Abstract:
The Upper part of the Kongdian formation of the Paleocene-Eocene age consists mainly of fine to medium sandstones. Samples analyzed are from depths of 1572.55 to 2298 m, representing a temperature range of 60.5 to 88.5°C. The petrographic analysis reveals that the reservoir of the Upper part of the Kongdian formation consists mainly of feldspathic and minor amounts of lithic arenite sandstones. The feldspathic sandstone belongs to this formation of composite sources: metamorphic, sedimentary and igneous. The majority of the sources of sandstone of the Upper part of the Kongdian formation came from metamorphic rocks. The carbonate cement of the Upper part of the Kongdian formation contains δ 13C with a range of -6.67 to -21.44 with a mean of -14.06 and δ 18O with a range of -1.25 to -12.69 with a mean of -6.97. The δ13C may suggest a mixed source from abiotic reaction zone, bacterial oxidation zone, bacterial sulphate reduction zone and from carbonate detrital grain. The majority of the sources of carbon came from the abiotic reaction zone (decarboxylation zone and liquid hydrocarbon generation zone). The δ 18O values in the carbonate cement of the Upper part of the Kongdian formation reflect a change in temperature and a change in pore waters chemistry.
Mutwakil Nafi, Fei Qi and Yang Xaing Hua, 2004. Type of Sandstone and Source of Carbonate Cement in the Kongdian Formation (Upper Part), South Slope of the Dongying Depression, East China. Journal of Applied Sciences, 4: 235-241.