吐哈盆地鄯深构造三叠系油藏成藏期次分析

鄯科1井是吐哈盆地台北凹陷首次钻穿三叠系的一口科学探索井,并首次在三叠系发现了轻质油流,通过对鄯科1井三叠系油藏进行成藏条件的分析,更主要根据当前在油气成藏期研究中较领先的有机包裹体鉴定和测温技术,确定了鄯科1井三叠系油藏的成藏期次.研究结果,中侏罗世西山窑组末期为鄯深构造三叠系油藏的第一个成藏期,为小规模的低熟油成藏;中侏罗世三间房组末期为鄯深构造三叠系油藏的第二个成藏期,也是主要成藏期,该期注入的原油被氧化稠化为沥青;晚侏罗世早白垩世为鄯深构造三叠系油藏的第三个成藏期,现在鄯科1井所产轻质油就是该期注入.通过成藏期次的研究,认为应在台北凹陷其它构造带寻找三间房组沉积末期成藏而没有被破坏稠化的油藏,其原油产量应远高于鄯科1井三叠系油层,并强调吐哈深层油气勘探在研究烃源岩和储集层的同时,要加强油气保存条件的研究.

OIL-ACCUMULATING STAGES OF THE TRIASSIC TPAP WITHIN THE SHANSHEN STRUCTURE IN TUHA BASIN

The Shanke_1,a scientific research well,is the first well which penetrated the Triassic and encountered light oil in the Taibei Depression,Tuha Basin.Based on the analysis of Triassic oil_accumulating conditions,a study of organic inclusions and advanced thermometry,three oil_accumulating stages are identified for the Triassic pool in well Shanke_1.The first stage is in late Xishanyao of Middle Jurassic,forming a small oil accumulation with a low organic maturity.The second stage,or the main one,occurs in late Sanjianfang of Middle Jurassic,but the oil trapped in this stage has been oxidized into asphalt.The third stage,lasting from Late Jurassic to Early Cretaceous,has resulted in accumulation of light oil,forming a productivity in Shanke_1.In Taibei Depression of Tuha Basin,therefore,we should continue searching for non_oxidized oil trapped during the second stage,which will have a much higher productivity than that in Shanke_1.It is also emphasized that petroleum preservation conditions,together with source and reservoir rocks,have to be deeply studied.