km²；利用年代地层格架剖面分析古隆起主体形成时间为怀远运动时期；中—晚寒武世为乌审旗隆起雏形期，晚寒武世末期隆起显著发育后被剥蚀，至奥陶纪马家沟组马三段沉积期隆起发生继承性活动，隆起面积减小，马四段沉积期—石炭系沉积前古隆起区地层发生非均一性抬升并遭受剥蚀，石炭纪及其之后进入埋藏保存的稳定期。乌审旗古隆起是在基底与构造薄弱带之上形成的，并受南部、北部的非共轴挤压以及盆内隆起传递的应力影响，发育成形态不规则的挤压型古隆起，该古隆起对沉积储集层和油气聚集具有一定控制作用。

鄂尔多斯盆地为典型的克拉通内盆地，油、气、煤、盐、铀等矿产资源丰富。研究构造运动的期次、序列与性质将为揭示克拉通盆地的成因与演化过程奠定基础，同时也将为探讨多种能源、矿产资源赋存的内在机制提供依据。基于近年来的高精度区域反射地震剖面和深井资料，结合周缘地质露头分析，通过厘定鄂尔多斯盆地的关键构造变革时期，建立了盆地演化的时-空框架。研究表明，鄂尔多斯盆地由下至上发育10个区域不整合面，分别为长城系、蓟县系、震旦系、寒武系、奥陶系、石炭系、三叠系、侏罗系、白垩系和第四系底界不整合面；盆地发育中元古界、寒武系-奥陶系、上石炭统-三叠系、侏罗系、下白垩统和新生界6个构造-地层层序。鄂尔多斯盆地的形成与演化受控于周缘板块构造作用，经历了中元古代早-中期大陆裂解、寒武纪-中奥陶世被动大陆边缘、晚奥陶世主动大陆边缘形成与碰撞造山、晚石炭世-二叠纪末期周缘裂解、中生代早期大型陆内坳陷、中生代中-晚期陆内前陆盆地和新生代周缘断陷等演化过程。鄂尔多斯盆地岩石圈深部的构造作用相对活跃，盆地内部发育中奥陶世、中-晚三叠世、早白垩世与晚中新世4期中酸性、中基性火山活动，其中，早白垩世晚期的火山活动强烈。结合周缘板块构造事件、盆内岩浆活动和盆地沉降-隆升过程分析，鄂尔多斯盆地经历了新元古代、晚奥陶世、中-晚三叠世、晚侏罗世-早白垩世、新生代5个关键构造变革期，这些构造变革期控制了盆地的构造演化和地质结构，对鄂尔多斯盆地的油气分布产生了深远影响。

Ordos Basin is a typical intracratonic basin, rich in mineral resources such as oil and gas, coal, salt, and uranium. Studying the periods, sequences and attributes of tectonic movement of the basin will not only lay the foundation for revealing the origin and evolution process of the craton basin, but also provide a basis for exploring the internal occurrence mechanism of the multiple energy and mineral resources. Based on high-resolution reflection seismic profile and deep-well data in recent years, in combination with the analysis of peripheral geological outcrops, this paper establishes a spatio-temporal framework of basin evolution by determining the key tectonic evolution periods of Ordos Basin. Studies have shown that there are 10 regional unconformities developed from bottom to top in the Ordos Basin, namely the basal unconformities in the Changchengnian, the Jixianian, the Sinian, the Cambrian, the Ordovician, the Carboniferous, the Triassic, the Jurassic, the Cretaceous and the Quaternary. Six tectono-stratigraphic sequences developed in the Mesoproterozoic, the Cambrian to Ordovician, the Upper Carboniferous to Triassic, the Jurassic, the Lower Cretaceous and the Cenozoic in the basin. The formation and evolution of Ordos Basin was controlled by the tectonization of the peripheral plates. It experienced the continental breakup in the early and middle period of the Mesoproterozoic, the development of passive continental margin during the Cambrian to the Middle Ordovician, the formation of active continental margin and collision orogeny in the Late Ordovician, the periphery breakup during the Late Carboniferous to the end of the Permian, the development of large-scale intracontinental depressions during the Early Mesozoic and intracontinental foreland basins during the Middle to Late Mesozoic, and peripheral fault depressions during the Cenozoic and other evolution processes. Tectonism in the deep lithosphere of Ordos Basin is relatively active. The basin is subjected to four periods of intermediate-acid or mafic-intermediate volcanic activities in the Middle Ordovician, the Middle and Late Triassic, the Early Cretaceous, and the Late Miocene, especially much extensive in the late period of the Early Cretaceous. Further, through analyzing the tectonic events of peripheral plates, intrabasin magmatic activity and basin subsidence-uplifting process, it is believed that Ordos Basin has experienced five key tectonic modification periods of the Neoproterozoic, the Late Ordovician, the Middle to Late Triassic, the Late Jurassic to Early Cretaceous, and the Cenozoic. These tectonic modification periods control the tectonic evolution and geological architecture of the basin, and have a profound impact on the distribution of oil and gas in Ordos Basin.

鄂尔多斯盆地中东部奥陶系深层白云岩是天然气勘探的重要目标,但针对该套白云岩储集层的研究相对较少,储集层特征及成因尚不清楚,从而制约了勘探进程。基于此,依据地震、岩心、薄片、测井、物性数据、地球化学特征和CT扫描等资料,笔者对该套白云岩储集层开展了系统研究。结果表明: (1)鄂尔多斯盆地中东部奥陶系深层发育膏溶孔型、颗粒滩型和生物扰动型白云岩储集层,其中膏溶孔型白云岩储集层岩性为含硬石膏结核粉晶白云岩,孔隙由膏模孔和微裂缝组成,平均孔隙度为2.57%;颗粒滩型白云岩储集层岩性为砂(砾)屑云岩、鲕粒云岩和晶粒化颗粒白云岩,孔隙包含粒间(溶)孔、粒内孔、晶间(溶)孔和微裂缝,平均孔隙度为4.65%;生物扰动型白云岩储集层岩性为斑状粉晶白云岩和斑状灰质粉晶白云岩,孔隙为晶间孔和微裂缝,平均孔隙度为2.54%。(2)膏溶孔型和颗粒滩型白云岩储集层的发育主要受沉积相、准同生溶蚀作用和石盐充填作用共同控制,含膏云坪和颗粒滩沉积分别是这两类白云岩储集层发育的物质基础,准同生溶蚀作用是储集层发育的关键,石盐充填作用是储集层致密化的主要因素。 (3)生物扰动型储集层发育主要受生物扰动和白云石化作用控制,前者为生物扰动型白云岩储集层发育创造基础条件,后者有利于晶间孔的形成与保存。该研究成果有助于对鄂尔多斯盆地中东部奥陶系深层白云岩天然气的勘探,期望能为下步勘探决策提供技术支撑。

The deep Ordovician dolomite in the mid-eastern Ordos Basin is an important target for natural gas exploration. There are few studies on this set of dolomite reservoirs,and the reservoir characteristics and genesis are unclear,which restricts the further exploration. Based on outcrops,cores,thin sections,loggings,physical property data and CT scanning data,the dolomite reservoir is systematically studied here. The dolomit reservoir of gypsum-dissolved pore type,granular beach type and bio-turbated type developed in deep Ordovician in the mid-eastern Ordos Basin. The gypsum-dissolved pore type reservoir is characterized by anhydrite nodule bearing micro-crystalline dolomite,and the pore is composed of gypsum molds and micro-fractures with an average porosity of 2.57%. The grain-beach dolomite reservoir is composed of calcarenite-rudite dolomite,oolitic dolomite and crystalline dolomite. The pores include inter-granular pores and micro-fractures,with an average porosity of 4.65%. The bioturbated dolomite reservoir is porphyritic micro-crystalline dolomite and porphyritic calcareous micro-crystall dolomite. The pores are inter-crystalline pores and micro-fractures, and the average porosity is 2.54%. Development of gypsum-solution pore-type and grain-beach type dolomite reservoirs was mainly controlled by sedimentary facies,quasi-synchronous dissolution and rock salt filling. The gypsum bearing dolomitic flat and grain-beach facies provided the basis for development of the two types of dolomite reservoirs. The quasi-synchronous dissolution was the key to development of the reservoir,and the rock salt filling was the main factor for densification of the reservoir. Development of bioturbated dolomite reservoir was mainly controlled by bioturbation and dolomitization. Bioturbation createed basic conditions for development of bio-turbated dolomite reservoir. Quasi-contemporaneous dolomitization was conducive to formation and preservation of inter-crystalline pores. The above results are conducive to the exploration of deep dolomite natural gas in the Ordovician in mid-eastern Ordos Basin,and may provide technical support for the further exploration.

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.

针对白云岩成因、原生白云石沉淀、白云岩孔隙成因等问题,在前人认识的基础上,补充四川和塔里木盆地典型案例的岩石学和地球化学特征分析工作,取得3项进展：①提出基于岩石特征、形成环境和时间序列的白云岩成因分类,不同成因白云岩之间的成岩域、特征域界线清晰,演化线索清楚,更具系统性和连续性;②建立不同成因白云岩的岩石学和地球化学特征识别标志,白云岩之间的岩石学和地球化学特征的变化具有规律性,是连续时间序列上形成环境变迁的响应;③重新评价白云石化作用对孔隙的贡献,阐明白云岩中的孔隙主要来自原岩的沉积原生孔、部分来自表生溶蚀和埋藏溶蚀作用,早期白云石化有利于孔隙的保存。这些认识对白云岩成因的理解、不同成因白云岩的判识具重要的理论意义,同时对白云岩储集层预测具有重要的指导意义。图6表4参53

以塔里木、四川和鄂尔多斯盆地多层系白云岩为研究对象,应用矿物岩石学分析、团簇同位素测温及U-Pb同位素测年等技术手段,开展白云石化路径及其成储效应研究。识别出保留原岩结构白云岩（微生物结构和泥晶结构）、埋藏交代白云岩Ⅰ（半自形—自形细、中、粗晶结构）、埋藏交代白云岩Ⅱ（他形—半自形细、中、粗晶结构）、埋藏沉淀白云石、粗晶鞍状白云石5种结构组分。前3者以岩石的形式存在,后两者以充填孔洞和裂缝的白云石矿物形式存在,并建立了5种白云岩结构矿物岩石学和地球化学特征识别图版。基于5种白云石结构组分的识别,建立了白云岩保持型、白云岩改造型和灰岩埋藏白云石化型等3类储集层的6种白云石化路径。白云石化前的原岩初始孔隙和白云石化路径是控制白云岩储集层发育的关键因素,白云岩保持型和白云岩改造型白云石化路径的成储效应最佳,且发育分布具有相控性和规模性特征,是深层碳酸盐岩油气勘探的首选对象。