吐哈盆地二叠系含油结核研究及生油前景分析

OIL-BEARING NODULES AND OIL-GENERATION PROSPECTS OF PERMIAN IN TURPAN-HAMI BASIN

吐哈盆地北部的台北凹陷北缘塔儿朗沟的中二叠统首次发现了巨厚的暗色泥岩夹油页岩、泥灰岩及巨型含油钙质结核 ,钙质结核顺层分布 ,大小不一 ,为成岩结核 ,其中含油结核为裂缝发育。油源对比结果表明 ,油来自其围岩中的暗色泥岩 ,与吐哈盆地南带台南凹陷已发现的前侏罗纪原油具有同源关系。地震、探井资料及盆地分析结果表明 ,台北凹陷北缘与准噶尔盆地南缘为中二叠世沉降沉积中心 ,该地区中二叠统深湖相泥岩是这两个盆地油气藏的主要烃源岩。两年多的勘探实践表明 ,台北凹陷自二叠纪以来是一个持续稳定沉降的凹陷 ,中二叠统湖相泥岩产出的烃类不但形成自生自储式油气藏 ,而且对该区侏罗系油气藏的形成有重要贡献。

The huge oil_bearing nodules,oil shale and marl interbeded in thick dark mudstone were firstly found in Middle Permian in the northern Turpan_Hami Basin.These nodules were distributed along different sizes of layers during diagenesis.The oil_bearing nodules have abundant fractures.The comparative result shows that the oil was derived from the dark mudstone in Middle Permian and has the same source as that of pre_Jurassic found in Tainan depression in the southern Turpen_Hami Basin.Synthetic analysis indicates that centers of subsidence and depocenter in the Middle Permian period are in the southern Jungger Basin and the northern Turpen_Hami Basin,where deep lake mudstone of Middle Permian is the main sourcerock.Exploration practice indicates that Taibei Depression has been a constant subsidence area since Permain period in which the hydrocarbon produced from Middle Permian lacustrine mudstone formed auto_generation and auto_reservoir oil_gas accumulation,which contributes to the oil_gas accumulation of Jurassic.