Reservoir screening using Iatroscan TLC-FID and identification of palaeo-oil zones, oil–water contacts, tar-mats and residual oil saturations in the Frøy and Rind petroleum accumulations

Combined thin layer chromatography (TLC) and flame ionization detection (FID) of the Iatroscan TLC-FID instrument were used for geochemical screening of 600 core samples from the Elf-operated Frøy Field and Rind Discovery on the Norwegian Continental Shelf. The results allowed a pseudo 3-D characterization of the bitumen distribution in the reservoirs. Calibration of the data to well log-defined oil saturations allowed much more detailed recognition of variation in residual oil saturations (ROS) and helped in determining present and palaeo-oil–water contacts (OWCs). The quantification of bitumen amount and composition between different reservoir units was used to define OWCs. Palaeo-oil zones within present condensate and water zones were identified using an empirical approach to measure bitumen content and composition from live oil zones, condensate zones and dry gas zones, respectively. In this way, the Iatroscan TLC-FID data can be used to reconstruct elements of the filling history of the reservoirs. The application of this technique for identifying compartments, barriers for fluid flow and tar mats is also demonstrated.