Development of joint moving-interface inversion methodology for geophysical DC resistivity and time-domain EM data

铀矿开采对加拿大经济至关重要，找到更多的铀矿矿床对该行业的未来至关重要。加拿大的大多数铀矿都位于萨斯喀彻温省北部的阿萨巴斯卡盆地。铀矿体位于地球表面以下数百米处，位于深基底岩的断裂带和基底岩上的沉积岩之间的交界处。基底岩石中的这些断裂带通常含有石墨，与周围岩石相比，石墨的导电性相对较好。电、电磁测量对地下导电特征的存在十分敏感，在寻找新的铀矿体中具有重要作用。这些调查的数据包含了石墨断层带的位置、深度、大小和电导率等信息。从这些调查中可以更好地确定断裂带的位置等，所需的钻井就越少，这可以显着降低勘探过程的费用。要从调查数据中得出这一信息，需要使用计算机模拟和解释技术。然而，目前的技术并不适合石墨断裂带的尖锐、独特的性质，而是产生模糊、模糊的断层表示。该项目将扩展以前为重力和磁数据开发的一种新的计算机解释方法，以包括电和电磁数据。这种新方法通过离散相邻岩石类型之间的界面来指定地下特征，然后移动和调整这些界面，以便为该地下模型计算的地球物理测量数据与测量数据相匹配。这与目前的方法相反，目前的方法是将地下分成许多小单元，并在所有单元中找到电导率值，以便计算和测量数据之间的匹配良好，并且物理性质从一个单元到下一个单元的变化是平滑的。

Uranium mining is important to Canada's economy, and finding more uranium ore deposits to mine is criticalto the future of this industry. Most uranium ore deposits in Canada are to be found in the Athabasca Basin in northern Saskatchewan. The uranium ore-bodies are located hundreds of metres beneath the Earth's surface at the junction between fault zones in the deep basement rocks and the sedimentary rocks which lie on top of the basement rocks. These fault zones in the basement rocks often contain graphite, which makes them relatively good at conducting electricity compared to the surrounding rocks. Electrical and electromagnetic surveys are sensitive to the presence of such electrically conductive features in the subsurface, and so play an important role in the exploration for new uranium ore-bodies in the Athabasca Basin. The data from such surveys contain information about the location, depth, size and electrical conductivity of the graphitic fault zones. The better the location, etc., of the fault zones can be determined from these surveys the less drilling is required, which can significantly reduce the expense of the exploration process. To derive this information from the survey data requires the use of computer modelling and interpretation techniques. However, current techniques are not suited to the sharp, distinct nature of the graphitic fault zones, producing instead fuzzy, indistinct representations of the faults. This project will extend a new computer interpretation approach, previously developed for gravity and magnetic data, to include electrical and electromagnetic data. This new approach specifies the subsurface features by discretizing the interfaces between neighbouring rock types, and then moving and adapting these interfaces so that geophysical survey data computed for this model of the subsurface match the data measured in a survey. This is in contrast to the current approach, which is to divide the subsurface into many little cells and to find the values of electrical conductivity in all the cells such that the match between computed and measured data is good and that the variation of the physical property from one cell to the next is smooth.