【作者】 章桂芳；

【导师】 陈汉林； 沈晓华； 邹乐君；

【作者基本信息】 浙江大学 ， 地质学， 2009， 博士

【摘要】 烃类物质微渗漏会引起地表的岩石、土壤、生物等地球化学异常的响应,从而在遥感图像上形成可识别的影像特征。针对松辽盆地西部斜坡区地域辽阔、地表覆盖相对简单的地面状况及良好的稠油勘探前景,本次研究以烃渗漏蚀变矿物在Landsat 7 ETM+（陆地卫星增强型专题制图仪）各个波段上的波谱特征为基础,采用主成分分析、波段比值,最佳指数因子和假彩色合成等多种遥感图像信息增强方法,对松辽盆地西部斜坡区的ETM+7图像进行处理,得到针对研究区域烃渗漏蚀变地物的特征主成分因子、波段比值因子和假彩色合成影像;综合合成影像上烃渗漏蚀变的理论影像特征和已有探井周边的实际影像特征确定烃渗漏蚀变区的影像特征,进而解译烃渗漏蚀变区;综合分析地面样本地球化学勘探数据、地质剖面与遥感解译结果,评价烃渗漏遥感探测的可靠性和有效性;对照区域地质资料讨论异常区的地质背景;根据地表地球化学勘探结果总结烃渗漏蚀变在地面上的变化规律,利用井下样本的地球化学测试数据和录井解释探索烃渗漏蚀变沿途的地球化学变化规律。本次研究主要取得了以下认识和进展:1.通过烃渗漏蚀变矿物特征波谱和特征矩阵的分析,首次提出针对松辽盆地西部斜坡区烃渗漏蚀变信息增强的特征主成分因子4个;通过特征波谱的分析,提出能有效增强松辽盆地西部斜坡区烃渗漏蚀变信息的波段比值因子4个。2.根据选取的特征主成分因子和波段比值因子的波谱统计特征及相关系数分析,采用最佳指数因子法（OIF）计算排序并经过判读后,选取5幅假彩色合成影像对于烃渗漏蚀变区的解译,结果显示烃渗漏蚀变异常区在这些影像上具有较稳定的分布范围,并且与区域地质背景紧密联系。3.异常区土壤样本的地球化学测试结果显示烃类物质微渗漏引起的地球化学变化在近地表土壤表现明显,测试结果与遥感解译一致:一级异常区的地面样本酸解烃（C₂-C₅）含量在解译的异常区内总体表现为高值,并与异常区的展布方向一致,表明烃类物质相对含量在近地表土壤中由于长期的吸附作用而明显提高;一级异常区的地面样本土壤蚀变碳酸盐测量结果与异常区的展布表现出正相关的关系,表明烃渗漏确实在近地表土壤中形成了蚀变碳酸盐的累积;土壤样本磁化率变化趋势图显示该区的磁化率变化方向与一级异常区有较明显的正相关关系,说明烃渗漏造成的还原环境会引起土壤和沉积物中高磁化率矿物的形成;由于烃渗漏形成了还原环境,造成三级异常区的Ce/La比值表现为低值。4.经过对富拉尔基南一级异常区地面范围与地质剖面比对发现:异常区（或周边）内的探井均钻遇油层,但异常区在地表的出露范围小于下伏实际含油砂体的分布范围,局部存在异常区与下伏含油砂体的偏移。原因可能是由该区地层及含油砂体向东倾斜的地形以及城区和嫩江水体等干扰因素引起的。5.1号和2号探井的井下样本的磁化率和蚀变碳酸盐测量值结果显示烃渗漏在垂向路径上引起的地球化学变化具有一定规律:近地表样品的磁化率小于深层样品的磁化率,近地表样品的蚀变碳酸盐大于深层样品的蚀变碳酸盐;在油页岩之上的深层泥岩样品中,磁化率与深度呈负相关,蚀变碳酸盐与深度呈正相关,并且在油页岩样品中达到最大值;砂砾岩样品的磁化率和蚀变碳酸盐含量随着深度的降低而骤减;磁化率在浅层样品中较稳定,蚀变碳酸盐在浅层样品中变化较大。研究结果表明本文提出的烃渗漏信息遥感图像增强与提取方法对于研究区域是有效和可靠的,遥感解译的烃渗漏蚀变异常区内的地表化探结果与烃渗漏引起的地表环境响应特征基本吻合,烃渗漏引起的蚀变异常在地面上和垂直路径上都具有一定的空间规律。更多还原

【Abstract】 Hydrocarbon leakage or migration would result in rock, soil and botanical anomaly in near-surface sediments which can be identified in remote sensing image. Because of its wide region, simple surface cover and promising deposit of heavy oil in Western slope zone of Songliao basin, China, the area is suitable for remote sensing study. The present study used ETM+ (Landsat 7 Enhanced Thematic Mapper Plus) image to identify the hydrocarbon-induced area based on the diagnostic spectral characteristics of the hydrocarbon-induced manifestations and the spectral enhancement including Principal Component Analysis (PCA), band ratioing, Optimum Index Factor (OIF) and False Color Composition (FCC). The optimum principal components, band ratios and false color compositions were achieved. According to the theoretical characteristics of hydrocarbon-induced manifestation and the tonal characteristics around the existed well, the hydrocarbon-induced area were interpreted in the whole area. Then, the identified tonal anomalies were discussed in the context of geochemical data and cross sections to validate the reliability of the result. The geological setting of the tonal anomaly was noted and the geochemical characteristic resulted from hydrocarbon leakage on the ground was priamaryly achieved. Geochemical measurement results of the samples from exploratory well and logging interpretation were used to imply the geochemical characteristic along with the vertical pathway of hydrocarbon migration. Main conclusions and developments of this study are listed below:1. In Western slope zone of Songliao basin, China, there are four principal components (PCs) have relatively good enhancement for delineating mineral and sediment anomalies caused by hydrocarbon leakage. And there are four band ratios have relatively good enhancement for delineating mineral and sediment anomalies caused by hydrocarbon leakage.2. The selected principal components and band ratios are used for statistical multi-bands combination analysis of OIF. Then according to the OIF result, five false color compositions have good representation of the hydrocarbon-induced manifestation. The interpretation result shows that the hydrocarbon-induced areas have steady distribution and were related close to geological setting.3. The geochemical measurements of ground samples indicated that the tonal anomalous area in remote sensing image is related close to soil chemistry changes: (1) The acidolysis hydrocarbon measurement of ground soil samples from the first-order promising area reveals that light hydrocarbon concentration is larger in the first-order promising area and the spatial distribution of light hydrocarbon concentrations mostly agrees with the distribution of the promising area. (2) the delta-carbonate test (ΔC) of ground soil samples from the first-order promising area indicates that the occurrence of anomalous concentrations of delta-carbonate is positive evidence for the tonal anomaly. (3) It is noted that the direction of the magnetic susceptibility is NNE, coincident with the anomalous area. Though the variation image can’t cover the whole anomaly because of the limited distribution of the surface samples, it implies that the correlation between magnetic properties and the surface anomalies caused by hydrocarbon is positive in this area. (4) The result of the Ce/La ratio in the third-order promising area is low indicating the reducing environment. The positive spatial correlation between tonal anomaly and reducing environment emphasizes the idea the identified anomaly has a geochemical origin.4. The strata section crossing the first-order promising area (southern Fulaer’ji) indicates that the most drilling wells around this anomalous area have met the oil-bearing layer. However, the surface anomalous area detected in the remote sensing interpretation is smaller than that which might be inferred from the profile and is often located updip and westward of the reservoir. And it is may caused by the eastward strata and the spectral disturbance of city zone and Nen River.5. The magnetic susceptibility (MS) and delta-carbonate (ΔC) of rock samples in wells Jiang 75 and Jiang 76 show the geochemical characteristics along with pathway of hydrocarbon migration as below: (1) MS value of near surface sample is smaller than that of deep-seated sample and the delta-carbonate content of near surface samples is much higher than that of deep-seated sample. (2) Above the oil-bearing layer, the magnetic susceptibility of sandy gravel sample is increasing along with the decrease of the depth. In contrast, the delta-carbonate content is decreasing when the depth is decreasing. And the lowest MS and highestΔC perfectly mark oil-bearing layer of the oil shale. (3) MS value and delta-carbonate content have very large variation in sandy gravel samples and decrease strongly when the depth is decreasing. (4) Samples of near surface exhibit an intense variation of the delta-carbonate content and relatively steady representation of magnetic susceptibility.The result suggests that the enhancement and interpretation of remote sensing image for the study area proposed are applicable and dependable for the study area. The relationship between the many kinds of field data and identified anomalies from remote sensing image suggests that the hydrocarbon-induced manifestation would cause characteristics both on the ground and along with the vertical pathway.更多还原