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Primary migration occurs as the fluid is released from the fine grained source rock. This process is viscosity dependant and so favours the release of gases and light oils.  Secondary migration occurs as the fluid moves through buoyancy and obeying Darcy’s law, to the reservoir trap. This migration route can be several 100 km in length but is generally much shorter and follows vertical fault or fracture systems. The migration rates of typically 1 to 1000 km/million years are more rapid than the mechanisms of fluid generation.

The pressure drops found during secondary migration can result is phase separation and preferential mobility for the gaseous phase. Fluid/rock interactions can increase or reduce contaminant levels by either contact metamorphism or rock scavenging. Fluid/aquifer interactions are an area in which Petrophase has made significant advances. The aquifer solubility of contaminants during migration can be used to understand and predict contaminant distributions within reservoirs.

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