Abstract:

The reservoir rocks of Lower Cretaceous Fuyu and Yangdachenzi unites wrer deposited in channels on the deltaic flood plain in Sanzhao area. The reservoir rocks mainly consist of fine lithic arkose and feldspathic litharenite with abundant matrix.Porosity ranges from 1% to 21.3%,with a mean of 10.9%.Permeability ranges from 0.01×10^-3 to 289×10^-3μm² with a mean of 1.53×10^-3μm².Main diagenesis includes compaction,cementation,dissolution,replacement and recrystallization.According to the texture;cathodoluminescence characteristics,carbon and oxygen isotopic composition, the contents of the main and trace elements,calcite cement formed in reducing condition during early diagenesis. Precipitation of calcite cement caused the decrease of porosity in sediments.Porosity formed by feldspar and intermediate/basic volcanic rock fragment dissolution makes up about one third of the whole porosity.Most smectite and kaolinite already changed into illite and chlorite,or mixed layered illite/smectite(I/S)and chlorite/smectite(C/S).Most changes of reservoir rocks occurred during early diagenesis.

Key words: reservoir rock, compaction, cementation, dissolution, diagenetic stage