When exploiting hydrocarbon reserves in lithologically and petrophysically complex glauconitic sandstones, potentially damaging fluid/rock and fluid/fluid interactions must be thoroughly investigated. This paper reports on the first phase of a comprehensive, multi-disciplinary study of such interactions conducted on samples from the Saladin field, located on the offshore North West Shelf of Australia. Core floods indicate that the formation is not susceptible to significant damage during the flow of simple brines. However, chemical analysis of core flood effluents after periods of stasis indicate continuing interactions between introduced fluids and fluids resident in the large volume of microporosity. Awareness of such delayed interactions will be important in restored state core analysis and when evaluating the damage potential of more complex fluid systems. The reservoir was found to suffer extreme damage on exposure to freshwater. The sum of evidence suggests that swelling of glauconitic smectite is the underlying cause of the damage, with pore throat plugging by mobilised glauconitic smectite and non-expandable glauconitic clays the probable damage mechanism. Saturation with calcium chloride solutions prevented water shock damage.

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