In sandstones, siliceous diagenetic overgrowths may commonly contain several generations of hydrocarbon fluid inclusions (FI's), generally of size no more than 10 µ. We successfully analyzed such inclusions in North sea sandstones from the Dunbar area, subthrusted reservoirs such as sub-Andean basins (Venezuelian and Colombian foothills) and carbonaceous series in areas of Pakistan, using synchrotron infrared microscopy. We addressed, for each case studied, molecular identification and mapping of the components, i.e. hydrocarbon content, and additional molecules such as CO2 , H2 O, in small volumes in their liquid and gas phase as well as the solid phases often associated as products or mechanically entrapped minerals. Semi-quantitative analysis leads to determination of the average composition of each inclusion, i.e equivalent aliphatic chain length (CH2 /CH3 ratios), CO2 and CH4 content. The quantitative method for hydrocarbon chain length measurements was tested first on some exceptionally large FI's (up to 500 µm) previously analyzed by gas chromatography after individual extraction. Homogeneity and /or heterogeneity of trapping as well association of oil with water or their separation is shown for each generation of FI corresponding to a specific organic fluid migration in sandstones from the Brent formation of Dunbar (North sea), and in siliceous reservoirs of subandin basins (Venezuelian and Colombian foothills). Microanalyses of solid phases closely associated within oil in such FI's indicate conditions of the dissolution-recrystallisation processes. Results are particularly promising in carbonaceous reservoirs of Northern Pakistan (Chorgali area, North Potwar basin) where first results pinpoint the effect of TSR mechanism in environments where evaporites were first deposited. PVT modeling of isochores using semi-quantitative SFTIR analyses leads to reconstruction of P-T conditions of diagenesis. Therefore by combining these results with data from organic matter (Genex modeling) and petrography, the onset of cementation was established in the Venezuelian and Colombian Foothills. The path of fluid migration along geological history was then reconstructed with Thrustpack 2D thermal modeling (IFP software), in Tunisian and Pakistani ore deposits and in the carbonaceous reservoir of Chorgali.