Three high carbonate belts and four secondary pore belts developed vertically in the reservoir rocks of the Eogene Shahejie Formation in Dongpu Depression.CO

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and organic acid generated from organic matter evolution dissolved feldspar grains and carbonate cements in shallow beds and formed the first secondary pore belt;the dissolution of feldspar grains in median depth resulted in the second and third secondary pore belts;the dissolution of carbonate cement in deep beds formed the fourth secondary pore belt.