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    2022, Volume 29 Issue 6
    25 November 2022
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    Towards a new era of diversified energy development: Innovation in theoretical petroleum geology to meet “dual carbon target”
    LI Desheng, LI Bohua
    2022, 29(6): 1-9. 
    DOI: 10.13745/j.esf.sf.2022.8.57

    Abstract ( 494 )   HTML ( 19 )   PDF (1796KB) ( 247 )  

    “Dual Carbon Target” is a basic policy for China's energy development. How to advance petroleum geology and promote energy diversification under such a policy directive is a key issue facing Chinese researchers in the field of petroleum science and technology development. This paper analyzes and studies China's historical carbon dioxide emissions, fossil fuel consumption, oil and gas reserves, and oil and gas production from 2000 to 2020, and believes that under the “carbon peaking” and “carbon neutrality” trends of dealing with global climate change, oil and gas will continue to play an important role in the energy sector in the 21st century. The petroleum industry of China should base on innovations both in theory and practice, succeed at its two breakthroughs—super-deep conventional oil and gas up to 10000 m well-drilling depth, and nano scale super-dense reservoir of unconventional shale oil and gas, and achieve unsurpassed productivity as well as low-carbon green transformation development. Oilfield water injection is the core technology for enhancing oil recovery in China. In the future, carbon dioxide injection should be vigorously promoted to achieve the dual goal of oil increase and emission reduction; while innovation in carbon dioxide capture and storage should be pursued to develop the carbon emission reduction sector of the petroleum industry. The 21st century is an era of diversified energy development. The development and utilization of the three kinds of renewable energy—hydropower, wind power, and solar energy—is a basic guarantee to achieve the “Dual Carbon Target”, and geothermal energy, biomass energy, and ocean energy are also important driving forces. In the 22nd century, renewable energy and new energy will provide energy security to mankind. Hydrogen energy will be the most promising new energy in the future.

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    Core theories of sedimentary basin structure and the related key research techniques: Frontiers and development directions
    YANG Shufeng, JIA Chengzao, CHEN Hanlin, JIA Dong, WEI Guoqi, XIAO Ancheng, GUO Zhaojie, CHENG Xiaogan, WU Lei, YIN Hongwei, ZHANG Fengqi, LIN Xiubin
    2022, 29(6): 10-23. 
    DOI: 10.13745/j.esf.sf.2022.8.12

    Abstract ( 347 )   HTML ( 22 )   PDF (2838KB) ( 303 )  

    On the basis of a systematic literature review of structural analysis of sedimentary basins, this paper summarizes the frontiers and development directions of the core theories of sedimentary basin structure and the related key research techniques. The core theories of sedimentary basin structure include theories on basin classification, basin-forming mechanism, quantitative deformation analysis, and basin filling process. Basin classification theory concerns with establishing basin classification schemes according to different classification criteria, and the development trend is to classify prototype basins based on resource and tectonic background while classify superimposed basins based on basin evolution. Theory of basin-forming mechanism is primarily based on quantitative simulation to study the basin subsidence process and its controlling factors under different mechanisms (pure thermal mechanism, tectonism, loading effect), and the development trend calls for three-dimensional formation dynamics simulation. Quantitative deformation analysis includes the theories of fault-related fold, critical wedge and salt tectonics, and the development trend is three-dimensional structural modeling and three-dimensional quantitative deformation analysis. Lastly, the theory of basin filling process emphasizes on the comparison of filling processes between basins with different tectonic settings and source-sink analysis of basin-orogeny processes, and the development trend is to incorporate multivariate source-sink analysis and quantitative basin analysis. The key frontier techniques for studying sedimentary basin tectonics include three-dimensional structural modeling, physical analog modeling, numerical simulation, and fracture prediction based on three-dimensional structural restoration. The techniques of physical analog modeling includes: modeling based on industrial CT scan imaging which can dynamically monitor, damage-free, the deformation evolutionary process inside the structural belt and accurately construct the three-dimensional spatial distribution of the deformation belt; modeling based on PIV finite strain analysis which can quantitatively analyze the deformation evolutionary process, intuitively display the strain distribution characteristics, and explore the rules of dynamic strain distribution; and modeling with hypergravity field which can simulate the structural rheological process at different scales and explore the dynamic mechanistic relationship between brittle deformation in shallow lithosphere and ductile rheology in deep lithosphere.

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    Multi-cycle superimposed sedimentary basins in China: Formation, evolution, geologic framework and hydrocarbon occurrence
    HE Dengfa
    2022, 29(6): 24-59. 
    DOI: 10.13745/j.esf.sf.2022.8.1

    Abstract ( 300 )   HTML ( 27 )   PDF (11062KB) ( 525 )  

    Understanding basin's geological structure and tectonic evolution and exploring its oil and gas distribution pattern is key to revealing the geological features of China, and the energy resources distributions, environmental changes, and potential hydrocarbon exploration targets in China. Based on the new data of recent petroleum exploration and using the methodology of comparative geo-tectonics, this paper studies the superimposed sedimentary basins in China from the view point of mobile geo-tectonic history, focusing specifically on the basin's tectonic evolution, tectonic subdivision, geologic framework, and pool-formation models, and explores the basin's oil and gas distribution patterns. According to our analysis, the superimposed sedimentary basins in China evolve through four tectonic cycles during the Meso- to Neo-Proterozoic, Cambrian-Devonian (or Middle Devonian), (Late Devonian-) Carboniferous-Triassic, and Jurassic-Quaternary Periods. The sedimentary basins in China can be subdivided into ten sedimentary basin areas: northern Xinjiang, inner Mongolian, Songliao, Tarim-Alax, Ordos, Bohai Bay, Qinghai-Tibet, Sichuan, southern China, and oceanic area. They can be further characterized by eight structural styles as foreland/cratonic-basin, foreland/sag, sag/faulted-depression, faulted-depression/sag, inverted faulted-depression, passive margin, or strike-slip superimposed basins, or as modified residual basins. Twelve types of hydrocarbon pool-formation are developed, which are represented by the Anyue rift trough, northern Tarim, Sulig composite delta, Mahu sag, Luliang uplift, Kuqa thrust belt, Daqing anticline, paleo-buried hill, central canyon channel, eastern Qaidam biogas, Sichuan intra-source rock, and Qinshui syncline coalbed gas. Within a sag/faulted-depression superimposed basin, oil and gas distributions are typically ordered spatially, with the interface area most favorable for hydrocarbon accumulation. However, oil and gas distribution patterns are highly heterogeneous across different structural styles. For example, in the foreland/cratonic-basin superimposed basins of central and western China, oil and gas distribute separately in isolation, whilst in the passive-margin/faulted-depression superimposed basins of the oceanic area, oil and gas zones distribute respectively along the inner and outer sedimentary belts. The multi-cycle superimposed basins in China generally have a distinctive ‘three ring-like’ oil and gas distribution pattern within each basin area.

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    Marine basins in China—a prototype-reconstruction analyses and ordered hydrocarbon accumulation patterns
    HE Zhiliang, LU Jianlin, Lin Juanhua, JIN Xiaohui, QI Lixin, XU Xuhui, HUANG Renchun, WANG Yi
    2022, 29(6): 60-72. 
    DOI: 10.13745/j.esf.sf.2022.8.4

    Abstract ( 154 )   HTML ( 7 )   PDF (5028KB) ( 207 )  

    There are three key scientific issues in the marine petroleum exploration in China, i.e., the prototypes of China's three major marine basins and their controls on the petroleum source material conditions; the control of Paleozoic multistage tectonic movements and Mesozoic/Cenozoic differential-superposition transformation on the hydrocarbon accumulation/enrichment in the marine carbonate strata; and the dynamic reservoir-forming processes and enrichment rules of marine petroleum in the complex structural areas and ultra-deep layers. Based on our prototype-reconstruction analyses, the basin prototypes and sedimentary models of the three cratons of China (South China, North China, Tarim) obviously differ between different periods under the effects of plate tectonic cycles, and can be divided into three combination types: intra platform depression, passive continental margin and rift (depression). The passive continental margin can be further divided into steep slope and gentle slope, with various source-reservoir allocation relationships formed in the marine strata. Several rounds of global plate tectonic reorganization take place since the Phanerozoic; and since the Late Triassic, especially, under the multiplate subduction-convergence tectonic framework, the three marine cratonic basins—Tarim, Sichuan, Ordos—undergo four superposition transformations and form the corresponding continental basin prototypes, with various types of complex geostructures developed including piedmont belt thrust-fold, differential subsidence-uplift, multi-detachment structures, deep strike-slip faults, as well as structures formed by tectonic magmatism. In the Tarim Basin, the inhibition of hydrocarbon generation due to great burial depth, high pressure and low ground temperature control the petroleum distribution, where the distribution depth of liquid hydrocarbon can exceed 10 000 m. The upper Middle and Late-Caledonian/Hercynian paleo structure controlls the early hydrocarbon migration and accumulation, while the active strike-slip fault zones of the Late Yanshanian to Himalayan control hydrocarbon enrichment in the later stage. In the Sichuan Basin, the ancient uplift/slope controll the initial hydrocarbon accumulation and form the ancient oil reservoir under an unique hydrocarbon source environment; cracked gas becomes the main gas source in the large and medium-sized gas fields. After the Late Cretaceous, large-scale fold, uplift and denudation result in the reorganization and reconstruction of the basin's fluid system. According to the degree of transformation, the models of petroleum accumulation/preservation are divided into (1) weak modification, where conventional/unconventional gas can be preserved in situ for a long time; (2) medium transformation, where conventional gas adjusts and re-accumulates while large-scale shale gas enrichment occurs; and (3) strong transformation, where conventional gas reservoirs are destroyed by intense modification while some unconventional gas reservoirs are preserved. In the Ordos Basin, Ordovician natural gas has two sources from three directions, where natural gas accumulation is closely related to unconformity and stratigraphic sequence boundary as well as lithological and lithofacies changes, while gas reservoirs generally experienced one adjustment process.

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    Marine basins in China: Petroleum resource dynamic evolution and exploration directions
    XU Xuhui, LU Jianlin, WANG Baohua, ZHENG Lunju, FANG Chengming, CAI Pengrui, ZHAO Linjie
    2022, 29(6): 73-83. 
    DOI: 10.13745/j.esf.sf.2022.8.21

    Abstract ( 204 )   HTML ( 10 )   PDF (5979KB) ( 146 )  

    Marine basin exploration is an important breakthrough in China's quest for oil and gas resources. Based on the analysis of China's petroliferous basins and theory of supercontinent cycle, we consider the three cratonic marine basins in China have in general experienced four evolutionary cycles since the Proterozoic. In this paper, the stratigraphic sequence and the juxtaposition-superposition characteristics of the marine prototype basins are clarified, and the three types of prototype basins and four source-control modes are summarized to show the prototype-basin control on the petroleum source-rock environment and distribution modes. In addition, the distribution maps of the main strata and source-rock types in the three basins are compiled, and the source-rock characteristics are defined. Based on the dynamic evolution model of hydrocarbon generation-expulsion-retention in the marine source rocks, the methodologies for dynamic evaluation of source-rock effectiveness and combined “conventional and unconventional” resource evaluation are established. Based on the new methodology, the hydrocarbon generation-expulsion volume and resource volume of marine strata are calculated, and the distribution of potential petroleum resources in key basins is clarified. The paper proposes 15 resource zones with more than 1 billion-ton (in total) and 13 zones with 0.5-1 billion-ton (in total) petroleum reserves, and points out the next key areas and directions of marine strata exploration.

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    Hydrocarbon occurrence and accumulation processes in reformed basins—theories outline
    LIU Chiyang, HUANG Lei, ZHAO Junfeng, WANG Jianqiang, ZHANG Dongdong, ZHAO Hongge, SHAO Deyong, LIU Weishuai
    2022, 29(6): 84-108. 
    DOI: 10.13745/j.esf.sf.2022.8.13

    Abstract ( 176 )   HTML ( 4 )   PDF (5946KB) ( 174 )  

    One of the distinguishing features of sedimentary basins in China is widespread, strong late-stage reformation. Late-stage basin reformation has a profound impact on the hydrocarbon occurrence conditions and accumulation processes, and poses significant challenges to geological research and oil and gas exploration. Reformed basins and the affected areas have become important targets for petroleum exploration and resource replacement in China. The five main types of late-stage reformation are uplift-denudation, subsidence-deep burial, thermal action, fluid activity, and tectonic deformation. In nature, complex reformation involving concurrent geological processes is more common. Reformed basins are structurally diverse, where petroleum occurrence and accumulation involve a combination of many reservoirs types. In this paper, the core theories of hydrocarbon occurrence and accumulation in reformed basins are outlined, which can be summarized into the ideas of ‘source control by prototype basin, reservoir control by diagenetic process, accumulation control by reformation, multi-source accumulation, dynamic accumulation-dispersion, and late positioning’. ‘Source control by prototype basin’ means the source rock of a reformed basin is formed in the hydrocarbon-rich sag of the prototype basin prior to reformation, and its current scale and property determines the hydrocarbon richness and hydrocarbon distribution in the basin. Two major diagenetic processes—original material deposition-burial and secondary reformation-remodeling—control the formation and preservation of various types of reservoirs—so is called ‘reservoir control by diagenetic process’. And ‘accumulation control by reformation’ refers to the regional late-reformation features and outcomes have direct control on the hydrocarbon occurrence, accumulation-positioning and distribution in the region. Multiple late-reformations can lead to multi-source reservoir developments, such as co-reservation and accumulation of hydrocarbons from source rocks with variable depth and maturity, mixed hydrocarbons from source rocks of different types and generations, as well as co-storage/co-existence of hydrocarbon and various non-hydrocarbon gases in the same basin. The basin has undergone multi-stage tectonic evolution and reformation, which inevitably lead to hydrocarbons multi-stage dynamic accumulation-dispersion and late-stage accumulation-positioning. Understanding the late-stage accumulation and positioning can help to understand the formation mechanisms of most hydrocarbon reservoirs of different eras.

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    Superimposition and composition control on hydrocarbon reservoirs in multi-cycle basins: Concept and practice in conventional and unconventional natural gas explorations
    GUO Tonglou
    2022, 29(6): 109-119. 
    DOI: 10.13745/j.esf.sf.2022.8.38

    Abstract ( 154 )   HTML ( 2 )   PDF (4144KB) ( 127 )  

    The Sichuan basin is a typical multi-cycle sedimentary basin in China and an important natural gas base with a large number of conventional, tight-sandstone and shale gas fields. The whole-basin, trans-stratum gas-bearing reservoirs are formed by predominantly vertical superimposition of marine, marine to non-marine transitional and continental strata with horizontal tectonic subdivision, and multi-cycle tectonic superimposition and modification in the vertical direction. In this study, the Puguang gas field, Fuling shale gas field, and Zhongjiang tight-sandstone gas filed are taken as examples to demonstrate the concept of superimposition and composition control on oil/gas pool formation—i.e., in superimposed basins every controlling factor affecting oil and gas accumulation and enrichment is controlled by many interrelated elements. Such factors not only increase in number with time but also are superimposed in space; and by unknown mechanism geological unites can combine together, such as structural and lithological bodies, and structural and stratigraphic traps. In general, superimposition controls oil and gas formation and evolution while composition controls oil and gas accumulation and position, and this rule applies to all large gas fields in the Sichuan basin. Therefore, further understanding of the superimposition and composition control in multi-cycle basins is of great significance for guiding oil and gas exploration research and practice in the Sichuan basin. This article systematically analyzes and summarizes the rule of hydrocarbon formation, accumulation and enrichment in large gas fields in the Sichuan basin. And, based on the exploration and development status of the Sichuan basin and multi-cycle characteristics three key research areas are proposed: (1)Tectono-paleogeography research aiming to clarify the superimposition and composition relationships between tectonic pattern, reservoir, hydrocarbon-source and trap-space, and their control over pool formation; (2)Regional tectonic evolution research towards better understanding the multi-cycle tectonic superposition process and its control on oil and gas generation and enrichment; (3)Structural classification and reservoir controlling research towards fine structural classification and better understanding the multi-stage structural control on gas-water relationship, hydrocarbon enrichment and reservoir transformation.

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    “Hydrocarbon accumulation chain”—concept, characteristics and application
    ZHAO Xianzheng, JIN Fengming, PU Xiugang, LUO Qun, ZHOU Lihong, JIANG Wenya, DONG Xiongying, SHI Zhannan, HAN Wenzhong, ZHANG Wei, WANG Hu
    2022, 29(6): 120-135. 
    DOI: 10.13745/j.esf.sf.2022.8.14

    Abstract ( 294 )   HTML ( 5 )   PDF (5930KB) ( 124 )  

    Mature basins still contain considerable oil and gas resources, but the current theory of oil and gas accumulation is increasingly inapplicable to the structurally complex, concealed reservoirs in mature basins. Inspired by the attributes of “chain”, this paper put forth the concept of “hydrocarbon accumulation chain” developed on the basis of existing theories, through a global-scale researching and comparison of hydrocarbon accumulation processes and distribution laws. A “hydrocarbon accumulation chain” refers to a series of oil and gas reservoir combinations that are closely related by formation mechanism and arranged in a specific way in space. “Hydrocarbon accumulation chain” accurately describes the pattern/process of hydrocarbon distribution/accumulation: It shows the beaded, chain-like distribution pattern of oil and gas reservoirs, and describes the process of oil/gas generation, migration, accumulation along dominant migration pathways. And, superposition of many such ‘hydrocarbon accumulation chains’ through the geological history gives rise to today's complex pattern of hydrocarbon accumulation. A complete ‘hydrocarbon accumulation chain’ contains the inner, middle and outer sections that have not only their own characteristics of but also continuity in the hydrocarbon accumulation background, condition, mechanism, enrichment law and distribution mode—and most of all, it is a compact, complete hydrocarbon generation-migration-accumulation system. The four main characteristics of “hydrocarbon accumulation chain” are source sharing by multiple chains; multiple reservoirs per chain; multi-chain network; and reservoir enrichment along dominant chains. The “hydrocarbon accumulation chain” concept has some unique practical advantages over other theories as it proposes “whole-chain thinking, entirety research, prospecting along the chain, and precision exploration”, which is of great significance for guiding exploration breakthroughs in new areas as well as maximizing the exploration potential of mature basins. This concept has been applied to the oil and gas exploration in the Jizhong-Huanghua depressions with great success.

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    Hydrocarbon accumulation conditions in and resource potential of the Asia-Pacific region
    LI Dawei, MI Shiyun, WEN Zhixin, WANG Zhaoming, LIU Zuodong, WANG Yonghua, WU Zhenzhen, NIU Min, ZHANG Qian
    2022, 29(6): 136-145. 
    DOI: 10.13745/j.esf.sf.2022.8.28

    Abstract ( 127 )   HTML ( 12 )   PDF (2198KB) ( 133 )  

    The Asia-Pacific region is an important oil and gas producing region and the largest oil and gas consumer market in the world. Of the 155 major sedimentary basins in this region, more than 90 have oil and gas fields (~6900 in total) or oil and gas occurrences. The region can be further divided into four subregions—East Asia, Southeast Asia, Australia-New Zealand and South Asia—according to geographical locations and structural characteristics, and there are about 131 major petroleum systems. This paper presents an overall analysis and summary of the oil and gas accumulation conditions (source rocks, reservoirs, caprocks, petroleum systems, etc.) in each subregions. On this basis, taking the play as the basic evaluation unit, the oil and gas resource potential of each basin is evaluated. The total recoverable conventional oil and gas resources in the Asia-Pacific region is 673.7×108 t of oil equivalent, or 6.1% of the world reserves. Unconventional oil and gas resources are mainly heavy oil, shale oil, oil shale, shale gas and coalbed methane. The total technological recoverable unconventional oil and gas resources is 390.4×108 t of oil equivalent, or 6.1% of the world reserves. According to the estimates of undiscovered resources and resources exploration level, offshore and deep-sea exploration will be the focus of the future: New strata and lithologic and stratigraphic traps in deep-sea and mature basins are the main exploration domains; marine deltas are an important prospecting target for natural gas fields; Cenozoic lacustrine facies of the back-arc basin group in Southeast Asia is a favorable exploration target for shale oil; and Devonian-Carboniferous cratonic basins in central Australia are the favorable shale gas exploration areas.

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    Petroleum resource potential, distribution and key exploration fields in China
    WU Xiaozhi, LIUZHUANG Xiaoxue, WANG Jian, ZHENG Min, CHEN Xiaoming, QI Xuefeng
    2022, 29(6): 146-155. 
    DOI: 10.13745/j.esf.sf.2022.8.27

    Abstract ( 583 )   HTML ( 48 )   PDF (2340KB) ( 361 )  

    Geological structures in China developed as the results of multi-cycle tectonic evolution of three plates and three tectonic domains, and several types of superimposed sedimentary basins are formed, such as craton/foreland, rift/depression and foreland/depression superimposed basins. The country's major petroleum resources are concentrated in the large superimposed basins. Rich in conventional and unconventional oil and gas resources, China has 1075×108 t of conventional oil, 83×1012 m3 of conventional natural gas, 134×108 t of tight oil, 21×1012 m3 of tight sandstone gas, 335×108 t of shale oil, and 56×1012 m3 of shale gas reserves. Onshore oil and gas resources are mainly distributed in Bohai Bay (onshore), Songliao, Ordos, Tarim, Sichuan, Junggar and Qaidam basins, while offshore oil and gas resources are mainly distributed in Bohai Bay (offshore) and East China Sea, and in Pearl River Estuary, Beibu Gulf, Yinggehai, and Qiongdongnan basins, northern South China Sea. In future, China's oil and gas exploration should adhere to the “secure resources supply, stabilize oil production, increase gas production” strategy and the proactive exploration idea, that is “develop conventional and unconventional resources in parallel, plan sea and land as a whole”. The key areas for conventional oil and gas exploration in China are stratigraphic-lithologic traps, foreland basins, marine carbonate reservoirs, and buried hills for onshore oil; carbonate reservoirs and foreland basins for onshore gas; marine strata and bedrock buried-hills of Bohai Sea for offshore oil; and deep-water lithologic traps and marine strata of South China Sea for offshore gas. And unconventional oil and gas exploration is to focus on the seven onshore oil and gas basins with tight oil and shale oil/gas resource potentials, and technical support for exploration and development should be strengthened.

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    Deformation mechanisms and structural models of the fold-thrust belts of central and western China
    JIA Chengzao, CHEN Zhuxin, LEI Yongliang, WANG Lining, REN Rong, SU Nan, YANG Geng
    2022, 29(6): 156-174. 
    DOI: 10.13745/j.esf.sf.2022.8.2

    Abstract ( 316 )   HTML ( 15 )   PDF (8053KB) ( 236 )  

    Based on complex structure interpretation and analogue modeling, we reveal that under lateral tectonic compression the fold-thrust belts of central and western China develop multi-layer detachments with varying deformation styles. For the contractional structural deformation with single basal detachment, there are two types of structural propagation mechanisms—critical and non-critical accretion, and three types of end-member deformation behaviors—brittle detachment, ductile sliding and viscous flow. And there are four main factors influencing the deformation processes and structural styles: detachment strength, strata composition, pre-existing basal structures and external dynamic processes. The fold-thrust belt developed a vertically superimposed composite structure controlled by multi-layer detachments, and we consider the complex slip-thrust regime can be disassembled vertically into various characteristic deformation layers controlled by different basal detachments. In addition, we show that the frontal foreland thrust belt forms multi-detachment structures from shallow to deep in deformation time sequence. Finally, a structural model of rejuvenated foreland thrust belts of the central and western China is constructed, along with the underlying deformation mechanisms, structural units and basic structural types. Based on the multi-stage tectonic evolutionary processes of the foreland basins and the Cenozoic basin-mountain coupling features, we present two types of hydrocarbon-rich thrust belts with different prospecting targets.

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    Formation mechanism of the Bozi-Dabei trillion cubic natural gas field, Kuqa foreland thrust belt
    YANG Xuewen, WANG Qinghua, LI Yong, LÜ Xiuxiang, XIE Huiwen, WU Chao, WANG Cuili, WANG Xiang, MO Tao, WANG Rui
    2022, 29(6): 175-187. 
    DOI: 10.13745/j.esf.sf.2022.8.18

    Abstract ( 196 )   HTML ( 13 )   PDF (6783KB) ( 146 )  

    The ultra-deep layer of the Bozi-Dabei area, Kelasu structural belt, Kuqa foreland basin is a crucial oil and gas exploration area in the Tarim Oilfield with the estimated natural gas resource exceeding one trillion cubic meters. Based on cores, cast sheets, analytical assays, well logging and production data, the oil and gas sources, reservoirs and caprocks in the Bozi-Dabei area are analyzed, and subsequently the oil/gas transport and charging characteristics are systematically studied, the hydrocarbon accumulation conditions and process are analyzed, and the formation mechanism of the giant Bozi-Dabei natural gas field is clarified. The general characteristics of oil/gas accumulation are early oil accumulation, late gas accumulation, overpressure charging, vertical transport, and efficient accumulation. And the “early-stage shallow burial, late-stage rapid deep burial” regiment enables the source rocks to generate hydrocarbon continuously, while the good reservoir-cap configuration and vertical transport via faults provide the pre-conditions for oil/gas migration and accumulation. Mature to over-mature source rocks, planar-arranged and vertical-stacked traps, high-quality reservoir facies belts, and huge thick gypsum-salt caprocks are effectively superimposed in the Bozi-Dabei area to form the large high-abundance, ultra-high-pressure natural gas reservoirs.

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    Tectonic evolution of and hydrocarbon accumulation in the western Junggar Basin
    WANG Xiaojun, SONG Yong, ZHENG Menglin, GUO Xuguang, WU Haisheng, REN Haijiao, WANG Tao, CHANG Qiusheng, HE Wunjun, WANG Xiatian, GUO Jianchen, HUO Jinjie
    2022, 29(6): 188-205. 
    DOI: 10.13745/j.esf.sf.2022.8.19

    Abstract ( 194 )   HTML ( 8 )   PDF (9130KB) ( 204 )  

    Based on the surface outcrop, seismic, drilling and dating data, the multi-stage tectonic evolution of the basin-mountain junction zone, western Junggar Basin is studied. The present basin-mountain structure is the result of multi-stage basin evolution under tectonic superposition and basin-orogenic belt interaction, where six tectonostratigraphic sequences—Carboniferous, Lower-Middle Permian, Upper Permian-Triassic, Jurassic, Cretaceous and Cenozoic—are delineated according to stratigraphic unconformities. In the western basin, Late Carboniferous tectonic activities form the Chepaizi and Zhongguai uplifts and Mahu, Shawan and Sikeshu sags. Under Early Permian extensional tectonic environment, three subsidence-sedimentation centers developed in the piedmont of Mahu, Shawan and Sikeshu, while important hydrocarbon source rocks formed in the west of the basin. Late-Middle Permian tectonic movement results in the inversion, uplift and denudation of the western piedmont sedimentary strata and basin-ward thrust fault. Large-scale Late Permian-Triassic depressions are centered in the Shawan sag and controlled by the northern fault of the Chepaizi uplift, with strata overlapping northward and westward burying, successively, the Zhongguai uplift, Mahu sag and piedmont fault belts. Pre-Jurassic tectonic coupling between the orogenic belt and basin varies in both style and intensity: From the Jurassic to Cretaceous, weak tectonic activities lead to continuous basin expansion and strata overlapping toward the orogenic belt, along with S-N/E-W migration of subsidence-sedimentation centers. While in the Cenozoic, strong depression in the North Tianshan results in the whole basin to tilt N-S, forming a Neogene foreland basin. Eventually, the multi-stage basin tilting/overturning and the late-stage overlaying of sedimentary strata over orogenic belt control the hydrocarbon accumulation in the western Junggar Basin, where late-stage buried thrust belt becomes the oil/gas enrichment zone.

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    Genetic analysis of typical strike-slip faults and related basins in China
    FENG Zhiqiang, LI Meng, GUO Yuanling, LIU Guangxiang
    2022, 29(6): 206-223. 
    DOI: 10.13745/j.esf.sf.2022.8.6

    Abstract ( 371 )   HTML ( 38 )   PDF (8877KB) ( 382 )  

    Strike-slip faults and strike-slip pull-apart basins are widely distributed in China. At present, few researches are concerned with the large variety patterns of strike-slip faults related to the different rheological structures of the lithosphere. There is no doubt that the lithosphere is the subject of the tectonic movement driven by regional stress field, hence, the stress field determines the way of movement, such as strike-slipping, stretching etc., whilst the nature of a lithosphere determines the movement scale and its specific form. Study of the large quantity and variety forms of strike-slip faults and basins show: many small strike-slip faults are distributed widely in the ancient craton, e.g., the strike-slip fault systems of Paleozoic strata in the Tarim Basin; a “destroyed craton” develops multiple strike-slip fault belts, e.g., the Tan-Lu fault belt, Lanliao-Yanshan fault belt and the eastern piedmont fault zone of Taihang Mountain in the eastern part of the North China Craton, and it can couple with the regional extensional stress field to form an echelon grabens (like the Bohai Bay Basin); large strike-slip faults (such as the northeastern segment of the Tan-Lu fault) develop on the relatively weak Paleozoic lithosphere, and its related independent strike-slip pull-apart basins. In the Meso-Cenozoic orogenic belt with poor consolidation, a linear large strike-slip fault is often formed, e.g., the Altyn and Haiyuan faults. Based on the strike-slip stress field and the strength and rheological characteristics of the lithosphere, we establish the coupling mechanism between the lower ductile-layer and the top brittle-layer of lithosphere properties. On this basis, the formation and evolutionary models of strike-slip faults with different lithosphere properties are established to better explain the genetic mechanisms of typical strike-slip faults and related basins developed in China.

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    Strike-slip faults in marine cratonic basins in China: Development characteristics and controls on hydrocarbon accumulation
    ZHENG Herong, HU Zongquan, YUN Lu, LIN Huixi, DENG Shang, JIA Huichong, PU Yong
    2022, 29(6): 224-238. 
    DOI: 10.13745/j.esf.sf.2022.8.7

    Abstract ( 287 )   HTML ( 10 )   PDF (6759KB) ( 226 )  

    As a new type of petroleum reservoir, the strike-slip fault-controlled oil and gas reservoirs show promising resource potentials. Here, through comparative analysis of the strike-slip fault development characteristics and control on hydrocarbon accumulation in the three largest marine cratonic basins (Tarim, Sichuan and Ordos) in China, the similarities and differences in fault architecture and movement characteristics between the three basins are revealed. In combination with the dynamic evolution of each basin, the formation mechanisms of the strike-slip faults are discussed and the fault controls on oil and gas reservoirs are systematically analyzed. We show that (1) all three basins develop small-medium displacement strike-slip faults, and the fault structures can be characterized by “layered deformation” in profile, segmentation in plan view and superposition architecture—formed as a result of episodic fault activity—in vertical view. (2) The formation mechanisms, distributions and movement periods of the strike-slip fault systems differ between basins. Being the oldest, the strik-slip fault system of the Tarim Basin experiences the longest evolution, where the northern strike-slip faults merge together from north to south while divide into eastern and western regions. In the Ordos Basin, a NWW-trending strike-slip fault forms in the southwestern margin as a result of intracontinental extrusion at the margin. And in the Sichuan Basin, under the influence of the Permian Emeishan mantle plume, the pre-existing basement faults reactivate and form the NW-, NWW- and nearly EW-trending transtensional strike-slip faults. (3) The strike-slip faults in the three basins all have important controls on oil and gas accumulation. For reservoir rock formation, fault-controlled/fault-dissolution fracture-cavity or fault-controlled fracture-pore reservoir rocks can form under coupled fault-fluid interaction/modification. For trap formation, fault-controlled/fault-dissolution fracture-cavity lithologic traps can form in carbonate rocks. And for migration, the steeply dipping strike-slip faults can directly connect source rocks and reservoir rocks to form very important vertical migration conduits for oil and gas.

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    Control of strike-slip fault on the large carbonate reservoir in Fuman, Tarim Basin—a reservoir model
    WANG Qinghua, YANG Haijun, LI Yong, LÜ Xiuxiang, ZHANG Yintao, ZHANG Yanqiu, SUN Chong, OUYANG Siqi
    2022, 29(6): 239-251. 
    DOI: 10.13745/j.esf.sf.2022.8.17

    Abstract ( 419 )   HTML ( 11 )   PDF (6974KB) ( 185 )  

    The exploration target for deep marine hydrocarbon in the platform basin area, Tarim Basin has changed from interlayer karst to fault-controlled reservoir, and a strike-slip fault- controlled oilfield is discovered in the Fuman depression area. The strike-slip fault and reservoir characteristics of the Fuman area differ from the paleo-uplift slope area of the basin. Therefore, it is necessary to establish a fault-control reservoir model for the study area. In this paper, the strike-slip fault system is described based on high-density 3D seismic data; the distribution pattern of different types of reservoirs is revealed by core, logging, and fracture-cavity recognition technology; the impact of strike-slip fault style and differential deformation on reservoir development is analyzed; and a strike-slip fault-control reservoir model is established. Here are the main conclusions: (1) The large carbonate hydrocarbon accumulation area of Fuman mainly contains cave, fracture-hole, fracture, and hole-pore type reservoirs formed by multi-stage strike-slip faulting and karstification. (2) Differential deformation of strike-slip faults controls the reservoir type and reservoir distribution by influencing the extent of the fracture zone and the fluid activity range—larger activity range corresponds to larger fracture zone, and reservoir development in the tenso- and compresso-shear sections is better than in the linear section. (3) The tenso-shear section is a catchment area with good fault connectivity conducive to meteoric water infiltration and thermal fluid upwelling for carbonate dissolution. The compresso-shear section, on the other hand, is a distributary area, where karst reservoirs developed mostly on the two sides of the fault zone, with relatively small fracture opening thus lesser fluid transformation compared to the tenso-shear section.

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    Characteristics and evolution of the main strike-slip fault belts of the central Sichuan Basin, southwestern China, and associated structures
    GUAN Shuwei, LIANG Han, JIANG Hua, FU Xiaodong, GU Mingfeng, LEI Ming, CHEN Tao, YANG Rongjun
    2022, 29(6): 252-264. 
    DOI: 10.13745/j.esf.sf.2022.8.8

    Abstract ( 353 )   HTML ( 14 )   PDF (6647KB) ( 272 )  

    We identify the property and distribution of main strike-slip fault belts of central Sichuan Basin according to the characteristics of associated structures in the gypsum-salt rock layers of the Lower-Middle Triassic Jialingjiang and Leikoupo Formations, as well as the dislocation position, direction and distance of carbonate platform margins in the Upper Sinian Dengying Formation. We find that large amounts of NW-trending en echelon folds and faults with dense distribution and left order arrangement are developed in the gypsum-salt rock layers. These en echelon faults and folds form two types of structural association with the deep (subsalt) strike-slip faults: one type is mainly developed in the Moxi area, where the en echelon structures situate right above the deep strike-slip faults; and the other type, with the en echelon structures distributed between the two strike-slip fault belts, is mainly developed in the slope area north of Moxi. According to the two structural types and the dislocation positions of the carbonate platform margins in the Dengying Formation, six main strike-slip fault belts are recognized in the central Sichuan Basin. Under the constraint of basin evolutionary frame, and based on the quantitative analysis of a representative growth structure between the Moxi and Gaoshiti areas, evolution of strike-slip faults in the central Sichuan Basin is divided into three stages, i.e., stages of (1) right-lateral strike-slip fault activity in the Late Ordovician-Silurian, (2) no fault activity from the Late Paleozoic to Triassic, and (3) left-lateral strike-slip activity since the Middle Jurassic. The carbonate platform margins of the Upper Sinian Dengying Formation in the central Sichuan Basin exhibit a regular step-by-step eastward dislocation with a distance of 20-40 km, which can be used as an indirect evidence for Caledonian right-lateral strike-slip activities. The central Sichuan Basin is located at the stable back-area of frontal uplifts in the northern upper Yangtze and Xuefeng foreland basins in the Late Triassic; however, due to rapid uplifts and differential evolution processes of orogenic belts around the Sichuan Basin, the central Sichuan area undergo compressional transformation and uplift since the Middle Jurassic, which triggers the strike-slip activities in the basement faults and early strike-slip faults.

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    Paleozoic paleogeographic reconstruction and evolution of the three continental blocks of central and western China
    YANG Fengli, XU Mingchen, ZHUANG Yuan, ZHAO Xixi, HU Yuyang, YANG Ruiqing
    2022, 29(6): 265-276. 
    DOI: 10.13745/j.esf.sf.2022.8.3

    Abstract ( 331 )   HTML ( 22 )   PDF (3832KB) ( 264 )  

    The Paleozoic paleogeographic position of the three continental blocks of central and western China—namely the North China, South China and Tarim blocks—in the global ocean-continent pattern has been under debate. Applying the latest research methods and ideas of paleogeographic reconstruction, along with the paleomagnetic measurements of Paleozoic cores (from the Ordos, Sichuan and Tarim basins in the study area), global Paleozoic paleomagnetic data, and constrains from major global geological events, this paper reconstructs and locates the paleogeographic position of the North China, South China and Tarim blocks using the GPlates software. The results indicate that the three continental blocks migrate mainly between the mid and low latitudes of ±30° during the Paleozoic and undergo at least three different clockwise rotations and azimuth conversions. And the migration rates of the three blocks oscillate at least three times between different high and low velocities. In response to the breakup and assembly of Paleozoic global oceans/supercontinents, the three continental blocks experience a series of crustal movements, including “archipelagic ocean” dispersion under ocean basin expansion, divergence/convergence coexistence under ocean basin subduction and collision, differential convergence/uplift under ocean basin subduction, differential divergence/convergence under transformation between old and new ocean basins, and differential divergence/convergence under the control of mantle plume. Obviously, the Paleozoic position of the three continental blocks of China in the global ocean-supercontinents pattern, along with differential tectonic settings, provide basic conditions for the formation and evolution of different types of basins or petroleum reservoirs of different strata and for the differential development of primitive reservoir materials within the three continental blocks.

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    Late Mesozoic continental arc migration in southern China and its effects on the evolution of offshore forearc basins
    ZHU Weilin, XU Xuhui, WANG Bin, CAO Qian, CHEN Chunfeng, GAO Shunli, FENG Kailong, FU Xiaowei
    2022, 29(6): 277-290. 
    DOI: 10.13745/j.esf.sf.2022.8.5

    Abstract ( 172 )   HTML ( 12 )   PDF (6595KB) ( 195 )  

    Forearc basins are closely linked to continental arcs in a subduction system. In southern China, widespread onshore magmatic belt and offshore forearc basins developed under multi-stage subduction since the Mesozoic. However, the arc migration pattern has been under hot debate, and the related forearc basins are little known because of limited offshore drilling and lack of access to onshore magmatic arc rock. Thus, new research designs are needed to observe the Late-Mesozoic subduction system/processes of southern China based on available data. In this paper, typical offshore wells containing Mesozoic layers are analyzed in detail; tectonics and sedimentation characteristics of offshore basins are systematically compared; and the development of forearc basins is analyzed in combination with the arc migration. Results show that the arc system extends roughly along the present-day coast of southern China from the Early Jurassic to Early Cretaceous: It mainly distributes in the southern East China Sea and extends to the northeastern South China Sea region in the Early Jurassic, then spreads widely southwards to the South China Sea in the Middle-Late Jurassic; since the Early Cretaceous it migrates eastward due to rollback of the subducted Paleo-Pacific slab. During this arc migration process, forearc basins are finally formed in the Middle Jurassic. And in response to the trenchward arc migration, angular unconformities in all forearc basins are formed and coarse clastic facies migrate trenchward in the Early Cretaceous. In the Late Cretaceous, the northern China Sea region is no longer in the subduction system and the forearc basin is replaced by regional unconformity; meanwhile, the East China Sea Basin becomes a backarc basin. Forearc basin evolution is primarily controlled by the migrating arc system, thus Mesozoic basins in the offshore South China Sea can provide important constraint on the regional arc migration pattern.

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    Tectonics of the Neoproterozoic basin and age of the Macaoyuan Group on the northern margin of the Yangtze Block
    LI Lushun, WANG Zecheng, XIAO Ancheng, HU Anping, CHEN Youzhi, Wang Qianqian
    2022, 29(6): 291-304. 
    DOI: 10.13745/j.esf.sf.2022.8.9

    Abstract ( 130 )   HTML ( 5 )   PDF (8175KB) ( 129 )  

    There are two key tectonic units—the Shennongjia uplift in the west and the Huangling uplift in the east—exposed in the Proterozoic in western Hubei and eastern Chongqing on the northern margin of the Yangtze Block, where prolonged sedimentation and extended deformation form the current Dabashan and East Sichuan thrust systems. In this paper, the regional Proterozoic deep basin framework is studied using comprehensive sedimentological and geophysical methods. Through the identification of rift fault boundary and internal basin tectonics, the topography of the Zhushan mountain of Nanchong in the west and the Yichang rift zone of Zhongxian in the east is revealed—they are considered to be the rift systems developed during the breakup of the Neoproterozoic Rodinia supercontinent, and separated by a rift block consisting of the Fenghuangshan anticline, Shennongjia uplift and Huangling uplift. Meanwhile, the chronology and sedimentology of the long-disputed Macaoyuan conglomerate on the south side of Shennongjia are studied by in-situ U-Pb isotope dating method. Dating of carbonate rocks yields ages of 759.2±17.6 Ma and 566.8±13.8 Ma, which confirms the Macaoyuan Group was filled in the Nanhua rift and formed on a depositional slope on the west side of the Zhongxian-Yichang rift. Subsequently, the sedimentary sequence of the Macaoyuan Group is established, and then the sedimentary filling framework of the Neoproterozoic rift basin in the northern Yangtze Plate is reconstructed by combining several sedimentary profiles across the rift belt and uplift.

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    Characteristics of a Cambrian normal fault system in the Southern Ordos Basin and its formation mechanism
    XIONG Weidong, XIAO Ancheng, WEI Guoqi, WU Lei, ZHANG Chunlin, WANG Yiping, YANG Liuyun, WANG Qianqian
    2022, 29(6): 305-313. 
    DOI: 10.13745/j.esf.sf.2022.8.11

    Abstract ( 104 )   HTML ( 12 )   PDF (5011KB) ( 139 )  

    The Early Paleozoic deep structures of the Ordos Basin are not well studied due to the complex tectonic superposition and great difficulty accessing the deep strata. Based on seismic data interpretation and field geological survey, we found a Cambrian normal fault system in the southern Ordos Basin made of a set of NE and nearly EW faults. Here, we present a detailed description and analysis of the plane and profile characteristics of this fault system, and combined with regional geological background,discuss the genesis of the fault system. Our results indicate that this fault system is formed by the inherited activities of preexisting Proterozoic NE-trending basement faults in the Cambrian. Meanwhile, small-scale EW-trending newly-generated faults are formed in some segments of the fault system. The discovery of this fault system may be of significance for understanding the evolution of the southern Ordos Basin in the Cambrian as well as for the regional hydrocarbon exploration.

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    Late Triassic diabase in the southwestern Ordos Block: Chronology, geochemistry and structural significance
    LUO Jinhai, CHANG Yinglei, CHEN Zhuo
    2022, 29(6): 314-324. 
    DOI: 10.13745/j.esf.sf.2022.8.10

    Abstract ( 175 )   HTML ( 12 )   PDF (3116KB) ( 138 )  

    A few of diabasic dikes intrude into limestone of the Middle Ordovician Majiagou Formation, Leijiagou Village, southwestern Ordos Basin. The diabase is enriched in HFSE (Nb, Ta, Ti, Zr, Hf, etc.) and geochemically similar to intraplate tholeiite, while geochemical evidence indicates the primitive magma experienced relatively strong crystallization differentiation. Zircon U-Pb dating by LA-ICP-MS yielded 206Pb/238U ages of 750-195 Ma for the diabase. According to the peak age combined with regional geological data, the formation age of the diabase is determined to be 224 Ma (Late Triassic). The diabase suggests an extensional structural setting like continental rift existed in the southwestern Ordos Block in the Late Triassic, while strong post-collisional extension of its western part probably strengthened the extensional structural setting. And relatively weak lithospheric stability—implied by the Late Triassic diabase—perhaps provided material basis for the subsequent igneous activities of the Early Jurassic-Early Cretaceous in the southwestern Ordos Block. The igneous activities of the Late Triassic and beyond increased the regional geothermal gradient and thermal evolution of hydrocarbon source rocks, potentially affecting the reservoir-forming environment of the southwestern Ordos Block.

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