Abstract: Within the reservoir intervals of the Dengying Formation, dolomitized grainstones and blue-mi-crobe-algal boundstones are well developed. Prima-
ry porosity in these rocks has almost completely dis-appeared as a result of precipitation of dolomite ce-ments. Although formed in different diagenetic envi-ronments and differing greatly in mineralogy and geochemistry, these dolomite cements exhibit a clear trend of variation: with increased burial and inward growth from the wall to the center of pores, the ce-ment becomes coarser in size and lighter in color,and contains more inclusions. Meanwhile, the iso-tope value becomes more negative and the cathodelu-minescence becomes brighter.

Key words: Reservoir, Primary porosity, Dolomite ce-ment, Diagenetic process, Sichuan basin