羌塘盆地隆鄂尼—昂达尔错地区布曲组白云岩储层成因及孔隙演化特征

发布时间：2019-06-21 07:07

【摘要】：利用剖面地质调查、岩心观察、薄片铸体鉴定、扫描电镜分析及物性测试等方法,结合地球化学资料综合分析,研究羌塘盆地隆鄂尼—昂达尔错地区布曲组白云岩储层成因及孔隙演化特征。结果表明:布曲组白云岩包括保留先驱灰岩原始组构白云岩、晶粒白云岩和白云石充填物;晶粒白云岩中细晶、自形白云岩储层物性最好,细晶、半自形白云岩储层物性次之;储集空间以晶间孔为主,局部发育晶间溶孔。布曲组沉积前的古地貌和沉积时的古气候控制白云岩在垂向和平面上的展布,即沉积环境决定储层的叠置形态;白云岩储层发育于台缘滩和台内浅滩环境,高位体系域晚期的咸化海水提供白云石化流体;白云岩储层经历准同生阶段、浅埋藏阶段、中—深埋藏阶段及构造热液改造阶段,浅埋藏阶段是储层孔隙发育的关键时期。在南羌塘地区,早白垩世晚期羌塘地块和拉萨地块的碰撞以剪切作用为主,形成深大断裂,大气淡水下渗稀释布曲组地层水,并俘获夏里组高~(87)Sr/~(86)Sr的地层流体,约74 Ma的构造热事件提供鞍形白云石的热源,形成鞍形白云石充填物。
[Abstract]:The genesis and pore evolution characteristics of dolomite reservoir in Buqu formation in Longeni-Andar fault area of Qiangtang Basin are studied by means of profile geological survey, core observation, thin slice casting identification, scanning electron microscope analysis and physical property test. The results show that the dolomite of Buqu formation includes retained forerunner limestone original fabric dolomite, grain dolomite and dolomite filling, fine grain, self-shaped dolomite reservoir physical properties are the best, fine grain, semi-self-shaped dolomite reservoir physical properties are the second, reservoir space is mainly intergranular pores, local development of intergranular dissolved pores. The paleogeomorphology before the deposition of Buqu formation and the paleoclimate control the distribution of dolomite in vertical and plane, that is, the sedimentary environment determines the superimposed shape of the reservoir, the dolomite reservoir is developed in the platform margin beach and intra-platform shoal environment, and the salted sea water in the late stage of the high system tract provides dolomitization fluid. Dolomite reservoir goes through quasi-syngenetic stage, shallow buried stage, middle-deep buried stage and tectonic hydrothermal transformation stage, and shallow buried stage is the key period of reservoir pore development. In the southern Qiangtang area, the collision between Qiangtang block and Lhasa block in the late early Cretaceous was dominated by shear, forming deep faults, dilute Buqu formation water by atmospheric fresh water infiltration, and trapping the formation fluid of Xiali formation high ~ (87) Sr/~ (86) Sr. The tectonic thermal event of about 74 Ma provided the heat source of saddle dolomite and formed saddle dolomite filling.
【作者单位】：国土资源部沉积盆地与油气资源重点实验室;中国地质调查局成都地质调查中心;中国地质大学(武汉)地球科学学院;
【基金】：国家科技重大专项(2011ZX05004-001) 国家油气基础性公益性地质调查项目(121201010000161110) 中国地质调查局项目(1212011221114)
【分类号】：P618.13

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