In order to determine the shale oil resource potential of Da’anzhai Member, Jurassic Ziliujing Formation of Sichuan basin, the hydrocarbon generation potential, reservoir property, oil content, and shale oil mobility conditions were comprehensively evaluated by FE-SEM, CLSM, He-measured porosity and permeability, N2 adsorption, and rock pyrolysis experiments. The results show that the hydrocarbon generation potential is poor, reaching mature to high mature stage, and oil and gas coexist in the Da’anzhai Member. The intercalated limestone is dense. The inter-calite pore connectivity is poor. The foliation fracture, interlayer fracture, and calcite cleavage constitute the main occurrence space of shale oil. The oil content of foliated clay shale is good, and fracture development is the premise of shale oil mobility and high yield. Vertically, the fractures of the interbedded combination of shale and limestone are relatively developed, making it the preferred sweet spot for shale oil. Layered structures are conducive to the formation of bedding planes. Layered shale has exploration potential in areas with high levels of thermal evolution. Based on the organic matter abundance, oil property, and lithofacies combinations, it is proposed that the northern Yilong and southern Dazhou are favorable exploration areas for interlayer type shale oil. While the areas between Yilong and Dazhou are favorable exploration areas for pure shale type shale oil.

The Hexi area is the main emergency groundwater source for Xiangtan City, Hunan Province, ensuring the urban water supply safety demand. Identifying the spatio-temporal evolution process of water supply hydrochemical components under the long-term influence of climate change and human activities has important practical guiding significance for the local development and utilization of groundwater resources and pollution control. In order to quantitatively reveal the evolution processes of karst hydrochemistry under long-term controls of precipitation and human activities, as well as the spatio-temporal distribution and evolution patterns of hydrogeochemical characteristics in the karst areas of Southern China, this study applies multivariate statistical analysis, geostatistical analysis, hydrochemical methods，and Piper diagrams, Gibbs models, and major ion ratios to analyze the spatio-temporal variation patterns and influencing factors of karst hydrochemistry in the study area, based on national groundwater quality monitoring data (2002—2021). The results show that: The karst hydrochemistry in the study area exhibits horizontal zonation in space, which can be divided into Hydrochemical Zone Ⅰ and Hydrochemical Zone Ⅱ. Along the overall flow direction of karst water from Zone Ⅰ to Zone Ⅱ, the hydrochemical components show a “positive increase”. The concentration of karst water chemical components has shown a phased change on the annual time scale over the past 20 years, with the overall evolution process being “stationary-rising-declining-stationary”. The key time nodes are 2007, 2011, and 2017. The spatial differences in karst hydrochemistry are mainly influenced by human activities. On the one hand, agricultural non-point source pollution and urban domestic sewage enter the aquifer through surface infiltration, increasing the concentration of some components in Zone Ⅱ; On the other hand, artificial groundwater exploitation alters the local karst water flow field, causing hydrochemical components within the study area to exhibit “reverse change” characteristics along the overall flow direction of karst water. The evolution process of karst hydrochemistry on the annual time scale is influenced by changes in annual precipitation, and the influence time can be traced back to 2-3 years ago. This study comprehensively applied mathematical and chemical methods to quantitatively reveal the evolution process of karst hydrochemistry under the long-term control of precipitation conditions and human activities, which can provide reference for analyzing the spatio-temporal distribution and evolution law of hydrogeochemistry in karst areas of Southern China.

Due to the presence of obstacles in the observation site or the unique characteristics of the target object, it is not always possible to lay out survey lines for electrical resistivity tomography in a straight manner. In some cases, even the electrode array cannot be placed directly above the target body. As a result, there are limitations on the application of resistivity tomography method under certain site conditions. This paper focuses on studying 3D electrical resistivity tomography technology for restricted observation sites. The study begins by designing three electrode array observation systems specifically tailored for restricted observation sites: “□” shaped observation system, “U” shaped observation system, and “L” shaped observation system. Subsequently, we investigate the 3D inversion imaging method for determining resistivity using any type of observation system. Finally, we analyze the detection effectiveness of different observation systems through model testing and apply “□” shaped observation system to detect the base structure of an ancient tower in Zhejiang Province. Based on both geoelectric model detection results and the actual site conditions, all three special observation systems for 3D electrical resistivity tomography can effectively capture 3D electrical characteristics below the restricted observation site, thereby providing valuable references for analyzing anomalies within the target area. Among them, the “□” shaped observation system demonstrates the best imaging performance, followed by the “U” shaped observation system, while the “L” shaped observation system shows relatively weak performance. In practical applications, it is essential to consider site conditions and exploration objectives when selecting the electrode array geometry and the number of electrodes, in order to optimize the imaging results.

The Wudun depression belongs to an area with a low degree of exploration. The oil source conditions in the Lower Jurassic outcrop area are good, and the oil and gas show well in many wells drilled. However, the sequence stratigraphic framework of the basin, the sequence spatial evolution characteristics and sedimentary distribution rules are not clear, which restricts the later exploration deployment, which restricts the next exploration deployment. The research on the sequence stratigraphic division and regional sequence stratigraphic framework of  Middle and Lower Jurassic in Wudun depression is carried out by comprehensively applying the data of logging, seismic, core, and analysis data. At first, the spectrum-attribute-trend analysis of logging, time-frequency analysis, geochemical analysis and other methods are used to divide the sequence, and six third-order sequences and 28 fourth-order sequences are divided. Then, the matching wavelet decomposition and reconstruction method is used to improve the resolution of seismic data, and the seismic multi-attribute dimensionality reduction fusion technology and multi-scale matching with well-seismic joint are used for sequence analysis, and then the Jurassic sequence stratigraphic framework is established in this area. At the same time, the logging sequence division results and seismic multi-attribute fusion analysis results are cross-verified to clarify the spatial evolution characteristics of the sequence. At the same time, the logging sequence division results and seismic multi-attribute fusion analysis results are cross-verified to clarify the spatial evolution characteristics of the sequence. On the basis of high-precision sequence analysis, under the constraints of fine structural interpretation and sedimentary palaeogeomorphology, the distribution characteristics of sedimentary facies belts at key horizons are finally determined by using the results of sequence interpretation at different levels. A set of ideas and methods for the establishment of regional high-precision sequence stratigraphic framework and the study of sedimentary laws in areas of low exploration degree have been formed.

In order to reasonably determine the creep long-term strength σs of marble under the coupling effect of hydration freeze-thaw, uniaxial compression tests and uniaxial compression creep test were carried out with three solution environments of acid, medium and alkali and different freeze-thaw cycles as the experimental control factors in an open-pit slope in northwest Hubei Province. Then, the long-term strength of marble was compared and analyzed by combining transition creep method, isothermal stress-strain curve cluster method, steady-state creep rate stress relationship method, strength failure time relationship method, and two new methods (long-term strength prediction method based on stress-strain curve and improved steady-state creep rate stress relationship method). The results show as follows: 1) under the same number of freeze-thaw cycles, the instantaneous and long-term strength under acidic environment is the smallest, followed by alkaline environment, and the neutral environment is the largest. 2) By using transition creep method, isothermal stress-strain curve cluster method, steady-state creep rate stress relationship method, long-term strength prediction method based on stress-strain curve, and improved steady-state creep rate stress relationship method, the average long-term strength values of the marble under different solution environments and freeze-thaw cycles is 46.70, 41.21, 39.74, 43.92 and 43.67 MPa, respectively. 3) The long-term strength prediction method based on stress-strain curve does not require time-consuming creep test, and can quickly predict the long-term strength of rocks based solely on the stress-strain curve determined by compression tests. Compared with traditional methods, the improved steady-state creep rate stress relationship method eliminates the strong subjectivity of taking inflection points.

The prediction and evaluation of deep-sea polymetallic nodules have entered into the data science paradigm, and the deep mining and fusion of big data for ore prospecting and ore indication are seriously needed. Through analyzing the research progress of  deep-sea polymetallic nodules evaluation, and discussing the application of big data approaches in mineral resources evaluation, the big data mining and fusion techniques towards resources evaluation of  polymetallic nodules are explored, in which, the major research contents and methods like the knowledge pedigree analysis for polymetallic nodules resources, the metallogenic characteristics mining methods based on data science, the fusion and integration methods based on spatial decision-making model with big data, the comparison and verification of quantitative prediction and evaluation on polymetallic nodules resource, are proposed. It creatively analyzes  conventional/unconventional resources evaluating data and its correlation with ore deposits, and establishes the spatial decision-making model with geological constraint and big data. On this basis,  feature extraction and fusion of the information from multi-source heterogeneous data are achieved to supply the technology solution based on big data for deep-sea mineral resources evaluation. The research on big data mining and fusion techniques could improve the accuracy and efficiency of polymetallic nodules resources evaluating, and has important theoretical value and practical significance to the efficient use of deep-sea resource-environmental data, the exploration and evaluation of new polymetallic nodules mining area, and the prediction and evaluation of other deep-sea minerals.

The tectonics of the Nansha trough-Northwest Palawan is important for understanding the origin and evolution of the South China Sea (SCS). Based on the analysis of geological and geophysical data in the southern margin of SCS, we suggest that the very thin crust of the Nansha trough may not be the remnant of the Proto South China Sea (PSCS), but may be an abandoned spreading center. As a result of a compressional event after the formation of the SCS, the thrusting structures developed very late on the Nansha trough and were not related to the opening of the SCS. The comparison between the extrusion of the Nansha trough and the Pagasa wedge in Northwest Palawan shows that the time of compressional termination in the east is earlier than in the west in the southern margin of the SCS. The ophiolite in South and Central Palawan was the product of its southern northward thrusting, indicating that the PSCS may subduct from south to north. It is suggested that the Southern Palawan ophiolite may derive from the oceanic crust of Neo-Tethys and the Central Palawan ophiolite may come from the PSCS. The subducted remnants of oceanic crust in different periods were finally overthrusted onto the island arc system. The Palawan ophiolite is the result of a long-term thrusting from south to north, and the time of the final emplacement may be the Middle-Late Miocene.

The time-domain electrical source electromagnetic detection method is an effective and fast method for detecting mineral resources. The polarization effect can lead to rapid attenuation of the electromagnetic response and even a symbol reversal phenomenon. In this paper, the Cole-Cole model is used to describe the polarization effect, and arbitrary fractional Cole-Cole models are rationalized by using the integer order rational approximation algorithm. Yee’s grid is used to divide the simulation area, and the three-dimensional numerical simulation of induction-polarization effect of electrical sources is realized based on the finite difference time domain (FDTD) method. The electromagnetic responses of three typical models, namely uniform half-space model, polarized half-space model and three-dimensional polarized body model, are numerically simulated. The results show that the electromagnetic response of  uniform half-space model is basically consistent with the analytical solution, and the relative error is less than 10%, which proves the feasibility of the three-dimensional numerical simulation method. The electromagnetic responses of  polarized half-space model and three-dimensional polarized body model both have negative responses in the late stage, which is consistent with the polarization theoretical results. 

The isotopic composition of seafloor hydrothermal sulfides can not only trace their sources but also record the fluids and their precipitation processes. This article analyzes the isotopic compositions of metals (lead, rhenium, osmium, iron, copper, zinc), non-metal (sulfur), and rare gases in fluid inclusions of global seafloor hydrothermal sulfides, and explores the relationship between the isotopic compositions of metals, non-metal, and rare gases in sulfides. The results indicate that there is a negative correlation between sulfur isotopic composition and osmium, iron isotopic compositions, as well as between iron, lead, and helium isotopic compositions in seafloor hydrothermal sulfides. There is a positive correlation between osmium isotopic composition and iron isotopic composition, and between xenon isotopic composition and lead, osmium isotopic compositions. During the stage of magma degassing and material injecting fluid, sulfides are formed with the characteristics of low δ34SVCDT values (about 0‰) and high 3He/4He (>8 Ra), 40Ar/36Ar (>300), and 129Xe/132Xe (>0.99) ratios. In the stage of fluid-rock interaction, as lead-containing minerals in the rock continue to dissolve, i.e., the degree of fluid-rock interaction increases, the lead content of pyrite, chalcopyrite, and sphalerite precipitated in the fluid increases, accompanied by a slight decrease in the 206Pb/204Pb ratios. In the fluid-seawater mixing stage, with the increase of seawater influence degree, the Os content (about 0×10-9) in sulfides can sharply decreased, and the δ57Fe value (<-1.6‰), the 187Os/188Os ratio (>1)  significantly increases; With the enhancement of fluid-seawater mixing degree, the δ34SVCDT values of pyrite in sulfides will increase with a slight decrease in the 3He/4He, 40Ar/36Ar, and 129Xe/132Xe ratios in its fluid inclusions, while their 3He/4He ratios will decrease with a decrease in its 130Xe/132Xe ratios. The above indicates that by comprehensively analyzing the isotopic composition and content of metals, non-metal, and rare gases, and discussing their relationships, the effects of magma degassing, fluid-rock interaction, and fluid-seawater mixing on seafloor hydrothermal circulation can be revealed, and the degree of fluid-rock interaction and fluid-seawater mixing during sulfide precipitation can be understood.

Shale oil is currently a hot and difficult topic in unconventional oil and gas research. The analysis of the types and genesis of fine-grained sedimentary lithofacies is an effective way to study the “source and reservoir” characteristics of shale oil and predict its “sweet spot”. The fine-grained sediments of the Qingshankou Formation in the Songliao basin are widely developed and are effective intervals for shale oil enrichment. Based on four parameters, including organic matter abundance, mineral composition, lithology, and sedimentary structures, six kinds of lithofacies of fine-grained sedimentary rocks of the Qingshankou Formation in the Songliao basin are divided in this paper, as clay shale with high content of organic matter and mud-grade lamination(A), felsic shale with medium-high content of organic matter and fine silt-grade lamination(B), felsic shale with medium-low content of organic matter and coarse silt-grade lamination(C), layered siltstone with low content of organic matter(D), layered ostracoid limestone with low content of organic matter (E) and layered dolomite with low content of organic matter (F). Then, the genesis of different lithofacies types were discussed from the perspectives of hydrodynamics and organic matter enrichment, and corresponding sedimentary models were established. In the static and salty water environment below the base of storm waves with high lake productivity, planktonic algae and clay flocs are uniformly suspended and settled, forming organic-rich clay lamination and lithofacies A is deposited. In a relatively static and brackish water environment below the normal wave base (with local turbulence near the wave base) with high lake productivity, the fine silt particles brought by delta runoff and flood flow continue to move towward the center of the lake basin, forming a felsic lamination through uniform suspension and sedimentation, and a clay lamination is formed during the period of intermittent suspension and sedimentation, and lithofacies B is deposited. Below the normal wave base, the flood which carries silt-grade particles are transported to the outer front of delta along the underwater distributary channel, and enter the front delta in the form of stable turbidity current. As the flow velocity gradually decreases, it forms a coarse to fine silt lamination, clay lamination is formed during the period of intermittent suspension and sedimentation, and lithofacies C is deposited. Below the normal wave base, the early sediments of the delta front, under the action of paroxysmal turbidity currents, collapse into deeper water, forming lithofacies D and E. Between the normal wave base and storm wave base, lithofacies F is formed in saline water environment under a relatively dry climate.

This paper briefly reviewed the history of the discovery and research of dinosaur eggs in Laiyang, Shandong Province, China. Combining with the new discoveries in the Laiyang basin in recent years, the composition of the Laiyang dinosaur egg fauna was revised from 4 oofamilies, 5 oogenera and 11 oospecies to 6 oofamilies and progress on the dinosaur eggs, 10 oogenera and 12 oospecies, 1 oofamily indet. and 1 doubtful oospecies. Compared assemblages with other dinosaur egg faunas in China, the Laiyang dinosaur egg fauna is a typical representative of the Late Cretaceous dinosaur egg fauna with diverse egg types and distinctive assemblage characteristics. At the same time, this combination also well reflects the high diversity of dinosaurs in the Wangshi Group of the Jiaolai basin during the Late Cretaceous. Further study on it will provide detailed paleontological evidence for further discussion on the paleogeography and paleoenvironment of Laiyang area in the Late Cretaceous.

Surface nuclear magnetic resonance (SNMR) emerges as a non-invasive geophysical method with widespread applications in the qualitative and quantitative detection of groundwater. Its utility extends to resource exploration, geological disaster warning, and environmental monitoring. However, the practical implementation of this method encounters challenges as weak SNMR signals often contend with the pervasive noise in complex environments, hampering effective signal acquisition. In response to this issue, we propose a novel SNMR data noise suppression technique based on a differential structure. This method involves the strategic placement of two receiving coils equidistantly above and below the transmitting coil. This configuration can cancel out a significant portion of ambient noise and mitigates the effects of transceiver coil coupling in real time. Numerical experiments verify that the new method can achieve noise suppression and the reliable acquisition of free induction decay (FID) signals.

Geomagnetically induced currents (GIC) are currents induced in conductive materials on the Earth’s surface due to Earth’s magnetic field variations. GICs have the potential to cause severe damage to manufactured infrastructure, including power grids, oil and gas pipelines, and high-speed railways, resulting in adverse consequences such as power system failures, communication disruptions, and damage to electronic equipment, ultimately affecting the stability and functionality of these systems. The significance of studying GIC lies in understanding their generation mechanisms and influencing factors, thereby providing a scientific foundation for developing effective prevention and mitigation strategies. Based on an in-depth review of the progress in GIC research, this paper elaborates on the mechanisms of GIC generation and the influencing factors, encompassing the impacts of space weather, Earth’s environmental conditions, and the power system on GIC. It provides an overview of the current state of GIC research, offering integrated assessments from space physics, geophysics, and electrical engineering. Furthermore, the paper provides a detailed description of the steps involved in estimating GIC, including using geomagnetic field data and modeling, along with calculating electric fields and GIC within conductors. It emphasizes analyzing how various geophysical parameters affect GIC estimates and their interrelationships. In conclusion, the paper discusses the challenges in GIC research, highlights the potential contributions of geophysics in addressing related issues, and provides a perspective on the future of GIC research.

With the significant improvement of high-density acquisition and daily acquisition efficiency, the amount of exploration data is growing exponentially. In order to save storage space and improve transmission efficiency, the research on high-fidelity compression and reconstruction of prestack seismic data is extremely urgent. EZW (embedded zerotree wavelet) algorithm has excellent compression performance. The traditional EZW algorithm for seismic data compression is based on data in the t-x domain. Because the wavenumber of prestack seismic data is wide and the frequency band is limited, the energy of the discrete cosine transform (DCT) data is mainly concentrated in the low-frequency in the DCT domain. This paper proposes a frequency division seismic data compression technology. Firstly, 2D-DCT is performed on the t-x data, and then frequency division is applied to the 2D-DCT data to obtain high-frequency and low-frequency data. By separately coding high-frequency and low-frequency data based on EZW, the low-frequency data has a high coding level to ensure the signal-to-noise ratio (SNR) of the reconstructed data, and the high-frequency data has a low coding level to improve the data compression ratio (CR). The synthetic data and field data experiments show that the compression ratio with the proposed method is higher than that with the conventional EZW at the same SNR.

Peridynamic theory uses integral form of motion equations, which can effectively avoid the problem that the spatial partial derivative does not exist. It is widely used in simulating discontinuous problems such as crack propagation and fracture damage in different material models. However, there are few studies on wave propagation and dispersion characteristics in peridynamic theory model. In order to study the propagation law of waves in peridynamic theory model, in the case of plane stress, the equations of motion in integral form are established, and the wavefield numerical simulation of isotropic plate model and plate model with parallel cracks are carried out, and the wavefields of longitudinal and shear waves in the classical continuum theory are compared and analyzed. Based on motion equations of ordinary state-based peridynamic theory, the dispersion relations for 1D and 2D are derived in detail. The influences of peridynamic parameters such as the number of material point, the radius of the horizon and the shape parameter on the dispersion curves are comprehensively discussed. In wavefield numerical simulation, the wavefield numerical simulation results of the linear peridynamic solid (LPS) model and the linear elastic solid of the classical continuum theory are in good agreement. The existence of cracks in the model will cause reflection and diffraction of waves during propagation. In the analysis of dispersion characteristics, the dispersion characteristics of LPS model are more consistent with those of the classical continuum model when the  radius of the horizon is smaller and the  shape parameter is larger.

Geothermal energy exploitation and utilization are closely related to groundwater transport and the evolution of water environment. In this study, wereviewed the development status and typical mining technologies for the shallow geothermal energy stored in the soil and phreatic aquifers, median-to-high-temperature geothermal energy in deep aquifers, and high-temperature geothermal energy stored in the hot dry rocks for informational purposes of sustainable development and utilization of large-scale geothermal resources. In particular, the shallow geothermal energy can be classified into ground source heat pump and ground water heat pump according to the subsurface heat source; Median-to-high-temperature geothermal energy can be exploited mainly by direct mining, combination of production and injection and standing column well system; And high-temperature geothermal energy can be exploited using enhanced geothermal systems (EGS) through reservoir reconstruction technique such as hydraulic fracturing or chemical stimulation. Furthermore, the potential impact of geothermal energy exploitation on the groundwater resources was analyzed and summarized following the reported site cases, mainly focused on the cold and heat accumulation brought by heat pump technology, the decline of groundwater level caused by hydrothermal exploitation and the possibility of microseismic events or fracturing fluid leakage caused by hydraulic fracturing of hot dry rocks. In the end, the approaches were proposed to promote the sustainable development of geothermal resources and reduce the negative impacts on groundwater resources, including improving the recharge capacity, maintaining the water balance in the process of mining and irrigation, maintaining the heat exchange efficiency and the re-balance of underground heat, and adopting new materials. 

Abstract： To carry out engineering geological evaluation of hydraulic reclamation areas such as Chongming Dongtan, this paper aims at the change in shear strength of the underlying clayey soil layers in Chongming Dongtan. Considering different reclamation times, soil samples from boreholes in five different reclamation areas (within the 1949 cofferdam, 1949-1964, 1964-1976, 1976-1990, and 1990-1998) were selected for direct shear tests, and the variation of shear strength of soils in different periods and layers were analyzed.  Moreover, the microstructure of the soil samples was observed by scanning electron microscopy, and the change in shear strength was analyzed qualitatively and quantitatively from a microscopic perspective. The results revealed that: 1) The shear strength of the clayey layer varied as， the clay layer in the 1949-1964 reclamation zone had the largestshear strength, and the peak shear stress at 50, 100, 200, and 300 kPa is 33.31, 46.68, 102.10 and 147.15 kPa, respectively. Little difference in shear strength between boreholes in silty clay layer was observed under various levels of vertical pressure. From west to east, the shear strength indexes of the clay layer showed an opposite trend to that of the silty clay layer, in relation to the trend in natural water content. 2) From west to east, significant changes in the microstructure of the soil samples were observed. The soil microstructure in clay layer changed from a flocculent/aggregate to a matrix structure， and the soil microstructure in silty clay layer gradually transitioned from a skeletal/aggregate structure to a matrix structure and to a flocculent/aggregate structure. 3)  The average pore diameter of the particle was negatively related to the cohesion and positively related to internal friction angle. In addition, the average shape coefficient of the particle was positively related to the cohesion and negatively related to internal friction angle. This indicated that average pore diameter  and the average shape coefficient of the particles were directly related to the shear strength indexes of the soil.

Dayangshu basin is a Late Mesozoic residual basin with a low degree of exploration and research. It shows a good exploration prospect with the industrial oil flows obtained from several wells in recent years in the southern depression. A systematic understanding of the source rocks and the hydrocarbon origin of Jiufengshan Formation is still uncertain. Based on the geochemical analysis data of source rocks and crude oils, including TOC、Rock-Eval、GC-MS, and carbon isotope, the hydrocarbon generation potential of source rocks of Jiufengshan formation are evaluated, the properties of crude oils and oil source are studied. The results show that medium-good source rocks are developed in the first member (K1j1) and the third member(K1j3) of Jiufengshan Formation, with w（TOC） of 1.76% and 2.59%, w（ S1 + S2） of 4.44 mg/g and 7.36 mg/g, bitumen of 0.21% and 0.09% respectively. The organic matter type of the K1j1 is mainly type Ⅱ1 including some typeⅠ, K1j3 is mainly type Ⅱ1 including some typeⅡ2, and the vitrinite reflectance (Ro) of the source rocks in K1j1 is mainly 0.70% to 1.60%, at the mature to high mature evolution stage. Ro in K1j3 is mainly from 0.50% to 1.10% and at the mature evolution stage. The hydrocarbon generation threshold of the source rock is about 1 300 m, and the hydrocarbon generation peak is about 1 750 m. The source rock has the characteristics of early hydrocarbon generation. The crude oils are light to medium, characterized by high viscosity, high wax, low sulfur, and high saturated hydrocarbon. The crude oil enriches light carbon isotope with δ13Coil from -30.40‰ to -29.38‰, δ13C sat from -30.78‰ to -29.07‰, and δ13Caro from -29.73‰ to -27.91‰, which indicates the source of lacustrine algae. The main peaks of alkane in oil are nC19 and nC21, OEP is 1.07 to 1.08, and Pr / Ph is 0.83 to 1.10. The crude oil can be divided into two groups based on terpenoid steroid marker. Group one includes the crude oil of Wells YC1 and Y3, with relatively high tricyclic terpane, C30D, Ts/Tm, C29Ts/C29 hopane, sterane C27R/C29R, regular sterane / hopane, rearranged sterane / regular sterane, C2920S / 20 (S+R), C29ββ/(ββ++αα) and low β-carotene. Group two includes the crude oil of Well YX4 and Well Y6, with high β-carotene and relatively low sterane terpane ratios, indicating that the maturity of Well YC1 and Well Y3 oil is higher than that of Well YX4 and Well Y6, and there are slight differences in sedimentary environment and parent material source. The oil and rock correlation of biomarkers shows that the crude oil of Wells YC1 and Y3 mainly comes from the source rock of K1j1, and the crude oil of YX4 and Y6 wells mainly comes from the source rock of K1j3. The potential hydrocarbon accumulations in this area are source-reservoir integrated accumulations and lower source rocks generation-upward migration accumulations.

The Lower Cambrian black rock series in Ziyang, Shaanxi Province is rich in organic matter and metal elements (Ba, V, Cr, Ni, Mo, Au), while there is still a lack of understanding of its organic geochemical characteristics. Based on the experimental results of polarized electron microscope, morphology under scanning electron microscope, organic carbon (TOC) and saturated hydrocarbon gas chromatography-mass spectrometry(GC-MS)，the coupling relationship of organic matter and inorganic matter, organic matter source and maturity, sedimentary environment were discussed. The results show that the content of organic matter is high in the study area, and there are two kinds of occurrence modes, dispersed organic matter and aggregated organic matter. The relationship between dispersed organic matter and clay minerals is close. The average total organic carbon (TOC) content was 2.95%, affected by lithologic differences, pyrite content and types. All the samples were rich in n-alkanes, isoprenoids, steroids and terpenes. The distribution range of carbon number was from C14 to C34, which showed obvious bimodal distribution characteristics and no obvious odd-even advantage. Isoprenoid alkenes indications showed obvious phytoalkane advantage, with low value of Pr/nC17(0.36) and Ph/nC18 (0.50); The abundance of terpenoids was tricyclic terpane > pentacyclic terpane > tetracyclic terpane, a small amount of gamma wax, and the distribution of tricyclic terpane C21-C23-C24 is asymmetric inverted “V” with low average value of Tm/ Ts ratio(1.03); The distribution of regular steranes in steroids showed an asymmetric “V” distribution of C29>C27 > C28 with low average ratio of C27 rearranged steranes / C27 regular steranes(0.18) and pregnane/ C29-20r steranes(0.84). As indicated above, the origin of organic matter is mainly marine lower organisms (such as bacteria, algae, and microorganisms) and plankton, and a small amount of terrestrial lower plants are involved in the source of organic matter in some rocks (siliceous rocks); The organic matter of the whole rock has a high maturity, but it has not reached the stage of over maturity; The black rock series comes from the semi closed-closed alkaline seawater environment with anoxic reduction and low salinity.

Fan deltas are widely developed in Xin’ancun and Dalianhe Formation of Tangyuan fault depression. According to core observation, well logging, seismic, lithology identification and grain size analysis, three subfacies including fan-delta plain, fan-delta front and pro-fan delta and eight microfacies are identified. From fan-delta plain to fan-delta front, the sedimentary characteristics of different microfacies changes regularly. The sediment textures such as the supporting type change from matrix-support to grain-support, the contact relationships between grains change from points to surfaces, grain separation from bad to good, the maturity from low to high, and the size of sediments from coarse to fine. The sedimentary bedding structures are massive bedding being miscellaneous in gravels that developed in fan-delta plain, and small-scale cross bedding with low angle and wave bedding developed in fan-delta front. The cumulative relative frequency curves are one-step and two-step type with low angle in fan-delta plain, but are two-step with steep slope and three-step type in fan-delta front. In the C-M diagram, the point group of fan-delta plain mostly concentrates in PQ section with large C and M value, and fan-delta front mainly concentrates in QR and RS section. Based on these studies, and combined with core characteristics and grain size analysis, it can be concluded that hydrodynamic mechanism of fan delta in this area is mainly traction current deposit, but gravity flow also plays some action.

The carbonate reservoir evaluation based on well logging data of Russian logging series is done in Yurubcheno oil field in Siberian platform. On the basis of the conversional log characteristic analysis, evaluation parameters from the logging data are given for identification of the reservoir types, fractures, shale intervals of the formation and tight reservoirs in the carbonate reservoir with dual porosity. The reservoirs are classified into matrix type, micro fracture type and macro fracture type. The preferential directions of fractured reservoir distribution are NE-SW and NW-SE which are consistent with the distribution of carbonate and the structural high of the buried hill. It generally locates 0-100 m under unconformity which corresponds to the distribution direction of the dolomite corrosion zone, which controls the distribution of the high production wells. But the distribution of the fractured reservoir is heterogeneous and anisotropic in this field. Factors controlling the distribution of oil and gas in this field are the lithology of the reservoir and its structural location in the buried hill. The reservoir in Yurubcheno Formation, which is pure dolomite and has good location in the structure, has high oil and gas yield. There is poor oil and gas production in the reservoirs in Dolgoktinskaya Formation, where the lithology is not pure dolomite, and the Kuyumbinskaya Formation which located at a lower structural location.

According to the data of seismic, aeromagnetic, well drilling, etc, the authors restudy the characteristics of the fault system in Yitong basin, analyzes its evolution and the control effect on the hydrocarbon accumulation. Yitong basin is a strike-slip stretching basin which is controlled mostly by the strike-slip fault of the north-west boundary in Cenozoic. The features and evolution of the basin’s faults are very complex, the faults can be classified as three distinction based on their characteristics and sizes.The first distinction faults include the north-west boundary fault and the south-east boundary fault; the second distinction faults include the stretching faults such as Maanshan fault, number 2 fault, number 3 fault, number 4 fault and the thrust fault along the north-west edge; the third distinction faults include the rest faults of the basin. The faults’ evolution features in Yitong basin took place in the regional dynamic setting that back-arc spreading caused by westward subduction of the Pacific plate, and the collision from the Indian plate also played a partial role in the E-W compression in the East China. Besides this, the distribution and uplift strength of rigid plates of Daheishan and Nadanhadaling Mountain play a great role on the fault evolution. The fault evolution includes two stages: the early dextral strike-slip stretching stage and the dextral strike-slip compressing stage in basin’s reverse period. The dextral strike-slip compressing forms the fault-folds belt by the north-west edge and it has great potential for hydrocarbon exploration.