In order to investigate the control of diagenetic environment on diagenetic evolution of red-beds reservoir

we studied the diagenetic environments of the Eocene red-beds in the eastern Dongying Sag Bohai Bay Basin through burial history reconstruction

thin section analysis

scanning electron microscopic observation

routine core analyses.On this basis

we described intensity of diagenesis and established evolutionary patterns of red-bed reservoirs under the control of diagenetic environment.The diagenetic environment of the Eocene red-beds in the eastern Dongying Sag is divided into two types according to the differences of control factor

range of influence and property types

namely original alkaline environment and burial acidic environment

which correspond to penecontemporaneous period-early diagentic stage A

early diagentic stage B-middle diagenetic stage A respectively.The diversity in diagenetic products and intensity is sharp due to the differences of diagentic environment.A diagenetic modification model of the Eocene red-beds reservoir was established based on quantitative description of diagenetic intensity

namely "early strong cementation and weak dissolution-middle and late moderate dissolution and weak compaction" under the control of diagenetic environment with alkality to weak acidity-moderate-strong acidity.Red bed reservoirs under the control of this model feature in a pore evolutionary pattern of "rapid-decreasing of primary porosity

slow-growing of secondary porosity in early stage;slow-decreasing of primary porosity

rapid-growing of secondary porosity in middle and later stages".