塔里木盆地上奥陶统良里塔格组划分对比

塔里木盆地良里塔格组岩石地层、生物地层及测井地层划分对比表明,该组为一明显的穿时性地层单元,塔北地区最薄,沙西的英买1井仅12 m,只含良里塔格组底部的Belodina compressa牙形石带;卡塔克隆起的中2井厚达878 m,既产Belodina compressa带,又产顶部的Yaoxianognathus yaoxianensis带;塘南地区(塘南1井)最厚可达1 271 m.塔北地区的良里塔格组仅相当于中央隆起带的良五—良四段,可能包括良三段底部的一部分,其上的桑塔木组大部与后者的良里塔格组中上部为同时异相关系。在中央隆起带上,良里塔格组可划分为5个岩性段,但相同岩性段在不同井区间并非完全等时,且隆起的主体上多缺失下部的2个段。综合分析良里塔格组地层、沉积及储盖组合特征,认为中央隆起带南北坡折带是较为有利的勘探区带。

Classification and Correlation of Lianglitag Fomation of Upper Ordovician in Tarim Basin

The stratigraphic classification and correlation in lithology and biostratigraphy and well log interpretation indicate that Lianglitag formation in Tarim basin is an obvious diachronous unit,in which the thinnest is in Tabei area,e.g.Well YM-1 in Shaxi has only 12 m in thickness,containing Belodina compressa zone of the bottom of this formation;Well Zhong-2 in Katake uplift has 878 m,indicated by not only Belodina compressa zone,buy also Yaoxianognathus yaoxianensis zone in the top of Lianglitag formation;the thickest is in Tangnan area,1 271 m thick in Well TN-1.Therefore,Lianglitag formation in Tabei area is corresponding to the Liang-5,Liang-4 members and some bottom part of Liang-3 of the central uplift zone;the most part of Sangtamu formation assumes heteropic relations with the middle-upper part of Lianglitag formation in Katake and Tangnan.Lianglitag formation in central uplift zone could be divided into 5 lithologic members,but the same member in different wells was not completely isochronal,and the lower 2 members are hiatus in the main part of the uplift zone.By synthetical analyses of the stratigraphy,sedimentary facies and the assemblage of reservoir and cap rocks,the slope breaks in the southern and northern of the uplift zone are considered as the advantageous exploration targets in this area.