Development of Deep Exploration in the Geothermal Areas of Tuscany, Italy

Abstract

The first deep well (2703 m) in the Larderello field was drilled in 1961, with the target of improving knowledge on the structural setting of the formation underlying the shallow exploited reservoir, their permeability and the physical chemical characteristics of the fluid encountered. This borehole proved the existence of deep fractures and of increase in temperature and pressure with depth. Production from deep wells was, however, considered uneconomic until the oil crisis of the 1970s, when the deep drilling program way given renewed impetus. Serious drilling problems were encountered in the central part of the Larderello field, where closely spaced fractures and corrosive fluids are encounter for very long depth intervals. These difficulties have so far prevented the development of a systematic production oriented deep drilling program in this area. Deep drilling gave commercially interesting results in the peripheral areas of Larderello and in the Travale and Mt. Amiata areas, where great thickness of impermeable formations are found before reaching the deep productive horizon.