Diagenetic characteristics of tight sandstone of Chang 4+5 reservoir in Longdong area, Ordos Basin
Online published: 2014-06-06
Based on the observations of rock thin sections, casting thin sections and scanning electron microscope, this paper summarized the diagenesis characteristics of the tight sandstone reservoir of Chang 4+5 reservoir in Longdong area, and studied the origin of the tight reservoirs in Zhenyuan-Huanxian Region and Huachi-Baibao area. The result show that the rock types of Chang 4+5 reservoir mainly are very fine grained-fine grained lithic arkose, feldspathic lithic sandstone and the transition between the two types. The rock debris is mainly plastic and soluble. And the content of flexible mica fragments is high. The compressive strength of the reservoir rocks is very weak. The chlorite coating can effectively inhibit quartz and feldspar overgrowth in Huachi-Baibao area. The cementation of iron carbonate is intensive, and the feldspar dissolution is relatively weak. In different areas, the characteristics of diagenesis are obvious different. The tight sandstones of Chang 4+5 reservoir are contributed by genetic types of rock, sediment size, rock composition, late diagenetic reconstruction and so on. The high-quality reservoir rocks are those massive sandstones of the underwater distributary channels, with slight quartz overgrowth in Zhenyuan-Huanxian area and proper chlorite coating in Huachi-Baibao area.
L IANG Mingliang , WANG Zuodong , ZHENG Jianjing , L I Xiaoguang , WANG Xiaofeng , QIAN Yu . Diagenetic characteristics of tight sandstone of Chang 4+5 reservoir in Longdong area, Ordos Basin[J]. Lithologic Reservoirs, 2014 , 26(3) : 22 -27 . DOI: 10.3969/j.issn.1673-8926.2014.03.005
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