【摘要】 QK-1天然气水合物钻探试验井位于西藏羌塘盆地毕洛错地区,主要钻遇中侏罗统夏里组粉砂质泥岩和布曲组灰岩。其有机质丰度、有机质类型、有机质成熟度等有机地球化学特征表明,南羌塘地区中侏罗统烃源岩的有机质丰度偏低,夏里组泥岩TOC介于0.26%~0.38%之间,达到差-中烃源岩标准,而布曲组灰岩TOC介于0.02%~0.08%之间,仅局部达到差烃源岩标准;两个组的烃源岩有机质类型主要为Ⅱ2型及Ⅲ型,较利于天然气的生成,其中夏里组的生气能力优于布曲组;该区烃源岩热演化程度较高,Ro为1.31%~1.63%之间,均达到高成熟阶段,而夏里组有可能已进入干气阶段。基于冻土区天然气水合物成藏条件分析,综合考虑夏里组烃源岩及沉积厚度特征,认为中侏罗统夏里组具备良好的天然气水合物勘探前景。更多还原

【Abstract】 The borehole QK-1,one of the scientific drilling holes of gas hydrate,is located at Biluocuo area in the Qiangtang Basin of northern Tibet,in which the silty mudstones of Xiali Formation(J2x) and limestones of Buqu Formation(J2b) were drilled. The geochemical characteristics of the abundance,type and maturity of organic matters of the source rocks reveal the following aspects: the organic matter abundance of source rocks in Middle Jurassic is lower; the silty mudstones in Xiali Formation have reached be poor-medium source rocks with TOC of 0. 26% to 0. 38%,and the TOC values of limestones in Buqu Formation are between 0. 02% and0. 08%,part of which has reached to be poor-hydrocarbon source rocks; the types of organic matters for source rocks in Xiali and Buqu formations are mainlyⅡ2-type or Ⅲ-type,which are beneficial to gas formation,and the source rocks of Xiali Formation is superior to that of Buqu Formation. The value of Rofor source rocks in this area is from 1. 31% to 1. 63%,showing that the organic matter has undergone a high-degree thermal evolution and is in a high-maturity stage,and the organic matter in Xiali Formation is even in an over-maturity stage.Combining all factors favorable for the genesis of gas hydrates,it comes to the conclusion that Xiali Formation is a potential exploration target.更多还原