Deep bedrock geothermal resources in the Maichen Sag,Beibuwan Basin and their potential for exploitation and utilization

The Maichen Sag in the south-central part of the Beibuwan Basin is abundant in geothermal resources that have not been widely exploited and utilized due to inadequate research on it.This study evaluated the geothermal resources in the Maichen Sag based on the regional geological setting and geothermal conditions.Grid units for assessment and a geological model for areas with geothermal resources were established using spatial analysis techniques.The spatial distribution models of the physical and thermophysical properties of the geothermal reservoirs were also built using the Kriging interpolation method.Based on the terrestrial heat flow distribution in the target areas,the spatial distribution of the geo-temperature field through the inversion under the constraints of the temperature data from boreholes were predicted.Factors such as deep geo-temperature,thermophysical properties of rocks,and terrestrial heat flow values,were integrated into this quantitative evaluation of geothermal resources through the geological modeling-based volume method and the geothermal reservoir engineering-based numerical simulation method.The results show that the Maichen Sag has favorable heat source conditions with intersected,deep-rooted faults and widely developed Upper Paleozoic fissured granite geothermal reservoirs.The northern outer slope zone at a burial depth of 3‒5 km on the tectonic plane of the basement in the sag is suggested to be a potential target area,where,as calculated using the volume method,is likely to be the home to the total geothermal resources of 80.4×10^(9)GJ(i.e.,2.75×10^(9)tonnes of coal equivalent(tce))in the bedrock geothermal reservoirs at a burial depth of 3‒6 km.The geotemperature of 172‒201℃at a formation depth of 5 km in the sag also indicates that the deep geothermal resources are of high value for exploitation.

Distribution,exploitation,and utilization of intermediate-to-deep geothermal resources in eastern China

The part of China,east of the Hu Huanyong Line,is commonly referred to as eastern China.It is characterized by a high population density and a well-developed economy;it also has huge energy demands.This study assesses and promotes the large-scale development of geothermal resources in eastern China by analyzing deep geological structures,geothermal regimes,and typical geothermal systems.These analyses are based on data collected from geotectology,deep geophysics,geothermics,structural geology,and petrology.Determining the distribution patterns of intermediate-to-deep geothermal resources in the region helps develop prospects for their exploitation and utilization.Eastern China hosts superimposed layers of rocks from three major,global tectonic domainsd namely Paleo-Asian,Circum-Pacific,and Tethyan rocks.The structure of its crust and mantle exhibits a special flyover pattern,with basins and mountains as well as well-spaced uplifts and depressions alternatively on top.The lithosphere in Northeast China and North China is characterized by a thin,low density crust and mantle,whereas the lithosphere in South China has a thin,low density crust and a thick,high density mantle.The middle and upper crust contain geobodies with high conductivity and low velocity,with varying degrees of development that create favorable conditions for the formation and enrichment of geothermal resources.Moderate-to-high temperature geothermal resources are distributed in the MesozoiceCenozoic basins in eastern China,although moderate temperature geothermal resources with low abundance dominate.Porous sandstone reservoirs,karstified fractured-vuggy carbonate reservoirs,and fissured granite reservoirs are the main types of geothermal reservoirs in this region.Under the currently available technical conditions,the exploitation and utilization of geothermal resources in eastern China favor direct utilization over large-scale geothermal power generation.In Northeast China and North China,geothermal resources could be applied for large-scale geothermal heating purposes;geothermal heating could be applied during winter along parts of the Yangtze River while geothermal cooling would be more suitable for summer there;geothermal cooling could also be applied to much of South China.Geothermal resources can also be applied to high value-added industries,to aid agricultural practices,and for tourism.

Deep geothermal resources in China:Potential,distribution,exploitation,and utilization

Deep geothermal resources mainly refer to the thermal energy stored in subsurface rocks and fluids therein at a depth of 3-10 km,which is a kind of renewable and sustainable clean energy unaffected by weather and seasonal changes.Large scale exploitation of the deep geothermal resources is of great significance to ensuring national energy security and achieving the“Carbon Peak and Carbon Neutrality”.Based on the latest terrestrial heat flow data,this paper estimated the potential of deep geothermal resources in the terrestrial areas of China,and the results show that the total amount of geothermal resources within 3e10 km under the Earth's surface in the terrestrial areas of China is 24.6×10^(15)GJ.In line with climate zones categorized,the geothermal resource proportion is 43.81%for severe cold regions,29.19%for cold regions,6.92%for mild regions,13.82%for hot summer and cold winter regions,and 6.26%for hot summer and warm winter regions.Statistics according to the burial depth range reveal that the resources within depth ranges of 3-5 km,5-7 km and 7-10 km under the Earth's surface are 4.3119×10^(15)GJ,6.37674×10^(15)GJ and 13.89594×10^(15)GJ respectively,showing an increasing trend of geothermal potential with increasing burial depth.The deep geothermal resources are mainly of medium-to-high temperature reserves,and the energy supply strategy can be optimized by combining the climate conditions and population distribution,as well as considering power generation.In regions of cold or severe cold climate,the geothermal resources may be applied to geothermal power generation and district heating in combination;in regions of hot summer and cold winter or mild climates,the resources can be used for geothermal power generation combined with cooling and heating;in regions of hot summer and warm winter climates,the resources may be applied to geothermal power generation combined with cooling and industrial and agricultural utilization.Exploitation of deep geothermal resources also can be combined with carbon dioxide sequestration,multi-mineral resources extraction and energy storage to realize comprehensive exploitation and utilization of various energy resources.It is suggested that theoretical technology research should be combined with pilot tests and field demonstrations,and large-scale economic exploitation of deep geothermal resources should be arranged in a coordinated manner,following the principles of overall planning and step-by-step implementation.

Controlling effects of cap rocks on the formation of deep geothermal resources

Cap rocks with high thermal insulation are important for deep geothermal systems at a depth of 3000‒6000 m.Based on the deep geothermal geological conditions in the Fujian-Guangdong-Hainan area of South China,this study established an ideal geological model of reservoir-cap rock assemblages and simulated the geothermal field distribution of cap rocks of different thicknesses and thermal conductivity.The simulation results show that the vertical geothermal temperature distribution in an uplifted area of a depression was present as inverted mirror reflections relative to the elevated area of the basement.Specifically,the isotherms above the elevated area are convex in shape,while those below the elevated area are concave.There is a temperature equilibrium line between the convex and concave isotherms.The heat flow moves from the depressed area to the uplifted area below the temperature equilibrium line and migrates in an opposite direction above the line.On this base,this study conducted the inversion of geothermal temperature fields in typical areas with thin,moderately thick,and thick cap rocks.The results indicate that,at the depth of 3000e6000 m,areas with thin cap rocks(igneous rock zone in the coastal area of Fujian)mainly host moderate-to low-temperature hydrothermal resources;areas with moderately thick cap rocks(Yuezhong Depression)have the geothermal temperature ranging between 100℃and 200℃and may develop moderate-to high-temperature hydrothermal resources and hot dry rocks(HDRs),with the former superimposing on the latter;and areas with thick cap rocks(onshore Beibuwan Basin)have a geothermal temperature of 120‒220℃,and contains mainly moderate-to high-temperature hydrothermal resources and HDRs.Therefore,it is recommended that the evaluation,exploitation,and utilization of deep geothermal resources be carried out according to the burial depth of the temperature equilibrium line and the specific demand for geothermal resources.

Structural Controls Analysis and Its Correlation with Geothermal Occurrence at Barrier Volcanic Complex (BVC), Turkana, Kenya

Geothermal is a clean energy source that is freely available in the subsurface. The exploitation of this vital resource needs intensive exploration in order to identify and quantify its occurrence. The three parameters considered when assessing the viability of a geothermal system include;heat source, fractures and fluids. Geological structures are important in transportation of fluids to and from the heat source aiding in recharge of the geothermal system and enhancing productivity. Remote sensing method was applied in mapping the structures at Barrier Volcanic Complex (BVC) by using hill shading technique which utilized four illumination angles of the sun (azimuth) i.e. 45°, 90°, 150°, and 315°, constant elevation of 45° and exaggeration of 10. The data used was Shuttle Radar Topographic Mission (SRTM) Satellite Imagery. ArcGIS Software was used for lineaments delineation and density mapping, PCI Geomatica was used to generate major faults, while Georose and Rockworks 17 were used to generate the rose diagrams. Geological structural analysis was done by delineating lineaments, determining the density distribution of lineaments and finally determining the structural trends of lineaments. The generated major faults in the area and the location of the occurrence of surface manifestations were compared with the generated lineaments. A total of 260 lineaments were generated whereby at 45° there was a total of 60 lineaments, at 90° 95 lineaments, at 150° 61 lineaments, and at 315° 44 lineaments. The results of structural analysis in the area as shown by the rose diagrams indicate an NNE-SSW and N-S trending of structures. In conclusion, the study area is highly fractured as indicated by the presence of numerous lineaments. These lineaments provide good recharge to the geothermal system and enhance the geothermal reservoir in the area.

Characteristics of geothermal field and evaluation of geothermal resource potential in the Yingjiang Basin

Geothermal resource,a green and sustainable energy resource,plays an important role in achieving‘emission peak’and‘carbon neutrality’targets.The Yingjiang Basin is located in the eastern branch of the Mediterranean-Himalayan high-temperature geothermal belt and exhibits considerable potential for geothermal resources.However,current investigations into the distribution of deep geothermal resources in this region are somewhat limited.In this paper,the transient plane source(TPS)method is used to measure the thermal conductivity parameters of 31 rock samples within the study area.Additionally,the one-dimensional steady-state heat conduction equation is employed to calculate the deep geothermal field,considering the constraints of rock thermal properties and terrestrial heat flow in the study area.Furthermore,the“stripping method”is used to determine the contribution rate of sedimentary layer to terrestrial heat flow,while the volume method is applied to estimate the geothermal resources at burial depths of 3000-5000 m.The results show that(1)The heat generation rate of granite is the highest with an average value of 4.52 mW/m^(3),followed by gneiss with an average value in the range of 2.0-3.5 W/(m·K),mudstone and sandstone being the lowest with an average value between 1.0 and 2.0 W/(m·K).(2)The main contributor of terrestrial heat flow in the study area is mantle heat flow,and the contribution of sedimentary layers to terrestrial heat flow only accounts for about 2%.(3)The geothermal resources in Yingjiang Basin within the depth range of 3000-5000 m is 93.6×10^(15)kJ,or 3.2×10^(9)tonnes standard coal equivalent(SCE).

Geothermal-type Lithium Resources in Southern Xizang,China

High-temperature geothermal water has abundant lithium(Li)resources,and research on the development and utilization of geothermal-type lithium resources around the world are increasing.The Qinghai–Tibetan Plateau contains huge geothermal resources;especially,Li-rich geothermal resources in southern Xizang,southwestern China,are widely developed.The Li-rich geothermal spots in Xizang are mainly distributed on both sides and to the south of the Yarlung Zangbo suture zone.Such resources are often found in the intensely active high-temperature Li-rich geothermal fields and,compared with other Li-rich geothermal fields around the world,the Li-rich geothermal fluid in the Xizang Plateau,southern Xizang is characterized by good quality:the highest reported Li concentration is up to 239 mg/L;the Mg/Li ratio is extremely low and ranges from 0.03 to 1.48 for most of the Li-rich geothermal fluid;the Li/TDS value is relatively high and ranges from 0.25–1.14%compared to Zhabuye Li-rich salt lake(0.19%)and Salar de Uyuni(Bolivia)(0.08–0.31%).Continuous discharge has been stable for at least several decades,and some of them reach industrial grades of salt lake brine(32.74 mg/L).In addition,elements such as boron(B),caesium(Cs),and rubidium(Rb)are rich and can be comprehensively utilized.Based on still-incomplete statistics,there are at least 16 large-scale Li-rich hot springs with lithium concentration of 20 mg/L or more.The total discharge of lithium metal is about 4300 tons per year,equivalent to 25,686 tons of lithium carbonate.Drilling data has shown that the depth is promising and there is a lack of volcanism(non-volcanic geothermal system).With a background of the partial-melting lower crust caused by the collision of the Indo-Asia continent and based on a comprehensive analysis of the tectonic background of southern Xizang and previous geological,geophysical,and geothermal research,deep molten magma seems to provide a stable heat source for the high-temperature Li-rich geothermal field.The Li-rich parent geothermal fluid rushes to the surface to form hot springs along the extensively developed tectonic fault zones in southern Xizang;some of the Li-rich fluid flows in to form Li-rich salt lakes.However,most of the Li-rich geothermal fluid is remitted to seasonal rivers and has not been effectively exploited,resulting in great waste.With the continuous advance of lithium extraction technologies in Li-rich geothermal fluid,the lithium resource in geothermal water is promising as a new geothermal type of mineral deposit,which can be effectively exploited.This is the first study to undertake a longitudinal analysis on the characteristics,distribution and scale,origin and utilization prospects of Li-rich geothermal resources in southern Xizang,research that will contribute to a deeper understanding of Li-rich geothermal resources in the area and attract attention to these resources in China.

Characteristics of geothermal reservoirs and utilization of geothermal resources in the southeastern coastal areas of China

Based on regional geological setting, stratigraphic distribution and other geological conditions, this paper summarized three types of geothermal reservoirs in the southeast coastal areas of China: Cenozoic sandstone or sandy conglomerate reservoir, Mesozoic granite fissure reservoir and Paleozoic karst reservoir. Cenozoic sandstone or sandy conglomerate reservoirs are mainly located in Cenozoic basins, such as Zhangzhou, Fuzhou, Sanshui and Leiqiong basins. The Tertiary sedimentary basins such as Leiqiong Basin and Sanshui Basin, are controlled by NE-trending faults, while the Quaternary sedimentary such as Zhangzhou and Fuzhou basins are controlled by NW-trending faults. Mesozoic granite fissure reservoirs are mainly distributed in the southeast coastal areas, such as Zhangzhou, Fuzhou, Fengshun, Yangjiang and southern part of Hainan Province. The distribution of good Mesozoic granite fissure reservoir in these areas is mainly controlled by NE-trending faults. Paleozoic carbonate reservoirs are widely distributed in these areas. Most carbonate rocks are from the upper Paleozoic strata, such as those in the area of Huizhou in Guangdong Province. The major types of geothermal systems in the southeast coastal areas of China belong to medium and low-temperature convection. The geothermal resources developed from the ground to-3 000 m underground could be utilized directly for space heating, greenhouse heating, aquaculture pond heating and industrial uses, as well as other purposes. The geothermal resources with a depth of 3 000~6 000 m underground is mainly featured by Hot Dry Rock(HDR) with a temperature ranges from 150 ℃ to 200 ℃, which is conductive to the development of Enhanced Geothermal System(EGS) and can be utilized for power generation.

The status quo and prospect of geothermal resources exploration and development in Beijing-Tianjin-Hebei region in China

The Beijing-Tianjin-Hebei region boasts rich geothermal resources and new achievements have been made in the exploration and development of geothermal resources in this region based on previous regional investigation.In detail,geothermal reservoirs of Gaoyuzhuang Formation of Jixian System and Changcheng System in Xiongan New Area have been recently discovered,opening up the second space of geothermal resources;the calculation method of the recoverable resources of geothermal fluid with reinjection being considered has been improved in Beijing-Tianjin-Hebei region,and uniform comprehensive assessment of shallow geothermal energy,hydrothermal geothermal resources,and hot dry rocks(HDR)geothermal resources in the whole Beijing-Tianjin-Shijiazhuang region has been completed.The scientific research base for cascade development and utilization of geothermal resources in Beijing-Tianjin-Hebei region has applied hydraulic fracturing technology to the geothermal reservoirs in Gaoyuzhuang Formation.As a result,the production capacity doubled and two-stage cascade utilization composed of geothermal power generation and geothermal heating were realized,with the first-phase installed capacity of 280 kW and the geothermal heating is 30000 m2.In this way,a model of the exploration,development,and utilization of geothermal resources formed.Large-scale utilization has become the future trend of geothermal resource development in Beijing-Tianjin-Hebei region,and great efforts shall be made to achieve breakthroughs in reinjection technology,geothermal reservoir reconstruction technology,thermoelectric technology and underground heat exchange technology.

Non-seismic geophysical analysis of potential geothermal resources in the Longgang Block,Northeast China

Although geothermal energy has many clear advantages,including its sustainability and environmentally friendly nature,research into potential geothermal resources across the Longgang Block,Northeast China,has been limited.Here we present the first analysis of the potential geothermal resources in this region that employs joint geological and non-seismic geophysical methods to identify target areas that may be economically viable.We acquire and analyze high-precision gravity,magnetic,and magnetotelluric sounding data,which are constrained using the petrophysical parameters of outcropping rocks across the Longgang Block,to conduct a comprehensive evaluation of the region’s deep geological structures and their geothermal resources potential,with a focus on identifying faults,rock masses,and thermal storage structures.We find that Archean granitic gneiss and Mesozoic rock masses in the deeper section of the Longgang Block possess weak gravity anomalies and high resistivities.We also identify thermal storage structures near these deeper geological units based on their extremely low resistivities.The data are used to infer the dip and depth of known or hidden faults,to constrain the spatial distribution of intrusive rock masses,and to determine the spatial distribution of subsurface thermal storage structures.The potential of the target areas for geothermal resources exploitation is divided into three grades based on contact depths between faults and thermal storage structures,and the scale of their thermal storage structures.Our results suggest that a joint non-seismic geophysical approach can be effective in locating and evaluating geothermal resources in complex geological settings.

Advances in Assessment of Geothermal Resources of South America

Updated data for 1417 localities have been assembled for purposes of assessments of geothermal resources in South America. Analyses of these data sets have allowed improved estimates of geothermal resource base and recoverable resources for thirteen countries in the continent. The results obtained have also allowed identification of more than 20 crustal blocks where the resource base per unit area (referred to the accessible depth limit of 3 km) is in the range of 100 to 1000 Giga Joules, while the recoverable resources per unit area are in the range of 1 to 100 Giga Joules. Most of the high temperature resources occur within regions of recent tectonic activities in southern and central Chile, highlands regions in Bolivia, and several localities along the magmatic arc covering western Ecuador, central volcanic belt of Colombia and northern Venezuela. In addition, isolated pockets of geothermal resources have been identified along the eastern Andean belt of Peru. There are indications of occurrence of medium and low temperature geothermal resources at depths of 1 to 3 km in several regions in the eastern sectors of the continent, mainly in the northeastern and central parts of Brazil. In addition, considerable progress has been made in assessments of low temperature resources associated with deep fracture systems in Precambrian terrains. Progress has also been achieved in assessment of low temperature resources in deep aquifers of Paleozoic sedimentary basins. The results of such estimates are currently being considered for planning large-scale exploitation of the Guarani aquifer system, which spans over large areas of western Uruguay, northern Argentina and southern Brazil.

CENOZOIC VOLCANISM AND GEOTHERMAL RESOURCES IN NORTHEAST CHINA

This paper is concentrated on Cenozoic volcanism and geothermal resources in Northeast China. There are a lot of Cenozoic volcanoes, a large area of volcanic rocks, a large number of active faults and rich geothermal resources in Northeast China. The time and space characteristics of Cenozoic volcanism and the space distribution characters of hot springs and high geothermal flux regions in Northeast China are described and discussed on the basis of geological, geothermal, drilling and volcanological data. It is revealed that the hot springs and high geothermal flux regions are related to the Cenozoic volcanism, rifting and faulting in Northeast China. It is especially emphasized that the hot springs and high geothermal anomaly areas are controlled by active deep faults. It is proposed that the Cenozoic volcanism regions, rift basins, active fault belts, activated plate suture zones and large earthquake occurrence points are the best areas for prospecting geothermal resources. The geothermal resources in younger volcanic zones are richer than those in older volcanic belts. The hot springs and active or activated faults might be a very good clue for looking for geothermal resources.

ADVANCES IN STUDIES ON GEOTHERMAL RESOURCES IN CHINA

Based on recent year’s advances in geothermal resources studies and explorations in China, this paper reviews the basic distributive characteristics of hot springs in the uplifted area and geothermal water in the Meso-Cenozoic sedimentary basins, suggests that two hydrothermal activity concentrated zones (South Tibet Autonomous Region - West Sichuan Province - West Yunnan Province and coastalarea of Southeast China), one large basin(North China Basin) and two smaller basins(Weihe Basin and Leiqiong Basin) are major areas of study and exploration of geothermal resources in China continent, considers that geothermal resources in China have certain potential of exploitation and should be used, but the scale of exploitation seems to be limited, they cannot occupy an important position in energy supply and can only be regarded as a supplementary energy source.

Geothermal Resources Potential Analyses of Tanggu Urban Area and the Vicinity,Tianjin

In order to construct a newly developed green area, the Tanggu urban area as the core part of Binhai new area,needs more and more clean energy year by year. This area is abound in geothermal resources endowed by the grand Nature.Based on the estimation of

Mathematical Model of the Geothermal Water Resources in the South Hot Spring System in Chongqing

The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south and small hot springs, which have not flowed naturally for 15 years. Now, bores pump geothermal water to the springs. If the water level drops below the elevation of the rivers, river-water will replenish the geothermal water, destroying this resource. It is therefore an urgent task to model the geothermal water system, to enable sustainable development and continued use of the geothermal water in Qiaokouba. A numerical simulation of the geothermal water system was adopted and a quantitative study on the planning scheme was carried out. A mathematical model was set up to simulate the whole geothermal water system, based on data from the research sites. The model determined the maximum sustainable water yield in Qiaokouba and the two hot springs, and the south hot spring and small hot spring sustainable yields are 1 100 m^3/d and 700 m^3/d from 2006 to 2010, 1 300 m^3/d and 1 000 m^3/d from 2011 to 2015, and 1 500 m^3/d and 1 200 m^3/d from 2016 to 2036. The maximum exploitable yield is 3 300 m^3/d from 2006 to 2036 in Qiaokouba. The model supplies a basis to adequately exploit and effectively protect the geothermal water resources, and to continue to develop the geothermal water as a tourist attraction in Chongqing.

Geothermal resources formation conditions and preferred target areas in a certain county of Western Sichuan, China

The geothermal resource is a form of "green" and renewable energy with huge development potential in terms of both environmental protection and economy. It was concluded that the exposed hot springs were mostly produced when fluids derived from atmospheric precipitation were heated deep and recurrently under the ground, developed banded geothermal reservoir in the pores of fault damage zones, fissure zones, hornification zones and dikes, and then moved upward with analyzing the geological and hydrogeological data as well as hydrochemical types of the naturally exposed hot springs in the studied region so as to ascertain the accumulation conditions of geothermal resources in a particular county in Western Sichuan and opt for suitable target areas for exploring geothermal resources. Four areas where geothermal resources are potentially located were proposed with analysis of their formation conditions based on this notion, and the "epsilon-shaped" structure in Zhimulin, the "epsilon-shaped" structure in Jiaochang, the vortex structure in Rewugou and the arcuate structure in Shidaguan were analyzed in this paper offering a reference for developing and exploiting the geothermal resources in the region as well as studying the development patterns of other hot springs in this region.

Evaluation of shallow geothermal energy resources in the Beijing-Tianjin- Hebei Plain based on land use

To discover the characteristics,distribution and potential of shallow geothermal energy in the Beijing-Tianjin-Hebei Plain area.This paper,based on a large amount of data collection and field investigations,evaluateed the shallow-layer geothermal energy in the study area through the analytic hierarchy process and comprehensive index method.Based on suitability zoning results superimposed with 1:100000 land use data,the study area is divided into encouraged,controlled,restricted and prospective mining areas regarding the development of shallow geothermal energy,and the economic availability of shallow geothermal energy in the encouraged and controlled areas are evaluated.The results show that the shallow geothermal energy in the Beijing-Tianjin-Hebei Plain can meet the heating and cooling demand of 6×10^(8) m2 of buildings,equivalent to 1.15×10^(7) t of standard coal,thus reducing carbon dioxide emissions by 2.73×10^(7) t and reducing sulfur dioxide emissions by 1.95×10^(5) t.According to the development and utilization mode,the energy demand level and the Beijing-Tianjin-Hebei coordinated development plan,the development and utilization of geothermal resources in the plain area has two types:Urban concentrated mining areas and rural scattered mining areas.The scale and level of intensive utilization of regional geothermal resources are of great significance.

Reconnaissance investigation of geothermal resources in parts of the Middle Benue Trough, Nigeria using remote sensing and geophysical methods

In Nigeria,the basement complex and the sedimentary basins house many thermal springs which are physical manifestations of geothermal energy.However,there are difficulties in accessing the sustain-ability of these resources due to ethical and security issues as well as limited data in Nigeria.Thus,identifying the precise location,temperature,and energy potential on a large scale has been a major drawback.This paper is the preliminary investigation of geothermal potential in parts of the Middle Benue Trough using satellite imagery,geology,regional gravity,and high-resolution aeromagnetic data.Landsat 8 scene was used to estimate the Land Surface Temperature(LST)in ArcGIS^(TM).Selected sites were classified as very low,low,moderate,and high LST.The intermediate and high classes happen to be possible geothermal zones,and they occupy 49% of the study area(38,077 km^(2)).The Riverline was superimposed on the LST,and the high-temperature sites were located by the identification tool.Streams/river data overlapped on the selected sites were regarded as thermal/warm springs.Remarkably,the LST results show lower temperatures(<36℃)at the famous thermal springs(Awe and Wukari)than some unknown rivers/streams found in Kwande(38℃),Ussa,(38℃),Gwer East(37℃),Yola Cross and Ogoja(36℃).Furthermore,the geophysical datasets,regional gravity,and high-resolution aeromagnetic data were interpolated to delineate the subsurface features associated with geothermal manifestations.The four layers from the LST were further evaluated using the geophysical approach.Gravity and mag-netic values revealed variations that could be linked to geothermal alterations.The correlation of the geophysical anomalies and LST with the geology of the study area uncovers essential information on energy potentials.Therefore,further investigation is required to estimate the depth of the causative body,the geothermal gradients,and the reservoir volumes.

Investigation Method and Utilization Mode of Geothermal Resources in Abandoned Mines in Huainan and Huaibei

With the depletion of coal resources due to excessive exploitation and the increasing adjustment of the national energy structure, in response to the call of national policy, some mines are forced to close, and the reuse of abandoned mine resources plays an important role in the sustainable development of mining industry. This paper analyzes the general situation of abandoned mines in Huainan and Huaibei, elaborates the research methods of geothermal temperature and calculation methods of geothermal reserves in abandoned mines, analyzes and studies the utilization prospect of geothermal resources in abandoned mines in Huainan and Huaibei, and draws the following conclusions: the temperature of geothermal resources in abandoned mines in Huainan and Huaibei is 25&#8451;- 60&#8451;, which belongs to the moderate-hot water and warm water resources in low-temperature geothermal resources, and can be used for geothermal heating, industrial geothermal and entertainment industries. Based on the previous experience in geothermal resource utilization mode, this paper provides theoretical and technical support for the demonstration project of resource utilization and development of abandoned mines in the Huainan and Huaibei mining areas.