| 基于工程开发原则的干热岩目标区分类与优选 |
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| 引用本文： | 何治亮,张英,冯建赟,罗军,李朋威.基于工程开发原则的干热岩目标区分类与优选[J].地学前缘,2020,27(1):81-93. |
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| 作者姓名： | 何治亮 张英 冯建赟 罗军 李朋威 |
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| 作者单位： | 1.中国石油化工股份有限公司, 北京 1007282.中国石油化工股份有限公司 石油勘探开发研究院, 北京 100083 |
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| 基金项目： | 国家重点研发计划项目(2019YFC0604903);中国工程院咨询研究项目(2019-XZ-35);国家自然科学基金重点基金项目(91755211) |
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| 摘 要： | 干热岩(HDR)是指不含或仅含少量流体,温度高于180 ℃,其热能在当前技术经济条件下可以利用的岩体。作为一种重要的非常规地热资源,干热岩的开发利用可以借鉴页岩油气的成功经验,采用相似的技术发展路径,找到“地热甜点”,开发出低成本且高效的钻完井技术,逐步形成和完善技术体系,建立与对象相适应的生产运行模式,以期实现对这种巨大资源的有效开发利用。增强型地热系统(EGS)被认为是干热岩资源开采的一种重要方式。EGS最初被称为工程型地热系统,后来才统称为增强型地热系统,是指通过实施特殊的工程工艺,改善地层储集性能或(和)向地层中注入流体,以实现对地热资源的有效开发。其基本方法原理为在干热岩体内钻两口或多口井,将低温流体通过注入井注入干热岩体的天然裂缝系统,或注入通过压裂技术在钻井之间建立的具有水力联系的人工裂缝中加热,通过吸收干热岩内所蕴含的热能,将流体温度提高到一定程度后从生产井采出至地表或近地表进行利用,形成人工热交换系统,用于发电或取暖等。采用EGS技术开发干热岩地热资源,选区选址恰当与否是能否取得成功的最关键环节之一。中深层地热资源可分为水热型和干热岩型两大类、五亚类。其中,干热岩根据其热储孔渗条件差异又可分为无水优储、无水差储和无水无储三亚类,适合作为EGS开发对象的干热岩资源为其中的无水优储和无水差储两种类型。五类地热资源规模呈金字塔形,开发技术难度逐渐增加。基于由热储埋深、热储温度、热储岩性、热储物性、盖层厚度、盖层断裂发育条件等组成的地质资源条件,由钻探成井技术、储层改造技术、管理运营技术组成的工程技术条件,以及由地热需求和资源经济性组成的经济市场条件三个因素,本文建立了三因素分析与多层次指标分解法相结合的干热岩EGS选区评价方法和关键指标,在国内干热岩资源条件较好的17个候选区中,优选出西藏羊八井高温地热区和渤海湾盆地济阳坳陷潜山分布带作为EGS试验有利区。
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| 关 键 词： | 地热资源 干热岩 选区选址 羊八井 济阳坳陷 |
| 收稿时间： | 2019-06-20 |
Classification of geothermal resources based on engineering considerations and HDR EGS site screening in China |
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| HE Zhiliang,ZHANG Ying,FENG Jianyun,LUO Jun,LI Pengwei.Classification of geothermal resources based on engineering considerations and HDR EGS site screening in China[J].Earth Science Frontiers,2020,27(1):81-93. |
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| Authors: | HE Zhiliang ZHANG Ying FENG Jianyun LUO Jun LI Pengwei |
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| Institution: | 1. China Petroleum and Chemical Corporation, Beijing 100728, China2. Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China |
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| Abstract: | In the context of geothermal energy, hot dry rock (HDR) is naturally heated crustal rock with a temperature above 180 ℃ that has little fluid and therefore can provide commercially useful thermal energy. HDR exists everywhere at varying depths. When its temperature not high enough for electricity generation, it often can supply sufficient heat for a variety of direct uses such as space heating and food or chemical processing. If only a small fraction of its thermal reserve can be accessed routinely with existing drilling methods, it would represents an essentially inexhaustible supply of heat, potentially capable of contributing substantially to the world's energy needs. As one of the essential unconventional resources, exploration and production of HDR resource can duplicate the success of shale oil and gas by using mature technologies such as hydraulic fracturing, drilling and completion techniques, reservoir engineering and so on. Although a wide variety of methods can be suggested for extracting energy from hot dry rock, the simplest—probably the most economical—one is to imitate nature by circulating water through it. Usually this will require somehow creating connected pores within the hot rock with enough exposed surface so that heat can be extracted by circulating water at useful high temperatures and rates over long periods of time. Again, a variety of methods can be suggested for producing the required flow passage and heat-transfer area, of which, hydraulic fracturing, i.e., enhanced or engineering geothermal system (EGS) technology, is the chosen one for the initial investigation in HDR program. During exploration of HDR geothermal resources by EGS technology, site screening is one of the most crucial step leading to ultimate success. The overall goal of the EGS program is to demonstrate the commercial feasibility of geothermal energy derived from hot dry rock. Therefore, its principal objectives are to confirm that the potential HDR resource is indeed large and accessible, develop a commercialized technology base for extracting the energy therefrom, and verify that the environmental and social consequences of HDR development are acceptable. On the consideration of resource, engineering and economics of geothermal exploration, middle to deep geothermal resources can be classified into two types: hydrothermal and HDR. The latter constitutes dry quality reservoir, dry inferior reservoir and dry non-reservoir rocks, according to reservoir porosity and permeability. The dry quality and inferior reservoirs are most suitable for ESG technology applications. The amount of natural reserves for the five geothermal resources are pyramid-like and with exploration difficulty increasing from top to bottom. Far more common, at depths of high rock temperatures, the combination of temperature, pressure and mineral deposition reduces any pre-existing permeability to a value too low to permit natural formation of an exploitable hydrothermal reservoir. This is a typical HDR situation. Occasionally, however, because of some geologic barrier, a hot permeable formation is not reached by the ground-water circulation thus unproductive of geothermal fluids. In this situation, permeability may vary widely, but usually is very low. Based on considerations of geological resources including burial depth, temperature, lithology and physical properties of the reservoir, thickness and fault development of caprock, engineering technology such as drilling and completion techniques, reservoir deformation, management and operation, and market requirement and economy, we propose an evaluation method and key indices for EGS site screening by combining tri-factor analysis and multi-tier index calculation. To test and verify this method, we selected 17 candidate regions in China with HDR geothermal resource advantages for HDR EGS site screening. After evaluation and optimization, we determined that the Yangbajing high-temperature geothermal region in Tibet and the buried hill geothermal region of the Jiyang depression in the Bohai Bay basin are among the best successful candidates for the superior zones for EGS testing. |
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| Keywords: | geothermal resource HDR (hot dry rock) site screening Yangbajing Jiyang depression |
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