Studi Daerah Resapan dan Pola Aliran Fluida Reservoir Hidrotermal Sileri, dieng dengan Metode ISOTOP 18O, 2H, dan 3H
The Dieng geothermal field is located in Central Java and characterized by two-phase reservoir liquid-dominated system with estimated temperature of 340ºC. The field has installed capacity of 60 MW and is divided into 3 reservoirs (Sileri, Sikidang and Pakuwaja) that separated by west-east and southwest-northeast main structural trends. The focal study is focused on determination of hydrological flow and recharge area in Sileri Reservoir by using geochemistry and stable isotopes δ18O, δ2H and radioisotope δ3H.
Hydrogeology and flow pattern in Sileri are generated by meteoric water that is recharging at elevation of 1,300 1,800 masl on the north of Sileri Reservoir. As meteoric water is heated up in the reservoir, the parent fluid is generated with temperature of 360ºC, 6,500 mg/L of Cl, -1.07 δ18O, and -50.82 δ2H. The parent fluid then undergoes boiling in HCE 29, HCE 30, and southward in HCE 28A. Meteoric water also infiltrates through west-east trending structure and affects HCE7B, 7C and 28A well fluids.
The hydrothermal fluid flows upward, condenses and appears as hot springs in the upflow zone near Pagerkandang. Condensated water also flows laterally to outflow in Sigemplong, Bitingan and Siglagah.