Scan-electron microscopy has been applied to the study of micropores in oil- and gas-bearing reservoir rocks in the USSR. Sandstones containing kaolinite cement may contain significant hydrocarbon reserves. In rocks of middle epigenesis, authigenic kaolinite and chlorite decrease porosity and permeability. Rocks of late epigenesis, although compactly packed with chlorite cement, may be brittle and fractured, producing micropores favorable to reservoir characteristics. Desirable attributes of electron-scan microscopy are described.