2D Inversion of Magnetotelluric Data from Wapsalit Geothermal Field, Indonesia

Abstract

Magnetotelluric (MT) measurements have been conducted at 30 sites around Wapsalit geothermal field in Buru Island, Indonesia. Analysis of two dimensional modeling of magnetotelluric data have been done to determine the location of geothermal prospect area. Field data in the form of time series is processed to produce an apparent rho and phase against frequency curve. From each curve then using a non linear conjugate gradient to find solution for the model that minimizes the objective function in the process of inversion modeling. Resistivity cross section with the smallest rms error is obtained by modifying the inversion parameters and mesh model initial through several iterations of the process. The result of the resistivity section obtained that low resistivity layer is visible from the surface to the depth of 1000 meter under sea level. Then in the middle of the area began at a depth of 500 meter to the depth of 1800 meter. The high resistivity predicted as the top reservoir at the depth between 1800 meter with resistivity values ranging about 30-200 ohm-m.