塔里木盆地塔东隆起带上震旦统沉积模式探究

An inquiry into the sedimentary model of Upper Sinian in Tadong Uplift of Tarim Basin

随着勘探不断向深层发展,震旦系白云岩因具备良好的生储盖组合条件而逐渐成为近源寻找原生油气藏的重要勘探领域。塔里木盆地塔东隆起带震旦系白云岩埋藏浅,6000 m以内可勘探面积达1.5×1010 m2,一旦突破,将带来巨大经济效益。前期受资料所限,研究主要侧重于盆地级的大区研究,对盆内区带级的精细研究开展的比较少,对塔东隆起带震旦系白云岩沉积模式研究更少,这不仅困扰着塔东隆起带震旦系的油气勘探,而且对整个盆地上震旦统岩相古地理编图也有重要影响。借助新的钻井资料和高品质地震资料,对塔东隆起带震旦系白云岩开展地震地层学和沉积学研究,建立上震旦统沉积模式,提出塔东隆起带震旦系为断陷沉积,发育2个北东—南西向的双断裂陷,裂陷中部受基底断块隆升影响,形成断块碳酸盐岩台地,发育浅水台地颗粒滩、潮坪相沉积。震旦纪末期,受构造掀斜运动影响,南部抬升,地层遭受剥蚀,形成现今北厚南薄的楔状地层分布模式。

With the fact that exploration marching towards deep reservoir,Because of its good source reservoir cap assemblage,Sinian dolomite has gradually become an important exploration target for near source explora⁃tion of primary oil and gas reservoirs.The Sinian dolomite in Tadong Uplift is shallowly buried,with an explo⁃ration area of 15000 km2 within depth of 6000 m.Once it breaks through,it will bring huge economic benefits.Limited by the data,the early research mainly focused on the large-scale study of basin scale,less on the de⁃tailed study of regional scale and less on the sedimentary model of Sinian dolomite,which not only puzzles the oil and gas exploration of Sinian System in Tadong Uplift,but also has an important impact on the lithofacies pa⁃leogeographic mapping of the whole basin.Based on the new drilling data and high quality seismic data,this pa⁃per studies the seismic stratigraphy and sedimentology of Sinian dolomite in the Tadong Uplift zone,establishes the sedimentary model of Upper Sinian,and proposes that the Sinian System in Tadong Uplift zone is rift depos⁃it,forming two NE-SW double rifted depressions.The central part of the rifting is affected by the uplift of the basement fault block,forming a fault block carbonate platform and grain beach and tidal flat facies are deposited in shallow water platform.At the end of Sinian Period,influenced by the structural tilting movement,the south⁃ern part was uplifted,and the strata were denuded,forming the present“north thick and south thin”wedgeshaped stratigraphic distribution pattern.