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901.
Abstract: Based on the technology of balanced cross-section and physical simulation experiments associated with natural gas geochemical characteristic analyses, core and thin section observations, it has been proven that the Puguang gas reservoir has experienced two periods of diagenesis and restructuring since the Late Indo-Chinese epoch. One is the fluid transfer controlled by the tectonic movement and the other is geochemical reconstruction controlled by thermochemical sulfate reduction (TSR). The middle Yanshan epoch was the main period that the Puguang gas reservoir experienced the geochemical reaction of TSR. TSR can recreate the fluid in the gas reservoir, which makes the gas drying index higher and carbon isotope heavier because C2+ (ethane and heavy hydrocarbon) and 12C (carbon 12 isotope) is first consumed relative to CH4 and 13C? (carbon 13 isotope). However, the reciprocity between fluid regarding TSR (hydrocarbon, sulfureted hydrogen (H2S)?, and water) and reservoir rock results in reservoir rock erosion and anhydrite alteration, which increases porosity in reservoir, thereby improving the petrophysical properties. Superimposed by later tectonic movement, the fluid in Puguang reservoir has twice experienced adjustment, one in the late Yanshan epoch to the early Himalayan epoch and the other time in late Himalayan epoch, after which Puguang gas reservoir is finally developed. 相似文献
902.
Abstract: The densities of CO2 inclusions in minerals are commonly used to determine the crystallizing conditions of the host minerals. However, conventional microthermometry is difficult to apply for inclusions of small size (< 5–10 μm) or low density. Raman analysis is an alternative method for determining CO2 density, provided that the CO2 density–Raman shift relation is known. This study aims to establish this CO2 density–Raman shift relation by using CO2 inclusions synthesized in fused silica capillaries. By using this newly-developed synthetic technique, we formed pure CO2 inclusions, and their densities were determined by microthermometry. The Raman analysis showed that the relation between CO2 density (D in g/cm3) and the separations (Δ in cm?1) between the two main bands (i.e. Fermi diad bands) in CO2 Raman spectra can be represented by a cubic equation: D (g/cm3)=0.74203(?0.019Δ3+5.90332Δ2?610.79472Δ+21050.30165)?3.54278 (r2=0.99920). Our calculated D value for a given Δ is between those obtained from two previously-reported equations, which were derived from different experimental methods. An example was given in this study to demonstrate that the densities of natural CO2 inclusions that could not be derived from microthermometry could be determined by using our method. 相似文献
903.
In order to understand the characteristics of magnetic variability and their possible implication for sub-sea methane venting,magnetic susceptibility (MS) of 145 surface sediment samples from the southern South China Sea (SCS) was investigated.Magnetic particles extracted from 20 representative samples were also examined for their mineral,chemical compositions and micromorphology.Results indicate that MS values range between -7.73×10-8 and 45.06x10-8 m3/kg.The high MS zones occur at some hydrecarbon-bearing basins and along main tectonic zones,and low ones are distributed mainly within the river delta or along continental shelves.Iron concretions and manganese concretions are not main contributors for high MS values in sediments,while authigenic iron sulphide minerals are possibly responsible for the MS enhancement.This phenomenon is suspected to be produced by the reducing environment where the high upward venting methane beneath the seafloor reacts with seawater sulfate,resulting in seep precipitation of highly susceptible intermediate mineral pyrrhotite,greigite and paramagnetic pyrite.It suggests that MS variability is possibly one of the geochemical indicators for mapping sub-sea zones of methane venting in the southern SCS. 相似文献
904.
1 IntroductionThe natural disasters, especially the flood and drought disasters, have occurred frequently inG uangdong area since ancienttim es.A ccording to historic statisticaldata,since the 17th century,the occurrence of the flood and drought disasters… 相似文献
905.
南海东北部首次成功实施海陆联合深地震探测,填补了海陆过渡带深地震探测的空白. 利用该次海陆联测地震数据,通过数据处理、震相分析、射线追踪、走时模拟等方法,获得了滨海断裂带附近的纵波地壳速度结构,探明了海陆联测剖面中滨海断裂带可能位置. 地壳速度结构为陆壳结构,地壳厚度由陆地向海区逐步变薄;在上地壳下部普遍存在一层速度为5.5~5.9km·s-1、厚度为2.5~4.0km的低速层,并向海区方向减薄,该区未发现明显的高速层. 滨海断裂带为一纵向低速带,位于南澳台东南35km处,对应于重、磁异常带,断裂带断至莫霍面,是华南陆区正常型陆壳与海区减薄型陆壳的分界地壳断裂. 相似文献
906.
在大地电磁(MT)测深法中,大地电磁响应函数经常出现个别频点分散、误差棒较大、形态异常等现象,在作反演解释时,许多地质特征难以有效提取出来,这些问题严重阻碍了MT的实际应用效能和发展.本文利用高阶统计量方法检验了MT信号的高斯性. 结果表明,MT信号是非高斯的. 根据任何高斯过程,其高阶统计量(高阶累积量,高阶谱)均为零的性质,通过信号的高阶谱恢复功率谱,再由功率谱估算MT响应函数,能有效抑制高斯有色噪声的影响,提高MT资料的处理质量. 从应用效果看,这种方法在抑制高斯有色噪声、提取信号中有用信息方面优于传统功率谱方法. 相似文献
907.
908.
2002年在京津冀地区进行了45个测点的地磁三分量测量,对测量资料进行通化处理,通化时间为2002年5月5日16~18时(世界时). 通化后的观测均方差分别优于1.5nT(地磁场总强度F),0.5′(磁偏角D和磁倾角I). 将国际参考地磁场(IGRF2000)作为地磁正常场,建立了京津冀地区地磁异常场的球冠谐模型(BTHASCH). 球冠极的空间位置坐标为39.5°N和117.0°E,球冠半角为4°. 在模型计算过程中,球冠谐函数的截断阶数分别取为1~10. 经综合比较, 最终采用的截断阶数为5. 建立了京津冀地区参考地磁场的球冠谐模型(BTHGRF).根据模型,绘制了京津冀地区地磁异常场图(ΔX、ΔY、ΔZ、ΔF、ΔD、ΔI)和京津冀地区地磁图(X、Y、Z、F、D、I). 相似文献
909.
利用国内大型风沙物理风洞实验模拟沙尘暴电现象,研究风沙起电机理,结果表 明,不同风速下不同沙粒会产生不同极性的电场强度和电位效应,风沙电随风速增大而增强 ,且随沙粒度增大而减小. 在沙漠区的16m,8m,4m和1m高度上观测到27次不同沙尘暴天气 过程的电场和风速随时间变化. 结果表明, 在晴天4个高度上的电场均为小正电场值,电场 随高度降低而减小,最大电场强度在5kV/m以下,日风速变化对各层电场起伏没有较大影响 . 有沙尘天气,各高度上的电场强度随风速变化而变化. 16m高度上电场均为负值,平均值 为 -20kV/m;中层8m 电场一般为较高正电场值,达到10~40kV/m,与16m高度上电场呈反相 关;下层1m 电场值变化一般很小,在1kV/m以下. 在强沙尘暴天气4个高度上的电场均为负 电值,电场值随高度降低而减小,16m高度上最大平均电场强度达到-200kV/m以上,瞬时值 超过 -2500kV/m,与晴天电场矢量相反. 相似文献
910.