Geological conditions of natural gas accumulation and new exploration areas in the Mesoproterozoic to Lower Paleozoic of Ordos Basin, NW China

Based on field outcrop investigation,interpretation and analysis of drilling and seismic data,and consulting on a large number of previous research results,the characteristics of ancient marine hydrocarbon source rocks,favorable reservoir facies belts,hydrocarbon migration direction and reservoir-forming law in the Ordos Basin have been studied from the viewpoints of North China Craton breakup and Qilian-Qinling oceanic basin opening and closing.Four main results are obtained:(1)Controlled by deep-water shelf-rift,there are three suites of source rocks in the Ordos Basin and its periphery:Mesoproterozoic,Lower Cambrian and Middle-Upper Ordovician.(2)Controlled by littoral environment,paleo-uplift and platform margin,four types of reservoirs are developed in the area:Mesoproterozoic-Lower Cambrian littoral shallow sea quartz sandstone,Middle-Upper Cambrian–Ordovician weathering crust and dolomitized reservoir,and Ordovician L-shape platform margin reef and beach bodies.(3)Reservoir-forming assemblages vary greatly in the study area,with"upper generation and lower storage"as the main pattern in the platform,followed by"self-generation and self-storage".There are both"upper generation and lower storage"and"self-generation and self-storage"in the platform margin zone.In addition,in the case of communication between deep-large faults and the Changchengian system paleo-rift trough,there may also exist a"lower generation and upper reservoir"combination between the platform and the margin.(4)There are four new exploration fields including Qingyang paleo-uplift pre-Carboniferous weathering crust,L-shape platform margin zone in southwestern margin of the basin,Ordovician subsalt assemblage in central and eastern parts of the basin,and Mesoproterozoic–Cambrian.Among them,pre-Carboniferous weathering crust and L-shape platform margin facies zone are more realistic replacement areas,and Ordovician subsalt assemblage and the Proterozoic-Cambrian have certain potential and are worth exploring.

Research Progress in the Petroleum and Natural Gas Geological Theory of China

The Chinese landmass, as a composite region, consists of multiple small continental blocks, such as Sino-Korea, Yangtze, Tarim, etc., and orogenic belts. Because of its distinctive tectono-sedimentary evolution, China＇s oil/gas-bearing regions differ remarkably from that elsewhere in the world. For instance, in comparison to the Middle East oil/gas-bearing regions which are characterized by Mesozoic-Cenozoic marine oil/gas-bearing beds, early oil and gas discoveries in China are distributed mainly in Mesozoic-Cenozoic continental sedimentary basins. Generation of oil from terrestrial organic matter, or terrestrial oil generation, and the formation of large oil/gas fields in continental sedimentary basins were previously the major characteristics of petroleum geology of China. However, in the past 20 years, a series of major oil and gas discoveries from marine strata have been made. Marine oil/gas fields in China are mainly distributed in the Tarim, Sichuan, and Ordos basins, which are tectonically stable and covered with Mesozoic-Cenozoic deposits. In these basins, hydrocarbon-bearing strata are of old age and the oil/gas fields are commonly deeply-buried. Cumulatively, 995 oil/gas fields have been found so far, making China the fourth largest oil-producing country and the sixth largest gas-producing country in the world. In terms of petroleum and natural gas geology, theories of hydrocarbon generation from continental strata, such as terrestrial oil generation and coal-generated hydrocarbons, etc., have been established. Significant progress has been made in research on the sequence stratigraphy of continental strata, formation mechanisms of ultra-deep clastic reservoirs, and hydrocarbon accumulation in the continental subtle reservoir. Regarding research on the marine petroleum geology of China, with respect to the major characteristics, such as deeply-buried reservoirs, old strata, and multiple phases of transformation, important advances have been made, in areas such as the multiple-elements of hydrocarbon supply, formation of reservoirs jointly controlled by deposition, tectonic activities, and diagenetic fluid-rock reactions, and oil/gas reservoirs formed through superimposed multi-stage hydrocarbon accumulation. As more and more unconventional hydrocarbon resources are discovered, unconventional oil and gas reservoirs are under study by Chinese petroleum geologists, who endeavor to come up with new discoveries on their formation mechanisms.

Effect of natural prolongation with geological features on maritime delimitation

The United Nations Convention on the Law of the Sea entitled the coastal States to naturally extend the continental shelf, which has caused more drastic disputes of maritime delimitation. This paper devotes to clarifying the significant concept of natural prolongation through an effect method combing the legal principles and technical analysis. Firstly, the classic samples with respect of the development of geological features are traced. Based on these samples, the classification with a model is proposed in order to affirm the concept＇s significance under certain geomorphologic situations. Lastly, scientific analysis is used to present two potential prolongation situations and emphasize that all the technical analysis on maritime delimitation should be complied with international law and protect the common interest of all the mankind.

Important Achievement and Advance of Natural Gas Geology and Geochemical Exploration in China

Academician Dai Jinxing has long been engaged in natural gas geology and geochemical researches,and has made prominent contributions to the establishment and development of China’s theory of coal-derived gas.He has opened up new areas of coal-derived gas exploration,natural gas formation theory and formation“ control conditions of large ” medium gas fields.

Geological Context and Statistical Assessment of the Impacts of Sugarloaf Twin Disasters, in Western Sierra Leone

In the event of natural disasters, Sierra Leone like any other country loses lives as well as properties and natural resources. Despite notable occurrences of small disasters in the country, only on August 14th sugarloaf landslide and the resulting flash flood (twin disasters) which affected Regent and other communities in 2017 have captured both national and international attention due to their alarming impacts. To obtain a better knowledge on the nature of the disasters, this research considered the geological context of the landslide and focused on statistical analysis of the impacts of the twin disasters using Statistical Package for Social Sciences (SPSS). Geological field-based approach and self-administered questionnaires of both closed and open-ended questions, personal interviews and observations were adopted as research techniques. Descriptive statistics and qualitative analysis were used to analyze the data of the research. Relevant literature from books, journals, and newspapers was also consulted, including Radio, Television discussions and the internet. Slope destabilization that caused the Landslide was linked to the geology of sub-surface formation (highly weathered olivine gabbro), lineaments and the rate of weathering. Study showed remarkable economic, social and political impacts as a consequence of the twin disasters. Study also revealed that families assisted the most in both financial and non-financial ways to the victims, and renowned misappropriation of donated disaster funds. All variables tested using student t-distribution and chi-square test of independence accepted the hypothesis. Information obtained from this work could be fundamental for policy makers and development practitioners (Osuteye & Leck, 2017).

Research on natural resources and environmental geology for urban sustainable development: a case study of Kunming

There exists synchronous growth in resources consumption and environment pollution in Kunming urbanization in recent years, which has led to the increasing pressure of urban sustainable development. Considering the environmental and social benefits in Kunming's water resources sustainable development, the authors provided a research finding the optimal urban population scale in different stages for urban water supply based on the sustainable development groundwater evaluating theoretical model. Through the research on the availability of construction site as well as the risk in underground space exploitation with the extenics theory method, we get a suitable partition map of land for urban construction and a risky partition map of underground space development. The results show that the appropriate population scale of Kunming will be less than 2.96×106 by 2020, and will reach (4.34--2.96)×106 optimized population scale after 2020 under the condition of economic-socially and environmentally sustainable development. It is significant to optimize urban construction land and use underground space under the condition of land resources sustainability in Kunming.

Planning and construction of Xiong’an New Area(city of over 5 million people):Contributions of China’s geologists and urban geology

China established Xiong’an New Area in Hebei Province in 2017,which is planned to accommodate about 5 million people,aiming to relieve Beijing City of the functions non-essential to its role as China’s capital and to expedite the coordinated development of the Beijing-Tianjin-Hebei region.From 2017 to 2021,the China Geological Survey(CGS)took the lead in multi-factor urban geological surveys involving space,resources,environments,and disasters according to the general requirements of“global vision,international standards,distinctive Chinese features,and future-oriented goals”in Xiong’an New Area,identifying the engineering geologic conditions and geologic environmental challenges of this area.The achievements also include a 3D engineering geological structure model for the whole area,along with“one city proper and five clusters”,insights into the ecology and the background endowment of natural resources like land,geothermal resources,groundwater,and wetland of the area before engineering construction,a comprehensive monitoring network of resources and environments in the area,and the“Transparent Xiong’an”geological information platform that is open,shared,dynamically updated,and three-dimensionally visualized.China’s geologists and urban geology have played a significant role in the urban planning and construction of Xiong’an New Area,providing whole-process geological solutions for urban planning,construction,operation and management.The future urban construction of Xiong’an New Area will necessitate the theoretical and technical support of earth system science(ESS)from various aspects,and the purpose is to enhance the resilience of the new type of city and to provide support for the green,low-carbon,and sustainable development of this area.

Imbalance Between Scientific Technology and Human Rights and Measures to Rectify the Imbalance——Taking Geological Disasters as an Example

I. Increase in Human Activity and Occurrence of Geological Disasters ＂A geological disaster is a natural disaster that happens in a geo- logical environment. It is a geological effect （phenomenon） caused or in- fluenced by Nature and （or） human factors that leads to losses to human life, property and the environment.TM Based on their cause, geological disasters can be divided into natural geological and artificial geological disasters. Natural geological disas- ters include those caused by natural effects. These include typhoons, rain- fall, melting snow and earthquakes,

Chemical kinetics evaluation and its application of natural gas generation derived from the Yacheng Formation in the deep-water area of the Qiongdongnan Basin,China

The natural gas generation process is simulated by heating source rocks of the Yacheng Formation, including the onshore-offshore mudstone and coal with kerogens of Type II2-III in the Qiongdongnan Basin. The aim is to quantify the natural gas generation from the Yacheng Formation and to evaluate the geological prediction and kinetic parameters using an optimization procedure based on the basin modeling of the shallow-water area. For this, the hydrocarbons produced have been grouped into four classes（C1, C2, C3 and C4-6）. The results show that the onset temperature of methane generation is predicted to occur at 110℃ during the thermal history of sediments since 5.3 Ma by using data extrapolation. The hydrocarbon potential for ethane, propane and heavy gaseous hydrocarbons（C4-6） is found to be almost exhausted at geological temperature of 200℃ when the transformation ratio（TR） is over 0.8, but for which methane is determined to be about 0.5 in the shallow-water area. In contrast, the end temperature of the methane generation in the deep-water area was over 300℃ with a TR over 0.8. It plays an important role in the natural gas exploration of the deep-water basin and other basins in the broad ocean areas of China. Therefore, the natural gas exploration for the deep-water area in the Qiongdongnan Basin shall first aim at the structural traps in the Ledong, Lingshui and Beijiao sags, and in the forward direction of the structure around the sags, and then gradually develop toward the non-structural trap in the deep-water area basin of the broad ocean areas of China.

Theory, technology and prospects of conventional and unconventional natural gas

The development of natural gas in China has entered a golden and leap-forward stage, which is a necessary bridge to clean energy. This in-depth study on the status quo, theory, technology and prospect of natural gas development shows:(1) The global remaining proven recoverable reserves of natural gas are 186×1012 m3, and the reserves-production ratio is 52.4, indicating a solid resource base for long-term and rapid development.(2) Ten formation and distribution laws of conventional and unconventional natural gas reservoirs have been proposed. In terms of exploration geology, the theory of conventional "monolithic" giant gas fields with different gas sources, and an unconventional gas accumulation theory with continuous distribution of "sweet areas" in different lithologic reservoirs have been established; in terms of development geology, a development theory of conventional structural gas reservoirs is oriented to "controlling water intrusion", while a development theory of unconventional gas is concentrated on man-made gas reservoirs.(3) With the geological resources(excluding hydrates) of 210×1012 m3 and the total proven rate of the resources less than 2% at present, the natural gas in China will see a constant increase in reserve and production; by 2030, the proven geological reserves of natural gas are expected to reach about(6 000-7 000)×108 m3, the production of conventional and unconventional natural gas each will reach about 1 000×108 m3, and the gas consumption will reach 5 500×108 m3. The dependence on imported natural gas may be 64% by 2030, and 70% by 2050.(4) Ten measures for future development of natural gas have been proposed, including strengthening exploration in large-scale resource areas, increasing the development benefits of unconventional gas, and enhancing the peak adjusting capacity of gas storage and scale construction of liquified natural gas.

Problems and Solutions of Velocity Modeling in Natural Gas Exploration

Recently, velocity prediction and modeling have been focus of the geophysical exploration in the high temperature and high pressure of the south China sea area, especially for new offshore exploratory areas. The error is large with great difficulty owing to fewer exploratory wells and misunderstanding. Firstly, on the basis of three typical velocity prediction and modeling examples in Ying-Qiong basin, it’s easy to put forward the corresponding not common but urgent problem in each instance, then combined with the velocity problem and misunderstanding to expand method discussion and solution, which include geological model to guide the velocity interpretation and analysis, the establishment of forward velocity of the auxiliary model explaining and constructing high precision velocity model. This research basically solves existing velocity problems in gas exploration of south China sea in recent years, and proposes corresponding solution and application, which is of great significance to the further exploration and productive practice.

Gas Geology of Chishui Depression and its Exploration Targets

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The dynamic analysis of natural environment change of nuclear test field in Lop Nur region of China

Using earth satellite observation means, remote sensing information distilled technique and regional research production, we have roundly analyzed and made an integrated evaluation about the Lop Nur nuclear test field in western China. This product reveals the rarely-known nuke explosion effect and response events of geology conditions. It also offers us legible and practical first-hand materials about human extreme effects, important engineering environment and intimidating influence process. By excavating and appraising the materials gradually on the natural environment factors changing in the test field through macroscopic elimination and typical filtration, it can supply basic scientific data for security of national nuclear usage, appraising the nuclear environment synthetically and developing nuclear strategy expediently.

“一核三赋能”自然资源行业复合型技能人才培养路径探索——以湖南工程职业技术学院环境地质工程专业群建设为例

在国家深化现代职业教育体系建设改革,产教融合持续推进的背景下,湖南工程职业技术学院环境地质工程专业教研室对自然资源行业复合型技能人才培养路径展开了研究,提出了以科研创新为核心力量,聚焦湖南自然资源产业绿色发展需求,构建了“一核三赋能”人才培养路径模型,实践证明具有较好的推广应用效果。

双井周期注CO_(2)联合降压法开采天然气水合物分析

相较于单纯地封存CO_(2),CO_(2)置换法开采天然气水合物(以下简称水合物)能够满足水合物资源开采和碳封存的双重需求。为确保安全高效开发水合物的同时提高CO_(2)封存率,按照双井周期注入CO_(2)联合降压法开采水合物的思路,以中国南海典型水合物藏为研究对象,建立了矿藏尺度水合物注采热—流—固—化四场耦合数值模型,并开展了连续、间歇、循环3类注入开采方案和单井降压开采方案的对比分析,然后模拟分析注CO_(2)辅助水合物降压开采的增产效果,最后对比了不同注入方案的CO_(2)回收和封存情况,探索了水合物法碳封存的可行性。研究结果表明:(1)邻井CO_(2)的注入有助于降低产水量并缓解降压开采引起的地质沉降;(2)间歇注入较循环注入可促进储层中CO_(2)水合物生成,扩大注入井附近的高温区域,有利于生产井附近水合物的分解;(3)连续注入方式有利于分解气体的产出,但双井注采模式降低了甲烷水合物分解程度;(4)双井注采的CO_(2)注入分为快速注入阶段、反转阶段和缓慢注入阶段,其中双井间歇注入方案的CO_(2)注入效率最高。结论认为,双井间歇注入CO_(2)复合降压法能够在安全、高效开采水合物的同时具有相对可观的碳封存效果,是一种实现水合物商业化开采和助力双碳目标实现的潜在方法,研究成果对于天然气水合物开发及CO_(2)地质封存具有理论指导意义。

地质联合基金资助成效分析及未来展望

中国地质调查局与国家自然科学基金委员会于2022年联合设立实施地质联合基金,以地球科学部“三深一系统”的顶层战略规划为纲,涉及深地、深海和地球系统等领域的基础研究,以及服务找矿突破、地质灾害与生态环境等领域的应用基础研究。2022~2023年度共资助项目59项,涉及大地构造演化及其资源能源效应项目39项,涉及表层地球系统研究,特别是地质灾害、水文地质与环境地质、地下空间等领域项目17项,涉及地质调查新技术新方法项目3项。资助项目中具有交叉属性的占比67%,反映了地质调查工作对综合技能要求的提升。地质联合基金实施两年以来,有关高校、科研院所、地勘单位等积极参与,有力推动了地质行业科技创新能力水平的提升,为地质事业的发展和科技创新注入了活力和动力。本文的系统总结为分析地质联合基金实施效果提供参考的同时,也对地质联合基金未来发展的方向和我国地质调查事业深度融合提出展望和建议。

美国典型富氦无机成因气田中氦气地质特征与聚集机制

美国广泛发育具有经济效益的富氦无机成因天然气田,如其中富氦氮气田甚至可以含有高达10%的氦。原地和周边地区的基底提供充足的氦源而氮气可来自不同圈层,且通常N_(2)/He(He>0.1%)在5~50之间。但是富氦氮气田在美国独特地质环境之外是否也有发现还需要进一步的研究。富氦二氧化碳气田中的氦主要也来自壳源且产量可观。科罗拉多高原上的富氦二氧化碳气田均被认为是来源于新生代晚期的岩浆活动,且该地区岩浆岩具有较高的U、Th含量。地下水溶气脱气-再溶解(Groundwater Gas Stripping and Re-dissolution,GGS-R)模型被普遍认为可以合理解释CO_(2)气藏中氮气、氦等惰性气体的聚集成藏机制。具体来说,幔源CO_(2)载体气充注时将溶解在地下水中的大气源惰性气体与壳源惰性气体脱出成藏,并与地下水达到水/气溶解平衡。虽然不同气田的平衡值各有不同,但是科罗拉多高原上的各气田均显示出相似的范围值,即在相应的储层压力和温度下为0~100 cm^(3)水/cm^(3)气。本文系统分析美国无机成因富氦气藏的氦气生成、运移和聚集机制,讨论氦气在经历氦源岩内游离相扩散初次运移后通过水溶相、气容相集流或是多相渗流方式进行的二次运移及由无机成因载体气N_(2)和CO_(2)共同参与的富集成藏机制,既可为我国氦气勘查提供理论认识依据,也可为二氧化碳地质评价和开发利用及安全封存提供参考。

复杂地层结构三维地质建模空间插值方法研究

三维地质体对于自然资源勘探、环境保护、自然灾害风险评估等领域都具有重要意义。在建模过程中,地质体的模型精度与插值算法有着直接关系。为研究不同插值算法的适用情况,文章对云南陆良某污染场地进行浅层三维地质建模,分别选取反距离权重法和自然邻域法,利用钻孔数据插值建模,并对模型结果进行目视检验和误差对比分析。研究结果表明:反距离权重法适用范围广,建模精度较高;相较于自然邻域法,反距离权重法更适用于地层结构复杂的三维地质建模,该方法对断层细节的描述更细致,模型更符合实际情况;而自然邻域法在断层明显的区域插值效果较差,不适用于地层结构复杂的情况。

Geological and Geophysical Conditions for Potential Natural Gas Hydrate Resources in Southern South China Sea Waters

The water depth in Nansha（南沙） waters,which is located in the southern South China Sea,varies from 200 to 2 500 m,with a deep-water（500 m） area of 500 000 km2.In this region,there are many depositional basins with various structural features,prone to the accumulation of organic material.The temperature and pressure conditions in the deep-water environment are suitable for the preservation of gas hydrate.At several sites,we have recognized bottom-simulating reflectors（BSRs） from seismic data.Regional geology analyses show that the Nansha waters may have abundant gas hy-drate prospects,especially in localities such as the Nansha trough and other deep-water basins of the central Nansha waters.

胶结坝在陕西普化水库工程中适应性研究

胶结坝技术具有就地取材造价低、施工简单工期短、漫顶不溃坝安全性高、减少弃渣环保好的优势。为确保普化水库胶结坝方案具有可靠的技术可行性和经济性,依据勘察设计资料结合设计方案优化过程,从大坝地形地质条件和天然建筑材料两方面进行适用性分析研究,并总结已建胶结坝工程特点。研究表明,胶结坝坝型对普化水库工程区的地形地质条件适应性强,坝体应力低,能够满足较软岩作为建基面的工程条件,设计过程要重点考虑库区料源和开挖料的可利用性。胶结坝在普化水库工程中应用是完全可行的,能够为工程建设带来良好的经济、环保、生态和社会效益。