FRESH-WATER SENSITIVITY OF GLAUCONITIC HYDROCARBON RESERVOIRS

Freshwater sensitivity tests were conducted on four glauconite/smectit e mixed-layer clays (G/S) with 10-20% smectite content in order to det ermine whether G/S with low expandability has the potential to swell o n contact with fresh water. Tests showed that three of the G/S samples underwent no visible swelling when immersed for up to 4 days in fresh water. In contrast, one sample was freshwater sensitive because, in a ddition to non-swelling G/S with low expandability, it contained a sma ll component of highly smectitic G/S that rapidly swelled on contact w ith fresh water. These results indicate that the presence of G/S with low expandability in a hydrocarbon reservoir should not render the res ervoir freshwater sensitive, but that individual reservoirs can contai n a compositionally-heterogeneous population of G/S grains that may in clude a highly freshwater-sensitive, smectitic component.