Three-dimensional temperature field simulation of a cooling of a magma chamber,La Primavera caldera,Jalisco, Mexico

The La Primavera caldera lies close to the triple junction of the Tepic-Zacoalco, Colima, and Chapala rifts in the western part of the Mexican Volcanic Belt. It is a promising geothermal field with 13 deep wells already drilled. We calculated solute geothermometric temperatures (Na–K, Na–Li, and SiO₂) from the chemistry of geothermal water samples; determined values are generally between 99°C and 202°C for springs and between 131°C and 298°C for wells. Thermal modelling is an important geophysical tool as documented in the study of this and other Mexican geothermal areas. Using the computer program TCHEMSYS, we report new simulation results of three-dimensional (3-D) thermal modelling of the magma chamber underlying this caldera through its entire eruptive history. Equations (quadratic fit) describing the simulated temperatures as a function of the age, volume and depth of the magma chamber are first presented; these indicate that both the depth and the age of the magma chamber are more important parameters than its volume. A comparison of 3-D modelling of the La Primavera and Los Humeros calderas also shows that the depth of the magma chamber is more important than its volume. The best model for the La Primavera caldera has 0.15 million years as the emplacement age of the magma chamber, its top at a depth of 4 km, and its volume as 600 km³. Fresh magma recharge events within the middle part of the magma chamber were also considered at 0.095, 0.075, and 0.040 Ma. The simulation results were evaluated in the light of actually measured and solute geothermometric temperatures in five geothermal wells. Future work should involve a smaller mesh size of 0.050 or 0.10 km on each side (instead of 0.25 km currently used) and take into account the topography of the area and all petrogenetic processes of fractional crystallization, assimilation, and magma mixing as well as heat generation from natural radioactive elements.     

基于多种估算方法的湖南省现今地温梯度综合确定

湖南省目前地热井多为深度较小(多在500m以浅)的热对流型,用地热井测温数据求取的地温梯度一般偏大很多。为解决对流型地热测得的地温梯度偏大问题,本文采用地热温标、管道模型及基于生热率的深部地温反推法等地温梯度估算方法,综合确定了湖南省现今的地温梯度。结果显示,湖南省高地温场大致沿中部的白马山岩体、沩山岩体、幕阜山—黄龙山岩体一线和湖南省东南部分布,地温梯度大于3.0℃/100m;5000m深度、6000m深度沩山岩体、热水圩一带的最高温度分别达到了218.69℃、216.70℃和258.99℃、256.60℃。深大断裂与多块体接合部位的构造形态相配合,使湖南省中部构造交汇带处于张开性的构造环境,有利于大气降水的深循环与深部热物质的上侵,是形成湖南省中部高地温场的主要原因。湖南省东南部是西太平洋板块俯冲与回撤的前缘,处于江南造山带与华夏板块的接合带,有利于大气降水的深循环与深部热物质的上侵;同时高放射性生热率的铀矿床、矿点也提供了较高的地壳热量,是形成湖南省东南部高地温场的主要原因。地温梯度及地温场的科学界定,为湖南省下一步寻找高温地热资源指明了方向。     

塔里木盆地中央隆起超深层现今地温场特征

塔里木盆地中央隆起是我国的大型油气聚集带。本文借助9口钻井的系统测温数据和86口钻井的试油温度数据，系统研究了该区的0~6000 m地温梯度、大地热流、超深层温度（6000~8000 m和奥陶系—寒武〖JP2〗系烃源岩底界面）分布特征。中央隆起区0~6000 m现今地温梯度介于14. 1~27. 8 ℃/km，平均值为20. 6 ℃/km；〖JP〗大地热流介于34. 4~60. 6 mW/m2，平均值为46. 7 mW/m2；6000 m埋深处温度介于98. 1~180. 2℃，平均值为137. 4℃；7000 m埋深处温度介于107. 4~198. 9℃，平均值为150. 0℃；8000 m埋深处温度介于117. 4~217. 5℃，平均值为162℃，受基底起伏、岩石热物性和构造作用等影响，整体上均具有由西北向东南逐渐增大的趋势。奥陶系—寒武系烃源岩底界面温度介于81. 6~228. 2℃和91. 0~248. 6℃，受到埋藏深度的影响，表现出巴楚凸起温度最低，塔中凸起温度次之，古城低凸起温度最高的特征，一定程度上影响油气的性质和保存。本研究不仅明确了中央隆起超深层温度场分布特征，而且为今后超深层油气勘探提供重要依据。     

沉积盆地地温梯度研究中应注意的问题

沉积盆地的地温场特征是油气勘探研究的重要内容之一。油气勘探工作者习惯于采用地温梯度而不是大地热流来描述沉积盆地的热状态,但是,地温梯度与计算井段密切相关,离开计算井段去谈地温梯度高低,很容易引起误解,尤其是在测温井段较短或测温深度较浅时,测温数据不能直接用于计算沉积盆地的地温梯度,否则,会得出错误的结论。然而,在实际研究工作中,这一点经常被忽视。为此,本文提出了“规一化”地温梯度的概念和计算方法,并以实例说明沉积盆地地温场研究中,采用“规一化”地温梯度来描述盆地热状态平面分布特征的必要性。     

淮南煤田现今地温场特征

在系统分析淮南煤田大量地面钻孔井温测井数据和井下巷道围岩温度测试数据的基础上,结合58块岩石样品的热导率测试结果,全面阐述了该区现今地温梯度和大地热流的分布特征。研究表明,淮南煤田现今地温梯度的众值介于2.50~3.50℃/hm之间,平均地温梯度为2.9℃/hm;大地热流值变化范围为31.87~83.9 m W/m2,平均热流值为63.69 m W/m2,地温梯度和热流值区均高于淮北煤田;大地热流受地温梯度控制明显,其变化特征和地温梯度分布较为相似,整体表现为中东部高,西部其次,东南部最小的特征。分析揭示,区内现今地温场和热流分布主要受区域地质背景和区内构造格局的控制。     

咸阳地热田钻孔温度测量及水动力系统

地热田温度场分析, 不仅为地热田类型划分和热源机理研究提供科学根据, 而且可以为确定地热田有利开采区域和深度提供直接依据。本文报道了咸阳地热田13口钻孔的系统(准)稳态测温数据, 对研究区温度的垂向分布特征做了初步分析, 并据此划分了地热田水动力系统。结果表明, 咸阳地热田属于以传导为主的沉积盆地型地热田, 地温梯度为26.2~40.1 ℃/km, 平均为32.4 ℃/km。然而, 与典型的传导型地热田相比, 咸阳地热田的地温场特征又存在特殊性, 表现为钻孔温度-深度曲线分段性明显: 浅部受地表水流动对温度场的影响, 地温曲线呈现出锯齿形波动; 钻孔中上部受地表水和深部水热活动影响较小, 温度曲线为传导性地热特征; 井孔中下部测温曲线明显"下凹", 揭示了地下水沿渭河断裂侧向补给的同时使地层温度降低; 井孔下部温度随深度异常增大, 表明存在异常压力流体封存箱。测温资料揭示了咸阳地热田水动力系统在垂向上存在多层结构: 浅部为垂向重力驱动型, 中上部为正常压实型, 中下部为侧向重力驱动型, 下部为封闭型。基于咸阳地热田水动力系统的多层结构, 建议将各系统赋存的地热资源分别进行规划和开发。     

冀中坳陷现今地温场分布特征

通过整理和分析53口井的系统测温数据和400余口井的试油测温数据,编制了冀中坳陷现今地温梯度分布图、折算了1 000-5 000 m深度的地温状况．结果表明,冀中坳陷的现今地温梯度一般为25．8-48．8℃／km,平均为32．4±4．2 ℃／km。地温沿构造、断裂延伸的方向展布,分布范围与下伏的基底构造基本一致,主体以NNE方向展布最为明显。横向上,地温梯度呈现低-高-低相间分布的特点,这与区域地质构造的凹、凸、凹分布相一致;纵向上,随深度的增大地温梯度有减小的趋势。     

沧县隆起北部地温场特征及其主控因素分析

沧县隆起北部地区地热资源丰富,但关于地热田的形成机制与主控因素仍存在争议.通过收集区域地质资料和井温资料,并结合热传导正演模拟,系统地分析了研究区内地温梯度横向与垂向的特征、不同地质条件下地温场的分布规律,并正演了两条实测地热剖面,分析了研究区内地温场分布的主控因素.研究表明,横向上地温梯度在凸起区相对较高,凹陷区相对...     

内蒙古海拉尔盆地乌尔逊凹陷热演化史

乌尔逊凹陷是内蒙古海拉尔盆地内勘验程度较高的一个南部凹陷,该凹陷沉积厚度大,地层发育全,生油条件十分优越,是海拉尔盆地主要产油气凹陷。主要烃源岩层是南屯组,其次是铜钵庙组和大磨拐河组。根据磷灰石裂变径迹法恢复的乌尔逊凹陷早白垩世古地温梯度为3.44℃/hm,接近现今地温梯度3.3℃/hm。古地温恢复及热演化史模拟表明,乌尔逊凹陷中生代以来经历了一个升温过程,下白垩统烃源岩热演化程度主要受现今地温场控制。热演化史与油气关系研究结合伊利石测年结果表明,乌尔逊凹陷油气成藏期主要有两期,为早白垩世晚期及古近纪以来,且以早白垩世晚期为主要成藏期;古近纪以来为第二期成藏阶段,烃源岩进入第二次生油高峰期。第二次成藏时期对乌尔逊凹陷油气藏的形成起着重要作用,是制约油气富集的重要因素。     

渭河盆地岩石圈热结构模拟及其对地热系统热源机理的启示

深部温度场与岩石圈热结构特征是认识地热系统深部热源机理的重要途径。本文在系统分析渭河盆地及其邻区现今大地热流特征基础上,基于旬邑—西峡宽角反射/折射地震测深剖面揭示的地壳分层结构,采用二维有限元方法,对渭北隆起、渭河盆地以及北秦岭构造带的深部温度场和岩石圈热结构开展数值模拟研究,在此基础上分析渭河盆地地热系统深部热源机理。结果表明,旬邑—西峡剖面上大地热流介于57.6～75.7mW/m²之间,平均为(70.4±4.7)mW/m²;地幔热流在29.5～38.6mW/m²之间,平均值为34.1mW/m²;莫霍面温度变化范围约在600～740℃之间;“热”岩石圈厚度约为95～110km。从渭北隆起—渭河盆地—秦岭造山带,大地热流、莫霍面温度和地幔热流值表现出低→高→低的变化规律,相应地“热”岩石圈厚度则表现出厚→薄→厚的变化趋势。渭河盆地地壳厚度减薄明显,莫霍面温度显著高于渭北隆起和秦岭造山带,暗示着渭河盆地地壳活动性显著。然而,从渭北隆起—渭河盆地—秦岭造山带,“热”岩石圈厚度变化范围不大,且渭河盆地内...     

幔源岩浆在地壳中分层侵位的控制因素：二维热-力学模拟

幔源岩浆在地壳内的上升和聚集样式不仅依赖于岩浆自身的性质, 还取决于围岩的强度和热状态。已有数值和物理模型大多关注岩浆自身物性对其上升过程的影响, 而对围岩流变强度或热状态如何影响岩浆的上升和聚集过程的研究相对薄弱, 尤其是周期性的幔源岩浆在壳内分层侵位的受控因素仍然不清楚。本文利用二维热-力学数值模拟方法, 通过发展多期岩浆脉冲和岩墙生成算法, 研究了岩浆从深部地幔上升至地壳内部侵位的动力学过程, 系统测试了地壳(围岩)地温梯度(上、下地壳的地温梯度分别以G_UC和G_LC表示)和地壳强度对岩浆上升过程和聚集样式的影响。模拟结果表明: (1)地壳地温梯度对岩浆的侵位深度有重要影响, 岩浆侵入冷地壳(G_UC=G_LC=12.5K/km), 岩浆主体在岩石圈深度聚集, 地表的相对高差小于140m;岩浆侵入温地壳(G_UC=G_LC=15K/km)在下地壳底部聚集形成岩浆房, 上升至上、下地壳界面, 岩浆房上方的地表地形呈现中心拗陷两翼隆起的形态, 地表最大高程可达3km; 岩浆侵入热地壳(G_UC=G_LC=17.5K/km)仅在下地壳底部聚集形成岩浆房, 地形演化特征与温地壳背景的情况类似, 但最大高程小于1.5km。(2)在同等地壳地温梯度条件下, 上、下地壳的相对强度决定了岩浆的聚集样式: 下地壳的强度越弱, 岩浆更易在下地壳聚集形成岩浆房; 上地壳的强度越弱, 岩浆更易在地表喷发。进一步分析表明: 岩浆的聚集样式受地壳地温梯度与地壳流变分层性的共同控制, 地壳越热且流变强度分层性越显著则越有利于岩浆在地壳中的多层级侵位; 每一期岩浆脉冲的供给均会导致岩浆房内部的超压值骤增。我们的模拟结果对理解火山喷发前壳内岩浆的赋存状态及岩浆活动区的地形演化具有启示意义。

     

河北雄县地热田钻井地温测量及地温场特征

根据研究区22口井的实测井温资料及前人的研究成果,开展了雄县地区地温场分析,对雄县地热田地温场的特点取得了以下认识：雄县地热田的盖层以传导热传递方式为主,热储层中源于供暖期热水生产和回灌引起的地下水受迫对流的影响,以对流热传递为主,不同静井时间的重复测温结果显示,静井时间的长短和井内流体的运移方式（抽水或回灌）控制了井内温度的分布及井内温度的动态变化：静井时间增加则测得的温度在中性点上下呈反向变化,生产井和回灌井的测温曲线存在明显不同,雄县热田第四系底部的温度为32.8 ℃～48 ℃,容城凸起为28 ℃～35 ℃,雄县热田第三系底部温度为64.5 ℃～81.3 ℃,容城凸起为45 ℃～60 ℃。雄县地热田盖层内的地温梯度为43.9～72.2 ℃/km之间,平均为51 ℃/km,容城凸起的井地温梯度为31.4～41.1 ℃/km,平均为37.1 ℃/km。雄县地热田内盖层导热流值变化为80.61～113.86 mW/m² 的范围。     

Thermal modelling of the Larderello geothermal field (Tuscany,Italy)

We present a 3-D thermal model of the Larderello geothermal field (Tuscany) to evaluate (1) the extent and contribution of the heat transfer mechanisms (conduction vs. convection) at the intermediate-upper crust levels, (2) the variability of the heat and mass fluxes entering from below and (3) the crucial role of the formation permeability. The model, composed by three main layers, considers the upper 10 km of the crust to better constrain the simulations with experimental data from borehole, fluid inclusion studies and hypocentral distributions. Several sets of simulations were carried out with different bottom boundary temperatures and different formation permeabilities for the two deeper layers. The results indicate that the present temperature (T) and pressure distributions in the Larderello field require deep reservoir rocks with higher permeability than the overlying capping units and underlying intermediate crust. Permeability values of 1 mDarcy for the reservoir rocks are enough to allow fluid convection, if the temperature at 10 km depth is as high as 500 ± 50°C. The presence of localized zones with formation permeability 50–100 times higher than the surrounding rocks strongly favours the migration of over-pressurized fluids, which episodically break through the overburden, feeding the presently exploited geothermal fields.     

北京市延庆地热田成因模式

通过对地热流体水化学、同位素以及热储岩石热物性测试,分析了延庆地热田大地热流特征、地热流体补给来源、年龄、循环深度以及热储温度等,从源、通、储和盖四方面系统总结了地热田成因。结果显示:延庆地热田属于由正常大地热流加热的非火山型地热系统,热田内大地热流值为75.6m W/m~2,地热流体补给来源于延庆西北部山区的大气降水。热田内三个主要热储中的地热流体年龄和循环深度存在一定区别。燕山期花岗岩、白垩系砂岩和蓟县系白云岩热储中地热水年龄分别为15～21ka、28ka、48ka。花岗岩和砂岩热储中地热流体循环深度约2500m。白云岩热储中流体循环深度为2900～3600m,热储温度分布范围为80.5～98.3℃,平均热储温度90.6℃。     

Differential Thermal Regimes of the Tarim and Sichuan Basins in China: Implications for Hydrocarbon Generation and Conservation

The uncertainty surrounding the thermal regimes of the ultra-deep strata in the Tarim and Sichuan basins, China, is unfavorable for further hydrocarbon exploration. This study summarizes and contrasts the present-day and paleo heat flow, geothermal gradient and deep formation temperatures of the Tarim and Sichuan basins. The average heat flow of the Tarim and Sichuan basins are 42.5 ± 7.6 mW/m2 and 53.8 ± 7.6 mW/m2, respectively, reflecting the characteristics of ‘cold’ and ‘warm’ basins. The geothermal gradient with unified depths of 0–5,000 m, 0–6,000 m and 0–7,000 m in the Tarim Basin are 21.6 ± 2.9 °C/km, 20.5 ± 2.8 °C/km and 19.6 ± 2.8 °C/km, respectively, while the geothermal gradient with unified depths of 0–5,000 m, 0–6,000m and 0–7,000 m in the Sichuan Basin are 21.9 ± 2.3 °C/km, 22.1 ± 2.5 °C/km and 23.3 ± 2.4 °C/km, respectively. The differential change of the geothermal gradient between the Tarim and Sichuan basins with depth probably results from the rock thermal conductivity and heat production rate. The formation temperatures at depths of 6,000 m, 7,000 m, 8,000 m, 9,000 m and 10,000 m in the Tarim Basin are 80°C–190°C, 90°C–220°C, 100°C–230°C, 110°C–240°C and 120°C–250°C, respectively, while the formation temperatures at depths of 6,000 m, 7,000 m, 8,000 m and 9,000 m in the Sichuan Basin are 120°C–200°C, 140°C–210°C, 160°C–260°C and 180°C–280°C, respectively. The horizontal distribution pattern of the ultra-deep formation temperatures in the Tarim and Sichuan basins is mainly affected by the basement relief, fault activity and hydrothermal upwelling. The thermal modeling revealed that the paleo-heat flow in the interior of the Tarim Basin decreased since the early Cambrian with an early Permian abrupt peak, while that in the Sichuan Basin experienced three stages of steady state from Cambrian to early Permian, rapidly rising at the end of the early Permian and declining since the late Permian. The thermal regime of the Sichuan Basin was always higher than that of the Tarim Basin, which results in differential oil and gas generation and conservation in the ultra-deep ancient strata. This study not only promotes theoretical development in the exploration of ultra-deep geothermal fields, but also plays an important role in determining the maturation phase of the ultra-deep source rocks and the occurrence state of hydrocarbons in the Tarim and Sichuan basins.     

Hydrogeochemistry and Origin of Thermal Groundwater in Bedrock Aquifers in Tianjin, China

INTRODUCTIONThermalgroundwaterisfoundtohaveoccurredinthebedrockcarbonateaquifersofLowerPaleozoicandMeso toNeo ProterozoicErathemsnearTianjin ,China .Thebedrockaquifersexistinthelayersbetweenabout 10 0 0mandmorethan 4 0 0 0mbelowthelandsurface .Thethermalwaterhasbeensuccessfullydevelopedoverthepast2 0yearstoprovideasourceofhotwaterforavarietyofresidentialandindustri alpurposes.Geothermalwellstappingtheaquifersarecapa bleofproducingcommercialquantitiesofhotwaterwiththetemperaturesranging…     

Near-surface Geothermal Gradient Observation and Geothermal Analyses in the Xianshuihe Fault Zone, Eastern Tibetan Plateau

The Xianshuihe fault(XSHF) zone, characterized by intense tectonic activity, is located at the southwest boundary of the Bayan Har block, where several major earthquakes have occurred, including the 2008 Wenchuan and the 2013 Lushan earthquakes. This study analysed underground temperature sequence data for four years at seven measuring points at different depths(maximum depth: 18.9 m) in the southeastern section of the XSHF zone. High-frequency atmospheric noise was removed from the temperature sequences to obtain relatively stable temperature fields and heat fluxes near the measurement points. Our measurements show that the surrounding bedrock at(the seven stations distributed in the fault zone) had heat flux values range from-41.0 to 206 m W/m~2, with a median value of 54.3 m W/m~2. The results indicate a low heat flux in the northern section of DaofuKangting and a relatively high heat flux in the southern section of Kangting, which is consistent with the temperature distributions of the hot springs near the fault. Furthermore, our results suggest that the heat transfer in this field results primarily from stable underground heat conduction. In addition, the underground hydrothermal activity is also an obvious factor controlling the geothermal gradient.     

珠江口盆地白云凹陷地温场特征及烃源岩热演化

通过对珠江口盆地白云凹陷108口钻井的地温数据(BHT、MDT、DST)进行校正、分析,以点到面重构白云凹陷的现今地温场,再结合地质与地球化学资料,正演恢复白云凹陷烃源岩的热演化史及生烃史.研究结果显示:(1)白云凹陷具有变地温场,地温梯度分布在35～60℃/km之间,呈现出南高北低的分布特征.(2)受控于白云凹陷变地...     

基于测井资料的共和盆地贵德扎仓地热田热储特征分析

青海共和盆地东部的贵德次盆扎仓地区发育复合型高温地热资源,先后施工完成的ZR1井3000 m裂隙型热储测温151.34℃, ZR2井4600 m干热岩热储测温214℃,展现共和盆地良好的地热资源潜力。本文首次报道ZR2井全井常规与特殊测井数据,评价了扎仓沟花岗岩热储的孔隙度、体积密度、岩石生热率、岩石力学、地应力等关键参数,结果显示:ZR2井温测井显示4 092.8 m温度达到180℃, 4602 m深度井温214℃;利用电成像测井识别出两段裂缝集中发育带,分别为4210—4220m和4310—4320m,并对全孔段裂缝的产状进行了统计分析;利用井壁崩落和三井径法,计算该钻孔现今最大主应力方向为近南北向;共解释岩性破碎地层(疑似含水)21.4 m/2层,岩性较完整地层70.4 m/7层,岩性完整地层376.1 m/27层,高放射性地层7.6 m/2层。热储测井解释结果为系统评价热储和开发利用提供参考。     

北京通州地温场特征及其影响因素

在收集整理大量地热井温度资料的基础上,系统分析了北京通州地区现今地温场特征,划分了地热异常区,并进一步估算了1000~3000 m埋深处的地层温度。研究表明,研究区现今地温梯度为1.34~3.12℃/100 m,平均值为1.88℃/100 m。大地热流值分布范围为47.1~75.9 mW/m2,平均值为63.2 mW/m2,其热流状态较好。在垂向上,研究区1000 m埋深处整体温度均超30℃,2000 m时高温异常区温度超60℃,3000 m时高温异常区温度超80℃。根据深部地层温度估算,在研究区的南部及东南部具有2处高温异常区,地温场分布形态与区域内主要断裂走向基本一致,主要受区域地质构造控制,岩石性质为地温场分布的重要影响因素。