气候变化领域集成服务门户(CCPortal): Geochemical constraints on the origins of calcite cements and their impacts on reservoir heterogeneities: A case study on tight oil sandstones of the upper triassic yanchang formation, southwestern ordos basin, China

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DOI	10..1306/01301918093
	Geochemical constraints on the origins of calcite cements and their impacts on reservoir heterogeneities: A case study on tight oil sandstones of the upper triassic yanchang formation, southwestern ordos basin, China
	Xi K.; Cao Y.; Liu K.; Wu S.; Yuan G.; Zhu R.; Zhao Y.; Hellevang H.
发表日期	2019
ISSN	0149-1423
卷号	103 期号:10
英文摘要	Calcite cementation has been identified as an active process in the Upper Triassic Yanchang Formation throughout its burial history and as a major diagenetic factor causing strong reservoir heterogeneities. The origins of calcite cements and their relevance to reservoir heterogeneities were investigated using a suite of petrographic and geochemical methods, including optical microscopy with fluorescence and cathodoluminescence, scanning and backscattered electron microscopy with energy-dispersive spectrometry, X-ray diffraction, X-ray fluorescence, electron probe microanalysis, quantitative evaluation of minerals by scanning electron microscopy, fluid inclusion analysis, and carbon and oxygen stable isotope analyses. The sandstones are compositionally immature with relatively high amounts of volcanic rock fragments. The two generations of calcite cements are Ca-I and Ca-II. The Ca-I calcites are distributed along the interface of sandstone and mudstone units and were formed during the Late Triassic to Early Jurassic at formation temperatures of approximately 90°C. The Ca-II calcite mainly developed in the lower part of the fining-upward sandstone units and was formed in the Late Jurassic at higher temperatures of approximately 110°C. The origins of calcite cements were constrained by geochemical and isotope measurements, fluid inclusion homogenization temperature, and in situ element analysis. The Ca-I calcite cement originated from dissolution of the lacustrine depositional carbonates in the interbedded mudstones and reprecipitation in the adjacent sandstones. The Ca-II calcite was mainly related to organic matter decarboxylation, with Ca2+ having been provided internally by volcanic fragment alteration and plagioclase dissolution. Calcite cementation had caused strong reservoir heterogeneities in the Yanchang Formation tight sandstones. The Ca-I calcite cementation destroyed reservoir properties along the interface of sandstones and mudstones. The lower parts of the fining-upward sandstone units were tightly cemented by Ca-II calcite, although they originally had high porosity and permeability. The middle-upper parts of the fining-upward sandstone units contain less calcite cements and thus have better preserved reservoir pores because of oil emplacement inhibiting the calcite cementation processes. Copyright ©2019.
语种	英语
scopus关键词	Analytical geochemistry; Carboxylation; Cementing (shafts); Cements; Dissolution; Electron probe microanalysis; Feldspar; Fluorescence; Isotopes; Mineralogy; Petroleum reservoir evaluation; Sandstone; Scanning electron microscopy; Volcanoes; Backscattered electron microscopy; Energy dispersive spectrometry; Formation temperature; Homogenization temperatures; Isotope measurements; Oxygen stable isotopes; Quantitative evaluation; Reservoir heterogeneity; Calcite; calcite; cement (construction material); detection method; fluid inclusion; geochemistry; hydrocarbon reservoir; Jurassic; lacustrine deposit; mudstone; organic matter; Permian-Triassic boundary; plagioclase; sandstone; Triassic; volcanic rock; China; Ordos Basin
来源期刊	AAPG Bulletin
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/125041
作者单位	Key Laboratory of Deep Oil and Gas, China University of Petroleum, Qingdao, China; Laboratory for Marine Mineral Resources, Qingdao, China; Research Institute of Petroleum Exploration and Development, Beijing, China; School of Geosciences, China University of Petroleum, Qingdao, China
推荐引用方式 GB/T 7714	Xi K.,Cao Y.,Liu K.,et al. Geochemical constraints on the origins of calcite cements and their impacts on reservoir heterogeneities: A case study on tight oil sandstones of the upper triassic yanchang formation, southwestern ordos basin, China[J],2019,103(10).
APA	Xi K..,Cao Y..,Liu K..,Wu S..,Yuan G..,...&Hellevang H..(2019).Geochemical constraints on the origins of calcite cements and their impacts on reservoir heterogeneities: A case study on tight oil sandstones of the upper triassic yanchang formation, southwestern ordos basin, China.AAPG Bulletin,103(10).
MLA	Xi K.,et al."Geochemical constraints on the origins of calcite cements and their impacts on reservoir heterogeneities: A case study on tight oil sandstones of the upper triassic yanchang formation, southwestern ordos basin, China".AAPG Bulletin 103.10(2019).