Exploration of the Monti Cimini Permit (Latium -Italy)

Abstract

Exploration in the Monti Cimini permit (Latium -Italy) is being carried out by AGIP on behalf of a Joint-venture with ENEL since 1979. Previous activity in the area by other companies in the 1950's and 70's included drilling of some wells on the Viterbo large structural high on the West side of the permit, site of several warm springs. The Mesozoic limestone reservoir was found at shallow depth, bearing water with a moderate temperature (60·-78°C). The renewed exploratory effort was based on two ideas: 1. There is no hydraulic connection between the Vi terbo high and the downfaulted area to the East which could have a higher temperature because of the influence of recent volc~ nic activity in the Vico area. 2. The possibility of a deeper reservoir below the shallow one in the Viterbo high should be investigated. After carrying out a comprehensive set of a geophysical, geochemical and temperature hole drilling, a deep exploratory well was drilled NE of Vico lake (Cimino 1). It struck the permeable Mesozoic reservoir at 2600 m with a temperature of 220·C, proving that the exploration hypothesis was right. The formation is underpressured and SUbstantial loss of circulation occured; the reservoir could not be adequately tested, even if it produced fresh water intermittently. The area will be further investigated by drilling. Next year the deeper prospects in the Western area will be tested by a 3500 m wildcat (Vetralla 1).