Fluid Inclusion Microthermometry and Dating of The Quartz Cement within The Upper Nubian Sandstone Reservoir, SE Sirte Bain, Libya

Quartz cement is the most important cementing agent in the Upper Nubian Sandstone reservoir within the Hameimat trough, SE Sirte Basin. Determining the timing and paleo-pore fluid compositions is important in order to understand the reservoir quality of the Upper Nubian succession. Fluid inclusions microthermometry study, using modified U.S.G.S. gas flow heating/freezing stage system, together with basin modeling was carried out to determine the time of quartz cementation and paleo-pore fluid compositions. Fluid inclusions study results give a precipitation temperature range of silica cement as 115˚C-128˚C. Investigation of these temperature with a burial history curves indicate onset of quartz overgrowth cementation was in Late Palaeocene probably from through flow of silica enriched pore fluid. Tice and Teu measurements indicate that these were complex brines.