The genesis model of carbonate cementation in the tight oil reservoir: A case of Chang 6 oil layers of the Upper Triassic Yanchang Formation in the western Jiyuan area, Ordos Basin, China

Autor: Li Shutong, Li Shixiang, Zhou Xinping, Ma Xiaofeng, Guo Ruiliang, Zhang Jiaqiang, Chen Junlin
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Open Geosciences, Vol 12, Iss 1, Pp 1105-1115 (2020)
Druh dokumentu: article
ISSN: 2391-5447
DOI: 10.1515/geo-2020-0123
Popis: Carbonate cementation is one of the significant tightness factors in Chang 6 reservoir of the western Jiyuan (WJY) area. Based on the observation of core and thin sections, connecting-well profile analysis as well as carbon and oxygen isotope analysis, it is found that ferrocalcite is the main carbonate cements in the Chang 6 reservoir of the WJY area. The single sand body controls the development of carbonate cements macroscopically. Both carbonate cements and calcite veins hold similar diagenetic conditions: the dissolution of plagioclase is the main calcium source and the de-acidification of organic acids is the main carbon source. The diagenetic stage is identified as the mesogenetic A stage. The sedimentary environment is of low salinity. Accordingly, the development model of carbonate cementation in Chang 6 reservoir is summarized into three types: “eggshell pattern,” “cutting pattern,” and “favorable reservoir pattern.” The development degree of carbonate cementation affects the physical properties of reservoir.
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