Exploration efficiency has increased since 1970 due to improvements in geophysical methods and to the development of organic geochemistry. A further increase in the success ratio of wildcat wells is expected during the 1990s by integrating all of the earth sciences in basin modeling.

Explorationists expect geochemistry to provide a clear answer to several essential questions for prospect evaluation, i.e., the existence and location of areas where hydrocarbons have been generated by the source rocks, the amount and type of hydrocarbons formed, the migration paths, and the quantity and type of petroleum accumulated in traps. With kinetic models of oil generation, such an answer can now be given to all questions related to the formation of hydrocarbons. Regarding migration, both approaches (observations and basin modeling) offer promising trends for individual trap evaluation. However, further work is needed before a quantitative figure of in-place reserves can be given.

In Italy, exploration encounters very different and complex geological situations, all governed by two regional major events: the Tethyan rifting during Mesozoic times, and the Alpine folding during the end of Tertiary times. In a well-known tectonic context, success in exploration may be greatly enhanced by taking into account modern concepts of organic geochemistry and basin modeling. Examples are given of bacterial and thermal gas prospects in the Po Basin (northern Italy), mainly from late Lower Tertiary and early lower Mesozoic sources, respectively. Occurrences of liquid oil at great depth in the same basin are also described, and the influences of kerogen type, burial history, and geothermal gradient are discussed. Immature heavy oils are present in the Adriatic Basin and in Si ily. Their conditions of formation are interpreted with respect to type of kerogen and to burial history. More generally, the important role of late subsidence associated with the Europe-Africa collision is emphasized.