Mechanism of Water-Rock Interaction of the Upper Triassic Xujiahe Formation in the Middle Part of Western Sichuan Depression
详细信息
- 责任者：Liu Sibing (State Key Laboratory of Oil-Gas Reservoir Geology & Exploitation ; Chengdu University of Technology ; Chengdu 610059 ; China) ; Shen Zhongmin
- 刊名：Acta Petrolei Sinica
- 出版年：2013
- 卷期：34(1)
- 关键词：碎屑岩储集层 ; clastic reservoirs ; 水岩作用 ; water-rock interaction ; 四川盆地 ; Sichuan Basin
- 页码：p.47-58
- 图表：illus., 3 tables, 32 refs.
- 分类号：1003
- issnNo：ISSN0253-2697
- isbnNo：CN11-2128/TE
摘要
Water-rock interaction acts as a bridge between the diagenetic mineral evolution and formation water ion change,through which minerals and formation water keep the water-rock system equilibrious,taking on a reciprocal relationship between them and giving proof of water-rock interaction.The present paper discussed the mechanism and conceptual model of water-rock interaction by comprehensively investigating microcosmic characteristics of minerals and chemical characteristics of formation water in Xujiahe Formation of the study area,the result showed that different water-rock systems,host-rock matrices and backgrounds of formation water are the key reason for the difference in water-rock interaction mechanism between member 2 and 4 of Xujiahe Formation.Feldspar in Member 2 of Xujiahe Formation is effectively preserved due to a higher K+/H+ activity ratio,while the feldspar-depleted material source is the most significant reason for the absence of feldspar in Member 4 of Xujiahe Formation,moreover,the dissolution of feldspar caused by a lower K+/H+ activity ratio can also result in the lower concentration of feldspar.Feldspar dissolution,authigenic mineral precipitation and clay mineral transformation are controlled mainly by the slowest reaction process in the ternary system of feldspar corrosion,ionic migration(K+) and illitization.Carbon and oxygen isotopes of carbonate cements indicated that Member 4 has an open water-rock system because of more acidic fluid than Member 2.The lack of organic CO2 in Member 2 of Xujiahe Formation was supposed to be related with less acidic fluid,marine lime argillutite as a source rock and the denudation caused by tectonic uplift,and to be less affected by the fractionation of CO2 migration.Based on these,we established conceptual models of water-rock interaction for aluminosilicate and carbonate rocks,respectively.Argillutite was proposed not to be a sealing factor but the first open object in a water-rock system,moreover,some argillutite(coal bed),as a material contributor and receiver,was thought indispensable in a whole water-rock system.
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