重磁震解释在崖北凹陷的应用及海磁日变校正的改进

IOCAS-IR > 海洋地质与环境重点实验室

	重磁震解释在崖北凹陷的应用及海磁日变校正的改进
	苏达理
学位类型	硕士
导师	付永涛
	2016-05-20
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	海洋地质
关键词	重磁震联合解释崖北凹陷地磁日变校正剩余时差和幅值差
摘要	地震勘探方法虽然具有较高的分辨率，但在复杂的地质条件下，尤其是在海洋地震勘探中仍存在着对中深层地质目标识别不清，浅部强反射层屏蔽，多次波干扰等问题。单一使用地震勘探方法存在局限性，经常难以得到满意的地质解释。海洋重力勘探和磁力勘探在具有较高横向分辨率的同时经济便宜，在我国愈发重视海洋地质调查的情况下，海洋重磁勘探可以作为海洋地震勘探的有效补充。本次研究综合利用了卫星测高重力异常数据，海洋高精度重力和磁力采集数据，基于Encom ModelVision解释平台，结合琼东南盆地的区域地质背景资料，在两条地震剖面及邻近钻井资料的约束下，对琼东南盆地崖北凹陷的两条测线进行重磁反演及联合解释，并对两条剖面中存在的地质异常体的物性进行计算。通过反演计算，琼东南盆地崖北凹陷前新生界沉积基底密度为2.70g/cm³。沉积地层的密度变化范围为2.18～2.51g/cm³。地震剖面1200m处的地质异常体经反演计算判断为新近纪时期喷出地表被后续沉积地层覆盖所形成的蘑菇状，低密度，中等磁性的火成岩体。结合磁力异常可推断在测区西部还有更大规模的发育的火成岩。并综合反演结果与崖北凹陷发育演化和沉积特征综合探讨了该火成岩及相应火山活动对崖北凹陷油气勘探的影响。在对所使用的海洋磁力数据进行地磁日变校正时时，发现了使用陆地台站记录到的地磁日变数据在进行时间匹配后与海洋磁测工区的实际地磁日变数据之间存在明显的相位变化和幅值变化。本文定义了剩余时差和幅值差以定量描述这种相位和幅值的变化。并基于中国周边海域多个工区的高精度磁力异常数据和相应陆地地磁日变台站记录数据，发现剩余时差和幅值差的普遍存在，并极大地影响了海洋磁测数据校正的精度。通过对多条测线的剩余时差和幅值差变化情况进行分析，发现了幅值差的变化与测线纬度密切相关，并且可总结出经验公式用于对地磁日变校正进行改进。剩余时差则没有明显的变化规律，推测其应与地球电离层不规律的变化有关。通过使用校正后的地磁日变数据，能更好从海洋磁测数据中分离出地磁日变的影响以便运用于磁法解释中。
其他摘要	The seismic exploration method has a high resolution in detecting layered medium and is widely used in marine geophysics exploration. However, when facing the complex geological circumstance in unexploited zone, the seismic exploration method has many defects such as its weak capability in detecting the interference of the multiple wave of shallow layer and the shielding effect of the shallow layer with strong reflection characteristic. Using single seismic methods may not lead to a well interpretation in nowadays marine geophysics research. The marine gravity and marine magnet research has a high lateral resolution and has a relatively cheap price. So it could be a good supplement of seismic exploration in ocean area. Under the information of geological background information, the author used the jointed interpretation method of marine gravity and magnetic data of two survey lines in Yabei Sag, which in the north part of Qiongdongnan Basin. Under the restriction of the seismic section and drilling information, we made a 2.5D initial model based on the Encom ModelVision interpretation software to conduct the inversion. The result shows that the deposition substrate of Pre Cenozoic group has the density of 2.70 g/cm³, and the density of sedimentary strata varies from 2.18g/cm³ to 2.51g/cm³. Under the inversion calculation , the geological anomalies at 1200m depth reveals to be the igneous diaper of low density and medium susceptibility which form in the late Neogene. And by analysis of magnetic data, there would be large area of igneous intrusions. As the related volcanic plays as a dual role of construction and destruction in the formation and accumulation of oil and gas, it should be considered in the future research of Yabei Sag. When we conduct the geomagnetic diurnal variation of the magnetic acquisition in this research, we found there is obvious time shift and amplitude changes between the geomagnetic diurnal variation data we collected in the base station in land and in the survey zone, which we defined those time shift and amplitude change as residual time difference and amplitude difference. Based on the massive data analysis of the residual time difference and amplitude difference of geomagnetic diurnal variation data from 15 survey zone in the offshore survey area in China, we found the residual time difference exists in nearly all survey zone. And we generate regular patterns of the time shift and amplitude change with their influential factors and suggest a correct method of nowadays geomagnetic diurnal variation of marine magnetic survey.
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/112521
专题	海洋地质与环境重点实验室
作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	苏达理. 重磁震解释在崖北凹陷的应用及海磁日变校正的改进[D]. 北京. 中国科学院大学,2016.

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