.Join Interpretation Geophysics Method (Magnetotelluric, Gravity, Magnetic) in Arjuno-Welirang Geothermal Field

Geothermal Power Plants is one in utilizing geothermal as a source of electric power. Electricic capacity can be generated by Geothermal Power Plants depend on the potential of the Geothermal Working Area, which in this case geothermal potential can be measured using geophysical methods. Have been done acquisition of geophysical methods consisting of Magnetotelluric, Gravity and Magnetic methods in Geothermal Working Arjuno area-Welirang, East Java. The data results by the geophysical acquisition then is processed and interpreted by correlating the pysical properties (Joint Interpretation). Join interpretation use to provide a information of the subsurface geology by utilizing several physical properties, such as density, suceptibilitas, and the resistivity which result by inversion process each of the above methods.These methods have the advantage of each instance method MT (Magnetotelurric) capable gave the picture of the subsurface resistivity bedding to a depth of several kilometers. Gravity method is able to show the boundary between source rock and reservoir , while magnetic method is able to show the existence of contacts between the rocks and hydrothermal fluids that show the loss of value of the magnetization of a rock. Besides the gravity and magnetic methods can show geology feature such as crack, faulting and the bedding boundary between the heat source rock, rock cap rock and reservoir rock. By doing correlation these third physical properties we can obtained information about boundary between the source rock, heat source, and the cap rock, so that the prosess estimated geothermal potential can be done accurately because it is done by considering many physical properties. The output of this study is geometric model of the geothermal reservoir are created by resistivity, density and susceptibility.