青海共和盆地干热岩赋存地质特征及开发潜力

青海共和盆地贮藏有丰富的干热岩地热资源。为提升共和盆地干热岩地热资源成因的理论认识,进一步推动干热岩资源的勘探,文章从共和盆地干热岩热源机制、盖层条件、储层特征等方面对共和盆地干热岩资源成因件进行了全面分析。首先,结合区域地质构造分析、地热地质调查、地球物理（航磁、地震）解译等手段,在共和盆地恰卜恰岩体内实施了4口深度为2927~3705 m的干热岩勘查孔,并在3705 m处钻获236℃的优质干热岩资源,为中国非现代火山区干热岩地热资源勘探的首个重大突破。其次,系统测试了钻孔不同深度花岗岩放射性,结果表明,共和盆地花岗岩体铀、钍、钾放射性含量略高于大地背景值,放射性生热率较低,对干热岩热源的贡献小,其热源可能来自壳内熔融体。第三,基于地质资料分析和航磁解译,圈定了共和盆地总体面积约1.4×104 km2的潜在干热岩分布区。最后,采用体积法评估了共和盆地干热岩资源潜力,结果表明,共和盆地3.0~6.0 km深度范围保守的、静态干热岩资源总量为8974.74×1018 J,换算标准煤可达3066.19×108 t,具有广阔的开发利用前景。      

Heat Aggregation Mechanisms of Hot Dry Rocks Resources in the Gonghe Basin,Northeastern Tibetan Plateau

Hot dry rock (HDR) is an important geothermal resource and clean energy source that may play an increasingly important role in future energy management. High-temperature HDR resources were recently detected in deep regions of the Gonghe Basin on the northeastern edge of the Tibetan Plateau, which led to a significant breakthrough in HDR resource exploration in China. This research analyzes the deep temperature distribution, radiogenic heat production, heat flow, and crustal thermal structure in the Qiaboqia Valley, Guide Plain, and Zhacanggou area of the Gonghe Basin based on geothermal exploration borehole logging data, rock thermophysical properties, and regional geophysical exploration data. The results are applied to discuss the heat accumulation mechanism of the HDR resources in the Gonghe Basin. The findings suggest that a low-velocity layer in the thickened crust of the Tibetan Plateau provides the most important source of constant intracrustal heat for the formation of HDR resources in the Gonghe Basin, whereas crustal thickening redistributes the concentrated layer of radioactive elements, which compensates for the relatively low heat production of the basal granite and serves as an important supplement to the heat of the HDR resources. The negative effect is that the downward curvature of the lithospheric upper mantle caused by crustal thickening leads to a small mantle heat flow component. As a result, the heat flows in the Qiaboqia Valley and Guide Plain of the Gonghe Basin are 106.2 and 77.6 mW/m2, respectively, in which the crust-mantle heat flow ratio of the former is 3.12:1, indicating a notably anomalous intracrustal thermal structure. In contrast, the crust-mantle heat flow ratio in the Guide Plain is 1.84:1, which reflects a typical hot crust-cold mantle thermal structure. The Guide Plain and Zhacanggou area show the same increasing temperature trend with depth, which reflects that their geothermal backgrounds and deep high-temperature environments are similar. These results provide important insight on the heat source mechanism of HDR resource formation in the Tibetan Plateau and useful guidance for future HDR resource exploration projects and target sites selection in similar areas.     

共和盆地壳内部分熔融层存在的地球物理证据与干热岩资源区域性热源分析

新生代以来,共和盆地及其周缘造山带无火山、岩浆活动,印支期隐伏花岗岩体岩浆余热与放射性元素衰变生热等难以构成共和盆地干热岩资源的主要热源,而共和盆地又为一高温地热异常盆地.目前已基本探明了共和县恰卜恰与贵德县热水泉干热岩体2处,圈定出干热岩勘查目标靶区16处.区域重力和区域航磁调查、区域天然地震成像、盆地尺度天然地震背景噪声层析成像勘查,以及超高分辨率重力异常、电阻率与Rayleigh波群相速度线性反演结果均表明共和盆地下伏发育有壳内部分熔融层,进而构成地处板内环境、高热流区共和盆地干热岩资源的区域性热源.盆地尺度MT勘查结果表明,共和盆地西盆地壳内部分熔融层埋深15~35 km,东西向长约41 km,南北向宽约34 km,厚度2~12 km.综合分析认为,该部分熔融层熔融程度最高可达4%~7%,15 km深处温度约为574℃,主体位于贵南南山推覆体系与共和准推覆体系深部主拆离滑脱推覆界面之下,兴海大型复合推覆体系主拆离滑脱推覆界面之上.挽近地质时期深构相、多层次、近水平展布的韧性拆离滑脱推覆构造界面的连续动态剪切摩擦生热,可能是部分熔融层形成的主要因素.      

Discussion on heat source mechanism and geothermal system of Qinghai Gonghe-Guide Basin

The Qinghai Gonghe-Guide Basin together with the alternatively distributed mountainous region shows characteristics that the conductive geothermal resource of the basin has high geothermal gradient, the granite occurs in the bottom of borehole for geothermal exploration, and the convective hot springs in the basin-edge uplift fracture are in zonal distribution and with high-temperature geothermal water. There are still some divergences about the heat source mechanism of the basin. In this paper, queries to the view of mantle-derived heat source have been put forward, coming up with geochemical evidences to prove that the radiogenic heat of granite is the heat source within the mantle. Additionally, temperature curve is drawn based on the geothermal boring and geochemical geothermometer has been adopted for an estimation of the temperature and depth of the geothermal reservoir, it has been found that the surrounding mountains belong to the medium-temperature geothermal system while the area within the basin belongs to the high-temperature geothermal system with the temperature of borehole bottom reaching up to 175-180 ℃. In this paper, discussions on the problems existing in the calculation of geothermal gradient and the differences generated by the geothermal system have been carried out.     

青海共和盆地结构构造与能源资源潜力

共和盆地处于西秦岭、南祁连、东昆仑造山带结合部,其中发现了高温干热岩及多套烃源岩,但地热藏和油气藏的成因、资源潜力与分布规律尚不清楚,难以对其开展准确评价和有效勘探开发。本文在系统研究共和盆地及周缘地层发育、沉积充填、构造变形与盆地深部结构的基础上,深入探讨了盆地演化的动力学机制,分析了盆地地热藏和油气藏的成藏主控因素,预测了有利分布区带和勘探方向。多期活动的哇洪山—温泉、多禾茂、瓦里贡、塘格木右行走滑逆冲断裂与青海南山左行走滑逆冲断裂异向、同向相交(切),叠加地幔上涌作用,导致在中新生代共和盆地长期处于走滑-伸展的独特环境,并控制了盆地7个隆起、断陷构造单元的展布及属性。它经历了6期演化阶段：早中三叠世处于昆北弧前盆地及陆缘火山弧带,共和盆地基底主要岩石发育;晚三叠世阿尼玛卿洋闭合并发生碰撞造山,共和盆地褶皱基底形成;晚三叠纪末期发生碰撞后伸展,发育初始小型陆内裂谷盆地;在侏罗纪—白垩纪区域性伸展环境下形成局部断陷盆地;古近纪晚期—中新世发育拉分-断陷盆地;中新世末至今发育陆内前陆盆地。形成了3个大构造-沉积层序和8个亚层序,发育了深海陆棚相-碳酸盐岩台地相-火成岩相以及多旋回的冲积...     

共和盆地地热能分布特征与聚集机制分析

位处青藏高原北部的青海省共和盆地,是一个自中生代以来形成的断陷盆地,周界由深大活动断裂控制,其内堆积有大厚度的第四纪和新近纪地层,揭露厚度达900～1440m,基底由印支期花岗岩组成,调（勘）查资料显示,盆地内具有热流值较高的特征,基底花岗岩地热梯度大于5℃,热异常明显。青藏高原宽频地震探测资料显示,共和盆地所在的东昆仑地块上地幔存在着一条宽达150km的低速带,其与巴颜喀拉地块深地幔中以大型低速异常体为特征的地幔热柱相关联,该低速带延伸到地壳,在共和盆地及其周边一带地表以下1～40km的不同部位形成热流异常区,导致在盆地浅部形成丰富的以干热岩、地下热水为主的地下热能资源,其不仅在城镇供暖方面具有现实推广意义,而且在发电等能源利用中潜力巨大。     

青海共和盆地岩石圈热-流变结构及地热意义

地球深度热状况是深部地球动力学和岩石圈活动性研究的重要内容, 岩石圈热结构和热-流变结构可以很好地揭示岩石圈范围内的热状况。近年来, 在青海共和盆地钻探揭露了深部高温干热岩体, 关于其热源机制尚未有定论。本文以青海共和盆地为研究对象, 分析壳内温度分布和流变强度, 探讨壳内低速体的地质属性。结果表明, 共和盆地的地壳流变结构从上而下分为脆性和韧性两层, 韧性层又包括中地壳和下地壳两层韧性层, 在上地壳尺度均表现为脆性破裂为主, 并逐渐过渡为韧性流变; 恰卜恰地区在脆性破裂的上地壳延伸至中下地壳时, 破裂沿一系列滑脱面发生韧性滑动, 局部地段形成壳内熔融, 为恰卜恰地区提供了额外的热源, 使其大地热流值(109.6 mW/m2)显著高于贵德地区(77.6 mW/m2)。这一认识为共和盆地壳内低速体存在提供了新的佐证, 也为区内干热岩热源分析以及高温地热资源探测开发提供了科学依据。     

张掖盆地地热资源地质特征分析与研究

在野外实地调查张掖盆地地热资源的基础上,对研究区地热田特征、热储特征、热储温度以及温度场特征进行了分析和研究。研究结果表明:张掖盆地属张扭性盆地,有利地热运移和富集,属中低温地热资源;地热田热储为新近系及白垩系砂岩、砂砾岩、含砾砂岩等,厚度为536 m;经钾镁地热温标估算,热储温度60℃;盖层为新近系上新统疏勒河组泥岩、泥质砂岩层;热源来自地壳深部的热传导。通过对研究区地热田特征、热储特征、热储温度以及温度场特征的分析和研究,可以为当地政府进一步研究、勘探及开发地热资源提供依据。     

张掖盆地地热资源赋存特征及成因分析

张掖盆地地处甘肃省河西走廊黑河流域中游地区,地势南东高北西低。已有勘探资料显示,张掖盆地赋存丰富的水热型地热资源。通过研究该区域地球物理勘探、钻探、地温测量及水文地球化学等成果资料,分析了张掖盆地地热资源赋存特征,探讨了其成因模式。张掖盆地地热田属沉积盆地型中低温地热田,热储为呈层状分布的新近系白杨河组砂岩、砂砾岩,选择钾镁地球化学温标计算热储温度为47～82°C,盖层为新近系上新统疏勒河组泥岩及第四系松散地层;地热水类型主要为碎屑岩类孔隙水,根据氢氧同位素特征推断其主要补给来源为南部祁连山区大气降水;祁连山北缘深大断裂和盆地内NNW向基底断裂是地热流体深循环良好的导水通道,地下水接受补给后沿导水断裂带或岩层孔隙裂隙运移,在深部热传导的增温作用下,赋存于碎屑岩类孔隙之中形成了本区的地热资源。水质分析结果表明：本区地热水属于溶滤型的陆相沉积水,水化学类型为Cl·SO₄—Na型,F-、SiO₂、溶解性总固体、总硬度含量随水温的升高而增大;区内地热水3H值普遍小于2.0 TU,说明形成年代较早;¹⁴C分析结果进一步证实,区域地...     

松辽盆地坳陷层控地热系统研究

松辽盆地是在印支运动末期至燕山运动早期形成的大型沉积盆地,其不仅蕴藏丰富的油气资源,也是我国主要的地热资源潜力区。本文以大陆科学钻探松科二井为基础通过建立盆地热导率、生热率、孔隙度等物性柱,分析了盆地深部地温场特征,最后给出了松辽盆地坳陷层控型地热系统的形成机制。松辽盆地物性具有明显的垂向分层特征,按照垂向变化可分为4段,分别为盖层段、储层段、稳态热传导段和基底段。热导率随岩性、沉积时代的不同存在较大的差异,总体上随深度的变大逐渐增大,储层段表现出热导率的快速增长,而基底段则热导率差异性大;生热率在白垩系沉积层总体偏低,表现出“冷壳热幔”的热结构;孔隙度表现为从1800 m到2700 m的储层段快速下降趋势,地层储水能力逐渐变弱。松辽盆地地热系统具有坳陷层控的特点,中、晚侏罗世莫霍面隆起形成的热隆张导致了后期浅部的断陷-坳陷双重结构。在坳陷沉积阶段沉积了河湖相为主的砂、泥岩地层,后期随着地下水的循环补给及聚热作用,在白垩系姚家组、青山口组、泉头组中形成了以砂岩为主且空间上由盆地边缘向盆地中心逐渐变薄的层控型地热系统。寻找高渗透热储层是松辽盆地地热探测的关键,本研究可以为盆地深部找热提供...     

The Experimental Investigations on Motion Features of Groundwater Flow near the Pumping Well

Hot springs are natural exposed points of the hydrothermal system. The hydro-geochemistry of hot springs can be used to interpret the formation of the hydrothermal system; and the 14C dating can be used to evaluate the renewability of the hydrothermal system. The hot springs exposed from fault zones in western Guangdong are classified as granite fissure water and clastic rock fissure water, which are sampled and tested. The results of water chemistry analysis show that hot spring water is mainly HCO3-Na type in the beginning, while the mixing of seawater leads to the increase of Cl-. Hydrogen and oxygen isotopes indicate that these hot springs mainly come from atmospheric precipitation, and water-rock interactions produce oxygen isotope exchange reactions, where a significant “oxygen drift” phenomenon can be observed. The relationship between δ13C and HCO3- indicates that there is a deep source of CO2 “dead carbon” in hot spring water. This systematic error is not considered in the existing 14C dating correction models. The 14C age of the deep source “dead carbon” correction proposed in this paper is close to the 14C age of the reverse chemical simulation correction, the Gonfiantinie model, and the Mook model. The deep source “dead carbon” correction method can improve the systematic error. Therefore, the 14C age corrected by the deep source “dead carbon” may be more representative in terms of the actual age of geothermal water.     

苏北盆地干热岩地热资源前景分析

苏北盆地属于中、新生代“断陷型”盆地,发育前震旦系变质基底及古生代海相台地沉积,经历燕山期大规模岩浆-火山-构造活动,之后连续断陷沉降并沉积了厚度巨大的新生代地层;新生代苏北盆地处于持续活跃的洋陆构造带内,其特殊的构造位置使区内拥有相对高的大地热流值和较大的地温梯度,具有巨大的地热资源潜力。基于区域地热地质综合研究,本文针对苏北盆地地质构造特征、地温数据、地球物理信息等系统分析,初步证实了盆地内不仅存在浅部中低温地热资源,而且推断出盆地深部拥有温度较高的干热岩资源,其热源主要来源于深部的地幔,是本地区新生代区域伸展裂陷、地幔上涌、岩石圈减薄等作用的结果。根据干热岩选区的科学准则,盆地内优势前景区拥有丰富的动态热源、导热效果极佳的热通道、规模巨大的优势热储、良好保温作用的热盖层,并依据此初步建立成因模型,为进一步勘探与开发提供参考依据。     

青海共和盆地干热岩地热储层水力压裂物理模拟和裂缝起裂与扩展形态研究

水力压裂是青海共和盆地干热岩地热资源开发的难点技术问题之一。本文基于升级改造的大尺寸真三轴水力压裂物理模拟实验系统模拟干热岩储层高温高压环境,利用青海共和盆地露头岩心进行水力压裂物理模拟实验,揭示干热岩储层水力裂缝的起裂和扩展规律。通过物理模拟实验发现：干热岩储层裂缝起裂可以通过文中提出的起裂模型判断起裂方式和预测起裂压力;水力裂缝在岩石基质中的扩展形态简单,仅沿最大主应力方向延伸;但是水力裂缝会受到岩石中弱面的影响,发生转向沿弱面延伸,形成较复杂的裂缝形态。因此,建议在干热岩储层实际施工中,在天然裂缝发育较丰富的层段开展水力压裂,以实现复杂裂缝网络提取地热能。     

Hydrogeochemical characteristics of hot springs exposed from fault zones in western Guangdong and their ~(14)C age correction

Hot springs are natural exposed points of the hydrothermal system. The hydrogeochemistry of hot springs can be used to interpret the formation of the hydrothermal system; and the ~(14)C dating can be used to evaluate the renewability of the hydrothermal system. The hot springs exposed from fault zones in western Guangdong are classified as granite fissure water and clastic rock fissure water, which are sampled and tested. The results of water chemistry analysis show that hot spring water is mainly HCO_3-Na type in the beginning, while the mixing of seawater leads to the increase of Cl~-. Hydrogen and oxygen isotopes indicate that these hot springs mainly come from atmospheric precipitation, and water-rock interactions produce oxygen isotope exchange reactions, where a significant "oxygen drift" phenomenon can be observed. The relationship between δ~(13)C and HCO_3~- indicates that there is a deep source of CO_2 "dead carbon" in hot spring water. This systematic error is not considered in the existing ~(14)C dating correction models. The ~(14)C age of the deep source "dead carbon" correction proposed in this paper is close to the ~(14)C age of the reverse chemical simulation correction, the Gonfiantinie model, and the Mook model. The deep source "dead carbon" correction method can improve the systematic error. Therefore, the ~(14)C age corrected by the deep source "dead carbon" may be more representative in terms of the actual age of geothermal water.     

沉积盆地型与隆起山地型地热系统地表地球化学异常模式差异性分析

地球化学勘探技术作为地热资源综合勘查技术之一,在地热勘探开发中发挥了重要作用。沉积盆地型与隆起山地型地热系统由于自身地质特征的不同,必然造成它们的地球化学判识指标和异常模式存在差异。目前国内外尚缺乏对这两种类型地热系统判识指标和地球化学异常模式差异性进行地质地球化学分析,导致针对不同的勘探对象在方法选择和异常解释上依据不足。以典型沉积盆地型地热系统——河北雄县地热系统,隆起山地型地热系统——安徽巢湖半汤地热系统为例,开展地球化学方法试验,建立了两种类型地热系统的地表地球化学异常模式,并从地热系统的地质因素(热源、热水、热储、通道、盖层)出发,对其地表地球化学异常模式差异性进行分析,表明隆起山地型地热系统地表地球化学异常模式为受导水断层、破碎带控制的正异常;沉积盆地型地热系统气体地球化学异常模式为受热储构造控制的正异常,微量元素地球化学异常为受氧化还原环境控制的负异常;二者在有效地球化学指标组合和异常形态上均存在差异。研究结果为不同类型地热系统勘探提供方法和理论依据。     

Indication of hydrogen and oxygen stable isotopes on the characteristics and circulation patterns of medium-low temperature geothermal resources in the Guanzhong Basin,China

Guanzhong Basin is a typical medium-low temperature geothermal field mainly controlled by geo-pressure in the west of China.The characteristics of hydrogen and oxygen isotopes were used to analyze the flow and storage modes of geothermal resources in the basin.In this paper,the basin was divided into six geotectonic units,where a total of 121 samples were collected from geothermal wells and surface water bodies for the analysis of hydrogen-oxygen isotopes.Analytical results show that the isotopic signatures of hydrogen and oxygen throughout Guanzhong Basin reveal a trend of gradual increase from the basin edge areas to the basin center.In terms of recharge systems,the area in the south edge belongs to the geothermal system of Qinling Mountain piedmont,while to the north of Weihe fault is the geothermal system of North mountain piedmont,where the atmospheric temperature is about 0.2℃-1.8℃in the recharge areas.The main factors that affect the geothermal waterδ18O drifting include the depth of geothermal reservoir and temperature of geothermal reservoir,lithological characteristics,water-rock interaction,geothermal reservoir environment and residence time.Theδ18O-δD relation shows that the main source is the meteoric water,together with some sedimentary water,but there are no deep magmatic water and mantle water which recharge the geothermal water in the basin.Through examining the distribution pattern of hydrogen-oxygen isotopic signatures,the groundwater circulation model of this basin can be divided into open circulation type,semi-open type,closed type and sedimentary type.This provides some important information for rational exploitation of the geothermal resources.     

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.     

试论地球深部地热能传输机理

本文在对前人地热成因认识归纳检验的基础上,通过演绎推理的方法,从几条基本的物理定律和基本假设组成的第一性原理出发,推理“地球内部热能从深部向浅表传输”的动力学过程,探讨深层地热能热源机制。热源机制问题从物理学的角度看,本质上就是热能从地球内部向近地表传输的问题。可以根据第一性原理,通过演绎法推理其可能的传输过程。深层热能传输的第一性原理由“温度的定义、热胀冷缩原理、阿基米德原理、热力学第二定律以及辐射、传导和对流三种热量传输方式的效率对比”5条基本的概念和定理组成。结合地球已知的圈层结构,通过演绎推理可知,在固态内核偏移驱动下,液态外核开始流动,在局部聚集导致地幔中形成上升的地幔柱;地幔柱在另一个地球圈层界面发生顶托作用,使得界面上凸,并产生烘烤加热作用,被烘烤的上层物质流变性增强发生侧向流动,于是物质垂直运动转换为水平运动。水平流动的热物质聚集到一定程度又会上浮产生垂直运动。如此垂直运动和水平运动不断转换,最终将地球深部地核中的热能传输到了地壳浅层。地球深部热能向浅表传输的过程会导致海底增生扩张、板块运动、盆山耦合等,同时也形成不同级别的控热构造系统。地球尺度的控热构造系统为:地球内核为生热构造,液态外核为储热构造,各级地幔柱和流动的高温物质为导热构造,地表的火山、温泉、地震为释热构造子系统。大陆地壳准固态流变物质的侧向流动是干热岩形成的主控因子,对于干热岩地热能勘查具有重要意义。     

鄂尔多斯盆地南缘延安地区中深层地热能特征研究

近年来水热型、浅层地热能发展产生的缺点问题日益突出,以取热不取水为原则,中深层U型水平对接换热技术成为新的技术方向。通过对鄂尔多斯盆地南缘延安地区地层岩性、地温梯度特征、热储层特征等特征研究,分析了研究区中深层地热资源潜力,研究结果表明鄂尔多斯盆地南缘奥陶系马家沟组为良好的热传导型热储,深部地温梯度为3.05℃/100m。当马家沟组深度在3157m时,对应温度达到110.67℃。测井及注水试验结果表明,奥陶系马家沟组为极弱含水层,几乎没有流体,属于良好的干热岩型地热资源,具有较高的开采价值。充分确定了该区地热地质条件良好、地热资源潜力巨大。为合理、高效开发利用该区地热资源提供了科学依据,对进一步开发利用该区的地热能具有重要意义。     

浅析开采条件下地下热水资源的演变

地下热水的分布可以分为埋藏型(或盆地型)和出露型(或温泉型).埋藏型分布于沉积盆地深处,热储层规模大,有较大的储存资源,但补给资源极为有限或缺乏,开采地下热水主要是消耗储存资源,可导致热水系统水位持续下降.出露型多见于山区,地下热水以温泉的方式出露地表,其储存资源和补给资源均有限,在温泉附近开采热水可导致温泉流量减小直至干涸,热水系统水位、水温也会持续下降.在某些特定条件下在温泉附近打成的自流孔可使地下热水资源量有所增加.温泉的自封闭作用可使其流量减少.