Reservoir Compaction by Silicification from Other Sources

Reservoir Compaction by Silicification from Other Sources 

When there are no dust inclusions around the grains it is frequently difficult to define the boundary between the detrital grains and the zones of secondary overgrowth when the optical orientation is continuous. Because of this the proportion of secondary silica is difficult to determine. However, in every thin section there will be portions where the boundaries between detrital grains and overgrowth rims of secondary quartz are clearer than in others and where the error in calculation will be minimized. 

The proportion of secondary quartz in reservoir rocks differs from bed to bed. However, the total amount of secondary quartz in the beds and in particular the proportion of completely sUicified layers varies considerably in the different sections. We may distinguish four classes of layers (1) little sUicified ones, mostly containing 2-5% secondary quartz, (2) moderately silicified ones with usually 7-10%, (3) highly sUicified ones with mostly 12-15% and (4) very highly silicified ones with mostly 17-20% secondary quartz. 

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