Airborne Electromagnetic

        The advancement of instruments over the last decade has made airborne EM a major geophysical method in mineral exploration and near surface applications. The new systems and the data sets generated by them offer many interesting and challenging research topics. For instance, the amount of data from an airborne EM survey can be hundreds or thousands times greater than that from a ground survey.

        Focusing on processing, modeling and interpretation, I have worked on data sets from most of the commercial airborne EM systems, including frequency-domain (DIGHEM, RESOLVE), time-domain (VTEM, HeliGEOTEM/HeliTEM, MegaTEM, SPECTREM, SkyTEM, AeroTEM, HeliSAM), and natural source (ZTEM) systems. The applications include mineral exploration (porphyry, massive sulphide, uranium, kimberlite, etc.) and environmental problems (groundwater). 3D modeling and inversion are featured in my research.

       近十年来仪器的进步使机载电磁勘探成为矿物勘探和近地表应用的主要地球物理方法。新系统及其生成的数据集提供了许多有趣且具有挑战性的研究课题。例如，空中电磁测量的数据量可能比地面测量的数据量大成百上千倍。

       我专注于处理、建模和解释，研究了大多数商用机载EM系统的数据集，包括频域(DIGHEM, RESOLVE)、时域(VTEM, HeliGEOTEM/HeliTEM, MegaTEM, SPECTREM, SkyTEM, AeroTEM, HeliSAM)和自然源(ZTEM)系统。应用领域包括矿产勘探(斑岩、块状硫化物、铀、金伯利岩等)和环境问题(地下水)。我的研究重点是三维建模和反演。

        Detailed geological interpretation relies on high-resolution 3D geophysical models, which are usually time-consuming to compute. For some really large surveys, the increase of computational cost can be exponential. I have been developing a new adaptive framework, referred to as survey decomposition that better scales the computation in a parallel computing environment.

        Survey decomposition uses two essential techniques. First it allows each datum to be simulated on its own mesh (with its own time stepping or frequency), eliminating the need of a massive global 3D mesh in the forward modeling. Second the number of randomly selected data (subproblems or local meshes) used in an inversion is adaptive to the degree of regularization. Together, they save significant amount of over-computing. Modeling of data on separate and customized meshes also enables the utilization of large-scale parallelization.

Survey Decomposition

        详细的地质解释依赖于高分辨率的三维地球物理模型，这些模型的计算通常很耗时。对于一些真正大型的调查，计算成本的增长可能是指数级的。我一直在开发一种新的自适应框架，称为调查分解，它可以更好地扩展并行计算环境中的计算。

       调查分解使用两种基本技术。首先，它允许每个数据在自己的网格上进行模拟(具有自己的时间步进或频率)，从而消除了在正向建模中需要大量全局3D网格的需要。其次，反演中随机选取的数据(子问题或局部网格)的数量与正则化程度相适应。总之，它们节省了大量的过度计算。在独立的和定制的网格上对数据进行建模还可以利用大规模并行化。

        The fluid transport in reservoirs can be traced by the electrical or electromagnetic signals associated with the fluid. A promising technique is monitoring the fluid, for examples, in hydraulic fracturing or carbon sequestration, using surface-based measurement. It is made possible by the steel cased wells that channel significantly enhanced current down to the depth of reservoirs.

        My focus on this project is to build the numerical capability of modeling the multiple casings existing in oilfields together with arbitrary 3D earth and frac models. The modeling program is then used to better understand the electrical interaction between casings and the earth, which leads to more effective monitoring strategies.

Electrical Reservoir Monitoring

        储层中的流体运移可以通过与流体有关的电信号或电磁信号来追踪。例如，在水力压裂或固碳过程中，一种很有前途的技术是使用基于表面的测量来监测流体。钢套管井能够显著地将电流引入储层深处，从而实现了这一目标。

        我的工作重点是在任意三维地球与压裂模型中建立多套管的数值模拟能力。 然后利用建模程序更好地理解套管与地球之间的电相互作用，从而制定更有效的监测策略。

Joint Interpretation

        Multiple data sets can be generated from different types of surveys at the same site. The sensitivity unique to each survey allows the earth's physical properties to be better inferred. The goal is to obtain a unified model that is supported by all the data sets. To achieve this, I have been working on developing the algorithms and workflows within the context of 3D inversion.

        A high-profile massive sulphide mining site Lalor served as a good testbed for my multi-data research. The site has been surveyed by more than 15 types of electrical and EM methods, producing a large amount of data at different scales from airborne, surface and borehole platforms.

        不同类型的调查可以在同一地点生成多个数据集。每一次探测所特有的敏感性使我们能够更好地推断地球的物理性质。其目标是获得所有数据集支持的统一模型。为了实现这一点，我一直在开发三维反演背景下的算法和工作流。

        一个引人注目的大型硫化物开采站点Lalor为我的多数据研究提供了一个很好的试验台。通过15种以上的电和电磁法对现场进行了测量，从空中、地面和钻孔平台获得了大量不同尺度的数据。

Research