Microscopic characteristics and geological significance of tight dolomite in well Xike-1,Xisha Islands,China

作者：Qin Na,Hong Xu,Da-peng Su,Meng Tao,Wei-wei Zhang,Zhao-peng Ji,Qing Wang

摘要：A recent study suggests that the deep dolomites in well Xike-1 located more than 1000 m deep have a very low porosity,and no permeability for most of the samples.Given that the largest oil and gas fields in the South China Sea are all composed of biohermal dolomites while the deep dolomites of Xike-1 serve as the caprock formations rather than the reservoirs,this represents the first discovery and is of great theoretical importance.In this paper,core photos of the tight dolomites are presented.Hand specimens description and systematic porosity-permeability reveal a very low porosity,and no permeability for most of the samples.PLM,SEM and XRPD analysis discovered that the dolostones in the deep tight dolomites are quite large in size and euhedral or subhedral in shape.Alizarin red-stained sections are mostly pink in color and have a full coverage,which are considered as evidence for multiple calcite intrusions after the formation of ankerite dolomites.Biological relict textures are developed.The order degree is medium to low.The dolomites could be the product of penecontemporaneous dolomitization.

發文機構：School of Earth Science and Technology Qingdao Institute of Marine Geology Shandong Provincial Key Laboratory of Sedimentary Mineralization and Minerals First Institute of Oceanography Ocean National Laboratory School of Geosciences and Engineering Yangtze University

關鍵詞：PERMEABILITYOrderdegreeTIGHTDOLOMITERocktypesGasoilexplorationengineeringXike-1ofShiISLANDChina

分類號： P61[天文地球—礦床學][天文地球—地質學]