30 June 2023, Volume 46 Issue 2

    

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The Study of Geothermal Geology and Hydro-environmental Geology
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  Research on time-frequency electromagnetic method detection of deep karst thermal reservoir and prediction of favorable area in Dongli Lake of Tianjin

  CHENG Zhengpu, LEI Ming, LI Shu, LIAN Sheng, WEI Qiang

  North China Geology. 2023, 46(2): 1-8. https://doi.org/10.19948/j.12-1471/P.2023.02.01

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  Tianjin is abundant in geothermal resources. As the main geothermal reservoir, Wumishan Formation of Jixian System is a typical carbonate reservoir. In order to find out the stratigraphic structure and concealed faults within 5 km of Dongli Lake in Tianjin, focus on the spatial distribution and structural characteristics of the main deep thermal reservoirs, and predict the favorable geothermal areas, the author first applied the timefrequency electromagnetic method, which is mainly used for deep oil and gas exploration, to the deep geothermal resources exploration of Dongli Lake, through high-standard data acquisition, fine data processing and resistivity inversion. Seismic and borehole data are used to calibrate the horizon and finely depict the stratigraphic structure. Seven concealed faults are inferred, all of which are NNE and NWW tensional normal faults. Cangdong Fault (F1) as the necessary channel of the main thermal fluid in the area, conducts heat, stores heat and controls the distribution and shape of geothermal anomaly areas; The thermal reservoir of Wumishan Formation is mainly distributed on the west side of Cangdong fault, the buried depth of the top interface is about -2200 ~ -2400m, and the resistivity profile shows a continuous increasing A-type electrical characteristics. When the karst fissures in the third and fourth sections are relatively developed, the accumulation of hot water in the fissures or faults causes local low resistivity anomalies and H-type electrical characteristics. It indicates the development position of the favorable geothermal area in the target depth, and four favorable geothermal areas are delineated in this paper, which provides important basic data and support for the subsequent development and utilization of geothermal resources.
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  The characteristics of the main ion components of geothermal fluid and geothermal origin analysis in Tianjin

  WANG Bing, ZONG Zhenhai, XIA Yubo, ZHANG Fenna, JIA Zhi

  North China Geology. 2023, 46(2): 9-16. https://doi.org/10.19948/j.12-1471/P.2023.02.02

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  Tianjin contains abundant low-temperature geothermal resources. The exploration and utilization of geothermal resources has a long history. After years of exploration and utilization, rich exploration results have been achieved. Based on the study of geological structure and hydrochemistry characteristics of geothermal fluid in main thermal reservoirs in Tianjin, this paper took a large number of geochemical data as the research object, and selected characteristic ions and mineralization degree of geothermal fluid in main thermal reservoirs to conduct R-cluster analysis and correlation analysis. It showed K+ in fractured reservoir is generally higher than that in porous reservoir, and the correlation between K⁺ and mineralization degree is low; Na+ and Ca²⁺ are positively correlated with mineralization degree, and the correlations were high; Cl^- and SO₄^2- of geothermal fluid in fractured reservoir were higher than those in porous reservoir, and they were positively correlated with mineralization degree; HCO₃^- had little correlation with mineralization degree. It used element proportional coefficient method to analysis hydrochemistry characteristics of geothermal fluid in Tianjin. It showed the bedrock geothermal system was relatively closed, which was conductive to the formation and preservation of geothermal fluid; the geothermal fluid belongs to marine saline sedimentary karst filtration. After comprehensively analyzing the data of hydrogeochemistry, isotopes and recharge conditions of geothermal fluid, it shows that the atmospheric precipitation is the supply source of geothermal water in Tianjin, the infiltration water is heated by the surrounding rock in the process of deep circulation and leaching with marine sedimentary carbonate rocks. Finally, the atmospheric infiltration - marine sedimentation mixed genetic dissolved filtered water is formed.
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  Three-dimensional modeling research of geothermal reservoirs on Panzhuang uplift area in Tianjin based on SKUA-GOCAD platform

  LIU Jie , ZHAO Kan

  North China Geology. 2023, 46(2): 17-23.

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  With the development of computer technology, three-dimensional modeling technology has gradually been introduced into geoscience field. SKUA-GOCAD software uses advanced algorithms combined with advanced computing techniques to achieve a three-dimensional visual representation of geological results. By collecting the boreholes’data and data of physical parameters of thermal reservoir on Panzhuang uplift area in Tian‐jin, this paper constructed a three-dimensional geological structure model based on the SKUA-GOCAD platform.The physical properties parameters was added to model and geothermal reservoir was integrated into the model with property modeling．Established property models of the geothermal reservoirs provides a valuable reference for the evaluation of geothermal resources in this area. At the same time, it verifies the reliability of the model which that the comparison of virtual wells and stratum contour diagrams which are generated by SKUA-GOCAD software and the original data and formation drawings is highly similar.
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  Evaluation and comprehensive utilization analysis of geothermal resources in Beijing-Tianjin cooperation demonstration zone

  ZHAO Yanting, SHEN Jian, XU Xinxin, WEN Shuang, SUN Xiaolin, DONG Lufei

  North China Geology. 2023, 46(2): 24-30. https://doi.org/10.19948/j.12-1471/P.2023.02.04

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  By analyzing the geological structure and geothermal geological conditions of the Beijing-Tianjin cooperation demonstration area, combined with land use planning and geothermal resource planning, this paper analyzes the development potential, economy and suitable mining degree of shallow geothermal energy, Guantao Formation thermal reservoir, Wumishan Formation thermal reservoir and deep hole heat transfer in this area, and puts forward the development, utilization and protection countermeasures, in order to realize the comprehensive utilization of resources. The analysis shows that the shallow geothermal energy resources in the area have great potential, and the thermal reservoirs of Guantao Formation and Wumishan Formation are rich in recoverable resources. It is economical to construct deep hole heat exchange wells in the northwest.
  
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  Analysis of the influence of the overlying strata on the reservoir characteristics of the Ordovician thermal reservoir in Tianjin area

  SUN Xiaolin, YANG Baomei, WANG Zhenkai

  North China Geology. 2023, 46(2): 31-37. https://doi.org/10.19948/j.12-1471/P.2023.02.05

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  The Ordovician thermal reservoir is a high-quality reservoir with great development potential in Tianjin. It has the characteristics of shallow burial depth, high temperature and high water quality.After years of drilling data statistics, it is found that the Ordovician thermal reservoir in different areas has a great difference in water-bearing condition, and its development and utilization has a great potential risk. Therefore, through the analysis and comparison of geothermal well data revealing the Ordovician thermal reservoirs, the differences among the water outlet capacity, fracture development degree, hydrochemical type, hydrodynamic conditions and reservoir temperature of the Ordovician thermal reservoirs are summarized under different overlying strata conditions. The results show that when the overlying strata are neogene or Mesozoic, the Ordovician reservoirs have relatively developed fractures and superior hydrodynamic conditions. The main factors affecting reservoir water-bearing capacity are weathering and leaching, and the reservoir characteristics are affected by regional structure. When the overlying strata are carboniferous, the Ordovician fractures are relatively weak, and the main factors affecting water-bearing capacity are structural fractures. Based on the coupling relationship through different factors, this paper analyzes the influence of the overlying strata on the characteristics of Ordovician thermal reservoirs, providing reliable basis for geothermal development and utilization.
  
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  Evaluation and analysis of heat reservoir reinjection ability of Neogene Guantao formation in Tianjin

  LI Shan, SUN Xiaolin, YANG Baomei, GAO Xinzhi

  North China Geology. 2023, 46(2): 38-44. https://doi.org/10.19948/j.12-1471/P.2023.02.06

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  The development and utilization of geothermal resources in the Guantao Formation in Tianjin are mainly concentrated in Wuqing District and Binhai New Area. During many years of geothermal development and utilization, the groundwater level of the thermal reservoir in the Guantao Formation has continued to decline. In recent years, the reinjection of the thermal reservoir in the Guantao Formation has continued to increase, to slow down the downward trend of the groundwater level. However, in the actual reinjection process, it is found that the reinjection capacity of different regions is very different. According to the existing data, the order of unit recharge volume of the Guantao Formation thermal reservoir is Tanggu Depression, Banqiao Depression, Dacheng Uplift and Wuqing Depression. This article analyzes the data from water rock tests and concludes that the larger the cementation degree of sandstone in the Guantao Formation thermal reservoir, the more unfavorable it is for reservoir recharge. The shale content directly affects the 3D porosity of sandstone, which in turn affects the recharge capacity of the thermal reservoir. It is inaccurate to judge the permeability of sandstone based on the apparent porosity obtained from logging tests. By studying the hydrochemical characteristics of thermal reservoirs, underlying strata lithology and runoff conditions, we have improved our understanding of the development and protection of geothermal resources in the Guantao Formation.
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  The characteristics and significance of the geothermal reservior fluid isotope characteristics of the mountain group in tianjin mountain ridge

  YUE Dongdong, JIA Xiaofeng, ZHANG Qiuxia, FENG Zhaolong, LI Shengtao

  North China Geology. 2023, 46(2): 45-50. https://doi.org/10.19948/j.12-1471/P.2023.02.07

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  In order to analyze the chemical origin, occurrence conditions and material sources of geothermal fluids in the Shanlingzi geothermal field in Tianjin, the isotopic characteristics of the geothermal fluids in the Wumishan Formation of the Jixian system in the Shanlingzi geothermal field in Tianjin were studied by collecting and testing geothermal fluid samples, and the origin and formation mechanism of the geothermal fluids in the Wumishan Formation were summarized. The results show that the 87Sr/86Sr range of geothermal fluid in Wumishan Formation of Jixian system in the study area is 0.711 3～0.711 8, indicating the origin of carbonate karst decomposition and showing obvious time accumulation effect. The ⁴⁰Ar/³⁶Ar range of Wumishan Formation geothermal reservior fluid in Jixian system is 301～412, which is much smaller than the mantle source ⁴⁰Ar/³⁶Ar, which can exclude the mantle source material origin. The δ³⁴S range is 34.1‰～34.6‰, and the gas components are mainly nitrogen and methane, indicating the reduction environment. The research results have certain reference significance for the development and utilization of geothermal resources in Shanlingzi geothermal field.
  
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  Analysis and evaluation of urban geological environment problems：take Liaocheng city, Shandong province as an example

  YANG Lizhi, WANG Guoming, HAN Bo, LI Zhuang, CHEN Yao

  North China Geology. 2023, 46(2): 51-62. https://doi.org/10.19948/j.12-1471/P.2023.02.08

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  Based on the data of basic geology, hydro-engineering-environment geological data and InSAR interpretation results of Liaocheng with different precision, this paper graded the existing environmental geological problems, such as land subsidence, soil salinization, water and soil pollution in central city area of Liaocheng, and analyzed the development characteristics and distribution range of environmental geological problems. The results show that: the land subsidence in the central city of Liaocheng from 2008 to 2018 was relatively uniform, with no obvious settlement funnel center. Since 2016, the land subsidence rate gradually slowed down, and the development degree of land subsidence gradually changed from moderate development to weak development; most of the soil in the study area was in a state of unsalinization, and the soil salinization phenomenon basically disappeared；The groundwater pollution in the suburbs of the study area is very light, and the shallow groundwater pollution in the urban and nearby areas is heavy, which is mainly affected by three nitrogen and semi-volatile organic indicators benzo [a] pyrene; Good grade water (class II, class III), poor grade water (class Ⅳ) and extreme poor grade water (class V) accounted for about 0.6%, 53.4% and 46% of the total area, respectively, some water sample nitrate, Cl^- , SO₄^2-single index to class V or classⅣ; The liquefiable sand soil was widely distributed in the study area, but there was no damage to the buildings. The results can provide the geological basis and technical support for urban planning, construction and sustainable development of Liaocheng city.
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  Shallow groundwater ages and implication to the intrinsic vulnerability of aquifers in piedmont plain of Taihang mountain

  LIU Hongwei, WANG Guoming, GAO Mingda

  North China Geology. 2023, 46(2): 63-68. https://doi.org/10.19948/j.12-1471/P.2023.02.09

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  Groundwater resources play an important role in water supply for industry and living，however, with the increasing of human activities, groundwater pollution has occurred in many areas. Therefore, groundwater protection research becomes an imperative basic work. Previous studies showed that groundwater ages can indicate the intrinsic vulnerability of aquifers, which reflected the potential pollution risk of groundwater. Taking the piedmont plain of Taihang mountain as an example, the groundwater ages and their implication to intrinsic vulnerability were studied based on 3H（3H /3He）isotopes. The results showed that the ages of the shallow groundwater in the study area were generally less than 40 years, which increased along the direction of groundwater flow from piedmont to plain, and presented a better zonation feature. Simultaneously, comparing with the method of indicating inherent vulnerability of aquifer by content of modern water in groundwater, it revealed that the distribution of groundwater ages also displayed a good indication. The results showed that inherent vulnerability of the aquifers in the study area showed a decreasing trend from the piedmont to the plain, and was discussed and verified with other indicators and data.
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  Research on the optimization of land spatial pattern based on "dual evaluation" : taking Anyuan County, Jiangxi province as an example

  WANG Chong, ZHANG Jing, PENG Bo, WANG Jilong, YU Junjie, WU Jiayu

  North China Geology. 2023, 46(2): 69-78. https://doi.org/10.19948/j.12-1471/P.2023.02.10

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  Based on the "dual evaluation" technical guidelines, according to the characteristics of resource and environmental endowments in Anyuan County, select seven factors as evaluation indicators, including ecology, land resources, water resources, climate, environment, disasters and location, integrated evaluation based on individual element evaluation, identify critical areas for ecosystem service functions, clarify the maximum reasonable scale and suitable space for agricultural production and urban construction. The results showed: the ecological protection red line of Anyuan County is mainly distributed in the high importance area and the higher
  importance area of ecological protection,the proportion is 79.2%;some ecological reserves have not been included in the ecological protection red line; 0.95% of the current arable land is in the unsuitable area for agricultural production;7.50% of the current construction land is in the construction unsuitable area.The evaluation results can provide a fundamental basis for optimizing the development and protection pattern of national land space, delineating three control lines, implementing land space use control, and ecological protection and restoration.
  
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  Research on mineral composition, engineering failure characteristics,and response measures of Cretaceous mudstones in Jiaodong

  LI Peng, GAO Xuelian

  North China Geology. 2023, 46(2): 79-88. https://doi.org/10.19948/j.12-1471/P.2023.02.11

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  The mudstone of the Upper Cretaceous Wangshi Group, widely distributed in the Jiaodong area of China, belongs to extremely soft rock and generally has swelling characteristics. After water absorption and loss in this formation, there is a phenomenon of swelling and shrinkage, which poses great safety hazards to construction projects. This article conducts mineral composition analysis, disintegration mechanism analysis, and expansion characteristic test index research on the mudstone, and basically grasps the basic characteristics of engineering damage in the formation. Through various test indicators, it proposes engineering response measures
  for the formation, which can avoid or reduce the safety hazards caused by the formation to engineering construction and operation. The research results of this article provide reference significance for the construction and operation of similar projects in the region.