The coupling relationship between pore evolution and hydrocarbon charging plays an important role in hydro-carbon accumulation.However

an accurate quantitative analysis of the pore evolution is difficult.A porosity evolution model was therefore constructed with quantitative calculation parameters determined through analyses of microfabric

authigenic minerals

diagenetic sequences and thermal evolution of feldspar-rich coarse clastic sandstone reservoirs in the second member of the Shahejie Formation(Es

2

) in the north part of Liaodong uplift.The results show that the water-rock reaction of feldspar together with its products has a dominant effect on the reservoir porosity.While analyses of parameters including reservoir sorting coefficient

cement mass fraction

plane porosity of residual primary intergranular pores

total plane porosity

and plane porosity of dissolved pores

are important to the accuracy of quantitative calculation.The research indicates that compaction caused the strongest damage to the reservoirs from 38 to 23.3Ma

resulting in a porosity decrease of 15%.Cementation

which lasted almost the whole diagentic period

followed up to cut back the porosity by another 10.4% on average.However

erosion from 19 to 2 Ma served to increase the porosity by 9.8%.The physical properties of the reservoirs were gradually improving with hydrocarbon-charging and deteriorating as hydrocarbon charging ended.