Simulation of burial diagenesis in the Eocene Wilcox Group of the Gulf of Mexico basin

Diagenesis may be evaluated quantitatively by using petrographic observatio ns and results of paleohydrologic reconstructions in combination with geoch emical reaction path model calculations. The authors have applied a reactio n path method by simulating diagenesis in the Eocene Wilcox sandstones in t he Gulf of Mexico basin to evaluate the effects of variable Pco(2), fluid c omposition, amount of rock reaction and burial history. The results show th at increases in Pco(2) cause the amount of carbonate phases to increase, in stead of creating secondary porosity, and closed system reactions with a ch emically evolved pore fluid cause a reduction in the amount of carbonate ph ases, thereby preserving primary porosity. Diagenesis resulting from increa sed rock reaction per pore volume is characterized by a dominance of Fe-fre e mineral phases, and albite forms in simulations at temperatures above 100 degrees C with neutral pH evolved fluids. The results approximate petrogra phic observations of previous workers on the Wilcox with only a few excepti ons. Continued simulations using different fluid compositions and organic a cid anions may increase the capability to reproduce observed paragenetic se quences. (C) 2000 Elsevier Science Ltd. All rights reserved.