摘要
白云岩既是南海油气储集层又与生物礁成因机制相关。对西沙群岛梅山组一段600~750 m岩心段进行采样分析,由于此段属于新层位(西科1井600~1 000 m)中深埋藏白云岩,可能属于对应油气盆地的储层,因而相关研究至关重要。通过扫描电镜(SEM)观察发现大量菱形晶体,结合能谱(EDS)元素分析认为菱形晶体含有Ca和Mg元素,X射线粉晶衍射(XRD)分析证实全部样品为白云石;样品表面碎屑物质为方解石,但是EDS检测出Si,说明样品中混杂陆源沉积;在光滑的白云石晶体上EDS能谱分析则未见Si。事实上,西科1井梅山组一段白云岩层MgO和SiO_(2)含量变大,且呈明显正相关关系,推测为海退期白云石形成过程中的陆源物质输入。XRD分析结果表明,620~646.5 m段岩心发育厚层白云石,其有序度中等,下伏646 m深处方解石占比开始增加。
In the South China Sea, dolomite is not only a kind of oil and gas reservoir, but also the deposits closely related to the genesis of reefal complex. In this paper, mineralogical analysis is made for the 600~750 m interval of core section of the Meishan Formation in the Xisha Islands. The research is focused on a new horizon of middle to deep dolomite, 600~1 000 m from the well of Xike 1, which may become oil and gas reservoir in the future. A large number of rhombic crystals are found by SEM. EDS analysis suggests that the rhombic crystals are dominated by Ca and Mg in elements. XRD analysis further confirms that they are dominated by dolomite;excluding the surficial clastic deposits which consists of calcite. EDS detected some Si from the samples,indicating the mixing of terrigenous materials. However, no Si has been found on the smooth surface of dolomite crystals by EDS. The content of SiO_(2) increases with MgO in the dolomite. It is speculated that there is terrigenous material input during the formation of dolomite in the regression period. XRD results found that thick dolomite of medium order is developed in 620~646.5 m of the core, and the proportion of calcite begins to increase from646 m.
作者
付和平
沈江远
马骁
许红
张道军
苏大鹏
董刚
闫桂京
刘新宇
闫琢玉
FU Heping;SHEN Jiangyuan;MA Xiao;XU Hong;ZHANG Daojun;SU Dapeng;DONG Gang;YAN Guijing;LIU Xinyu;YAN Zhuoyu(China University of Petroleum(East China),Qingdao 266580,China;Qingdao Institute of Marine Geology,China Geological Survey,Qingdao 266071,China;Changjiang University,Wuhan 430100,China;First Institute of Oceanography,Ministry of Natural Resources,Qingdao 266061,China;Zhanjiang Branch of CNOOC(China)Ltd.,Zhangjiang 524057,China;CNOOC EnerTech-Drilling and Production Co.,Zhanjiang 524057,China)
出处
《海洋地质前沿》
CSCD
北大核心
2021年第6期31-38,共8页
Marine Geology Frontiers
基金
国家自然科学基金(41872114)
国家科技基础资源调查专项课题(2017FY201407)。
