Design of a Borehole-to-Surface Resistivity Survey for the Magma Energy Deep Exploration Well

Abstract

Design of a borehole to surface survey using the proposed the DOE Magma Energy Program's deep exploration well in Long Valley Caldera is discussed. High and low resolution surveys were considered. The ability to located structural boundaries was determined by generating data sets for a 3D conductor in a half space containing a conductive well casing, adding random noise and inverting the data using 2D inversion. The high resolution survey was able to resolve the locations of most of the boundaries of the conductor within 200 m even with 15% random noise added. However use of 2D interpretation for 3D wells caused errors in locating the bottom the conductor away form the well. Interpretation techniques to correct for this distortion must be developed. The low resolution survey was able to determine very gross structures with a resolution of the order of 1000m.