(1. Shandong Bureau of Geology and Mineral Resources, Jinan 250013; 2. Shandong Geology and Mineral Engineering Group Co., Ltd., Jinan 250013; 3. Shandong Institute of Geology and Mineral Resources, Jinan 2500 14)
About the author: Xu (196 1-), male, professor-level senior engineer, whose research interests are hydrogeology and environmental geology.
Based on the analysis of the distribution characteristics, geological conditions and the present situation of exploration and development of geothermal resources in Shandong Province, this paper puts forward some suggestions on the exploration and development planning of geothermal resources, predicts the prospect of geothermal resources in Shandong Province, and provides a basis for the relevant departments to formulate long-term development plans and guide the exploration and development of geothermal resources in Shandong Province.
Keywords: geothermal resources; Geothermal area; Development and utilization
Nowadays, geothermal energy has become one of the important alternative energy sources after coal and oil, and another important green new energy source after solar energy and wind energy. Geothermal resources integrate heat energy and water resources, which can be used not only for geothermal power generation, but also for heating, bathing, medical treatment, leisure and recuperation, breeding, planting, textile printing and dyeing, food processing and so on. In addition, the development and utilization of geothermal resources can promote the development of geothermal resources exploration, geothermal well construction, ground development and utilization engineering design and construction, geothermal equipment production, water treatment, environmental engineering, catering, tourism and holiday. It is a new industry, which can greatly increase social employment, promote economic development and improve people's quality of life. It has obvious social, economic and environmental benefits and broad development prospects.
1 Distribution characteristics of geothermal resources
Shandong province is rich in geothermal resources in China. At present, geothermal resources have been discovered in 15 cities except Rizhao and Laiwu. According to statistics, there are 5 natural hot springs 100 in the whole province, and more than 0/00 artificial exposed geothermal boreholes/kloc-0. The geothermal resources in Shandong Province are mainly medium-low temperature geothermal resources that can be directly utilized, with the characteristics of wide distribution, many types, moderate buried depth, mainly medium-low temperature and good development and utilization conditions. According to the investigation results of Shandong Bureau of Geology and Mineral Resources, it is preliminarily estimated that the shallow geothermal resources with a depth of 3000m in Shandong Province are about 3. 1863× 1020J, which is equivalent to the heat of1500 million tons of standard coal combustion, and can be developed for heating, industrial utilization, hot water supply, bathing, health care, recuperation, entertainment and greenhouse culture. According to the exploitable amount of geothermal resources, if it can be fully industrialized, the potential economic benefits can reach10 billion yuan per year. At the same time, it can solve the employment problem of tens of thousands of people every year, which is conducive to social stability and the economic, social and environmental benefits will be immeasurable.
According to the comprehensive factors such as geological structural conditions, types of thermal reservoirs, lithology and pore characteristics, burial and forms of thermal reservoirs, Shandong Province is divided into four geothermal regions: eastern Shandong, Yishu fault zone, central and southern Shandong and northwestern Shandong.
Ludong geothermal area: Ludong geothermal area is located in the east of Yishu fault zone, with Shandong Peninsula as the main body, and its administrative divisions include Weihai, Yantai, Qingdao, Weifang and Rizhao. It is an area where geothermal hot springs are exposed intensively, and the surface heat is obvious, with 13 hot springs exposed. Among them, there are 7 medium-temperature hot springs and 6 medium-high temperature hot springs.
Geothermal area of Yishu fault zone: located in Yishu fault zone, including Weifang, Linyi and Rizhao. The medium-high temperature hot springs (Tangtou Hot Springs) 1 exposed naturally and the geothermal outcrops (geothermal holes) 1 exposed artificially in this area.
Central South Shandong Geothermal Area: It is located in the vast area west of Yishu fault zone, south of Qihe-Guangrao fault zone and east of Liaocheng-Lankao fault zone, including Laiwu, Jining, Zaozhuang and parts of Weifang, Zibo, Jinan, Heze, Liaocheng, Dezhou and Binzhou. There is little surface heat display in this area, and natural hot springs are exposed in 1 (Qiaogou Hot Springs), with low temperature. There are 17 geothermal outcrops (geothermal holes) exposed artificially. Among them, there are 7 low-temperature geothermal holes, 7 medium-temperature geothermal holes and 2 medium-high temperature geothermal holes.
Geothermal area in northwest Shandong: The geothermal reservoir in northwest Shandong includes the area north of Guang Qi fault and west of Liaokao fault. Including Dongying, Binzhou, Dezhou, Liaocheng and parts of Heze. This area is the most widely distributed area of geothermal resources in the province, with 67 geothermal outcrops (geothermal holes) exposed artificially.
2 Geothermal geological conditions
2. 1 eastern Shandong geothermal area
There are two ridges and one depression in this area (Jiaobei uplift, Jiaolai sag and Jiaonan uplift), which is called "herringbone" structure in eastern Shandong, and the two ridges and one depression are generally northeast-northeast. Neotectonic activity is strong, neotectonic faults are developed, and the activity intensity increases from south to north. The bedrock lithology of Jiaobei and Jiaonan uplift in eastern Shandong geothermal area is mainly granite and metamorphic rocks, which are brittle and have poor permeability, and mainly rely on cracks and fracture zones to conduct water. The distribution of thermal anomalies is controlled by structure, and hot springs are exposed at the intersection of two sets of faults or different contact zones of rock mass. Groundwater circulates along the fault in the recharge area, is heated by the deep ground temperature, and then rises to the shallow part under the action of water pressure difference, forming a thermal anomaly. Thermal storage is distributed in groundwater drainage areas, generally located in valleys, mountain basins and piedmont plains, and hot water supply areas are located in hilly areas with higher terrain. Because of the strong neotectonic activity in Jiaobei Uplift, the faults in it are often in an open state, and the cracks are not easy to be blocked, and the water conductivity is enhanced, which creates conditions for the circulation of groundwater depth. Therefore, 13 of the 14 hot springs in eastern Shandong is located in Jiaobei uplift. The neotectonic activity of Jiaonan uplift is weak, and most faults are gradually closed due to erosion and hydrochemical precipitation, which is not conducive to the formation of underground hot water circulation system, so no geothermal anomaly has been found in this uplift area so far.
The geothermal system in the heat storage area is of deep circulation convection type. The thermal reservoir is buried shallowly, and the caprock is Quaternary sediments, with a thickness generally less than 50m and poor thermal insulation conditions. The type of thermal reservoir is fractured zonal thermal reservoir, and the thermal reservoir rocks are mainly Mesozoic granitic rocks and early Cambrian metamorphic felsic rocks. The thickness of thermal reservoir is180 ~ 280m ~ 280m. Most of the thermal reservoirs are relatively independent hot water structural systems, and there is no obvious hydraulic connection between them. The chemical composition of water in adjacent thermal reservoirs is similar, but there are some differences in water temperature and chemical composition content. The cause of thermal storage is that atmospheric precipitation seeps down to the deep along the contact zone between faults and different rock masses, and rises to the shallow along the channel after being heated by surrounding rocks, and the reservoir is formed in the rock stratum with good permeability. The temperature of thermal storage is controlled by fault structure, and the water temperature is relatively high, generally 65 ~ 90℃. The salinity of underground hot water is low, generally 500 ~ 2500 mg/L, and the hydrochemical types are complex, mainly HCO _ 3 SO _ 4-Na, Cl-Na and Cl-Na _ Ca. The space shape of geothermal reservoir in geothermal field is irregular, controlled by faults, and it is mostly belt-shaped or oval in plane, and its long axis direction is consistent with the trend of thermal control faults. The spatial shape is like irregular mushrooms, and the distribution area is small, generally less than 1km2.
2.2 geothermal area of Shu fault zone
This area is an earthquake-prone area in Shandong Province with strong neotectonic activity. There are four main faults in this area from west to east, namely Mianqi-Gegou fault, Yishui-Tangtou fault, Anqiu-Juxian fault and Changyi-Dadian fault. From the deep structure, the thermal storage area of Yishu fault zone is Moho uplift zone, and the geothermal flow density is 62mW/m2, which is higher than the thermal storage areas on both sides. Yishu fault zone is a high-temperature geothermal zone with thin crust, high upper mantle and shallow conductive layer. The geothermal system is of deep circulation convection type, and the thermal storage type is of fissure belt type, which is distributed in the depression. The convex areas on both sides of the depression are hot water supply areas, and the higher heat flow value and the more developed neotectonic faults in the area create conditions for the formation of geothermal system. Thermal reservoirs are mainly composed of metamorphic granitic rocks in early CAMBRIAN, igneous rocks and sandstone shale in Mesozoic, so thermal reservoirs can be formed at the edge of the depression and ideal structural parts. Thermal storage thickness 150~250m ~ 250 m, and thermal storage area is not large. The burial depth is generally about 200m, the water temperature is about 60℃ and the salinity is about 3000 mg/L.
2.3 Southern Shandong geothermal area
The geothermal reservoir in central and southern Shandong Province is a Luxi uplift area in structural unit, bounded by Weishan Lake-Jining-Pingyin. According to the different characteristics of thermal storage, it is further divided into two subregions: hilly and mountainous areas in central and southern Shandong and potential uplift areas in southwestern Shandong. After the late Jurassic, under the action of Yanshan movement and Himalayan movement, the original unified basement fractured, forming a series of convex zones and concave zones along the fault. The convex zone was eroded and the concave zone was deposited in Mesozoic and Cenozoic. The Moho surface in the hilly and mountainous sub-region of central and southern Shandong Province is deeply buried, and the geothermal flow density is 48 ~ 50mW/m2, which is the lowest in Shandong Province. Geothermal anomalies in this area are generally located near the intersection of uplift and depression, and at the intersection of NW, NE and SE neotectonic faults that control the depression. The sub-region of submarine uplift in southwest Shandong is an active alternating zone of groundwater runoff near hills and mountains, and groundwater activities have great influence on its geothermal field. According to the stratigraphic and structural characteristics, the Niujiaodian-Liulisi fault in the eastern part of chiping is divided into two sections, the northern section is the northern margin of Taishan Uplift, which is a monoclinal structure with gently dipping strata to the north. The Cenozoic strata are Carboniferous-Permian and Ordovician-Cambrian in Lower Paleozoic. The southern section consists of a series of alternating protrusions and depressions. The uplift is the Neogene underlying Taishan Group and the Lower Paleozoic, and the depression is deposited with thick Cenozoic and Mesozoic Jurassic strata, and the lower part is the Paleozoic.
The types of thermal reservoirs in the hilly sub-region of central and southern Shandong are zonal thermal reservoirs and CAMBRIAN-Ordovician carbonate fractured layered thermal reservoirs. The former is metamorphic rock with fracture development in early CAMBRIAN, and its thermal storage thickness is150 ~ 260 m; The latter is mainly limestone with thermal storage thickness120 ~ 200 m. It is a deep circulation convection type. Hot springs and underground hot water wells are mostly distributed at the intersection of NW-trending and nearly N-S, NE-trending or nearly E-W faults or in the contact zone between Mesozoic rock mass and Paleozoic limestone. The hydrochemical type is sodium chloride or chlorine. Calcium sulfate. Na type. The salinity is 4500 ~ 1700 mg/L, and the geothermal well temperature is 27 ~ 7 1℃. The thermal reservoirs in the north of southwest Shandong are Ordovician limestone, Carboniferous and Permian sandstone and limestone. Thermal reservoirs have the characteristics of fault zones and fault zones, and their water abundance is quite different. The thermal reservoirs in the southern section are mainly Ordovician karst fracture thermal reservoirs and Neogene pore thermal reservoirs, mainly conductive thermal reservoirs. Ordovician limestone thermal reservoirs are mainly distributed in Yanggu, Heze and Qingguji uplift, with a water temperature of 50 ~ 60℃ and a large area, which is characterized by both layered and banded thermal reservoirs. The buried depth of thermal storage is generally between 200 ~ 1600 m, the water temperature is between 40 ~ 80℃, the salinity of hot water is 400 ~ 3500mg/L, and the hydrochemical type is SO4 Cl-Na Ca.
2.4 Northwest Shandong geothermal area
The geothermal area in northwest Shandong belongs to a part of Mesozoic and Cenozoic fault basins developed on the North China platform. It is based on the Archean metamorphic rock series, on which a set of lower Paleozoic dominated by marine carbonate rocks and upper Paleozoic with land-sea interaction to continental facies developed. Compared with other thermal reservoirs, the Moho surface in the geothermal area of northwest Shandong has relatively high heat flow value and strong water-rich thermal storage, which is the area with the greatest development potential of hot water resources. The source of hot water supply in the area is atmospheric precipitation, and the way of supply is lateral runoff supply. Generally speaking, the geothermal system is a warm-water geothermal resource formed under the geothermal flow mechanism dominated by heat conduction, and there is also the possibility of a convective geothermal system near the deep fault zone in the bedrock thermal reservoir in the raised area. Its formation and distribution are controlled by geological structure and formation lithology. Thermal storage systems are mainly divided into pore type and local karst fracture type. Underground hot water mainly occurs in pores and fractures of Neogene clastic rocks, CAMBRIAN-Ordovician karst fractures and fractures of Taishan Group metamorphic rocks. The caprock is composed of cohesive soil and sandy soil, with a thickness of 900 ~ 1000 m, and the heat source mainly comes from the deep crust and the upper mantle to conduct heat flow. The thermal storage water temperature of clastic rocks is 40 ~ 80℃, that of bedrock is 50 ~ 90℃, and the geothermal gradient is generally 3 ~ 4.5℃/100 m. ..
The Neogene layered porous thermal reservoir is a set of interbedded deposits of sand and mudstone dominated by extremely thick fluvial facies, with a thickness of 500 ~1300m and a floor burial depth of 700 ~1600m. The main thermal reservoirs are Guantao Formation and Dongying Formation. Lower Paleozoic karst fracture thermal reservoirs are distributed in Cenozoic or Upper Paleozoic strata in uplift area, which are scattered in islands and have a small area. Karst fracture thermal storage has both layered and fault thermal storage characteristics, and the thermal storage characteristics depend on geological structure and karst development degree. The water content of limestone thermal reservoir directly covered by Neogene is much higher than that covered by Carboniferous-Permian. The water-rich near the fault is the strongest and the temperature is higher, while the water-rich far away is poor and the temperature is lower. Karst fractured thermal reservoir is an important thermal reservoir in this area, which is characterized by higher water temperature and water quantity than Cenozoic thermal reservoir. According to the data of three karst fractured geothermal wells in northwest Shandong thermal storage area/kloc-0, the water abundance of limestone thermal storage is quite different, and the salinity of karst fractured thermal storage hot water is high, reaching 6.30 ~14.37 g/L.
3 Present situation of geothermal resources exploration, development and utilization
The exploration of geothermal resources in Shandong Province began in 1950s. From 65438 to 0958, Shandong Bureau of Geology and Mineral Resources conducted geothermal exploration in Zhaoyuan, Wendeng, Weihai, Jimo and other places in Jiaodong Peninsula, and found some hot water spots on the basis of the original hot spring dew point. From 65438 to 0996, geothermal fields (spots) such as Tangtou, Weihai, Zhaoyuan, Jin 'an, Fujiazhen, Zibo, Muping Longquan and Feicheng Anjiazhuang were successively explored. Since the end of 1990s, with the attention of local governments at all levels to the problems of resources and environment, great progress has been made in the exploration of geothermal resources in Shandong Province, including the Yellow River Delta, the northwest of Jinan, Lubei and other key areas, and dozens of counties with geothermal prospects have carried out the exploration of key areas. There are more than 30 new geothermal wells in Heze, Liaocheng, Dezhou, Binzhou, Dongying, Jinan and other stratified thermal storage areas, and the water temperature is between 42-80℃. At present, the province's geothermal field exploration has accumulated 140 times, with an accumulated investment of more than 50 million yuan.
Shandong Province has a long history of geothermal utilization, which can be traced back to 1000 years ago according to relevant data. Officially as a resource development began in the 1920s, but it was only used for bathing. Since the reform and opening up, especially since the 1990s, the geothermal development projects in Shandong Province, which mainly aim at health care, recuperation and heating, have developed rapidly, but there is a big gap compared with other provinces and cities and abundant geothermal resources. At present, there are 46 geothermal development units in the province, and the main development projects include hot spring bathing, heating, swimming, domestic hot water supply, planting, breeding and tourism. In 2003, the geothermal heating area of the whole province was 5.5× 105m2, which was 7 times higher than that of 3× 104m2 in 2000, which was a national increase.
4 Shandong geothermal resources development and utilization of ecological and environmental significance
Structural pollution is very prominent in Shandong province, with the total emission of main pollutants such as sulfur dioxide ranking in the forefront of the country, and the environmental quality of major cities is at a low level. The air pollution caused by coal burning in Shandong Province is particularly prominent during the heating period in winter, and the contribution rate of coal burning to air pollution is above 70%. The pollutants emitted by coal combustion are harmful to the ecological environment, especially to human health. Emissions such as sulfur dioxide, nitrogen oxides, ozone and carbon monoxide will cause respiratory diseases and increase the incidence of lung cancer. According to relevant research data, air pollution is closely related to the incidence of lung cancer. Polycyclic aromatic hydrocarbons (PAHs) attached to particulate matter are usually the main substances that cause lung cancer, such as benzo (a) pyrene, which is the product of coal combustion at a certain temperature. If the concentration of benzo (a) pyrene in the air increases by one ten thousandth, the cancer mortality rate of residents will increase by 5%. The development and utilization of geothermal resources for heating will change the energy structure, greatly reduce the air pollution caused by coal burning, greatly improve the quality of urban ecological environment and promote the health and quality of life of residents. While saving traditional energy, many countries make use of geothermal resources to exert their remarkable ecological and environmental benefits. Because geothermal energy has replaced most of the fuel and coal, the atmospheric environment in Reykjavik, Iceland has been fundamentally improved, and the carbon dioxide content, the chief culprit of the greenhouse effect, has decreased from 270,000 tons in 1960 to 3,000 tons in 2000 (a decrease of 98.9%). Thanks to the clean air brought by geothermal development, Iceland has just become one of the three countries named by the United Nations as the most suitable for human habitation. Compared with coal-fired boiler heating, geothermal heating in Diequan District of Tianjin is only 4× 104m2, which reduces sulfur dioxide emission 18 t/a, soot emission 30 t/a and coal ash emission 580 t/a. ..
The geothermal resources in Shandong province are widely distributed and rich in reserves, which has laid a good foundation for the development of heating. Geothermal heating can be used in large and medium-sized cities such as Jinan, Dongying, Dezhou, Liaocheng, Heze, Linyi and other parts of cities. At present, Dezhou, Dongying, Liaocheng, Heze and other cities have made a good start in geothermal heating. Geothermal heating in Dezhou City has developed from the blank of 1.998 to 3.0× 1.05 m2 in 2003, and only sulfur dioxide 1.35t/a, soot 225t/a and coal ash 4250t/a are reduced each year. The geothermal heating in Dongying City increased by 2.5× 105m2 in three years. According to the development and utilization plan and trend forecast of geothermal resources in this city, in the future 100, the geothermal heating in this city will develop to 1.5× 106m2, which can reduce the sulfur dioxide emission by 675 t/a and the soot emission by1kloc-0/25t/a every year. It is predicted that in the next 10 year, the geothermal heating area in the whole province will reach 6.4× 106m2, and the annual emission of sulfur dioxide, smoke dust and coal ash will be reduced by 2880t/a (table 1).
Table 1 Geothermal Heating and Pollutant Reduction Forecast Statistics of Shandong Province
sequential
5. Suggestions on the exploration and development planning of geothermal resources
Geothermal is a non-renewable or poorly renewable resource. In this sense, it has similar exploration and development properties with natural gas, coal and other mineral resources in this area. The exploration and development of geothermal resources is a high-risk and high-input industry. In order to reduce blindness and detour, the prospect of geothermal resources is predicted, which provides a basis for the relevant departments to formulate long-term development plans and guide the exploration and development of geothermal resources in the province.
5. 1 Evaluation of exploration and development conditions of geothermal resources
5. 1. 1 Areas with good geothermal exploration and development conditions
All geothermal sub-regions in Linqing Depression, most geothermal sub-regions in Jiyang Depression and parts of Chengning Uplift, the northern margin of Jiaobei Uplift and Jiaolai Basin, Liaodong-Yanggu Uplift, Heze Uplift and the western part of Guqinglong geothermal area have great geothermal resources potential. Within the recoverable depth of 2000 meters, the geothermal resources of Neogene thermal storage and Paleozoic CAMBRIAN-Ordovician thermal storage are extremely rich, with good water quality, moderate water temperature and superior exploration and development conditions. Especially, Neogene thermal reservoir is the first choice for geothermal exploration and development because of its shallow burial, difficult exploration technology and low cost.
The counties and cities with the most potential for exploration and development are: Hekou, Dongying District, Kenli, Lijin County and the north of Guangrao County; Bincheng, Yangxin, Zhanhua, Huimin and Boxing counties of Binzhou City; Dezhou Decheng, Linyi, Pingyuan, Yucheng, Qihe, Xiajin, Wucheng and other counties and cities; Dongchangfu, Yanggu, Linqing, guanxian, Shenxian and Gaotang in Liaocheng; Juancheng, Dongming, Peony, Cao Xian and Dingtao counties in Heze City; Shanghe, Jiyang County, Tianqiao and Licheng District in the north of Jinan; Feicheng, Tai 'an City; Zhaoyuan and Mu Ping in Yantai City; Huancui in Weihai and hot outcrops in various places.
5. 1.2 Areas with good geothermal exploration and development conditions
The areas with good geothermal exploration and development conditions include Chengning Uplift geothermal sub-region in the geothermal area of northwest Shandong, Yishu fault zone geothermal depression, Yishui-Linyi area in the south, Donge Niujiaodian-Linzi-Shouguang-Niutouzhen concealed Ordovician limestone section in the geothermal area of western Shandong. The geothermal resources in these areas have great potential and are very rich. The thermal reservoir of Neogene Guantao Formation is thin and has little development value, while the top surface of Cambrian-Ordovician thermal reservoir is shallow and the exploration technology is not difficult.
The counties and cities with exploration and development prospects are: Zouping and Wudi in Binzhou City; Ningjin, Leling, Qingyun and Northwest Ling counties in Dezhou; Chiping, Liaocheng City; Gaoqing, Huantai, Zhoucun, Zhangdian, Zichuan and Linzi in Zibo; Zhangqiu, Penglai, Taian, Yinan, Laiwu, Qufu, Xintai and other places.
5. 1.3 areas with general geothermal exploration and development conditions
The geothermal resources in Linzi, eastern Luxi geothermal area, Changyi-Dadian fault zone, Yuanguyu limestone and marble section of Mesozoic in Jiaolai basin have great potential. The thermal reservoir of Neogene Guantao Formation is thin and its resources are few. The Cambrian-Ordovician thermal storage resources are large, and the top interface is shallow, so the exploration and development technology is not difficult.
The counties and cities with general exploration and development prospects are Changqing, Pingyin, Weifang, Qingzhou, Zhucheng, Anqiu, Gaomi, Changle, Changyi, Laizhou, Qixia, Mu Ping, Haiyang, Pingdu, Jimo, Jiaonan, Jiaozhou, Rongcheng, Rushan, Dong 'e, Wenshang, Dongping, Ningyang, Yanzhou, Surabaya and Wuyang.
5.2 Evaluation of Main Exploration and Development Thermal Storage
Geothermal resources in Shandong province are widely distributed and have great potential. Neogene hot water and some buried hill CAMBRIAN-Ordovician karst fissure hot water exist in the recoverable depth of 2000 meters, which is the main target layer for finding and exploring geothermal resources in the future.
(1) In the geothermal areas in northwest Shandong, north of Qihe-Guangrao fault and west of Liaocheng-Lankao fault, including Linqing depression, Jiyang depression and Laoling, Qingyun and Wudi uplift of Chengning uplift, the thermal reservoirs of Neogene Guantao Formation and Paleogene Dongying Formation are the main exploration and development targets.
(2) The karst fissure hot water of CAMBRIAN-Ordovician carbonate rocks is the main target layer for exploration and development in Luxi geothermal area south of Qihe-Guangrao fault and east of Liaocheng-Lankao fault. While exploring and developing the geothermal water of Paleogene Guantao Formation in Chengning Uplift, Linqing Depression and Jiyang Depression Uplift, we can also take into account the exploration and development of karst fissure-cave geothermal water in Ordovician-Cambrian carbonate rocks in Lower Paleozoic. Near the junction of uplift and depression in the geothermal area of western Shandong, and the intersection of NW-trending, NE-trending and SE-trending neotectonic faults that control the depression should also be the focus of exploration.
(3) The geothermal area in eastern Shandong is explored and developed into a hot spring intensive area in Jiaobei Uplift and the northern margin of Jiaolai Basin, and a limestone and marble area in Yuanguyu underlying Jiaolai Basin.
(4) The exploration and development of the geothermal area in Yishu fault zone mainly focus on the edge of depression and ideal structural parts, early Cambrian metamorphic granitic rocks, Mesozoic thick igneous rocks and sand shale, and pay attention to the banded areas near both sides of Yishu fault zone.
5.3 Geothermal resources development and utilization evaluation
Geothermal resources in Shandong Province belong to medium-low temperature hot water type, which is suitable for direct development and utilization. However, due to the difference of water quality and quantity, it has different uses in direct utilization. In the geothermal-rich northwest of Shandong Province, the temperature of the lower member of Neogene Minghuazhen Formation is low, generally 35 ~ 45℃, and the water quality is good, with the salinity of 1 ~ 2g/L, which can be directly used for domestic water and industrial and agricultural water. The hot water temperature of Neogene Guantao Formation is 45 ~ 70℃, and the salinity is 2 ~15g/L. It is rich in many trace elements beneficial to human health, which are suitable for both water and heat, and can be used for comprehensive utilization such as heating, bathing, recuperation, greenhouse planting and aquaculture. The karst fractures in Dongying Formation and Ordovician-Cambrian carbonate rocks have high hot water temperature and high salinity (5-20 g/L salt water), and are rich in trace elements and radioactive elements such as radon, which are beneficial to human health, and are suitable for both water and heat. Focus on the development and utilization of medical care, hot spring vacation, heating, planting and breeding and industrial processes. In other areas, due to the small amount of geothermal resources and low corresponding heat, most of them are natural hot springs, which are generally suitable for spa treatment except for some areas that meet the heating requirements.
Countermeasures and suggestions on exploration, development, utilization and protection of geothermal resources
The exploration, development and utilization of geothermal resources in Shandong Province are in a partial and sporadic initial stage. With the reform and opening up and the rapid development of social economy in this area, the level of urban modernization in this area has been continuously improved, and geothermal energy, as a kind of green energy, has higher and higher development and utilization value. The exploration and development of geothermal resources should focus on cities and key economic development zones, and carry out key exploration and development experiments to provide demonstration experience for the comprehensive development and utilization of geothermal resources in the province.
(1) correctly understand the characteristics of geothermal resources. Geothermal resources are formed under specific geological, structural, hydrogeological and hydrogeochemical conditions. Because of its deep burial, long supply route and weak regeneration ability, its resources are limited, not inexhaustible. It is necessary to maintain long-term, sustained and stable exploitation of its resources, realize planned and reasonable development and utilization, and prevent resource loss and environmental geological problems caused by blind and disorderly exploitation. Therefore, we must attach importance to and do a good job in the protection of geothermal resources.
(two) to formulate and strictly implement the development, utilization and protection plan of geothermal resources. In order to develop, utilize and protect geothermal resources scientifically and reasonably, its development and utilization should follow the principle of paying equal attention to open source and throttling, development and protection; According to different uses, the geothermal resources are mined and managed by layers.
(3) The exploration, development and utilization of geothermal resources should be closely combined with the construction of ecological province, urban environmental protection, tourism development and the development of efficient ecological agriculture. Through the development and utilization of geothermal resources, we can improve and protect the environment, stimulate economic development, promote consumption and improve people's living standards.
(4) The exploration, development and utilization of geothermal resources should implement the comprehensive development and utilization policy of "combination of exploration and mining", "cascade development and multi-use of one water", and adhere to the principle of "easy first, then difficult, shallow first, then deep, and combination of depth and depth". Focus on the exploration and development of the central city of geothermal area in northwest Shandong province, which is rich in geothermal resources, concentrated in thermal anomalies and superior in transportation location. Strengthen the research on geothermal development and utilization, and develop bathing, medical care, aquaculture and tourism based on the development of geothermal resources. Make full use of abandoned oil wells in petroleum exploration and development to develop geothermal resources, and on the basis of comprehensive research, find feasible technical methods and routes to transform some abandoned oil wells into hot water wells.
(5) Establish geothermal reserves. According to the needs of economic development and people's life, the rational exploitation scheme and environmental protection scheme of geothermal resources are formulated. In the process of development, it is necessary to formulate well layout plans according to the burial and distribution of geothermal resources, strictly follow the recoverable amount of hot water, and prevent environmental geological problems such as resource depletion and land subsidence caused by over-exploitation.
(6) Strengthen the dynamic monitoring of geothermal resources development. Geothermal resources are limited, and the regeneration ability is weak. In the process of mining, its water level, water quantity, water quality and water temperature will change with the mining process. In order to monitor the dynamic information of geothermal resources development in time and avoid environmental geological disasters such as land subsidence and hot water resource depletion caused by over-exploitation, we should strengthen the dynamic monitoring of geothermal resources development.