The structural deformation and the source rock system evolution of the southern Apennines thrust belt (SATB) are studied along a regional structural profile traversing the Monte Alpi–Tempa Rossa oil fields. In part I (the accompanying chapter), the reconstruction of the structural evolution and the thermal history was addressed to calibrate the burial history of the source rocks along the cross section. Here in part II, the generation and expulsion of hydrocarbons were modeled to test a potential source rock interval and identify geometric factors explaining the observed differences in the nature of the oil found in the three major structural trends. Organic-rich, laminated limestones that were penetrated by a few wells in the region represent the best source rock candidate to date. The source interval shows total organic carbon (TOC) values as much as 4% and hydrogen index as much as 632 mg HC/g TOC. This source rock also contains high amounts of sulfur (3–6% in kerogen).

Rock samples and asphaltenes isolated from the oil were analyzed to determine both primary bulk kerogen decomposition and compositional kerogen decomposition products. For the latter, the results include determination of the kinetics of dry gas (C₁), wet gas (C₂–C₅), light oil (C₅–C₁₄), and heavy oil (C₁₅₊) components. The southern Apennines Cretaceous source rock behaves as a type I kerogen equivalent, consistent with the distribution of the activation energies dominated by a single activation energy. Most of the predicted generated and expelled hydrocarbons are heavy and light oils. Thermal conditions for secondary cracking of the generated oil into gas could have been reached only in the footwall of the major thrusts. The measured kinetic parameters allow the modeling of a favorable timing of trap formation with respect to hydrocarbon generation and expulsion. When the measured bulk and compositional kinetics are used in the modeling, no oil generation is reached in the Tempa Rossa trend. The model shows that the Tempa Rossa heavy-oil field has been filled by oil that was generated deeper in the surrounding of the structure. Compositional kinetic simulation is consistent with the results of the geochemical analyses performed on several oils from the region. The original oils in the reservoirs should have an API gravity of about 25° API. Only subsequent geological processes (uplift and erosion) provide the pressure-volume-temperature variation responsible for the compositional grading column at the present time.

Finally, kerogen transformation ratio vs. depth shows that the three different transformation ratio-depth zones should be considered to fit the thermal history of the southern Apennines. This two-dimensional information can be used to predict the distribution of potential source rock kitchen areas in the surroundings of the modeled section to guide future exploration.