Origin analysis of carbonate cements in Chang 8 reservoir in southeastern margin of Ordos Basin
Online published: 2011-08-20
Carbonate cements are the most important authigenic minerals in Chang 8 reservoir in southeastern margin of Ordos Basin, and they are mainly ferrocalcite, with some dolomite and ferrodolomite. Based on thin slice and SEM inspection, inclusion enclave temperature measurement, carbon and oxygen isotope analysis and potassium ferricyanide coloring analysis, it is proved that calcite cementation started from the early diagenetic stage and lasted to the late diagenetic stage of B stage. In the early diagenetic stage, there generated light calcites, while to the late diagenetic stage, there generated a great quantity of ferrocalcites because of the organic material decarboxylation under thermocatalysis. Ferrocalcite generated in late diagenetic stage filled the remained intergranular pores with a semi-basal or basal cementation, which enormously lowers the accumulation capacity of the reservoir.
Key words: diagenesis; diagenetic facies; Triassic; Wuxia area; Junggar Basin
TAN Kaijun , XU Duonian , YIN Lu , DAI Dongdong , QI Wen . Origin analysis of carbonate cements in Chang 8 reservoir in southeastern margin of Ordos Basin[J]. Lithologic Reservoirs, 2011 , 23(4) : 65 -69 . DOI: 10.3969/j.issn.1673-8926.2011.04.012
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