Characteristics, development and utilization of geothermal resources- a Nordic perspective

Geothermal energy is classified as a renewable energy source and it utilizes the heat generated in the earth primarily from the natural radioactive decay of isotopes of uranium, thorium and potassium. Heat is extracted from the earth to generate geothermal energy via a carrier, usually water occurring either in the liquid or steam phase. In the late 19th century and the early 20th century, the first developments of geothermal resources for power generation and household heating got underway successfully. Many of these geothermal fields are still being utilized today, proving their sustainability. Today geothermal energy is being utilized in more than 72 countries around the world and of the Nordic countries Iceland and Sweden have been in the forefront in each of their respective fields. While geothermal heat pumps are widely used for space heating in Sweden, geothermal energy covers 55% of the primary energy consumption in Iceland where it is used for space heating, power generation and industrial purposes. Future developments aim at expanding the range of viable geothermal resources by improving the capabilities to generate electricity from geothermal resources at temperatures as low as 100℃, as well as developing geothermal resources where water needs to be introduced, so-called hot dry rock resources. But the biggest expansion is expected to continue to be in the installations of geothermal heat pumps.     

The Statistical Prediction of the Vitrinite Reflectance and Study of the Ancient Geothermal Field in Songliao Basin,China

The resource of the gas from coal and coal measures deep in Songliao Basin hasbeen drawing more and more attention to.It is necessary to find out the evolution regulari-ty of the geothermal field of the basin in addition to a series of geological studies in orderto predict its resources because the ancient geothermal field of the basin is one of themain factors controlling the generation,evolution and disappearance of oil and gas.Inthe recent twenty years,it is generally believed that vitrinite reflectance is the best quanti-tative marker for the ancient geothermal field.In the present paper,a systematic studyof the vitrinite reflectance value of Songliao Basin and its influence factors is made by mul-tiple statistical analysis so as to reconstruct the evolutional process of the Moho and thecorresponding geothermal field.Then,an overall prediction is made of the vitrinitereflectance and the distribution of J_3-K_1 fault basin group at the bottom of SongliaoBasin,which provides the evidence for the furth     

Geochemical and Isotopic Techniques Constraints on the Origin, Evolution, and Residence Time of Low-enthalpy Geothermal Water in Western Wugongshan, SE China

Geothermal resources are increasingly gaining attention as a competitive, clean energy source to address the energy crisis and mitigate climate change. The Wugongshan area, situated in the southeast coast geothermal belt of China, is a typical geothermal anomaly and contains abundant medium- and low-temperature geothermal resources. This study employed hydrogeochemical and isotopic techniques to explore the cyclic evolution of geothermal water in the western Wugongshan region, encompassing the recharge origin, water–rock interaction mechanisms, and residence time. The results show that the geothermal water in the western region of Wugongshan is weakly alkaline, with low enthalpy and mineralization levels. The hydrochemistry of geothermal waters is dominated by Na-HCO3 and Na-SO4, while the hydrochemistry types of cold springs are all Na-HCO3. The hydrochemistry types of surface waters and rain waters are Na-HCO3 or Ca-HCO3. The δD and δ18O values reveal that the geothermal waters are recharged by atmospheric precipitation at an altitude between 550.0 and 1218.6 m. Molar ratios of major solutes and isotopic compositions of 87Sr/86Sr underscore the significant role of silicate weathering, dissolution, and cation exchange in controlling geothermal water chemistry. Additionally, geothermal waters experienced varying degrees of mixing with cold water during their ascent. The δ13C values suggest that the primary sources of carbon in the geothermal waters were biogenic and organic. The δ34S value suggests that the sulfates in geothermal water originate from sulfide minerals in the surrounding rock. Age dating using 3H and 14C isotopes suggests that geothermal waters have a residence time exceeding 1 kaBP and undergo a long-distance cycling process.     

Application of Organic Inclusions in Offshore Oil—Gas Exploration

Studies of organic inclusions from the offshore oil and gas fields provide much information about the number of times,temperature,depth,time and phase state of oil-gas migration,as well as about the composition of organic inclusions.On the basis of the type,character,composition and distribution of organic inclusions in the Zhu-Ⅲ Depression at the Pearl River Mouth,information can be developed about the source rocks of oil and gas,and their evolution and migration.     

我国建立第一个地热资源数据库

Demonstrative geothermal resources data-base consists of 3 subsystems ; 1) Geotemperature&rock thermo一physical property ; 2 ) Hydrogeological testing parameters of thermal water&thermal water sites;3)Chemical composition of thermal fluids in geothermal areas. Data-base system is accompanied with software set including various programs for calculation on geothermal gradient, radioactive heat productivity and hydrogeological parameters,for identification of thermal water chemical type,for comparision of different geothermometers and for ploting lithological colum，geotherms , histograms ofthermal conductivity&. heat productivity, chemical composition of thermal waters, isotherms as well as curves of water table and flow rate.
     

中国地热资源研究的进展

Based on recent year's advances of 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一Cenozonic sedimentary basins,suggests that two hydrothermal activity concentrated zones (S Tibet Autonomous Region-W Sichuan Province-W Yunnan Province and coastal area of SE China)，one large basin (North China Basin) and two smaller basins (Weihe Basin and Leiqiong Basin) are major areas of studies and explorations of geothermal resources in China continent, corysiders that geothermal resources in China have certain potential of exploitation and should be used，but thescale of exploitation seems to be limited, they cannot occupy an importan position in energy supply and can only be regarded as a supplementary energy source.     

Geologic Features of the Petroleum-rich Sags in the Bohai Bay Basin

More than 40 years have been passed since exploration and development of oil-gas began in the Bohai Bay Basin. Though we have faced with many difficulties during our exploration, exciting discoveries in petroleum-rich sags have been made in recent years. Studies show that the petroleumrich sags are characterized by multiple sets of oil-gas accumulation in the pre-Eogene to Neogene strata in profile and large-area connection or superimposition of oil-gas reservoirs in different strata. Therefore, petroleum-rich sags continue to be a focus of future oil-gas exploration in the Bohai Bay Basin. There is still a great potential of petroleum resources. Inshore and offshore areas, onshore stratigraphic reservoirs, high-precision exploration in old oilfields, reservoirs inside buried hills, and volcanic reservoirs will contribute a lot in increasing the annual oil-gas production and reserves in the basin.     

西藏羊八井地热水的氢、氧稳定同位素组成及氚含量

Isotopic data on drill hole water and surface water samples from the Yengbajain geothermal area as well as an ice sample from the glacial amphitheater in the Mt. Nyainqintanglha to the northwest of the Yangbajain basin are presented in this paper. In consideration of isotopic fractionation during steam separation, the hydrogen and oxygen isotopic ratios for thermal waters collected at the mouths of drill holes have been calibrated. The D/H ratio of thermal waters is similar to that of local precipitation, indicating their meteoric origin. The δ D and δ^18O values of the thermal waters of --150--160 and -17-20‰, respectively are the lowest among those well-known geothermal fields in the world.The recharge area of the geothermal system is at elevation of about 4,800--5,000 m. Drill holes along the axis of a tongueshaped zone where loose Quaternary sediments have been cemented by siliceous material show greater δ D and δ^18O values and discharge tritiumfree thermal waters. It is suggested that the thermal waters may be derived from superhcated water and steam which find their way upwards along the tectonic fractures within the granitic base overlain by Quaternary sediments. The classification of drill hole geothermal waters have been made in accordance with their δ D and δ^18O values and chloride contents. The “oxygen shift” of the thermal waters seems to be 2‰, due to isotopic exchange reactions between geothermal waters and reservoir rocks     

Genetic Classification of Natural Gases in the Oil—Gas Zone and Its Application in the Sichuan Basin

On the basis of the carbon isotopic compositions of methane(CH4) and its homologues and the differences in isotopic values for CH4 and ethane (C2H6) and the correlation and compositional char-acteristics of hydrocarbon gases, the author has proposed a genetic classification of natural gases in the oil-gas zone.They are classified as biogenetic and abiogenetic gases in terms of the types of hydrocarbon-generating precursors (or parent materials) and their thermal evolution stages.Biogenetic gases can also be further divided into two series: biochemical and thermochemical gases,with the lat-ter formed at different evolution stages.Gases generated from type-I and -II1 organic matter are called oil-series gases, those from type-III, coal -series ,and those type -II2,mixture-type gases.Gases generated from two or more than two types of precursors are called mixture-source gases.According to those mentioned above, natural gases from the major oil-gas pools in the Sichuan Basin have been discriminantly analyzed,and the results are concordant with the distribution and de-velopment of hydrocarbon-source rocks as well as with their characteristics, indicating a prospective application.     

李四光教授倡导的中国地热研究

李四光教授是中国地热研究的倡导者,作者以中国科学院地质研究所地热室近20年来的研究工作为基础,从大地热流、深部地热、区域地温场、地热数学模拟、地热实验和分析测试系统、地热资源、矿山地热以及油田地热等八个方面阐述了我国地热研究的进展,以资缅怀和纪念李四光教授诞生100周年。     

大港探区前第三系显微荧光分析及油气运聚特征研究

对大港探区中区岩石粒间油气成因的显微迹象进行了荧光显微分析 ,对该区油气生成、运移、聚集及成藏规律进行了研究 ,并对油气资源进行了评价。结果表明 ,港古井区油气运聚具有上下小、中间井段相对大的规律 ,反映出本区生产的油气可能来自侧向运移 ,而具规模性的油气运聚主要发生于中间井段 ;而扣井区油气运聚则表现出明显不同成熟度的油气从下向上的纵向运移特征。表明岩石矿物粒间油气成因的显微迹象荧光特征研究是评价油气藏的一个重要补充 ,具有良好的应用前景     

过渡际与多因复成油气藏

在中国油气域中，多因复成油气藏占有相当重要的地位，它主要分布于过渡际（包括壳体演化阶段转换期及正负构造单元过渡带）中。主要原因有四个方面：①过渡际中具备集结多渠道油气源条件，空间过渡际者尤为突出，②过渡际中发育有自成系统的油气运移通道网络，可将多个油气源的油气汇聚于同一圈闭之中；③过渡际中存在形式多样的圈闭类型；④过渡际中具有多种类型的储盖组合。此外，空间过渡际中的地温场往往较高也是一个重要因素。值得指出的是，压性环境和张性环境的过渡际状况有所不同，因而，各自的成藏条件、油气藏类型和油气聚集带的展布方式亦有较大的差异。     

塔西南高精度航磁油气地质构造调查

受勘探难度大和地震品质差等诸多影响,塔里木盆地西南地区(简称塔西南)的油气资源勘探历经数十年,至今尚未获得实质性重大突破。本文根据近年来在塔西南实测的高精度无人机航空磁测数据资料,针对盆地的基底结构、凹陷分布及特征,主要断裂构造及其对油气运移、聚集的控制规律,局部异常与含油气有利圈闭构造及其分布特征等与油气成藏相关的地质问题进行了探讨,取得了一些认识,成果可为塔西南进一步开展油气勘探战略选区及深部资源评价提供了重要参考。     

贵州地区油气勘探反思

文章简单回顾了贵州40余年油气勘探历史，较客观地评价了贵州地区油气地质条件，提出了符合贵州石油地质条件的油气勘探方针，指出贵州油气勘探要想有所突破应注重研究油气成藏机制，勘探重点应放在浅层气藏成藏领域上。     

柴达木盆了立体地质与油气预测

笔者在柴达木盆地进行3次野外地质调查，收集并参考了大量资料，编绘了柴达木盆地地质图、纵横剖面图、构造等高线图、等厚度图和不同深度地质图，借以研究盆地地下地层、构造、湖盆演化历史，并对古生代海相油源和含油区、中侏罗世油源和中新生代含油气区及油气田进行预测。     

过渡际油气藏及其形成条件分析

过渡际是油气藏形成的特殊场所，原因在于过渡际中物质基础雄厚。地温场较高、储盖组合配置得当、有自成系统的油气运移通道网络以及存在多种圈闭类型。     

鄂尔多斯盆地下寺湾地区三叠系延长组油气富集规律

通过对下寺湾地区延长组沉积特征及演化、油气的生成条件、储层特征、油气的运移、圈闭条件及圈闭类型的综合研究,系统地分析了下寺湾地区延长组油气的富集因素和分布规律。     

论塔里木盆地形成大油气田的地质条件

塔里木盆地的油气勘查工作已有40年的历史,取得了丰富的地质资料和油气成果。特别是1984年塔北沙参2并获高产油气流,实现了我国古生代海相油气田的首次重大突破,而后,该盆地的油气勘查工作出现了新高潮。从1988年以来又连续实现了新构造、新层位上的新型油气藏的重大突破。笔者从油气资源、构造条件、成藏条件等方面论述该盆地形成大型——特大型油气田的地质条件。