东营凹陷沙三下—沙四上亚段泥页岩岩相沉积环境分析

Study on shale facies sedimentary environment of lower Es3-upper Es_4 in Dongying sag

根据岩心及其分析化验资料,从岩石的颜色、成分、结构、有机质丰度等方面划分泥页岩岩相类型;从古气候、古物源、古水深、古盐度和古水体的氧化还原性5个方面分析古环境,建立环境指标分级量化标准。研究结果表明,东营凹陷沙四上亚段—沙三下亚段沉积环境特征具有气候由干燥—半干燥—半潮湿,水体由半深水到深水、从强还原性逐渐到还原性、盐度从盐水到咸水到半咸水,物源从较少到较多的规律变化,共划分了6个环境组合;并建立了沉积环境与泥页岩岩相之间的关系,即有机质丰度主要受盐度控制,盐水区为含有机质的岩相,咸水区和半咸水区为富有机质的岩相;结构主要受气候和水深控制,气候干燥—半干燥、半深水环境发育纹层状的岩相,气候半潮湿、深水环境发育层状的岩相;岩性主要受气候和物源控制,气候干燥、物源少的环境发育泥质灰(云)岩和灰(云)岩的岩相,气候半潮湿、物源较多的环境发育灰质泥岩的岩相。

According to the core color, component, structure organic matter abundance of system cored wells, shale facies of the lower Es3-upper Es4 in Dongying sag were divided. The ancient environment was analyzed by climate, provenance, water depth, salinity, oxidation and reduction, and a standard of classification and quantification was established. The findings in-clude： climate from arid to semiarid to semi-humid, water from semi-deep to deep and strong reduction to reduction, salinity from saline to salt to brackish, and provenance from less to more. The ancient environment can be divided into six environ-mental combinations. This study establishes the following relationships between the sedimentary environment and facies. The organic matter content of shale facies are mainly affected by salinity： saline range develops less organic matter facies, and salt and brackish range develops rich organic matter facies. Structure of shale facies are mainly controlled by climate and water depth： arid and semiarid climate and semi-deep water environment develops lamina facies, and semi-humid climate and deep water develops stratiform facies. Lithology of shale facies are mainly affected by climate and provenance： arid climate and less provenance environment develops argillaceous limestone and limestone, and demi-humid climate and more provenance environment develops lime mudstone.