准噶尔盆地腹部区中生界不整合面类型及纵向结构

Types and vertical structures of Mesozoic unconformity in the compressional abdominal area of Junggar Basin

准噶尔盆地腹部中生界不整合面对于隐蔽油气藏的形成具有重要的意义。在对构造背景深入研究的基础上,依据对钻井岩心、综合录井、地震反射等方面的分析,将不整合界面类型归结为上超/削蚀型、整一/削蚀型、上超/整一型、整一/整一型4种类型。分析了下三叠统上仓房组底界、中侏罗统头屯河组底界、下白垩统吐谷鲁群底界和下侏罗统八道湾组底界4个重要的不整合面特征,认为区内不整合的分布受控于盆地的类型。发现不整合面具有明显的3层结构:界面之上砂砾岩、砂岩层;界面之下的风化粘土层;界面之下的半风化岩石。认为不整合面有助于形成多层系削截型岩性圈闭,同时可以作为油气聚集的遮挡层和储集层。

The recognition of unconformities and their vertical structures is of significance for understanding the tectonic history and petroleum accumulation regularities in the Junggar Basin.According the analysis of tectonic background,outcrops,compound loggings and seismic data,it has a conclusion that there are four types unconformities：onlap/erosion truncation type,concordance/erosion truncation type,onlap/concordance type,concordance/concordance type.Four important unconformity surfaces were identified and analyzed.It‘s founded that the unconformity has three vertical structures.The upper is glutenite,sandstone layer,the middle is named the decomposed clay layers and the bottom is partial-decomposed rock layers.The unconformities in the compressional abdominal area are not only the important paths for the oil and gas migration,but also are the favourite place for the oil and gas accumulation.