Fluid inclusion studies to determine the palaeotemperature and hydrocarbon quality in petroliferous basins

Abstract Hydrocarbon bearing fluid inclusions (HCFIs) along with the coeval aqueous inclusions could be utilized in petroleum exploration industry for determining the paleotemperature and American Petroleum Institute’s (API) gravity of oils in a basin. These parameters can indirectly yield a quick assessment on the hydrocarbon quality in a basin. Here we use fluid inclusion data as a tool to study the paleo temperature and hydrocarbon quality of two offshore basins in India (dry wells from a proven basin and non-proven basin). Towards this objective temperature of homogenization (Th) of coeval aqueous fluid inclusion, assemblages seen associated with HCFIs and fluorescence emission features of oils in HCFIs were studied. Depthwise comparison of two basins studied are accorded with the microthermometrically obtained Th data and spectroscopically determined (fluorescence) API gravity values that gives an estimation of the paleotemperature and hydrocarbon quality. The Th and, fluorescence emission features of oils in HCFIs (leads to API gravity) presented allow us to make a qualitative assessment of oils in these basins. This study brings out the potential information stored in HCFIs/ adjacent brine fluid inclusions, as a tool for determining the paleotemperature and API gravity of oils in petroliferous basins.