利用钻井资料和实测分析资料对大港油田沙一段中部和东二段2套区域性泥岩盖层封闭条件的差异性进行了研究,认为造成沙一段中部泥岩盖层之下油气较东二段泥岩盖层之下油气富集的主要原因是盖层条件的差异性,差异性主要表现在2个方面:沙一段中部泥岩盖层较东二段泥岩盖层不仅厚度大、分布面积广,而且具有更强的微观封闭作用和综合封闭能力；沙一段中部泥岩盖层封闭沙三段泥岩生成排出的油和气均是有效的,而东二段泥岩盖层封闭沙三段泥岩生成排出的气是有效的,但封闭沙三段泥岩生成排出的油则是无效的.%With the help of the data of the drilling and actually tested analyses, the differences in the hydrocarbon sealing of the mudstone cap rocks between Middle Esl and Ed2 of Dagang Oilfield are studied. The achievements show that the differences of the sealing conditions between the two regional cap rocks are the main reason for the hydrocarbon enrichment beneath the mudstone cap rocks in Middle Es, and Ed2- In detail, the contrasts are shown as following: both the thickness and area of the former are bigger than the later, and furthermore more stronger micro-sealing action and combined sealing ability are available; both the oil and gas generated and expulsed from Es3 mudstone are effectively sealed by Middle Es, mudstone cap rocks. However, although the sealing of Ed2 mudstone cap rocks to the gas from the same rocks is favorite, its sealing ability to the oil from the formation is invalid and disappointed.
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