Geochemical Thermodynamics of Diagenesis in Reservoirs for Oil and Gas

Key words: 
• reservoir /
• diagenesis /
• geochemical thermodynamics /
• reservoir evolution

Abstract: Diagenesis plays an important role in reservoir quality. Prediction of chemically diagenetic trend is the key of reservoir evaluation. In order to search after the predicting method for reservoir quality basing on the diagenesis, thermodynamic models of some main kinds of diagenesis affecting porosity and permeability, including dissolution of feldspars, carbonate minerals and calcitedolomite equilibrium, have been constructed. With the help of these models, we can calculate the dissolutionprecipitation trend of diagenetic minerals. Based on these trends, we can analyze the developing extent of secondary pores in clastic reservoirs, karstification and dolomitization in carbonate reservoirs, which provide the geochemical data for the reservoir evolution.