高温岩体地热开发的技术经济评价

介绍了对美国Fenton Hill(芬登山)地区高温岩体地热开发所作的投资分析，以及应用MIT经济模型进行的高温岩体地热发电开发成本的预测与评价。研究认为，高温岩体地热资源从技术上来说是重要的潜在能源，但钻井技术和人工储留层的建造技术是阻碍其商业发展的关键因素；目前高地温梯度的高温岩体地热发电已具有商业竞争力，采用先进的线性钻井技术后，将使所有等级的地热梯度的高温岩体地热发电电价具有商业竞争能力。     

Borehole measurements in the field of hot dry rock experiments

The logging group examined the value of different types of borehole logging in the context of HDR developments and considered the limitations of current techniques and the scope for further development. They recommended that the main development effort should concentrate on methods of fracture detection, both at the borehole wall and in the far field. They further recommended that such work would best be done as part of a collaborative international effort.     

Introduction: Background to the workshop

A joint EEC-US Workshop on Hot Dry Rock was held in Brussels in May, 1986, bringing together invited specialists from all the HDR research teams in the European Community with their counterparts from the USA and Japan. After presenting progress and plans for HDR within their own projects, the delegates held specialist discussions on drilling and well completion, logging and formation characterisation, microseismic monitoring, stimulation and flow processes in fractured granitic reservoirs and the geochemistry of HDR systems. The papers arising from the Workshop form the content of this Special Issue.     

Current status of seismic and borehole measurements for HDR/HWR development

Seismic and borehole measurements provide significant information about HDR/HWR reservoirs that is useful for reservoir development, reservoir characterization, and performance evaluation. Both techniques have been widely used during all HDR/HWR development projects. Seismic measurements have advanced from making passive surface measurements during hydraulic fracturing to making passive observations from multiple boreholes during all phases of HDR/HWR development, as well as active seismic measurements to probe regions of the reservoir deemed to be of interest. Seismic data provide information about reservoir extent, locations and orientations of significant fractures, and areas of thermal drawdown. Recent advances include the ability to examine structures within the seismically active zone using statistics-based techniques and methods such as seismic tomography. Seismic method is the only means to obtain direct information about reservoir characteristics away from boreholes. Borehole measurements provide high-resolution information about reservoir characteristics in the vicinity of the borehole. The ability to make borehole measurements has grown during the course of HDR/HWR development as high temperature tools have been developed. Temperature logging, televiewer logs, and electrical property measurements have been made and shown to provide useful information about locations of fractures intersecting wellbores, and regions where water leaves and enters injection and production wellbores, respectively.     

The Soultz-sous-Forets project

Research teams from France and Germany will collaborate in the drilling and testing of an exploration borehole at Soultz-sous-Forêts, in the Upper Rhine Valley. At this site, fractured granitic basement lies beneath a well-characterised sedimentary sequence some 1300 m thick, and a marked thermal anomaly is observed within these sediments. The borehole will penetrate about 500 m into the basement, with the aim of identifying the cause of the thermal anomaly and assessing the suitability of the site for subsequent HDR experimentation and development.     

增强型地热系统热开采过程的数值模拟研究

增强型地热系统（EGS）是指采用人工方法在地下3 ~ 10 km内的干热岩体中形成储层、通过灌输采热流体以开采出干热岩中热能用于地面发电的地热利用系统,是一种极富潜力的可再生清洁能源利用技术。循环流体在地下热储中的流动与换热对EGS的采热性能有重要影响。本文首先对EGS数值模型进行了综合评述,然后基于一套自主开发的三维瞬态数值模型模拟了不同渗流条件下EGS地下热储内的热流过程。通过对模拟结果的分析,揭示了均匀压裂的人工热储中流体短路的形成机理,并通过对比双井和三井系统中流场和局部地热开采率分布,结合当前钻井工艺和裂隙激发技术水平,探讨了抑制流体短路、优化EGS采热性能的可能方案。     

Monitoring and interpretation of seismic observations in hot dry rock geothermal energy systems

As the value of microseismic monitoring during development of HDR reservoirs is already proven, the discussion group concentrated on assessing what further improvements might be made. They suggested improvements both to the receivers and to the methods of analysis, with particular reference to the derivation of different source mechanisms from the signals received.     

Present status and remaining problems of HDR/HWR system design

HDR/HWR can be one of the major sources of energy for the world in the 21st century because of the size of HDR/HWR resources and the environmental benefits offered by clean HDR/HWR energy. Over the last 25 years, significant advances have been made in the creation and operation of stimulated reservoirs, but little is yet known about the details of joint structure within the body of the reservoir. Continued developments and improvements to the technologies that support HDR/HWR development are essential to increase our understanding of these reservoirs.     

Field characterization for HDR/HWR: a review

Field characterization for HDR/HWR entails a number of studies in various academic fields prior to, or at the initial stage of HDR/HWR development. Although guidelines are not yet well defined, field characterization will be important for the efficient progress of HDR/HWR research on both a laboratory and field scale. The decision might be taken to stop a project based on new knowledge obtained during development in order to minimize the total risk of the project. This paper is an overview of field characterization in HDR/HDR research throughout the world since 1982. The HDR/HWR field experiments, temperature of the targets, regional and local geology, evaluation of fracture distribution in the exploration stage, and geochemistry for reservoir maintenance, will all be reviewed.     

Hot dry rock geothermal energy in Japan: Developments by Miti and Nedo

For the last ten years, MITI and NEDO have been supporting field work in Japan aimed at developing techniques of HDR reservoir creation. Early work was performed at 300 m depth at Yakedake and, more recently, two existing 1800 m boreholes have been acquired at Hijiori; the bottom hole temperature on this site exceeds 250°C. Plans are in hand for hydraulic fracturing aimed at reservoir creation.     

Stress and rock mechanics issues of relevance to HDR/HWR engineered geothermal systems: review of developments during the past 15 years

This paper reports the findings of the Stress and rock mechanics working group of the Academic Review of Hot Dry Rock/Hot Wet Rock (HDR/HWR) Engineered Geothermal Systems convened in Sendai, Japan in 1997. Key developments in the fields of stress and rock mechanics that are relevant to the development of HDR/HWR systems and that have occurred since the last Academic Review in 1982 are described. Rock mechanics is here taken to include basic studies of fluid flow through fractures. Key unresolved issues that are important for HDR/HWR systems are also discussed.     

高温岩体圈定的思路与方法探讨

高温岩体地热资源开发利用首先要解决的是在目前技术和经济条件下可以开发利用的高温岩体分布地区和赋存深度及规模。提出了高温岩体圈定的基本思路应该是在对高温异常区的岩石类型及分布、断裂构造格架及其活动性、火山活动和岩浆侵入的类型及时代等基础地质研究的基础上,并充分利用地球物理探测技术、遥感技术、地球化学方法,配合少量深钻验证工程来进行。特别强调了在高温岩体地热资源圈定和评价中多种方法和技术的相互配合、相互补充、相互验证。     

Renewable hot dry rock geothermal energy source and its potential in Pakistan

Geothermal energy source, one of the viable renewable energy sources, has encouraging potential to generate full base-load electricity, which has not been explored so far in Pakistan. Though the country can be benefited by harnessing the hydro-geothermal options of energy generation in areas where sources exist, but most of these sources lie in extreme remote and inaccessible rugged mountainous ranges away from the urban-industrial centers. On the other hand, the present study shows that the HDR geothermal option is one of the most viable renewable sources considering the tectonic setup of Pakistan. Results of the study highlight the HDR geothermal energy prospects at relatively deeper depths than hydro-geothermal resources in water-free condition. The basement tectonic analyses reveal that the HDR prospects could be found even just below the urban-industrial centers of Pakistan where there are no hot springs and/or geysers like southern Indus basin in Sindh province or the Kharan trough in the western Balochistan province. Presence of high earth-skin temperature gradient trends derived from satellite temperature data and the high geothermal gradient anomalous zone derived from scanty data of bottom-hole temperatures of some of the oil and gas exploratory wells, indicates encouraging prospects for HDR energy sources in southern Indus and Thar Desert regions inclusive of Karachi synclinorium area. These high geothermal gradients have been inferred to be the result of the deep-seated southern Indus and the Thar fossil-rift structures. Moreover, the prospects of the HDR geothermal energy sources have also been inferred in the Chagai Arc region and the Kharan–Panjgur tectonic depression in the western part of Pakistan based on the analysis of integrated geophysical data. If HDR prospects are developed, they can offer the sustainable, CO₂-free and independent of time, of day, of weather or season, and the base-load energy-generation resource.     

塔深1井超深井井斜控制技术应用分析

塔深1井设计井深8000m,完钻井深8408m．首次在塔河油田钻探寒武系地层,没有可供借鉴的经验。在钻井过程中．借鉴以往的防斜打直技术,不断探索和完善,解决了钻具组合和钻井参数配合、超深井段动力、液力有效传递等问题．特别是在五开井段6800-8408m超深井段钻探中取得了宝贵经验,对以后再进行超深井钻井以及井斜控制技术具有一定的借鉴意义。     

河坝构造复杂工程地质问题与安全优快钻井技术对策

河坝构造钻井工程难度大,存在漏、塌、卡、涌、毒、硬、斜等问题,钻井效率低、周期长,需要在工程地质特征基础上,提高钻井工程工艺的针对性。本文在岩石力学实验基础上,建立工区岩石力学参数剖面,表明该构造地层岩石致密,抗压强度、抗剪切强度、硬度大,可钻性差。根据地层孔隙压力、坍塌压力、破裂压力剖面,开展井壁稳定性分析,表明该区纵向多压力系统,陆相地层坍塌压力高,易井壁失稳;海相地层异常高压,安全钻井液密度窗口窄,井壁力学稳定性差。结合工程地质特征,提出优化井身结构设计,优选气体钻井、泡沫钻井、垂直钻井、复合钻井、旋转导向钻井等钻井技术,优选钻头型号,优选钻井液,优选防漏堵漏技术等钻井对策。现场实钻证实,上述对策大幅提高了机械钻速,有效减少了钻井复杂情况,大幅缩短了钻井周期,实现了河坝构造海相超深气井优快钻井。     

影响元坝气田超深井钻井提速的工程地质因素及技术对策

元坝气田工程地质特征异常复杂,钻井难度大,存在井漏、井涌、卡钻、井塌、高含硫化氢、高压水层等工程地质复杂问题,钻井效率低,周期长,建井成本高.从油气藏的基本地质特征、岩石力学性质、井壁稳定性等方面,分析认为,储层埋藏超深,钻遇地层岩性复杂、储层特征多样、油气立体成藏、油气水分布复杂、各油气藏特征差异大,岩石致密、强度大、可钻性差,异常高压-超高压、纵向多压力系统、井壁力学稳定性差、安全钻井液密度窗口窄,是钻井提速的工程地质影响因素.结合工程地质特征,提出了优化井身结构设计,优选空气钻井、泡沫钻井、液体欠平衡钻井、“螺杆+PDC钻头”和“涡轮+孕镶金刚石钻头”复合钻井、旋转导向钻井等钻井技术,以及优选高效钻头,优选钻井液体系等钻井提速技术对策,能够满足元坝气田海相超深井安全、快速钻井的需要.     

二连宝饶油田水平井地质导向技术分析研究

在水平井钻进过程中,地质导向技术是保证井眼顺利着陆,并在油层中水平穿行一定距离的关键技术。结合二连宝饶油田6口水平井的钻井实践,探讨了利用随钻测井技术、综合录井技术,建立“导眼法”地质导向方法,采用“大波浪法”控制井眼轨迹,在现场及时指导钻进方向,实现准确着陆、保障井眼轨迹尽可能多地位于油层中,在现场实践中效果显著,对今后的水平井施工具有重要的现实意义。     

Modelling of a european prototype hdr reservoir

The European Hot Dry Rock Geothermal Energy Project, located in the Rhine graben at Soultz-sous-Forets, Alsace, France, is entering a new phase in its development. Over the next few years the existing HDR system will be developed to form an operational Scientific Prototype HDR System. This paper provides an introduction to the collaborative reservoir modelling studies undertaken as part of the European Programme. In particular the paper addresses the general methodology adopted in the reservoir design process and focuses on one of the preliminary objectives of the study, assessment of the minimum HDR doublet separation required to meet the thermal performance objectives during circulation. Two “preliminary reservoir designs” are adopted as starting points for the study, the first based on exploitation of large scale planar fractures, the second on the development of a modular (multi-cell) system based on 3 cells supporting 51/s production each. Estimates were obtained using models based on both idealised geometry and empirical observations of reservoir circulation at the Camborne School of Mines (CSM) HDR project. The results indicate that a wellbore separation of around 400m would be required for the multi-cell system to achieve the required thermal performance of 10% thermal drawdown, or less, during 10 years circulation at 151/s production. Whereas, the wellbore separation required for the single fracture design would be in excess of 650m.     

Progress in the HDR/HWR projects at Tohoku University, Japan

This paper presents an outline of the series of HDR/HWR projects conducted by Tohoku University since 1983, starting with the Γ-project, which was followed by the HWR, Fractal and MTC projects. The final goal of these projects is to establish/develop the design methodology for engineered geothermal reservoirs. A brief review of each project is also presented, with emphasis upon the progress of the main research topics, such as monitoring of reservoirs by active/passive acoustic techniques, rock mass properties, in situ stress, modeling and simulation and water/rock chemical interaction.     

Prediction of the SnO2-based sensor response for hydrogen detection by artificial intelligence techniques

SnO₂-based nanocomposites are reliable sensors to detect hydrogen leakage and satisfy safety protocols. Although the hydrogen detection response (HDR) of these sensors has been deeply studied in the laboratory, there are no models to estimate this parameter. Consequently, this study uses three machine learning classes (i.e., gene expression programming, support vector regression, and artificial neural network) to calculate the HDR of pure and Ag-, Co-, Pd-, Pt-, and Ru-decorated SnO₂ nanostructures. These models only need nanocomposite chemistry and operating conditions to estimate the HDR of SnO₂-based sensors. Comparing these models’ performance by the ranking analysis and spider-graph indicates the multilayer perceptron neural network is superior to the other models. This model shows the highest accuracy (regression coefficient = 0.9882, average absolute deviation = 2.74, and root mean squared errors = 8.05) for estimating the HDR of SnO₂-based sensors. This model also anticipates that Pd and Ru are the best and worst dopants to decorate the SnO₂-based sensors.