当前位置: X-MOL 学术Geophysics › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Geophysical inversion for 3D contact surface geometry
Geophysics ( IF 3.3 ) Pub Date : 2020-10-21 , DOI: 10.1190/geo2019-0614.1
Christopher G. Galley 1 , Peter G. Lelièvre 2 , Colin G. Farquharson 1
Affiliation  

Geologists’ interpretations about the earth typically involve distinct rock units with contacts between them. Three-dimensional geologic models typically comprise surfaces of tessellated polygons that represent the contacts. In contrast, geophysical inversions typically are performed on voxel meshes comprising space-filling elements. Standard minimum-structure voxel inversions recover smooth models, inconsistent with typical geologic interpretations. Various voxel inversion methods have been developed that attempt to produce models more consistent with such interpretations. However, many of those methods involve increased numerical challenges and ultimately the underlying parameterization of the earth is still inconsistent with geologists’ interpretations. Surface geometry inversion (SGI) is a fundamentally different approach that effectively takes some initial surface-based model and alters the position of the contact surfaces to better fit the geophysical data. Many authors have developed SGI methods. In contrast to those, we are the first to develop a method with the following characteristics: we work directly with 3D explicit surfaces from an input geologic model of arbitrary complexity; we incorporate intersection detection methods to avoid unacceptable topological scenarios; we use global optimization strategies and stochastic sampling to solve the inverse problem and aid model assessment; and we use surface subdivision to reduce the number of model parameters, which also provides regularization without adding the complication of trade-off parameters in the objective function. We test our methods on simpler synthetic examples taken from early influential literature, and we demonstrate their typical use on a more complicated example based on a seafloor massive sulfide deposit. Our work provides a geophysical inversion approach that can work directly with 3D surface-based geologic models. With this approach, geophysical and geologic models can share the same parameterization; there is only a single model, with no need to translate information between two inconsistent parameterizations.

中文翻译:

3D接触面几何的地球物理反演

地质学家对地球的解释通常涉及不同的岩石单元,它们之间具有接触。三维地质模型通常包含代表接触的棋盘形多边形表面。相反,地球物理反演通常在包含空间填充元素的体素网格上执行。标准的最小结构体素反演可恢复平滑的模型,这与典型的地质解释不一致。已经开发了各种体素反演方法,其试图产生与这种解释更一致的模型。但是,这些方法中的许多方法都涉及越来越多的数值挑战,并且最终,地球的基本参数设置仍然与地质学家的解释不一致。表面几何反演(SGI)是一种根本不同的方法,可以有效地采用一些初始的基于表面的模型并更改接触面的位置以更好地拟合地球物理数据。许多作者开发了SGI方法。与此相反,我们是第一个开发具有以下特征的方法的:我们直接从任意复杂度的输入地质模型中处理3D显式曲面;我们采用了相交检测方法,以避免出现不可接受的拓扑情况;我们使用全局优化策略和随机抽样来解决逆问题和援助模型评估;并且我们使用曲面细分来减少模型参数的数量,这也提供了正则化而没有在目标函数中增加权衡参数的复杂性。我们从早期有影响力的文献中选取了更简单的合成示例,对我们的方法进行了测试,并在基于海底块状硫化物矿床的更复杂示例中证明了它们的典型用法。我们的工作提供了一种地球物理反演方法,可以直接与基于3D地面的地质模型一起使用。通过这种方法,地球物理模型和地质模型可以共享相同的参数设置。仅存在一个模型,无需在两个不一致的参数化之间转换信息。地球物理模型和地质模型可以共享相同的参数化;仅存在一个模型,无需在两个不一致的参数化之间转换信息。地球物理模型和地质模型可以共享相同的参数化;仅存在一个模型,无需在两个不一致的参数化之间转换信息。
更新日期:2020-10-27
down
wechat
bug