基于DPHP测量数据提取热导率参数的方法研究

基于DPHP实测数据研究了提取热导率参数的两种方法:极值法和拟合法.极值法利用温度曲线的峰值及对应时间计算热导率,测量过程中的采样间隔是影响计算结果的关键因素,热导率相对误差同采样间隔与峰值时间的比值有关,当比值小于0.02时,相对误差不超过±1%.采用抛物线拟合采样最大温度值相邻的数据计算峰值温度能够在一定程度上弥补采样率过大的问题.但对于过大的采样间隔获得的数据应使用非线性拟合法.非线性拟合法要求拟合模型对实测数据有良好反映,但理论模型与实际探针模型的差异导致实测数据只是在最大温度前后吻合较好,因此需要对拟合数据窗口进行选择.基本原则是数据区间内应当包含温升最大值,而且上升段的数据量应少于衰减段的数据量.     

东昆仑断裂带东部晚更新世以来活动特征及其大地构造意义

近EW向展布的东昆仑断裂带是巴颜喀拉地块北边界,其东延的活动性质和东端点位置对于探讨青藏高原东缘形成的动力学机制具有重要推动意义,也是鉴定断裂带地震危险性的基础.基于对东昆仑断裂带东部地貌卫星影像解译、地表破裂调查、阶地坎变形量测量和阶地测年数据,得到分析如下:(1)罗叉段属于全新世活动断层,存在长约50 km的反"L"形古地震地表破裂展布区;(2)晚更新世晚期以来在压剪作用下,罗叉段以左行滑动为主,速率为7.68~9.37 mm a-1,垂直滑动速率为0.7~0.9 mm a-1,与西侧各段的活动速率基本一致,表明属于东昆仑断裂带东延部分;(3)高速线性水平滑动的近EW向东昆仑断裂带,向东滑动受华南地块阻挡,转为近SN-NNE向岷江断裂带、龙门山断裂带的垂直活动及其间的龙门山和岷山的隆起,两种构造体系转换的区域限制了东端点位置;(4)罗叉段和玛曲段组成"玛曲空区",玛曲段的地震危险性较罗叉段更高,应引起注意.     

探究单源双能CT螺距对标准水模能谱成像数据的影响

目的:探讨单源双能CT不同螺距的能谱成像(GSI)扫描对标准水模的CT值和水碘浓度值的影响。方法:采用GEDiscovery750HD单源双能CT的GSI扫描模式对GE公司标准水模进行扫描,选择辐射剂量相近(180~192.5mAs范围)的6个扫描协议,分别对标准水模进行两种螺距(1.375︰1和0.984︰1)扫描,扫描野为M,扫描层厚5mm,连续扫描6层,共获得12组数据。根据扫描螺距不同分为两组:大螺距组(螺距1.375︰1)、小螺距组(螺距0.984︰1)。获得的图像利用GSI分析软件,以1.25mm进行无间隔标准算法重建70keV单能量图像及水(碘)基物质图像,于标准水模中心及3、6、9和12点放置面积为3000mm²圆形感兴趣区(ROI),对两种图像进行测量,记录各ROI的CT值及其SD值、水(碘)值及其SD值,采用SPSS软件配对样本t检验进行统计学分析。结果:大、小螺距组水的CT值分别为(1.39±1.90)HU和(1.97±1.74)HU,SD值分别为(7.21±0.55)HU和(6.47±0.56)HU;大、小螺距组水(碘)基物质图像的水(碘)值分别为1001.95±1.47和1002.19±1.34,其SD值分别为4.88±0.36和4.49±0.37。两组间差异均具有统计学意义(P<0.05)。结论:扫描参数螺距对GSI数据获得有影响,使用较小螺距扫描条件可提高诊断可靠性。     

张裂型盆地地热参数的垂向变化与琼东南盆地热流分布特征

海洋热流数据是开展海洋地球动力学研究和油气资源评价的基础数据.为深入认识琼东南盆地的地热特征,本文首先利用耦合沉积作用与岩石圈张裂过程的数值模型分析了张裂型盆地主要地热参数的垂向变化特征;并通过钻孔资料的详细分析,获得了琼东南盆地44口钻孔的热流数据;结合海底地热探针获取的热流数据,对琼东南盆地地热特征及其主要影响因素进行了简要分析.结果表明:沉积作用的热披覆效应对表层热流有较明显的抑制作用,由于沉积物生热效应与披覆效应的共同作用,同一钻孔处海底表层热流与钻孔深度3000~4000 m处热流或与海底间的平均热流差异很小,可以一起用于分析琼东南盆地的热流分布特征;莺歌海组、乐东组热导率随深度变化小于黄流组及其下地层热导率的变化,钻孔沉积层平均热导率约为1.7 W·(m·K)-1,钻孔地层生热率一般低于2.5 μW·m-3,平均生热率为1.34 μW·m-3,平均地温梯度主要介于30~45 ℃/km,热流介于50~99 mW·m-2,陆架区热流主要集中于60~70 mW·m-2,深水区钻孔具有较高的地温梯度和热流值;从北部陆架与上陆坡区往中央坳陷带,热流值从50~70 mW·m-2,增高为65~85 mW·m-2,并且往东有升高趋势,在盆地东部宝岛凹陷、长昌凹陷与西沙海槽北部斜坡带构成一条热流值高于85 mW·m-2的高热流带.进一步分析认为,琼东南盆地现今热流分布特征是深部热异常、强烈减薄岩石圈的裂后冷却作用、晚期岩浆热事件、地壳与沉积层的生热贡献以及沉积作用的热披覆效应等多种主要因素综合作用的结果.     

Thermal structure about southwest sub-basin of South China Sea

There are some factors, such as the topographic relief, sedimentary thickness and thermal conductivity, magmatic activity and thermal cooling, influencing the seafloor heat flow and the evolution of lithosphere structure in southwest sub-basin (SWSB), South China Sea. On the base of the geological structure characteristic of SWSB this paper will discuss some other factors including thermal anomaly area, dike produced by magma intrusion and lithosphere relief, by modeling and calculating. Calculating results indicate partial areas where temperature is higher than vicinity in the lithosphere, which we call thermal anomaly here containing thermal anomaly area and dike in this paper, could decrease heat flow below, increase above, and gradually increase to two sides; heat flow in upwelling parts of lithosphere is usually higher than sinking parts, and in the middle is of a gradual transition.     

Terrestrial heat flow from project CESAR, Alpha Ridge, Arctic Ocean

During two months in spring, 1983, a multidisciplinary study, project CESAR, was undertaken from the sea ice across the eastern Alpha Ridge, Arctic Ocean. In the geothermal program, 10 gradiometer profiles were obtained; 63 determinations of in situ sediment thermal conductivity were obtained with the same probe, and 714 measurements of conductivity using the needle probe method were obtained on nearby core.Weighted means of the thermal conductivity of the sediment are 1.26 W/mK (in situ) and 1.34 W/mK (core), consistent with the compacted sediment encountered across the ridge and with the lithology. Calculated terrestrial heat flow values, corrected for the regional topography, range from 37 to 72 mWm⁻²; the average is 56+/−8 mWm⁻².Some temperature and heat flow versus depth profiles exhibit non-linearities that can be explained by physically reasonable (but otherwise unsubstantiated) variations in bottom water temperatures preceding the measurements; models are hypothesized that reduce the curvatures. Two heat flow values considerably higher than others in the area may be explained by higher bottom water temperature over several years, while the low value is consistent with a recent deposition from a slump. This hypothetical modelling reduces the scatter of heat flows and reduces the average to 53+/−6 mWm⁻².The CESAR heat flow is somewhat greater than expected for a purely continental fragment but is consistent with crust of oceanic origin. The heat flow is similar to values obtained in Cretaceous back-arc basins. Based on the oceanic heat flow-age relationship, the heat flow constrains the age of the ridge to 60–120 million years. The heat flow observed on other aseismic features in the world's oceans suggests that the Alpha Ridge has experienced no significant tectono-thermal event in the last 100 million years.     

青海柴达木盆地大地热流测量与统计热流计算

１９９１年６-８月对青海柴达木盆地２１个石油勘探孔进行了钻孔温度测量,其中８个用于热流计算;从油田已有的测温资料中选取了１４个孔用作热流研究．为解决线性温度段与采样段的不匹配,对１７６块岩样的实测热导率与岩样的埋藏深度及地层年代之间的相关性进行了系统分析,求出热流计算段的加权平均热导率,共获得２２个热流值,其变化范围３２-７５ｍＷ／ｍ^２,平均约５３ｍＷ／ｍ^２．为阐明全盆地热流分布趋势,采用网格化方法计算统计热流．实测和统计热流一致表明,柴达木盆地热流值呈西高东低的分布特征．     

Heat flow in random medium: First order theory

Summary Steady state heat flow in a weakly random semi-infinite medium is considered from a geophysical point of view. The principal finding of the present investigation is that the variance of thermal gradient (vertical) is several times larger than the variance of thermal conductivity. The variance of the thermal gradient decreases with increasing depth of measurement but approaches a certain constant value, which depends upon the spectral characteristics of thermal conductivity. The variance of heat flow is generally lower ( 10%) than the variance of the thermal gradient, but it behaves similarly. The dip of the medium (assuming it to be randomly layered) significantly affects the variance of the thermal gradient. The variance is miniumum for an intermediate dip.     

川东北地区异常高压形成的地温场背景

利用四川东北地区现有的钻井测温数据及测定的岩石样品热导率数据,计算了12口钻井的大地热流值. 结果表明,川东北地区现今地温梯度为18～25 ℃/km,平均21 ℃/km,大地热流值介于41～57 mW/m2之间,平均为49 mW/m2. 在此基础上,利用镜质体反射率(Ro)资料对研究区热史进行了恢复,认为研究区在255Ma左右古热流达到最高值(62～70 mW/m2),此后热流持续降低直到现今;研究区中-新生界不整合面的剥蚀厚度最大,可达约2100 m;异常高压是在低热流的地温场背景下形成的.     

青海柴达木盆地大地热流测量与统计热流计算

１９９１年６—８月对青海柴达木盆地２１个石油勘探孔进行了钻孔温度测量,其中８个用于热流计算;从油田已有的测温资料中选取了１４个孔用作热流研究．为解决线性温度段与采样段的不匹配,对１７６块岩样的实测热导率与岩样的埋藏深度及地层年代之间的相关性进行了系统分析,求出热流计算段的加权平均热导率,共获得２２个热流值,其变化范围３２—７５ｍＷ／ｍ２,平均约５３ｍＷ／ｍ２．为阐明全盆地热流分布趋势,采用网格化方法计算统计热流．实测和统计热流一致表明,柴达木盆地热流值呈西高东低的分布特征．     

利用地下流体氦同位素比值估算大陆壳幔热流比例

地下流体中的氦同位素 3He来自地幔的排气作用 ,4He则是铀、钍衰变的产物 .由于铀、钍元素在大陆地壳中富集 ,4He通量与地壳热流呈正相关关系 ;同时 3He通量与地幔热流之间呈正相关 .所以地下流体的氦同位素比值 （3He / 4 He）与大陆壳幔热流比值 （qc/qm）呈反相关关系 .根据欧亚大陆和加拿大地盾的地下流体氦同位素比值数据和相应的壳幔热流比值数据 ,统计出 qc/ qm 与 3He / 4 He之间的回归关系 :qc/ qm =0 81 5- 0 30 0ln（3He / 4 He） ;此处 3He/ 4 He的单位是RA（大气的 3He/ 4 He比值 ） .有了地表热流值和壳幔热流比值即可得到地壳热流和地幔热流 .利用该公式以及热流值估算了中国主要盆地的壳幔热流值 ;根据这些数值得出的热岩石圈厚度和地壳平均生热率结果与地震学研究成果一致 .氦同位素比值是区分大陆热流中地壳热流值和地幔热流值的有用参数 .     

南海西南次海盆的地热流特征与分析

为系统地了解南海西南次海盆的地热流特征,本文通过对研究区及邻域地热流数据的补充采集、收集整理和统计分析,获得了87个有效的地热流数据、一批热导率和生热率的地热参数资料,地热流测点在空间上覆盖了整个区域.研究区的地热流数据分布结果表明,西南次海盆热流密度的平均值为98.1±14.8 mW·m^-2,洋陆过渡带为103.6±19.4 mW·m^-2,南沙岛礁区和西部陆缘分别为79.0±15.5 mW·m^-2和78.3±15.6 mW·m^-2.研究区表层沉积物热导率的平均值0.86±0.06 W·mK^-1,生热率的平均值1.11±0.17 μW·m^-3,海底温度的平均值为2.43±0.01℃.综合海底地形地貌、地质与地球物理资料,认为研究区的热流特征在空间上具有一定的分布规律,表现为：（1）洋盆区测点的热流密度平均值高于两侧陆缘;（2）东南缘洋陆过渡带上测点的地热流密度值高于邻近海盆和南沙岛礁区的测点,而西北缘这种特征不明显;（3）西北翼的热流密度值总体比东南翼高;（4）沿着古扩张中心方向,西南次海盆热流值具有自东北向西南端方向逐步增大的趋势,表明海盆区同时存在着洋中脊与大陆裂谷两种不同的热状态,西南段裂谷热流值比东北段洋中脊高.对西南次海盆沉积物的热导率和生热率值参数的测量及数据空间分析可见,这两种热参数的空间分布无明显规律性,可能与海盆形成之后复杂的沉积环境相关.根据热流-洋壳年龄之间的关系,在西南次海盆东北段26个测站数据中,发现靠近古扩张中心的数据与理论值呈负偏移,而远离古扩张中心的数据呈正偏移,此现象是海盆内地热流数据受不同类型的地下流体影响所致.

     

Multi-functional heat pulse probe measurements of coupled vadose zone flow and transport

Simultaneous measurement of coupled water, heat, and solute transport in unsaturated porous media is made possible with the multi-functional heat pulse probe (MFHPP). The probe combines a heat pulse technique for estimating soil heat properties, water flux, and water content with a Wenner array measurement of bulk soil electrical conductivity (EC_bulk). To evaluate the MFHPP, we conducted controlled steady-state flow experiments in a sand column for a wide range of water saturations, flow velocities, and solute concentrations. Flow and transport processes were monitored continuously using the MFHPP. Experimental data were analyzed by inverse modeling of simultaneous water, heat, and solute transport using an adapted HYDRUS-2D model. Various optimization scenarios yielded simultaneous estimation of thermal, solute, and hydraulic parameters and variables, including thermal conductivity, volumetric water content, water flux, and thermal and solute dispersivities. We conclude that the MFHPP holds great promise as an excellent instrument for the continuous monitoring and characterization of the vadose zone.