渤海湾盆地东濮凹陷膏盐岩与油气的关系  

Relationship between Gypsum-salt Rock and Oil-gas in Dongpu Depression of Bohai Gulf Basin

作　　者：刘景东 蒋有录 谈玉明[2] 慕小水[2] 

机构地区：[1]中国石油大学地球科学与技术学院,山东青岛266580 [2]中国石化中原油田分公司,河南濮阳457001

出　　处：《沉积学报》2014年第1期126-137,共12页Acta Sedimentologica Sinica

基　　金：国家科技重大专项(编号:2011ZX05006-004)资助

摘　　要：从东濮凹陷蒸发岩系的地质特征出发,系统分析了膏盐岩对油气成藏诸要素的影响及其对油气分布的控制作用。研究结果表明,东濮凹陷烃源岩与膏盐岩共生,膏盐岩—砂泥岩过渡带烃源岩有机质丰度最高;膏盐岩发育区烃源岩有机质类型以Ⅱ1型和Ⅰ型为主;膏盐岩的高热导作用使盐上烃源岩生烃门限深度降低和盐下烃源岩过成熟门限深度增加,有效地扩大了生烃窗范围。膏盐层下部砂岩储层孔隙度相对正常压实地层而言整体偏大,且具有随深度增加表现为先增加后减小,孔隙度最大值出现在膏盐层下部一定距离内。膏盐层不仅对油气具有很强的封堵能力,而且易于形成盐下、盐间、盐上及盐岩边缘等多种圈闭类型。膏盐层厚值区形成的异常压力明显大于膏盐层边缘区,油气更易于在膏盐层的遮挡下向膏盐层边缘区运移。综合分析认为,东濮凹陷膏盐层边缘区不仅具有良好的供烃和圈闭条件,而且具备油气充注的通道和动力条件,是最有利的油气聚集区。Dongpu depression is located in southeastern Bohai Bay Basin, five sets ot gypsum-salt rock clevelopect, and the maximum cumulative thickness can be up to 950 m. The lithologic variation of gypsum-salt layer can be divid- ed into three zones including gypsum-salt zone, gypsum-salt and sand-mudstone transition zone, sand-mudstone zone. Exploration practice confirmed that gypsum-sah rock on hydrocarbon enrichment in vertical or in horizontal has an ira-portant controlling role, performing for nearly 93.7 % of oil and nearly 80% of gas in Dongpu depression distribution in the north part, and most oil and gas distributes among gypsum-sah layers. Controls of gypsum-sah rock on pool forming elements were systematically analyzed, and the results show that the source rock in gypsum-sah and sand-mudstone transition zone has the highest organic matter abundance because of its advantage for high quality source rock accumulation and preservation, the next is that in gypsum-sah zone, and that in sand-mudstone zone have relative lower organic matter abundance. Meanwhile, the farther source rock away from gyp- sum-salt rock, the lower organic matter abundance it has, and when the distance between source rock and gypsum-sah rock exceeds 30 or 40 meters, the influence on organic matter abundance by gypsum-sah rock decreases significantly. For high water salinity, many halophilic bacteria and algae adapted to high salt environments thrive and become a ma- jor source of sedimentary organic matter, which is conducive to the formation of sapropelic organic matter. For the gyp- sum-sah rock has high thermal conductivity and low heat generation rate, it can transmit ground temperature easily from deep stratum to shallow stratum, which could result in source rock in the upper part of gypsum-sah stratum has lower temperature gradient and abnormal high temperature than that of no gypsum-sah stratum, to the contrary, source rock in the lower part of gypsum-sah stratum has higher temperature gradient and abnormal low temperature than that

关 键 词：膏盐岩 有机质 油气生成 油气运移聚集 油气分布 东濮凹陷 

分 类 号：TE122.2[石油与天然气工程—油气勘探]