车镇凹陷郭局子洼陷沙三下亚段页岩岩相类型及特征

Types and Characteristics of Shale Lithofacies in Guo Jvzi Subsag, Chezhen Sag

摘要: 郭局子洼陷沙三段页岩有机质丰度高、类型好，具有良好的页岩油气生烃潜力，但前人针对该区泥页岩的基本岩相特征研究较少。综合沉积学、岩相学理论，在岩心精细观察描述、薄片分析及测试资料分析基础上，重点考虑有机质含量、沉积构造和岩性等要素，对郭局子洼陷沙三下亚段重点层组(12~13层组)开展泥页岩岩相划分。结果表明：1) 郭局子洼陷沙三下亚段12~13层组主要发育富有机质纹层状泥质灰岩夹灰条相、富有机质层状泥质灰岩夹灰条相、含有机质层状灰质泥岩夹砂条相、块状灰质泥岩相等多种岩相类型。2) 北部陡坡带主要为砂岩夹层发育区，南部缓坡带主要为碳酸盐岩夹层发育区，13s层组具有脆性矿物含量高、生烃指示好的特点，发育规模较大的富有机质纹层状–层状泥质灰岩夹灰条相，是最有利的油气勘探目标层系。3) 古物源、古水深(古地形)、古气候等因素控制了泥页岩的岩石成分、有机质含量及纹层分布。该研究成果明确了郭局子洼陷泥页岩优势岩相的分布规律，能够为下步该地区的区带评价和页岩油井位目标优选提供基础理论依据。

Abstract: The abundance and type of organic matter in Es3 member of Guo jvzi subsag are high and have good hydrocarbon generation potential of shale oil and gas, but there are few previous studies on basic lithofacies characteristics of shale in this area. In this paper, based on the comprehensive theory of sedimentology and lithofacies, detailed description of the core, thin section analysis and analysis of test data, the shale lithofacies of key strata of the lower member of Es3 in Guo jvzi subsag were divided, with emphasis on organic matter content, sedimentary structure and lithology. The results show that: There are a variety of lithofacies types in the 12th and 13th formation of the lower member of Es3 in Guo jvzi subsag, including organic-rich lamellar marlaceous limestone with limeston thin interlayer facies, organic-rich layered marlaceous limestone with limeston thin interlayer facies, organic-rich lamellar mudstone with sand thin interlayer facies, and massive limestone mudstone. The northern steep slope zones are mainly sandstone interbedded zone, while south gentle slope belt are mainly rich in carbonate interlayer. The 13s layer has high brittleness mineral content, indicating good hydrocarbon generation characteristics, and develop organic-rich lamellar and layered marlaceous limestone with limeston thin interlayer facies, which is the most favorable oil and gas exploration target strata. The rock composition, organic matter content and laminae distribution of mud shale are controlled by the factors such as paleosource, paleodepth (paleotopography) and paleoclimate. The research results clarify the distribution law of dominant lithofacies in the shale of Guo jvzi subsag, which can provide the basic theoretical basis for the next step of zone evaluation and optimal selection of shale oil well target in this area.