3D Effects on 2D Resistivity Imaging – Modelling and Field Surveying Results

Today resistivity surveying plays an important role in many large-scale area investigations. The existence of 2D effects on 1D resistivity modelling is a well known problem; however, former studies show that 3D effects in 2D surveying are less evident. The results presented here show that, nevertheless, there is an advantage in performing 3D inversion. A comparison between 2D inversion and 3D inversion has been made with analysis of data from two different synthetic models and three field datasets. From the synthetic study it is clear that 3D inversion give higher contrast, less inversion artefacts and better model recognition than 2D inversion. From the field studies it is also evident that 3D inversion gives models with higher contrast. With only limited ground truth data it is not always possible to determine which model is closest to the true one; however, where ground truth data is available it is clear that the 3D inversion gives a better result. In addition we show that the choice of array configuration have a significant influence on the result, with gradient array generally giving better results than the other options.