An hydrocarbon potential revision of two gas fields of the northern Adriatic Sea (Porto Corsini M. W and Armida fields; fig 1) has been performed. The target of the revision was the optimization of the residual gas recovery and, particularly, the recognition of levels never involved in the fields production. From log analysis, correlations and pressure data, the presence of numerous new gas levels, represented in particular by sublayers, was pointed out. These sublayers, previously included in the main fields levels, are characterized by independent mineralization and were never opened to production. The new sublayers subdivision was then compared with the already completed layers allowing to identify several undrained levels. Besides, the identification of sublayers with a high SW open to production allowed to justify the water and sand production of some completions. Finally, a detailed correlation allowed to locate some sub-seismic faults, which determine hydraulic barriers, and to better define structural blocks, taking also into account the gas-water contacts and available pressure data comparison (original or recorded during the productive life of the fields). In the Porto Corsini M. W field, a significant amount of residual reserves was recognized, especially in the PLQ and PL3 zones, without considering the historical levels of the PL2 zone. Besides, the PL1 zone levels were examined from a qualitative point of view: some of these layers will be tested and/or put in production during the W.O. in progress. Also in the Armida field the main levels of the PL2 zone were not considered in this residual reserves evaluation study. On the contrary, in the PL3 and PL1 zones and at the base of the PL2 many sublayers were analyzed; as a whole, the re-evaluation provided an appreciable reserves increase. The detection of the original contacts and of some faults suggests the existence of hydraulic barriers and the presence of unexploited hydrocarbon bearing areas that could be drained by well side-tracks.

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