环湾论——鄂尔多斯盆地延长组深层石油成藏规律

探讨鄂尔多斯盆地三叠系延长组湖湾区暗色泥岩生烃潜力及环湖湾区石油成藏规律。通过分析湖湾区暗色泥岩生烃指标(TOC、S1+S2、HI、氯仿沥青"A"含量、烃含量、干酪根类型及有机质成熟度)、原油成熟度,综合湖湾区分流河道砂岩发育特征及与泥岩接触关系分析,结果表明:1湖湾区暗色泥岩为好-中等烃源岩,可以成为生烃灶;2延伸入湖湾区的分流河道砂岩、湖湾砂坝砂岩为石油运移通道,石油由湖湾沿分流河道向外运移;3湖湾西侧发育砂岩上倾尖灭圈闭,湖湾内砂坝为透镜体状岩性圈闭;4由湖湾近源运移到岩性圈闭中形成侧生侧储或自生自储岩性油藏。该结果使鄂尔多斯盆地延长组的生烃区面积及石油勘探区域得到扩大。

Theory of surrounding bay:Petroleum accumulation regularity of deep level in Yanchang Formation,Ordos Basin,China

This paper discusses the hydrocarbon-generating potential of the dark mudstone in the lake bay area and the oil accumulation rule in the surrounding lake bay area of Triassic Yanchang Formation in Ordos Basin.Through analysing the hydrocarbon-generating index (TOC,S1 +S2 ,HI, chloroform bitumen “A”content,hydrocarbon content,kerogen type and maturity of organic matter) of the dark mudstone and the crude oil maturity and combined the development characteristics of the distributary channel sandstone with the contact relationship of mudstone,the obtained results show as follows.①The dark mudstone in lake bay area is a good-secondary hydrocarbon source rock,and can become hydrocarbon-generating kitchen.②The distributary channel sandrocks or lake bay sandbank sandstone extending into the lake bay area can be used as oil migration channels.③The sandrocks up-dip wedge out trap develops on the west side of the lake bay and the sandbank in the lake bay is a lenticular lithologic trap.④The laterally reservoired or the authigenically reservoired lithologic oil pools are formed when the mudstone migrates from the proximal of the lake bay to the lithologic trap. The research results extends the hydrocarbon-generating area and enlarges the oil exploration area of Yanchang Formation in Ordos Basin.