重震联合界面反演技术研究
发布时间：2019-05-12 17:50
【摘要】：目前,随着勘探目标愈加复杂,传统单一地球物理方法无法满足当前的勘探要求,并且受到地球物理反演问题多解性影响,使得综合地球物理勘探之路势在必行。联合反演的目标是获得满足不同地球物理数据的地球物理模型,因此,需要不同地球物理方法之间存在一定的联系,而波速与密度之间的关系较为明显,所以在联合反演中,重震联合反演的研究较多,本文研究二维界面的重震联合反演。二维界面的重震联合反演采用能够较好反映界面信息的反射波与重力数据联合。在重力正演方面,利用2.5D直立六面体剖面界面模型,进行重力正演;在地震波走时正演方面,采用快速行进法(FMM)分区多步方法,利用不等间距差分解决起伏观测面或界面的地震反射波走时正演,并利用线性旅行时插值法(LTI)进行了射线追踪。在反演方面,分析了前人在联合反演研究中使用的目标函数,通过分析认为该目标函数受重力异常和地震走时单位选取的影响较大,经过研究得出联合反演的目标函数采用归一化目标函数,解决了这一问题。利用理论模型测试了不同目标函数的反演效果以及不同权重因子下的反演结果。理论模型测试结果表明,本文提出的归一化目标函数基本不受重力异常和地震走时单位选取的影响,而且这一目标函数受权重因子的影响也较小。同时为了提高计算效率,从反演计算量最大的正演计算入手,引入并行运算,大大提高了反演的计算效率。最后,将该方法用于M?re陆缘地区的莫霍面深度反演,利用卫星重力数据和海底高频地震仪(OBS)莫霍面反射波走时进行联合反演,得到了莫霍面深度。通过应用研究认为该方法具有一定的实用性。
[Abstract]:At present, with the increasing complexity of exploration targets, the traditional single geophysical method can not meet the current exploration requirements, and is affected by the multiple solutions of geophysical inversion problems, which makes the road of comprehensive geophysical exploration imperative. The goal of joint inversion is to obtain geophysical models satisfying different geophysical data. Therefore, there is a certain relationship between different geophysical methods, and the relationship between wave velocity and density is more obvious, so in joint inversion, There are many studies on joint inversion of heavy earthquakes. In this paper, the joint inversion of heavy earthquakes at two-dimensional interface is studied. In the joint inversion of heavy earthquakes at the two-dimensional interface, the reflected waves and gravity data which can better reflect the interface information are combined. In the aspect of gravity forward modeling, 2.5D vertical hexahedral section interface model is used to carry out gravity forward modeling. In the aspect of forward modeling of seismic wave travel time, the fast forward method (FMM) partition multi-step method is used to solve the travel time forward modeling of seismic reflected wave on undulating observation surface or interface by using unequal spacing difference. The linear travel time interpolation method (LTI) is used for ray tracing. In the aspect of inversion, the objective function used in the joint inversion research is analyzed, and it is considered that the objective function is greatly affected by gravity anomaly and seismic travel time unit selection. Through the research, it is concluded that the objective function of joint inversion adopts normalized objective function, which solves this problem. The inversion effect of different objective functions and the inversion results under different weight factors are tested by using the theoretical model. The test results of the theoretical model show that the normalized objective function proposed in this paper is basically not affected by gravity anomaly and seismic travel time unit selection, and this objective function is less affected by the weight factor. At the same time, in order to improve the computational efficiency, the parallel operation is introduced from the forward calculation with the largest amount of inversion computation, which greatly improves the computational efficiency of inversion. Finally, the method is applied to the Moho surface depth inversion in the M?re continental margin area, and the Moho surface depth is obtained by using the satellite gravity data and the travel time of the reflected wave on the (OBS) Moho surface of the seafloor high frequency seismograph. Through the application research, it is considered that the method has certain practicability.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P631
[Abstract]:At present, with the increasing complexity of exploration targets, the traditional single geophysical method can not meet the current exploration requirements, and is affected by the multiple solutions of geophysical inversion problems, which makes the road of comprehensive geophysical exploration imperative. The goal of joint inversion is to obtain geophysical models satisfying different geophysical data. Therefore, there is a certain relationship between different geophysical methods, and the relationship between wave velocity and density is more obvious, so in joint inversion, There are many studies on joint inversion of heavy earthquakes. In this paper, the joint inversion of heavy earthquakes at two-dimensional interface is studied. In the joint inversion of heavy earthquakes at the two-dimensional interface, the reflected waves and gravity data which can better reflect the interface information are combined. In the aspect of gravity forward modeling, 2.5D vertical hexahedral section interface model is used to carry out gravity forward modeling. In the aspect of forward modeling of seismic wave travel time, the fast forward method (FMM) partition multi-step method is used to solve the travel time forward modeling of seismic reflected wave on undulating observation surface or interface by using unequal spacing difference. The linear travel time interpolation method (LTI) is used for ray tracing. In the aspect of inversion, the objective function used in the joint inversion research is analyzed, and it is considered that the objective function is greatly affected by gravity anomaly and seismic travel time unit selection. Through the research, it is concluded that the objective function of joint inversion adopts normalized objective function, which solves this problem. The inversion effect of different objective functions and the inversion results under different weight factors are tested by using the theoretical model. The test results of the theoretical model show that the normalized objective function proposed in this paper is basically not affected by gravity anomaly and seismic travel time unit selection, and this objective function is less affected by the weight factor. At the same time, in order to improve the computational efficiency, the parallel operation is introduced from the forward calculation with the largest amount of inversion computation, which greatly improves the computational efficiency of inversion. Finally, the method is applied to the Moho surface depth inversion in the M?re continental margin area, and the Moho surface depth is obtained by using the satellite gravity data and the travel time of the reflected wave on the (OBS) Moho surface of the seafloor high frequency seismograph. Through the application research, it is considered that the method has certain practicability.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P631
【参考文献】
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