摘要
塔深5(TS5)井于2021年完钻,井深9 017 m,是目前亚洲第一深井,同时也是塔里木盆地台盆区第一口在8 780～8 840 m的上震旦统白云岩段获得油气突破的钻井,也是继轮探1井寒武系盐下突破后,超深层白云岩领域的又一重大发现.为了探究其油气成因,分别对TS5井震旦系凝析油和上部奥陶系重质油,及其邻区寒武系挥发油和奥陶系凝析油进行了有机地球化学特征对比.结果表明,TS5井震旦系凝析油和白云岩储层氯仿抽提物的正构烷烃系列均分布完整,指示了其生烃母质形成于强还原环境;其与奥陶系正常油-超重质油和雅克拉地区凝析油总体具有相似的生物标志化合物和碳同位素分布特征,反映均具有相似的油源;其等效镜质体反射率(Rc)值为1.7％,成熟度高于奥陶系重质油、寒武系挥发油,与邻区凝析油相当,处于高成熟阶段.综合生物标志化合物和碳同位素证据,推测TS5井震旦系油气源来自下寒武统玉尔吐斯组,其与上覆玉尔吐斯组泥页岩构成良好的储盖组合,喜马拉雅晚期来自周边较低部位玉尔吐斯组生成的高成熟凝析油气,沿斜坡运移至震旦系白云岩构造圈闭内形成了一定规模的凝析气藏.TS5井震旦系油气突破,发现了新的含油气层系,丰富了超深层油气成藏过程,为塔里木盆地超深层勘探指明了新的探索方向.
Abstract
[Objective]The Well Tashen 5 that was completed in 2021 has a burial depth of 9 017 m and is cur-rently the deepest drilling well in Asia.It is also the first hydrocarbon breakthrough in the dolomite sectionof Upper Sinian at a depth of 8 780-8 840 m in the Tarim Basin.This is a major discovery in the field of ultradeep dolomite after the breakthrough of the Cambrian subsalt from the Well Luntan 1.[Methods]To better understand the hy-drocarbon generation process,the organic geochemical characteristics of the Sinian condensate and the Upper Ordo-vician heavy oil in the Well Tashen 5 and its neighboring Cambrian volatile oil and Ordovician condensate were compared.[Results]The n-alkane series of both the condensate and the chloroform extracted from dolomite are well distributed in the Sinian of the Well Tashen 5,indicating the domination of anoxic environment during the dep-osition of organic matter.Both biomarker compounds and carbon isotope distributions in the Sinian hydrocarbons of the Well Tashen 5 are similar to those of the Ordovician normal oils-ultraheavy oils and condensate oils of the Yakla region,implying the same hydrocarbon source between the Well Tashen 5 and the Yakla region.Equivalent vitrinite reflectance(Rc)in the Sinian hydrocarbons of the Well Tashen 5 is 1.7％,which is higher than the Rc of the Up-per Ordovician heavy oil and Cambrian light oil but is comparable with condensate of nearby regions and belongs to the high maturity stage.It is reasonable to suggest that,the Sinian hydrocarbons of the Well Tashen 5 were mainly sourced from the overlying Lower Sinian Yurtus Formation that also was the seal rock layer.The high-maturity con-densate was generated by the Yurtus Formation in the depression area during the Late Himalayan Period and was transported into the structure traps rich in Upper Sinian dolomites along the slope.[Conclusion]The breakthrough of Sinian hydrocarbons in the Well Tashen 5 has discovered a new hydrocarbon-bearing layer,displayed the process of ultradeep hydrocarbon formation,and indicated a new exploration direction for ultradeep exploration in the Tarim Basin.
基金项目
国家自然科学基金企业创新发展联合基金项目(U21B2063)
中国石化科技部项目(P21048-1)
维普
万方数据