Introduction and MethodsTo identify the unconventional shale oil exploration potential of the third member of the Palaeogene Dongying Formation (Ed3) in the Nanpu Sag, Bohai Bay Basin, variations in paleoclimate and paleoenvironment and their influence on organic matter accumulation were investigated through analyzing mineralogical and geochemical characteristics of forty-nine mudstone samples.ResultsResults show that the Ed3 mudstones exhibit strong heterogeneity with the organic carbon content ranging from 0.30% to 2.66%, petroleum potential yield ranging from 0.44 to 11.41 mg/g, and hydrogen index ranging from 57 to 466 mg/g TOC, which are dominated by mixed kerogen and low maturity to maturity. Multiple mineralogical and geochemical proxies suggest that the semi-humid to semi-arid paleoclimate during the Ed3 period governed the fluctuations of paleoenvironmental elements. From bottom to top, the paleowater depth varied in an order of shallow water, deep water, and shallow water, respectively, and the corresponding paleosalinity of brackish water, fresh water, and brackish waterr, respectively. Water column evolved from weak oxidation to weak reduction, and then to weak oxidation, respectively. Two development models of the Ed3 mudstones under semi-humid to humid and semi-arid to arid climate were summarized based on the influence of paleoenvironmental elements on organic matter supply and preservation/degradation in sediments. Mudstones were deposited in a deep-water environment with high primary productivity under the semi-humid to humid climate. The mixed aquatic and terrigenous organic matte were efficiently preserved in stratified and reduced water columns, resulting in high organic matter accumulation. Nevertheless, mudstones were developed in a shallow-water environment with medium primary productivity under the semi-arid to arid climate. Here, aquatic organic matter was oxidized and degraded in the oxidation condition, leading to low organic matter accumulation.DiscussionThe exploration of unconventional shale oil in the Ed3 member of Nanpu Sag should focus on the organic-matter-rich mudstones developed in the humid climate.

In the northern part of the Songliao Basin, the Aonan Depression is a significant structural feature. It plays a crucial role in the relationship between tectonic evolution and deep natural gas accumulation mechanisms. While previous studies have revealed faulting and sedimentary characteristics in the region, the precise connection between tectonic evolution and hydrocarbon accumulation, particularly for deep natural gas, has not been systematically studied. This research uses structural modeling and stratigraphic restoration to reconstruct the tectonic evolution of the third section of the Shahezi Formation and develops a 3D geological model of the study area. The results show that the tectonic evolution of the Aonan Depression can be divided into three stages: rifting, sagging, and inversion. Each stage significantly controls hydrocarbon distribution. A self-sourced, self-storage gas system formed in the Shahezi Formation, while the Denglouku and Yingcheng formations exhibit a source–reservoir combination. The study reveals how tectonic evolution influences hydrocarbon accumulation and distribution on a regional scale. Based on these findings, a “rift-controlled source, sag-controlled storage, and structure-controlled trapping” accumulation model is proposed, providing new insights into tectonic evolution and hydrocarbon accumulation mechanisms, with important implications for similar basins’ exploration and structural studies.

Cement-based materials are essential components of engineered barrier systems in geological disposal facilities for both hazardous and radioactive waste. This review provides a comprehensive examination of the application of cement-based materials in various aspects of geological disposal. Specifically, it details the use of cement paste backfill for mine tailings, which has shown a reduction in permeability by 95 %, and cementitious grouts for ground stabilization, achieving a compressive strength increase of 20 %. Shotcrete applications for rock support demonstrate enhanced adhesion properties, with a 30 % improvement in bond strength. Cementitious matrices for low- and intermediate-level waste immobilization have been optimized to reduce leachability by 40 %. Concrete containers for high-level waste and spent fuel are discussed, highlighting their ability to maintain structural integrity under high radiation and thermal loads for over 100 years. Cement-based seals for repository closure are also examined, with a focus on their self-sealing properties and long-term durability. The long-term performance of these engineered barriers is influenced by deterioration processes such as physical, chemical, and biological degradation. This review discusses optimization strategies, including the development of alternative binder systems that reduce CO₂ emissions by 30 %, the incorporation of nanoengineered cements that enhance mechanical properties by 25 %, the use of smart additives that provide real-time monitoring capabilities, and the creation of multifunctional composites that combine strength and self-healing properties. Future research directions are highlighted, emphasizing the need for advanced predictive models, innovative material formulations, and integrated monitoring technologies to ensure the long-term safety and performance of geological disposal systems.

The North China Craton（NCC） experienced pervasive lithospheric thinning in the Early Cretaceous, but the thinning process and thinning mechanism are still controversial. To shine a new light on the thinning events this paper focuses on the Beidashan Pluton of Liaoning Province, eastern NCC to conduct detailed field geological survey, combined with laboratory research including petrographical, geochemical, U-Pb zircon chronological and Lu-Hf isotopic analyses, so as to explore the formation age, source area and petrogenesis of the Beidashan pluton. The lithology of the Beidashan pluton is porphyritic biotite monzogranite which has a weighted mean age of 117.1±1.4 Ma by zircon U-Pb dating. The quasi peraluminous porphyritic biotite monzogranite is rich in silicon（69.15%-69.87%） and alkali（8.46%-8.66%） and poor in magnesium（0.80%-0.90%） and calcium（2.03%-2.04%）, and is enriched in large ion lithophile elements（LILEs）（Rb, Th, K, Ba） and depleted in high field strength elements（HFSEs）（Nb, Ta, Ti）. The rare earth element（REE） pattern is right-leaning, showing a steep linear slope for light REE（LREE） and flattening of heavy REE（HREE）. The zircon saturation temperature of granite melt（763.14-768.87℃） is clearly lower than that of A-type granite（＞ 800 ℃）. The above characteristics generally represent high-k, calc-alkaline I-type granitoids. Zircon ε Hf （t） values range from-21.49 to-19.04, and the two-stage Hf model ages(t DM2 ) range between 2536-2383 Ma, indicating the monzogranite is mainly derived from partial melting of Paleproterozoic ancient basaltic crust. According to the chronological and petrogeochemical analyses, the Beidashan pluton was formed under regional extensional environment caused by slab roll-back of the paleo-Pacific plate during the Early Cretaceous, and the upwelling asthenosphere caused large-scale delamination of the deep lithosphere of the North China Craton resulting in lithospheric thinning.

Fracture characteristics at bedrock reservoirs in the Kunbei fault terrace belt in the southwest of Qaidam Basin, China, are investigated based on cores, thin sections, formation microscanner imaging, and production data. Results show that the weathered unit at the top of bedrocks is not an effective reservoir because of extremely low porosity. A semi-weathered unit is a potential reservoir, where formation water migrating along early effective fractures could form dissolution fractures and pores as primary storage space, and fractures can also act as seepage channels. Four fracture types can be identified from bedrock reservoirs, e.g., structural ones, diagenetic ones, weathering ones, and dissolution ones, while shear fractures related to faults are the most important ones. Fracture types and characteristics are different in granite and slate, e.g., high fracture density results in intensive dissolution in granite. Fracture density is closely related to tectonic stress. The bedrock reservoirs near fault zones and semi-weathered units are potential oil and gas exploration targets in the Kunbei fault terrace belt. Effective fractures govern dissolution behaviors as well as dominant seepage directions, which play a significant role in the development of bedrock reservoirs.

为研究低温氮吸附实验条件下脱气时间对中煤阶煤孔隙结构测试结果的影响,对北宿矿的气煤进行了低温氮吸附实验研究.实验设计脱气温度为120℃,时间为1.0、1.5、2.0、2.5、3.0 h.结果 表明:比较不同脱气时间下,孔隙结构、孔容、吸附量等的变化情况,在脱气温度120℃时,北宿矿煤样最佳的脱气时间为2.0 h.脱气温度在120℃时,水分对北宿矿煤样孔隙结构起到决定性作用,孔隙结构复杂情况是从复杂到简单,简单到复杂的来回交替发生.北宿矿煤样的孔隙主要集中在8～15 nm,出现2个峰,有2个最可几孔径,分别在7～8 nm和12～15 nm,前者大于后者.

Early Cretaceous granitic rocks are widely distributed in the Great Xing’an Range, northeast China. However, their precise age and tectonic evolution remain controversial. This study presents new zircon U–Pb, Lu–Hf, and whole-rock geochemical data for the granitic plutons in the Yili area, Xing’an Massif, northern Great Xing’an Range. The aim of this study was to decipher the tectono-thermal history and obtain further understanding of the geodynamic setting of the large-scale Late Mesozoic magmatism in the Great Xing’an Range. Zircon U–Pb age dating indicated that the plutons were emplaced during the Early Cretaceous, with ages of 132.2–130.1 Ma. The plutons showed similar geochemical features, characterized by high concentrations of SiO2 and Na2O + K2O and low concentrations of P2O5, CaO, MgO, and TFe2O3. The plutons were enriched in light rare earth elements and large ion lithophile elements and depleted in heavy earth elements and high-field-strength elements. Such features indicate that the plutons are highly fractionated with I-type granite affinity. These findings, combined with pluton ε Hf(t) values of + 5.25 to + 8.28 and two-stage model ages (t DM2) of 661–855 Ma, indicate that the primary magmas originated from partial melting of juvenile basaltic crustal material accreted during the Neoproterozoic. These results combined with regional geological evolution indicated that the generation of Early Cretaceous plutons in the northern Great Xing’an Range might be closely related to the post-collisional gravitational collapse and subsequent extension resulting from the closure of the Mongolia-Okhotsk Ocean. Their generation also superimposed the back-arc extension resulting from retraction of the Paleo-Pacific subduction plate.

Carbon dioxide (CO2) flooding is an effective method to enhance oil recovery in low-permeability reservoirs. Studying key geological factors controlling oil displacement efficiency is of great significance to the CO2 injection scheme design in low-permeability reservoirs. Focusing on low-permeable H reservoir in Songliao Basin, China, this paper describes the contact and connection of sand bodies, natural fractures and high-permeability zones with core samples, log data and experiment firstly. After that, the impact of interaction of sand body connection, natural fracture and high-permeability zone on oil displacement efficiency is determined by using geological and dynamic data in CO2 injection area. Results indicate that the connection of single sand bodies between injectors and producters wells primarily controls CO2 flooding in low-permeability reservoirs. Furthermore, coupling of sand body connection, natural fractures and high-permeability zones is the key geological factor governing oil displacement efficiency of CO2 injection in low-permeability reservoirs, where well or generally-connected sand bodies can improve the efficiency significantly. Meanwhile, the dominant seepage channels in other directions have no influence on producers, which is beneficial to improve CO2 flooding efficiency.

本文对大兴安岭北段宜里地区二长花岗岩进行了系统的地球化学及锆石U-Pb同位素年代学研究,旨在查明其成岩时代及岩石成因,并探讨其构造意义.宜里地区二长花岗岩中的锆石均呈半自形—自形,振荡生长环带明显,暗示其岩浆成因.锆石LA-ICP-MS U-Pb同位素定年结果显示,宜里地区二长花岗岩形成于175. 8～174. 5 Ma,为早侏罗世岩浆事件的产物.岩石具有富硅(SiO2=71. 23%～74. 52%)、富碱更富钾( Na2O+K2O=6. 31%～8. 31%,K2O=2. 58%～4. 78%)、贫镁(MgO=0. 43%～1. 50%)、贫钙(CaO=0. 91%～1. 81%)的特征,铝饱和指数( A/CNK=0. 97～1. 16),属于准铝质—弱过铝质高钾钙碱性花岗岩.富集Rb、Th、K等大离子亲石元素,相对亏损Nb、Ta等高场强元素和P、Ti等元素,轻重稀土元素分馏较强(La/Yb)N=14. 07～50. 34,无明显Eu异常(δEu=0. 88～1. 71).花岗岩熔体的锆石饱和温度(714～745℃)明显低于A型花岗岩(＞800℃),显示出高分异I型花岗岩的特征.岩石学及地球化学特征表明,宜里地区二长花岗岩的形成与俯冲形成的上涌热流加热新增生下地壳发生部分熔融有关.结合区域构造演化及构造判别,认为研究区早侏罗世二长花岗岩形成于蒙古—鄂霍茨克大洋板片南向俯冲作用相关的活动大陆边缘环境.

Carbon dioxide (CO 2 ) flooding is an effective method to enhance oil recovery in low-permeability reservoirs. Studying key geological factors controlling oil displacement efficiency is of great significance to the CO 2 injection scheme design in low-permeability reservoirs. Focusing on low-permeable H reservoir in Songliao Basin, China, this paper describes the contact and connection of sand bodies, natural fractures and high-permeability zones with core samples, log data and experiment firstly. After that, the impact of interaction of sand body connection, natural fracture and high-permeability zone on oil displacement efficiency is determined by using geological and dynamic data in CO 2 injection area. Results indicate that the connection of single sand bodies between injectors and producters wells primarily controls CO 2 flooding in low-permeability reservoirs. Furthermore, coupling of sand body connection, natural fractures and high-permeability zones is the key geological factor governing oil displacement efficiency of CO 2 injection in low-permeability reservoirs, where well or generally-connected sand bodies can improve the efficiency significantly. Meanwhile, the dominant seepage channels in other directions have no influence on producers, which is beneficial to improve CO 2 flooding efficiency. Keywords Low-permeability reservoir , carbon dioxide , sand body connection , natural fracture , high-permeability zone

石头梅矿区是三塘湖煤田的重要组成部分,储量巨大、成煤条件良好.从矿区地质条件看,中新生代以来构造运动相对平静,地层基本以水平状展布,倾斜角度变化不大,水文地质条件简单.矿区煤炭资源以储层浅、层数多,厚度大,含水少、灰分低、挥发分高、热值高,硫、磷、氟、砷等有害元素含量低为特征.主要煤种为优质不粘煤和长焰煤,局部层位煤岩含油量偏高,近地浅表层煤腐植酸含量高.基于其资源特征和区域地质、地理、气候条件,经过深入的野外勘察、现场调研和资料分析,针对矿区严重缺水,而风能、太阳能异常丰富的特点,提出实施"节水低碳绿色多元长链"的绿色矿山建设方案,为石头梅露天矿的可持续发展奠定基础.

Natural fractures play an important role in the seepage system of Paleogene sandstone reservoirs at Nanpu Sag. Characteristics and formation mechanisms of natural fractures and stress-sensitivity permeability are comprehensively investigated and their impact on water injection is discussed based on core and log data (FMI and diplog data) as well as stress-sensitivity permeability measurement. Results show that high-angle shear fractures, including NE-SW strike fractures and NW-SE strike fractures, are widely developed in the study area, which were primarily developed during the late Paleogene and late Neogene. The present maximum horizontal principal stress is orientated at N60°–80°E, approximately parallel to the NE-SW fractures, contributing greatly to the seepage system at the early oilfield development stage. Fractures in the study area can be divided into three phases and are characterized by obvious stress-sensitivity permeability, which is closely related to fracture aperture and throat size. Since the fracture occurrence enhances stress sensitivity of permeability, it is necessary to regulate well pattern based on dynamic behaviors of fractured reservoirs at different development stages.

班公湖-怒江洋晚期的构造演化存在诸多争议.以在西藏日土东新发现的高镁流纹质岩石为研究对象,开展了年代学、地球化学等方面的研究.LA-ICP-MS锆石U-Pb测得样品113.69±0.82 Ma(MSWD=2.7)的谐和年龄,证明其为早白垩世晚期岩浆活动的产物.岩石地球化学分析显示,样品具有富硅(70.27％～75.72％)、高镁(3.50％～4.12％)、高Mg#(82.68～84.79)等特征.稀土元素呈现富集轻稀土、相对亏损重稀土(LaN/YbN=7.00～9.34),存在较为明显的Eu负异常(δEu=0.50～0.65);富集Th、U,亏损Ba、Sr、P和Ti等元素,微弱的Nb、Ta亏损.在构造环境判别图解上,样品落于陆缘弧区域,表明其形成于大洋岩石圈俯冲的构造背景.研究结果为沙木罗组海相地层的厘定提供了确切的同位素年龄,同时也为探讨班公湖-怒江洋白垩纪时期的构造演化提供了新的依据.

The solar radiation or insolation at a specific locality on the Earth's surface is determined by the distance of this point from the sun and by the angle with which the radiation hits the earth's surface. The theory that variations in the earth's orbit determine the amount of radiation and therefore the climate which is the Milankovitch Cycle. In non‐marine lacustrine rift basin, the changes of climate can be recorded by the palaeontology, and it also plays an important role in controlling lacustrine fluctuations. The lacustrine fluctuations are indicated by coastal onlap, which is the landward or lake‐ward onlap of non‐marine coastal deposits. In this paper, based on borehole data, wireline logs, seismic datasets, biostratigraphic data and palaeontology, the lacustrine fluctuation curve can be reconstructed from the onlap of lacustrine deposits in non‐marine sequences. The durations and magnitudes of these changes can be used to construct charts showing cycles of the relative rising and falling of lake level. In addition, the changes of lake level can also be reflected by the palaeontology such as pollen. The living conditions and distributions of pollen can be a good indicator for climate changes and lacustrine fluctuations in an a non‐marine setting. The calculation of the Milankovitch Cycle can be determined by the GR log in the study area which keeps a record of cycle changes. All climatic changes and lacustrine fluctuations are mainly resulted from the Milankovitch Cycles, and therefore, through the reconstruction of lacustrine fluctuations, climate changes and the Milankovitch Cycle, the correspondences among them can be clearly addressed. All the results can contribute a lot in theory research in the study area and lead to a new focus in practical hydrocarbon exploration and exploitation.

Tangbei Area, a complex syn-depositional fault development area, is located in petroliferous Bohai Bay Basin with abundant petroleum resources in the Paleogene. The way to figure out possible migration pathways and potential accumulation accommodation controlled by syn-depositional faults has become a key issue for predicting favorable reservoirs. Based on seismic volume and wireline logs, we carried out fine seismic interpretation, document the faults and their combinations in plane view and section view, and reveal its influence on hydrocarbon migration and accumulation. The results indicate that fine seismic interpretation in the study area provides the distribution and characteristics of syn-depositional faults generated by regional tectonic activities. In addition, syn-depositional faults play an important influence on basin structure and the pathways and traps for hydrocarbon migration and accumulation. Three types of syn-depositional faults are divided based on their locations. It is found that syn-depositional faults in steep slope zone are much favorable for hydrocarbon migration and accumulation. Syn-depositional faults in different depositional periods throughout basin evolution act as pathways for hydrocarbon migration, as well as act as seals, which depend on surrounding lithology associations and sealing or leaking properties through time.

为了探讨西藏南部江孜一带侏罗系/白垩系界线时期海洋沉积环境的变化,本研究对采自藏南江孜甲不拉沟剖面的样品进行了常量、微量和稀土元素分析.Fe2O3+MgO与TiO2、Al2O3/SiO2关系判别图显示,从晚侏罗世维美组到早白垩世甲不拉组,研究区构造运动相对平静,基本上以大洋岛弧的构造演化为主,继承性明显.Mn、Fe、V、Co、Ni、REE等指标元素和U/Th、V/Cr、Sr/Ba、Lan/Ybn、V/(V+Ni)等比值结合显示,沉积条件从维关组浅海富氧、高盐、高沉积速率的环境演化为早白垩世甲不拉组深海、水体分层、沉积速率降低、具有明显深海沉积特征的环境.地化数据分析结果总体上与岩性成因分析相一致,即从维美组砂岩的浅海相沉积到甲不拉组下部的粉砂岩和上部的钙质泥岩、黑色页岩,水体经历了由浅到深的变化过程.

稀土是重要的战略资源,海洋是稀土矿产重要的赋存场所.以国家自然科学基金委员会首次南海科考表层沉积物样品为研究对象,利用扫描X射线荧光光谱仪、电感耦合等离子体质谱仪等开展了地球化学分析,重点探讨了南海表层沉积物中稀土元素的分布特征及其影响因素.数据显示,南海不同海域表层沉积物中稀土元素的含量差别较大,25个站位中含量超过边缘海平均含量的有13个,超过大陆沉积物平均含量的有14个,最高含量为593.30×10-6.纵向上,稀土元素含量有随沉积物厚度加深而增大的变化趋势.结合之前对南海多金属结核和结壳是稀土元素富集情况的研究,认为随着勘探工作的深入开展,有望发现具有开采价值的稀土资源远景区域.

In this study, we picked 45 samples with different depth (larger than 400 m) from the Niutitang Formation in Chongqing area, South China. The mineral compositions and the geochemical properties (maturity) of these shale samples were characterized by using the X-Ray diffraction and Rock eval, respectively. Then, the properties of these samples (the porosity and the permeability) were measured and the pore size distributions were derived using the mercury intrusion data. The results showed that quartz and clay minerals (most illite) are the two major mineral compositions. The total carbon content (TOC) of the Niutitang shale samples from the studied well is no more than 1% and the maturity value of these shale samples is very high, indicating that the organic matter now is in the gas production window. The ink-bottle shape and slit shape pores are widely spread in these shale samples. No correlations can be found between porosity and permeability values. The fractal dimension D-f1 shows that the burial depth does not have big influence on the pore size distributions of shale samples but the fractal dimension D-f2 indicates that the burial depth could affect the heterogeneity of pore geometry. The methane adsorption capacity value of Niutitang shale samples is around 1.14-2.6 m(3)/t, which is close to the value of Longmaxi shale.

The seismic merging dataset, wireline logs, core photographs, thin sections, and other geological information were employed to investigate sequence architecture and reveal depositional evolution of Enping Formation in Lufeng Depression, Pearl River Mouth Basin. The results showed that one second‐order sequence and four third‐order sequences were identified based on the unconformities along basin margin/slope and correlative conformities in the basin centre. In addition, several associated sedimentary facies or microfacies (including braided channel deposits, subaqueous distributary channel deposits, beach‐bar deposits, and so on) that were recognized within sequence stratigraphic framework and depositional evolution were revealed by well tie–seismic correlations with seismic attributes extracted from the stratal slicing in terms of sand sections/units in Enping Formation. It was characterized by progradational process from seismic attributes in general that the delta deposits gradually retrograded. Through comprehensive analysis, it can be concluded that episodic tectonic movements and subsequent uplift played an important role in controlling sequence architecture. Sediment supply and lacustrine level fluctuations derived from accommodation space changes exerted an essential effect on depositional evolution. This study provides new and robust insights into understanding the sequence architecture, depositional evolution, and hydrocarbon exploration in Enping Formation. In addition to the significance for academia, study of sequence architecture and depositional evolution are of great importance for hosting potential hydrocarbon reserves, because they are frequently related to important and potential reservoirs. Consequently, investigating sequence architecture and depositional evolution are significant economically as well.