Three-dimensional Modeling For Transient Electromagnetic And Software Development

With the development of the theory of forward modelling and computing technology, three dimensional forward modelling of the Transient electromagnetic method(TEM) has been paid extensive attention by many researchers. The application of TEM has been widely used in many aspects such as solid mineral exploration, hydrogeological investigation and engineering geophysics. Now and in the future, the trend of TEM development is three dimensional exploration with high resolution and accuracy.In this trend, the three dimensional TEM forward modelling with high accuracy is key to the development of TEM applications. Since the engineering demand of exploration with high resolution and accuracy, the griding technic in three dimensional forward modelling of TEM should become more complex and accurate. At present, complex geoelectric model griding is limited by lack of effective method and tool. The traditional way of griding method uses input text to describe the physical. This method based on manual griding with low efficiency and accuracy. The manual griding is not valid in complex modelling and inefficient in checking the availability of the Yee cell of the Finite-Difference Time-Domain(FDTD) method. Besides, the traditional griding method cannot intuitionally reflect the spatial relations among the geological structure in the model. In this circumstance, using computer assistant design can make the modelling and griding of three dimensional geoelectric model more efficient and accurate.Based on the above, this paper accomplished a secondary development of the GID software. The result of this secondary development are the griding data which can be directly used in the FDTD forward modelling. The generating of the griding data is accomplished automatically by the code of this secondary development. And the secondary development method is valid of both uniform and ununiform grids of the FDTD method. At last, based on the secondary development method proposed by this paper, three dimensional forward modelling using FDTD method, is made to reveal the distribution of electromagnetic field in the circumstance of complex geoelectric model.