Diagenesis of anhedritite in the Cretaceous reservoir and its influence on the hydrocarbon distribution in southeast Jianghan Basin

The property of the Cretaceous Formation Yuyang reservoir in the southeast of the Jianghan basin, with great heterogeneity, is controlled by microfacies and diagenesis. All diagenesis types can be found in the research area. The processes of compaction, pressure solution, cementation, and displacement reduce porosity and permeability, while the resolution process can form a quantity of intergranular, intragranular and fold pores, which improve the reservoir quality. The crucial factors that reduce the porosity and permeability are the cementation and displacement of anhedritite, which comes from the gypsum sector of the source rock in the Xingouzui Formation. The sulphate migrates into the reservoir together with the hydrocarbon. Where the anhedritite occurs tends to be the place where the hydrocarbon appears, implicating that the hydrocarbon distribution is controlled by the anhedritite.EI0139-42+643