Geothermal exploration by geochemical methods of the thermal area El Pilar-Mundo Nuevo, state of Sucre, Venezuela

A geochemical survey was carried out in 1985-86 in the El Pilar-Mundo Nuevo area, Paria peninsula, state of Sucre, Venezuela. The aim was to ascertain a possible geothermoelectric exploitation of the area, characterized by many natural manifestations with temperatures in the range 80 - 100 deg. C. Through a series of different classifications of water and gas samples it was possible to operate a selection of the most significant chemical compositions that allowed useful geothermometric indications. Several geothermometric techniques based on fluid-rock interaction have been applied at the same time to evaluate some reservoir parameters. The area of concern seems to be promising for the recovery of high enthalpy geothermal resources; a deep reservoir appears to be constituted by a relatively low salinity (< 5000 ppm), neutral brine with computed temperatures between 250 and 300 deg. C and high CO2 partial pressure. A second shallower reservoir is supposed to exist, with a temperature of the order of 200 - 220 deg. C. Both reservoirs result to be water-dominated, and boiling appears to take place at 160 deg. C, at a very shallow level. The piezometric level (elevation 150 m) regulates the areal distribution of water springs and fumaroles. Self-sealing allows accumulation of fluids at least in the deep reservoir which can receive it recharge from local meteoric water. A batholith is inferred at some depth, supplying the hear to the deep fluids. (author). 50 refs, 23 figs, 8 tabs