ANALISIS KARAKTERISTIK PANASBUMI DAERAH OUTFLOW GUNUNG ARJUNO-WELIRANG BERDASARKAN DATA GEOLOGI, GEOKIMIA, DAN GEOFISIKA (3G)

Abstract

The research has been done  to analyzed characteristics of geothermal outflow at Mt.  Arjuno-Welirang  area,  based on geology,  geochemistry,  and  geophysics  data. Geochemistry data is used to determine type of fluid, temperature of reservoir, and framer of reservoir rocks. Geochemistry data  in outflow area produces bicarbonate water (HCO3) with the temperature of reservoir  in  this area about 145°C  to 175°C and  the  framer of  reservoir rock  is  basaltics. Analysis  of characteristics  geothermal system  components  (caprock  and reservoir)  based  on  physical properties  i.e. resistivity and density.   Resistivity value is resulted  from 2D magnetotellurics model and density value is resulted from 3D gravity model. From these results,  impermeable  (caprock) area  have a resistivity value about ≤ 10 Ohm.m with curve pattern in which side is thicker and density values is between 1,49 gr/cm3 and 2,4 gr/cm3 with distribution patterns  from west to east and the depth of  top  layer  from caprock   is  about  500 to 1000  m,  and type of  material  is  secondary  clay  mineral  and controlled  by  Fault Puncung.   For the  permeable  (reservoir)  in this  area  have a resistivity values at between 10 and 60 Ohm.m and density value is between 2,4 gr/cm3 and 2,67 gr/cm3 with  the depth about ≥1,5 km and type of material rock  is andesit-basaltic  lava  that produce of old lava bodies Mt.Arjuno-Welirang complex that spread out at west to south which earlier Kuarter age.
 
Key words: Type of Fluid, Temperature, Reservoir Rock, Resistivity and Density Value.