塔里木盆地顺北一区奥陶系鹰山组与一间房组沉积特征

近年来,塔里木盆地顺北地区油气藏的持续发现揭示了其较大的勘探潜力.通过开展岩心观察、薄片鉴定、常规测井曲线和成像测井图像分析以及元素地球化学测试,对顺北一区奥陶系鹰山组上段与一间房组沉积环境进行了分析,结合沉积相识别标志,系统描述了研究区沉积特征,指明了优质储层类型及有利发育区.研究结果表明:①顺北一区奥陶系鹰山组上段...

Sedimentary characteristics of Ordovician Yingshan Formation and Yijianfang Formation in Shunbei-1 area,Tarim Basin

In recent years,the continuous discovery of oil and gas reservoirs in Shunbei area of Tarim Basin reveals its great exploration potential.Through core observation,thin section identification,conventional logging curves and imaging logging image analysis and element geochemistry test,the sedimentary environment of the upper member of Yingshan Formation and Yijianfang Formation of Ordovician(O_1-2y-O₂yj)in Shunbei-1 area was analyzed.Combined with the identification marks of sedimentary facies,the sedimentary characteristics of the study area were described,and the high-quality reservoir types and favorable reservoir development areas were pointed out.The results show that:(1)The mass fraction of Mn of the upper member of Yingshan Formation and Yijianfang Formation of Ordovician in Shunbei-1 area 1 is greater than 200×10^-6,the average value of Sr/BA is 2.0254-3.2602,and the average value of U/Th is 2.02,mostly greater than 0.75,the average value ofδU is 1.29,mostly greater than 1,which shows that the whole study area was in a marine sedimentary environment with water depth changing from deep to shallow,normal salinity,warm and humid weak oxidation-weak reduction.(2)The upper member of Yingshan Formation and Yijianfang Formation of Ordovician in the study area is an open platform facies deposit,with two subfacies developed:platform flat and intra-platform shoal,and six microfacies,such as limestone flat,dolomite-limestone flat,dolomite flat,sandy debris shoal,bioclastic shoal and granular beach.(3)As a whole,the study area is mainly dominated by limestone flat microfacies.In the vertical direction,the sandy debris shoal and bioclastic shoal microfacies are more developed in Yijianfang Formation than in the upper member of Yingshan Formation.The development of intra-platform shoal subfacies is weakened from east to west in the plane.