青藏高原羌塘盆地首口油气科探井(QK-1)新发现  

New discoveries on the first petroleum scientific drilling(QK-1)of the Qiangtang Basin,Tibetan Plateau

作　　者：王剑 王忠伟 付修根 宋春彦[4] 谭富文[4] 韦恒叶 Jian Wang;Zhongwei Wang;Xiugen Fu;Chunyan Song;Fuwen Tan;Hengye Wei(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Qiangtang Institute of Sedimentary Basin,Southwest Petroleum University,Chengdu 610500,China;School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Chengdu Center,China Geological Survey,Chengdu 610081,China)

机构地区：[1]西南石油大学,油气藏地质与开发工程国家重点实验室,成都610500 [2]西南石油大学羌塘盆地研究院,成都610500 [3]西南石油大学地球科学与技术学院,成都610500 [4]中国地质调查局成都地质调查中心,成都610081

出　　处：《科学通报》2022年第3期321-328,共8页Chinese Science Bulletin

基　　金：国家自然科学基金重大研究计划重点支持项目(91955204);第二次青藏高原综合科学考察研究(2019QZKK0803)资助。

摘　　要：羌科-1井(QK-1)是藏北高原第一口油气地质科学探井,也是目前世界上海拔最高的科探井.通过实施羌塘盆地科探井及其配套地质浅钻,在油气封盖条件、优质烃源岩、油气显示及地层沉积序列等方面取得了一系列新发现.钻探发现了两套区域性优质盖层:雀莫错组(J_(1-2)q)硬石膏层厚达353.8~365.0 m,夏里组(J_(2x))含膏泥质岩厚达230.0~252.0 m.钻井、地震资料及沉积相综合分析表明,这些盖层区域分布连续、稳定,同时油气封盖性能良好,从而证实羌塘盆地具备较好的油气封盖条件.与QK-1配套的地质浅钻揭示,北羌塘盆地边缘带上三叠统滨岸沼泽至三角洲平原相区发育了较好的烃源岩.泥质烃源岩总有机碳(total organic carbon,TOC)含量达2.0%~3.6%,厚36.0 m,TOC含量大于1%的烃源岩厚达61.0 m.有机质类型包括II_(1)、II_(2)和III型,热演化程度为高成熟-过成熟阶段,以生气为主.预测北羌塘盆地中心覆盖区前三角洲至陆棚相区可能具有比盆地边缘相带更好的优质烃源岩.因此,北羌塘盆地不仅存在优质烃源岩,而且可能还具有较大的生烃潜力.QK-1共揭示14层气测异常,结合地表露头油气显示,表明羌塘盆地有过大规模油气生成聚集与破坏过程,同时存在油气有利保存区带.QK-1钻遇了侏罗系完整连续的地层沉积序列,总体上表现为冲洪积相逐渐演化为滨至浅海相及碳酸盐台地,地层沉积序列资料为羌塘含油气盆地分析提供了新的依据.QK-1 is the first scientific drilling designed to solve the key problems in petroleum geology in the Qiangtang Basin on the northern Tibetan Plateau.Its altitude is 5030 m,and the well depth is 4696.2 m.It is also the highest-altitude scientific drilling on the globe,and is located in the Lake Bandaohu area in the northern Qiangtang Basin.By performing the QK-1 and its affiliated shallow drillings,a series of new discoveries have been made in regard to highquality regional seals,source rocks,petroleum displays and the Jurassic strata succession.(1)Two sets of caprocks,which could be regional high-quality seals,were discovered through drilling,i.e.,an anhydrite layer in the Quemoco Formation(J_(1-2)q)(354–365 m thick)and a gypsum-bearing mudstone in the Xiali Formation(J_(2x))(230–252 m thick).Comprehensive analyses of drilling and seismic data show that the distribution of these caprocks is regionally continuous and stable.Moreover,petroleum displays and well logging data reveal that these two caprocks are characterized by low porosity,good permeability(the mean permeability is 0.265×10^(-3)μm^(2),and the mean breakthrough capillary pressure is 9.0 MPa),and good sealing.(2)The northern Qiangtang Basin contains high-quality hydrocarbon source rocks in Upper Triassic deltaic facies.The affiliated shallow drillings reveal a good Upper Triassic hydrocarbon source rock in a coastal swamp-deltaic plain facies on the northern Qiangtang Basin margin.The two mudstone source rock members have a thickness of 36.0 m and total organic carbon(TOC)values of 2.0%–3.6%,and a thickness of 61.0 m and TOC values of>1.0%,respectively.The organic matter type is II_(1)-,II_(2)-and III-type kerogen with high to over-thermal maturation.Well logging,seismic data and facies analyses indicate that the pro-deltaic to shelf mudstones in the covered area in the central northern Qiangtang Basin are better source rocks than those in the deltaic plain on the basin margin.(3)Well logging petroleum displays provide important insights for pe

关 键 词：羌科-1井(QK-1) 封盖层 烃源岩 油气显示 沉积序列 羌塘盆地 

分 类 号：P618.13[天文地球—矿床学]