【作者】 陈挺；

【导师】 刘展；

【作者基本信息】 中国石油大学 ， 地球探测与信息技术， 2010， 硕士

【摘要】 重磁火成岩成像方法,是由火成岩体引起的重磁异常反演得到视密度和视磁化强度值,据此依据火成岩的密度和磁性特征圈定出火成岩体赋存的空间位置,其成像的正确与否取决于反演的精度,重磁三维视密度和视磁化强度值反演的基本思路是,将地下场源区域划分成若干小长方体单元,通过反演确定每个单元的物性。这种反演思路的主要问题是计算量巨大和多解性严重。针对这两个问题,本文提出了基于重磁场特征和综合地质、钻井信息的反演约束机制,实现了重磁异常的物性定量反演。如何有效地利用重磁场空间形态特征信息和已知的信息对解进行约束是提高反演可靠性的关键。本文通过研究概率成像扫描函数,引入核函数的方差函数代替概率成像扫描函数,改善了地质体的局部收敛性,从而利用概率成像技术对目标地质体进行定性约束。在定性约束的基础上,以地质、钻井、地震等资料作为定量约束,利用剖分单元和重磁场局部特征相关关系,采用多体搜索技术,确定异常源空间赋存状态,将据钻井和地震资料形成的点约束或线约束变为体约束,这样就对未知剖分网格的物性取值区间进行了约束,而能够直接确定物性值的剖分网格越多,解空间的维数也就越低,实现对解空间降维。从而建立初始定性-半定量模型,由此形成了可行的重磁物性三维定量反演算法。设计理论地质模型进行方法实验研究,测试了输入参数的选取原则和反演方法对各种重磁场源及其组合的反演效果。模型试验结果表明,本文方法提高了重磁成像的分辨力,使对场源体的边界刻划更为精细,对叠加异常体也能够正确归位,从而改善了重磁成像的整体效果。应用本研究方法对阳信洼陷地区重磁异常进行了视密度和视磁化强度反演,并依据视磁化强度和视密度的三维分布值进行了火成岩体推断解释,在阳信洼陷地区推断出火成岩21个,与钻井吻合度较高,达到了重磁成像的基本要求。更多还原

【Abstract】 The method for gravity and magnetic imaging of igneous rock, according to the gravity and magnetic anomaly of igneous rock, virtual density and magnetization depression were inversed. From the inversion results, the spacial distribution of igneous rock was deduced. And the imaging quality depends on the accuracy of the inversion, to the existing location-field 3d inversion technique, the basic idea is to divide the underground field source area into small cuboid units, through modeling element fitting inversively to determine these units. The main inversion problems are of the great amount of calculation and multi-solution seriously. In order to solve these two problems, we use the local gravity and magnetic field feature, and comprehensive geological and local information of drilling to form constraint mechanism, and we realize the quantitative physical property inversion based on the gravity and magnetic anomaly.How to effectively use the morphological characteristics of gravity and magneitic field and the known spatial information to constraint the solution are the key to improve the reliability of the inversion. this paper improve probability tomography scan function, through the introduction of the kernel variance function instead of probability tomography scan function, improve the local convergence of the geological body, using probability imaging technology to constraint the target geological-mass qualitativly. Then, on the basis of qualitative constraints, using geology, drilling and seismic data as quantitative constraints, using the relevant relation of the local characteristics of gravity and magneitc field and geological unit, determine the geological distribution in space by multiple search technology, this will make point constraint or line constraint into volume constraint, through constraint the property value interval of unknown grid, and the more of directly determined grid, the lower of the dimension of solution space, then reduct the dimension of solution space. Then we establish the initial qualitative - semi-quantitative model, and form the feasible 3d gravity and magnetic physical property quantitative inversion algorithm.Geological model is designed based on above research results, test the input parameters and selection principle, and study the imaging results of single source and combined source. Model test shows that this method improves the image resolution of gravity and magnetic field, the boundary of the source of superposition is more elaborate, and can correct of position of stack abnormal body, so as to improve the overall effect of gravity and magnetic imaging.This method was applied to inverse virtual density and magnetization of igneous rock in YangXin area, depending on the intensity of the virtual density and magnetization, and deduced the spatial distribution of igneous, delineating 21igneous in YangXin area, and inosculation higher with drilling information, achieve the basic requirements of gravity and magnetic imaging.更多还原