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Characteristics of Life Evolution Stages and Reservoir Control in the Development of Extensional Faults in the Dongying Sag
, Available online  , doi: 10.12090/j.issn.1006-6616.2023147
Abstract (14) PDF (3106KB)(4)
The formation process of fractures from scratch has multiple evolutionary stages, such as recessive and dominant. It is very difficult to identify the growth stages of fractures from the embryonic stage of the recessive stage to the old age at the end of the dominant stage. In order to solve this problem , This paper takes the Dongying Sag of the Bohai Bay Basin as the research object, and uses physical simulation, numerical simulation and other methods to reproduce the evolution process of the entire life stage from embryonic stage to old age of the basin-controlling boundary fault Chennan Fault and the inherent characteristics of each stage; On this basis, qualitatively and quantitatively determine the relative age of the main faults in the Dongying Sag and the fault activity patterns at each age stage, and establish a reservoir control model; The research results show that the transtensional faults in the Dongying Sag can be divided into embryonic stage (RA (Relative Age) = (0-1], micro cracks or induced crack zones), juvenile stage (RA = (1-2], fault core formation , the crack surfaces are intermittently connected), the youth stage (RA=(2-3], the plate-shaped main section is connected and the fault distance is clear), the prime stage (RA=(3-4], the fracture zones are formed on both sides of the fault core, and the plate There are six stages: the old stage (RA=(4-5], slope-flat section, complex derived structures), and the extinction stage (RA=(5-6], the fault stops moving or reverses). stage; The activity mode of a fault is closely related to its age, duration and activity intensity. If a fault remains highly active, the fault will enter the old age stage; research on the storage control effect shows that: embryonic stage, juvenile stage Faults mainly control traps, faults in the youth stage mainly control sand and reservoirs, and faults in the prime and old stages control the entire life-stage process of oil and gas generation, transportation, accumulation, and dispersion. The accumulation control ability of the Chennan Fault is evaluated as "strong" based on comprehensive advantages of reservoir control factors, oil and gas enrichment degree, oil and gas enrichment scale and other factors. Re-understanding the ability of faults to control reservoirs from the development and evolution stages of fault life will effectively promote and improve the theoretical research on fault reservoir control and the level of mature exploration areas.
Diagenesis of the Ediacaran Deng 2 Member microbial dolomite reservoir in the Penglai area of the Sichuan Basin: Insights into the formation and evolution of high-quality reservoirs
, Available online  , doi: 10.12090/j.issn.1006-6616.2024062
Abstract (15) PDF (3522KB)(2)
[Objective] The microbial dolomite of the second member of the Dengying Formation (Deng 2 Member) in the Penglai area of the Sichuan Basin are widely distributed and are considered potential targets for deep carbonate oil and gas exploration. Unlike conventional high-quality reservoirs characterized by porosity and karst fractures, the carbonate rocks of the Deng 2 Member mainly consist of microbial dolomite. The genesis and diagenetic evolution of these high-quality reservoirs remain unclear. [Methods] This study, based on field outcrops and core samples, employs petrographic thin sections, scanning electron microscopy (SEM), cathodoluminescence, and CT scanning to conduct a detailed analysis of the microbial dolomite reservoirs in the Dengying Formation. The aim is to gain a deeper understanding of the effects of diagenesis on pore formation and the development of high-quality reservoirs. [Results and Conclusion] The results indicate that the microbial carbonate reservoirs in the study area are characterized by low porosity and very low permeability, predominantly consisting of fracture-porosity (cavity) type microbial dolomite. The reservoir space is primarily composed of intergranular dissolution pores, residual framework dissolution pores, intragranular dissolution pores, and small to medium-sized dissolution cavities, with minor occurrences of intercrystalline pores and intercrystalline dissolution pores. The Deng 2 Member has undergone multiple diagenetic processes, with penecontemporaneous dissolution and early epigenetic dissolution being key factors in enhancing porosity. [Significance] These findings enhance the understanding of the genesis of high-quality microbial carbonate reservoirs in the Ediacaran System of the Sichuan Basin and provide valuable information for deep oil and gas exploration and development in the region.
Difference of crustal stress direction in the south section of Huayingshan fault zone in Sichuan basin: Insights from In-Situ Borehole Image Logging
, Available online  , doi: 10.12090/j.issn.1006-6616.2023109
Abstract (12) PDF (5174KB)(2)
The Huayingshan Fault Zone, as the largest fault zone in the Sichuan Basin, has a great difference in structural phenomena and geological structures on both sides, which disturbs the crustal stress field of the basin. In order to better understand the direction of crustal stress in the crust of Huayingshan fault zone, and improve the understanding of crustal deformation, tectonic activity and seismicity in tectonically active regions. On the basis of collecting and organizing data from 8 boreholes in the southern section of the Huayingshan Fault Zone, combined with modern tectonic stress field in China and seismic focal mechanism solution data from the southeastern edge of the Sichuan Basin, comprehensive analysis was conducted on the data results of borehole breakouts and drilling-induced tension fractures obtained from imaging logging. The results show that the orientation of the maximum horizontal principal stress (SH) of most boreholes in the southern section of the Huayingshan Fault is NWW-SEE, which is consistent with the direction of the regional stress field in the Sichuan Basin. Among them, the maximum horizontal principal stress (SH) of one borehole is NEE-SWW. The orientation of the maximum horizontal principal stress (SH) of all boreholes in the central region of the southern section is NEE-SWW, which deviates counterclockwise from the stress field in the Sichuan Basin region. The stress deflection is mainly influenced by the comprehensive effects of changes in the basement properties of the Huayingshan Fault Zone, tectonic stress and regional stress field.
, Available online  , doi: 10.12090/j.issn.1006-6616.2023087
Abstract (14) PDF (2386KB)(4)
Since the collision and compression of the Indo-European continental plates caused uplift and intra-land deformation of the Qinghai-Tibetan Plateau, as well as lateral escape and rotation of the Sichuan-Yunnan rhombic massif, a large number of paleomagnetic studies have been conducted on the rotation of the central and western parts of the Sichuan-Yunnan rhombic block, but the rotation of its eastern part is relatively absent. Since fluvial geomorphology is very sensitive to the rotation of the massif, this study extracted 22 basins in the eastern part of the Laoying Shan of the Sichuan-Yunnan rhombus using a 30 m resolution digital elevation model (DEM), and determined the rotation and uplift in the Laoying Mountains by analysing four geomorphological parameters, including local topographic relief ratio, river longitudinal profile, river steepness index and basin azimuth. The results show that the amount of uplift in the Laoying Shan area since the Late Miocene is around 350 m. The uplift trend is high in the north and low in the south; the overall distribution of the river steepness index values decreases from north to south, with the high values mainly in the northern part of the Laoying Shan area and the low values mainly in the top of the Laoying Shan area and the southern part of the Laoying Shan area. The results of the basin azimuth also indicate that the rotation of the Laoying Shan area is about 15° counterclockwise. The analysis shows that since the Late Miocene, the west of the Yuanmou Fault in the Sichuan-Yunnan block has been less influenced by strike-slip faults and mainly rotated clockwise, while the east of the Yuanmou Fault has been influenced by strike-slip faults, and counterclockwise rotation with differential uplift has occurred.
, Available online  , doi: 10.12090/j.issn.1006-6616.2023093
Abstract (15) PDF (3308KB)(7)
Monsoon climate is formed by the seasonal reversal of wind direction and precipitation caused by the difference of heat capacity between the mainland and the ocean. Asia is the region with the most typical monsoon climate in the world, and also has the largest population affected by monsoon climate. Heavy monsoon rainfall is easy to induce a variety of secondary disasters, which seriously influences the security of human production and living in the region. Therefore, it is important to understand the formation process of the Asian monsoon. Based on the theory of compare the past to the present, this paper aims to expound the components of Asian monsoon, list the main factors affecting the formation and evolution of Asian monsoon, and summarize the research progress of South Asian monsoon and East Asian monsoon as shown in the sedimentary records of key locations in Asia. The results show that in the Paleogene, the Indian plate collided with the southern margin of the Asian continent and changed the distribution of sea and land in Asia, resulting in the initial uplift of the Tibetan Plateau and the monsoon climate in both South Asia and East Asia. However, at this time, the Asian continent was still mainly controlled by the planetary wind system, and the Asian monsoon was in the gestation and formation stage, and distributed locally in strips in the southern margin of the Asian continent. By contrast, with the overall uplifting of the Tibetan Plateau in the Miocene and approaching its present altitude, the Asian monsoon entered the development stage of strengthening, which strongly affected the geological evolution process in the region. Since the Middle Miocene, controlled by the uplifting of the Tibetan Plateau and the development of the Arctic and Antarctic ice caps, the Asian monsoon has experienced several stages of stable development. This provides a reference for scientific and rational use of it in the study of Asian system earth science. In longitudinal time, the development process of South Asian monsoon and East Asian monsoon is similar, both of which mainly experienced the gestation stage of Paleogene, the strengthening stage of Neogene and the stable development stage of Quaternary. In the horizontal spatial distribution, the development of South Asian monsoon and East Asian monsoon is synchronized, and the factors controlling its development are consistent.
Formation and evolution of the Yuncheng Salt Lake and source of the saline ions
, Available online  , doi: 10.12090/j.issn.1006-6616.2024003
Abstract (31) PDF (4974KB)(6)
The Yuncheng Salt Lake, nestled in the Fen-Wei graben system's heart, stands as not only China's but also the world's earliest known salt lake. Despite its historic significance, fundamental geological background of the lake remains underexplored, with a lack of consensus among researchers. This study delves into three pivotal aspects: the process of geomorphic change in Cenozoic era and the formation of Fen-Wei graben system, the Yellow River's historic course through the Sanmenxia Gorge and the resultant disappearance of the ancient Sanmen Lake, and the Fenhe River's diversion from the Yuncheng Basin and the birth of the Yuncheng Salt Lake. Our findings suggest that evolution of the lake began in the Paleogene to mid-Neogene period, influenced by the coastal Pacific domain and the Tibetan Plateau. Around 700, 000 years ago, a significant geological shift occurred: the Yellow River breached the Sanmenxia Gorge, flowing eastward to the sea. This event marked the end of the ancient Sanmen Lake and the formation of Yuncheng Salt Lake. Approximately 70, 000 years ago, during the middle Late Pleistocene, the Fenhe River rerouted, leaving the Yuncheng Basin. This change transformed the lake from an open to a closed system, solidifying its current form. The ongoing tectonic activity along the northern fringes of the Zhongtiao Mountains further sculpted the landscape, creating sedimentary depressions that amassed saline minerals, eventually giving rise to a natural salt lake through prolonged cycles of precipitation and evaporation. Salt of the lake primarily originates from deep subterranean salt formations. The primary fault controlling the lake acts as the main conduit for these salts, while the marine high magnesium dolomite from the Longjiayuan Formation in the northern edge of Zhongtiao Mountain supplies magnesium ions. These research will offer a crucial geological foundation for the ecological preservation and sustainable development of Yuncheng.
, Available online  , doi: 10.12090/j.issn.1006-6616.2023196
Abstract (21) PDF (1395KB)(4)
Rock core disking is one of the typical phenomena in high in-situ stress environment. The geometric characteristics and section shape of rock discing are related to the state of in-situ stress, and the site where this phenomenon occurs may not be suitable for in-situ stress measurement. Based on this phenomenon, the relationship between in-situ measurement data and in-situ stress of disked rock cores is established, and in-situ stress estimation is carried out to complement the in-situ stress measurement data. Based on the relevant hypotheses and theories at home and abroad, the physical and geometric characteristics of the disked rock cores are measured, and the stress state of the original rock is combined with the stress magnitude estimation formula based on the core discing. The in-situ stress of the 30~120m position of disked rock cores in Dandong, Liaoning Province was estimated. 73 representative disked rock cores were selected to estimate the in-situ stress magnitude of the section, and the measured data of hydraulic fracturing were supplemented. The supplemented in-situ stress data were more close to the reality. Compared with other estimation formulas based on core discing, the factors taken into account are more comprehensive, the measurement accuracy requirements are lower, and the calculation results are less biased and fluctuate. The results of calculation and comparison show that this method is suitable to be used as a supplementary source of in-situ stress data.
, Available online  , doi: 10.12090/j.issn.1006-6616.2023097
Abstract (43) PDF (3540KB)(9)
Hanjia gully debris flow is located on the left bank of the Fujiang River, Fenghe Village, Xiaohe Town, Songpan County. Debris flow has occurred frequently in recent years, with the largest debris flow occurring in August 2022, seriously threatening the life and property safety of villagers in Hanjia gully. By means of remote sensing interpretation, field investigation and FLO-2D numerical simulation, the characteristics of Hanjia gully debris flow and its current situation of prevention and control engineering were investigated. The existing prevention and control engineering could not meet the requirements, and an improved prevention and control engineering was proposed. The hazard of debris flow with different rainfall frequencies and with or without prevention and control engineering was calculated by FLO-2D simulation. Thus, the effectiveness of improved prevention and control engineering is verified. The results show that Hanjia gully is located in the "8.8" Jiuzhai Valley earthquake disturbance area, and the debris flow source is rich after the earthquake, which leads to frequent debris flow during the heavy rainfall every year. Fenghe Village and Pingsong Highway are in the low hazard zone under the frequency of rainfall once in 10 years. The existing prevention and control engineering can effectively prevent and control debris flow disasters. Under the frequency of rainfall once in 50 years, Fenghe Village is in the high hazard zone of debris flow, debris flow out of the drainage channel, washed away Pingsong Highway, the existing prevention and control engineering can not meet the requirements. After adopting the improved control engineering such as multi-stage blocking dam and cutting and bending of drainage channel, the volume of debris flow accumulation is reduced by 50.2 % and the accumulation area is reduced by 86 %. The high hazard zones are all located in the drainage channel, and the governance effect is remarkable.
Risk assessment of geological hazards in the mountainous and hilly areas of western Zhengzhou City
, Available online  , doi: 10.12090/j.issn.1006-6616.2022116
Abstract (73) PDF (3945KB)(9)
The mountainous and hilly areas in the western part of Zhengzhou have a complex geological environment, and geological hazards such as collapses, landslides, and debris flows occur frequently, in particular, the “7•20” extreme rainstorm in 2021 caused a large number of geological hazards. In the past, a single method was mainly used to evaluate the risk of geological hazards, and there were problems such as slightly low evaluation accuracy. Through the research and analysis of the geological environment background, geological disaster distribution characteristics and formation conditions in the study area, 8 evaluations are selected: slope, landform, engineering geological rock group, elevation, distance from fault, distance from river, rainfall and human engineering activities factors, and the weighted information method was used to evaluate the risk of geological hazards in the study area. The results show that: the area of low-risk area is 1387.14 km2, accounting for 32.59% of the total area; the area of medium-risk area is 1803.18 km2, accounting for 42.36% of the total area; the area of high-risk area is 1066.47 km2, accounting for 25.05% of the total area, The actual situation is basically the same, and the evaluation accuracy is 93.11%. The evaluation results can provide an important basis for the prevention and control of geological hazards in the study area.
Analysis of soaking deformation characteristics of large-thickness discontinuous collapsible loess
, Available online  , doi: 10.12090/j.issn.1006-6616.2023174
Abstract (69) PDF (1515KB)(3)
[Objective] The widely distributed discontinuous loess stratum in the Guan zhong Plain area of China necessitates, due to its unique stratigraphic structure, the indoor calculated value of the self-weight wetting amount in evaluating the wetting property of the foundation has a large difference with the measured value in the field. [Methods] Therefore, taking the loess stratum on the north bank of Wei he River as the research object, indoor wetting test and on-site large-scale test pit immersion test were carried out to compare the influencing factors of the difference between on-site and indoor wetting amount. [Results] The following results were obtained from the study: (1) The ratio of self-weight wet depressions between the field test and the indoor test at the site was less than 0.1, and the reasons for this discrepancy include the discontinuity and inhomogeneity of loess layers, the sampling disturbance factor of the indoor test, and the difference in immersion conditions of the field test. (2) The layer bow effect formed by the discontinuity of loess is the main reason for the difference between the indoor test and the field test. It weakened part of the upward transmitted deformation, hindered the downward transmitted gravity stress, and caused the discontinuity of the percolation process. (3) Combining the results of the stratification calculations of the four test sites, it can be seen that most of the self-gravitational wetting in the field test occurred in the Q3 soil layer. For the Q2 loess, there is a large difference between the field measured values and the indoor test values. Therefore, the Q2 loess layer is considered to have little or no wetting. [Conclusion] The shape of the saturated zone range obtained by numerical simulation is basically consistent with the field test results, and the numerical simulation method is more advantageous when observing the experimental results. When calculating the amount of wet subsidence by self-weight, the calculation method of stratification according to the age of strata can be adopted. In Q3 stratum, the method of correction coefficient in the specification is selected, and the Q2 loess stratum is determined by on-site test pit immersion test. [Significance] The research methodology of this paper can provide theoretical guidance for future engineering construction in the Guan zhong Plain.
Characteristics of Karstification and Groundwater Enrichment in Laiwu Basin
, Available online  , doi: 10.12090/j.issn.1006-6616.2023166
Abstract (79) PDF (1610KB)(7)
 Hydrogeological survey and karst spring survey provide basic hydrogeological data for this paper. In this paper, Characteristics of karstification and groundwater enrichment were researched in Laiwu Basin through research methods of data collection, field geological survey, hydrogeological drilling and rock and mineral testing. Results show that carbonate strata are concentrated in the southern part of Laiwu basin with monoclinal structure controlling by geological structure, which scatters in the northern and eastern region sporadically. Karst development is affected by many factors such as formation lithology, geological structure, groundwater dynamic conditions and magma intrusion. The principal surface karst features are grike and karst valley. In addition, principal underground karst features are dominated by dissolution fissure and dissolution hole within 400m depth. Karst groundwater is mainly concentrated in fault basin, hanging wall, groundwater pressure discharge area and anticlinal flank of mine. This paper can provide scientific and technical support for the exploitation and utilization of groundwater resources in the water-scarce mountainous areas of central and southern Shandong Province.
Research on the Spatial Structure Characteristics and Formation Mechanism of the Deda Ancient Landslide Based on Microtremor Survey Method in Sichuan Province, China
, Available online  , doi: 10.12090/j.issn.1006-6616.2023183
Abstract (75) PDF (4139KB)(7)
The topography and geological structure of the eastern Tibetan Plateau are extremely complex. The high development density and intricate spatial structures of large ancient landslides in alpine canyon areas, such as those in the Jinsha River Basin. The hazards resulting from the creep deformation and resurgence of these ancient landslides are particularly severe. The Deda ancient landslide, situated in Deda Township, Batang County, Sichuan Province, is a significant ancient landslide influenced by the Chalong-ranbu fault activity. The spatial structural characteristics of this ancient landslide are complex, with localized resurgence deformation observed at the landslide front. This study employs various methods, including remote sensing interpretation, on-site investigations, Microtremor Survey Method (MSM), and engineering geological drilling, to further elucidate the spatial structural characteristics of the Deda ancient landslide. The research reveals that the Deda ancient landslide can be divided into three parts in plan view: Deda I landslide (I), Deda II landslide (II), and the rear wall of the Deda ancient landslide (Ⅲ). Through MSM combined with drilling verification, the study proposes a scheme for classifying the shear wave velocities of shallow and deep sliding zones, with a relative error in sliding zone depth identification generally ranging from 2.6% to 4.8%. The research uncovers that Deda I landslide features two sliding zones, with a burial depth of 18.7-20.1 m for the shallow sliding zone (S1) and 36.2-49.9 m for the deep sliding zone (S2). And the volume of Deda I landslide is approximately 8.7-12.0×106 m3. Deda II landslide has one sliding zone, with a burial depth ranging from 25.2 to 38.6 m and a landslide volume of approximately 6.3-9.6×106 m3. A comprehensive analysis suggests that the formation of the Deda ancient landslide is the result of various factors, including fault structures, rainfall infiltration, and river erosion. The complex landslide structure and its genesis are identified as the primary controlling factors for the landslide being in a state of creep deformation. The research methods and insights presented in this study can serve as a reference for the spatial identification and risk prevention of large ancient landslides in the eastern Tibetan Plateau.
, Available online  , doi: 10.12090/j.issn.1006-6616.2023168
Abstract (87) PDF (956KB)(5)
Tectono-thermal history is not only important to understand basin evolution and its geodynamic mechanism, but also the key question to be solved for source rock maturation study. With the increasing energy demand and difficulty in oil and gas discovery on land, sea basin has gradually become an important replacement area for oil and gas exploration and a hotspot of the national energy strategy research. Qinnan Depression is on northwest of the Bohai Sea area, with good exploration prospects but low exploration degree. In this study, 25 artificial wells have been established based on 3 seismic profiles in the Qinnan Depression, and then their tectonic subsidence history and thermal history has been modeled to reconstruct the tectonic-thermal evolution history of this depression. The results indicate that since the Cenozoic era, the Qinnan Depression has undergone three stages of rifting and stretching during the sedimentary periods of the Kongdian Formation to fourth member of the Shahejie Formation (65-42 Ma), the third member of the Shahejie Formation (42-38 Ma), and the third member of the Dongying Formation (32.8-30.3 Ma), with a total stretching factor of 1.27~2.05. Corresponding to the three stages of stretching, the basal heat flow of the Qinnan Depression has experienced three stages of increase, reaching a peak of 64.0~89.0 mW/m2 at the end of the deposition of the third member of the Dongying Formation (~30.3 Ma), and then decreased gradually until present. There is a good coupling relationship between the tectonic-thermal evolution process and fault activity in the Qinnan Depression, and multiple stages of heating are conducive to the mature and hydrocarbon generation of its source rocks.
Landslide Displacement Prediction Based On EEMD-CNN-LSTM Model
, Available online  , doi: 10.12090/j.issn.1006-6616.2023145
Abstract (348) PDF (1892KB)(31)
The prediction of landslide displacement is an important part of landslide monitoring. Although time series methods based on deep learning paradigms have achieved some success in predicting landslide displacement, the non-stationary, periodic, and trending characteristics of landslide displacement data make it prone to overfitting in current time series models. In this paper, we propose a landslide displacement prediction model based on the combination of Isolation Forest (IF) anomaly detection, Ensemble Empirical Mode Decomposition (EEMD), Convolutional Neural Networks(CNN), and Long Short-Term Memory (LSTM) neural network, which addresses the volatility of landslide displacement data and the characteristics of displacement composed of periodic and trending components. The Baijiabao landslide in the Three Gorges Reservoir area, which is affected by rainfall, is selected as the research object. The IF algorithm is used to detect anomalies in the original landslide displacement data. The trend and periodic components of the landslide displacement are extracted based on the EEMD method, and the overall displacement is predicted using the LSTM model. The accuracy of the prediction is evaluated using four indicators: RMSE, MAE, MAPE, and R2. The results show that the proposed EEMD-CNN-LSTM model is superior to traditional LSTM models, random forest methods and EEMD-LSTM methods under both external influences of rainfall and without rainfall, which can greatly reduce overfitting and improve the accuracy of prediction.
Fracture network complexity of tight sandstone and its influencing factors
, Available online  , doi: 10.12090/j.issn.1006-6616.2023128
Abstract (201) PDF (1766KB)(13)
The fracture network complexity analysis of tight sandstone plays an important role in hydraulic fracturing optimization, fracture network prediction and fracture modeling. Based on the experimental study on the dynamic evolution process and main controlling factors of complex fracture network in sandstone, the complexity analysis of fracture network is carried out by deeply discussing the fractal and multifractal spectrum characteristics of fracture network. The results show that the initiation and propagation of cracks run through the whole process of stress-strain, and the complexity of fracture network is mainly controlled by its own microscopic fabric characteristics, and has obvious scale and confining pressure effects. The fractal dimension of the three-dimensional fracture network and the average spectral width of the multifractal spectrum can represent the complexity and heterogeneity of the spatial distribution of the fracture network, respectively. The higher the content of quartz, feldspar and other brittle minerals in sandstone, the larger the porosity and the smaller the particle size, the more complex the spatial distribution of fracture network and the weaker the heterogeneity. Clay minerals are not conducive to the formation of complex fractures. The larger the compressive strength and elastic modulus, the more complex the spatial distribution of the fracture network and the weaker the heterogeneity.