--> ABSTRACT: Reservoir Quality Prediction Through Simulation of Compaction and Quartz Cementation, by R. H. Lander, O. Walderhaug, A. Lyon, A. Andersen; #91020 (1995).
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Reservoir Quality Prediction Through Simulation of Compaction and Previous HitQuartzNext Hit Cementation

R. H. Lander, O. Walderhaug, A. Lyon, A. Andersen

We have developed a forward numerical model that simulates the effects of compaction and Previous HitquartzNext Hit cementation through time on rock porosity and composition. Model predictions are consistent with measured porosity, intergranular volume (IGV), and Previous HitquartzNext Hit Cement fractions for samples from the Jurassic of the Norwegian Shelf, the Tertiary of the Gulf of Mexico, and the Ordovician of the Illinois basin.

Previous HitQuartzNext Hit cementation is modeled as a precipitation rate controlled process where Previous HitquartzNext Hit cement is derived from dissolution at nearby stylolites and grain contacts according to the method of Walderhaug (1994). Dissolved silica then diffuses short distances from sites of dissolution to sites of precipitation. Within the model frame of reference (based on a 1 cm3 of material upon deposition) no silica dissolution is modeled. Previous HitQuartzNext Hit surface area available for precipitation of Previous HitquartzNext Hit cement is a function of the proportion and size of detrital Previous HitquartzNext Hit grains, the fraction of clay coatings, and the extent of cementation.

Compaction is modeled by an exponential decrease in IGV as a function of effective stress. The formulation includes a term for defining a minimum possible IGV. This compaction model is consistent with compaction arising from grain rearrangement, ductile grain. deformation, and brittle failure of grains. In addition, the model considers the effect of fluid overpressures.

The model is better able to predict porosity for Previous HitquartzNext Hit cemented sandstones that occur within basins characterized by large fluid overpressures than models dependent on long-range transport of silica in solution. Models based on long range silica transport require widespread fluid fluxes greatly in excess of that indicated by transient flow simulations. Furthermore our model is consistent with the occurrence of high IGV at depth (eg., Paxton and others, 1990) unlike models that depend on intergranular Previous HitquartzNext Hit dissolutions a source of Previous HitquartzTop cement. In addition the model accurately reproduce the experimental results of Pittman and Larese (1991) for compaction of lithic grain rich samples.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995