吐哈盆地洼陷区中下侏罗统岩性油气藏风险勘探新发现及勘探前景

New discoveries and exploration prospects of Middle and Lower Jurassic lithologic reservoirs in depression area of Turpan-Hami Basin

近期吐哈盆地风险探井沁探1井、预探井吉7H井在台北凹陷下侏罗统三工河组获得重要发现,实现了吐哈盆地洼陷区岩性油气藏勘探的重大突破,展现了吐哈盆地“下洼进源”勘探的良好前景。基于新钻井取得的地质认识,系统梳理和总结了洼陷区岩性油气藏有利成藏条件,指出下一步勘探方向。研究表明:①台北凹陷侏罗系水西沟群发育八道湾组、三工河组、西山窑组3套烃源岩,新钻井揭示出三工河组不仅发育区域性盖层,也是优质烃源岩,重新评价显示台北凹陷水西沟群生烃潜力大;②下侏罗统三工河组是洼陷区勘探主力目的层,发育辫状河三角洲沉积体系,洼陷区砂体发育,在次生溶蚀和构造裂缝作用下,5000 m以深仍发育有效储层;③台北凹陷下侏罗统存在葡东、红北、陵北、丘东和疙北五大岩性油气藏有利区带,勘探潜力大,是吐哈盆地未来勘探的重要方向。

Recently,risk exploration Well Qintan1 and exploration Well Ji7H in the Turpan-Hami Basin have made important discoveries in the Lower Jurassic Sangonghe Formation in Taibei Sag.The two wells realized a major breakthrough in lithologic oil and gas reservoir exploration in depression area,and showed a good prospect of“lower depression source”exploration in Turpan-Hami Basin.Based on the two wells,the favorable conditions of lithologic reservoir formation in the sag area are systematically summarized,and the directions of further exploration are specified.The results show that:(1)Three sets of source rocks,namely Badaowan Formation,Sangonghe Formation and Xishanyao Formation,are developed in Shuixigou Group of Jurassic in Taipei Sag.The new drilling reveals that Sangonghe Formation is not only a regional caprock,but also a high-quality source rock.The source rock re-evaluation shows that Shuixigou Group in Taipei Sag has great hydrocarbon generation potential.(2)Sangonghe Formation of Lower Jurassic is the main target layer for exploration in the depression area.Braided river delta sediments are developed.Sandbodies are developed in the depression area.Due to secondary dissolution and structural fractures,effective reservoirs are still developed at a depth of more than 5000 m.(3)There are five favorable zones of rock reservoirs in the Lower Jurassic of Taibei Sag:Pudong,Hongbei,Lingbei,Qiudong and Gebei,which have great exploration potential and are an important direction of future exploration in Turpan-Hami Basin.