Is Grain-to-grain Pressure Solution Contributing to Quartz Cementation in Sandstones?

The role of grain to grain pressure dissolution versus dissolution at stylolite or clay induced dissolution (CID) of silica in quartz rich sandstones is evaluated from careful examination of samples from the Precambrian Hanglecćrro Formation located on the Varanger Peninsula in northernmost Norway. The Hanglecćrro Formation is an orthoquartzite where all porosity is gone leaving an end product suitable for studying compaction processes in detail. The study show that the intragranular volume (IGV) in all samples is above what would be expected from grain to grain dissolution confirming that this mechanism is not important in siliciclastic sandstones. The variability in IGV was found to be a function of textural parameters where sorting was found to be the main factor reducing IGV. Textural parameters are important only during mechanical compaction. During chemical compaction IGV will remain constant. Empirical equations that predict the IGV as a function of effective stress and textural parameters should be incorporated into state-of-the-art reservoir quality predictive tools in order to more accurately predict mechanical compaction, and the expected porosity range in any given sandstone.