库车凹陷克拉2气田储层成岩作用和油气充注特征

克拉2气田是中国陆上勘探已知最大的天然气气田，下白垩系巴什基奇克组砂岩是其主力储层.为了揭示本区储层成岩作用和油气充注之间的成因联系，综合应用偏光显微镜、阴极发光显微镜、扫描电镜、CT扫描三维重构、X-射线衍射、荧光光谱、显微测温和激光拉曼等技术手段研究了克拉2气田储层的成岩作用和油气充注期次及特征，并且探讨了油气充注对成岩作用的影响.研究结果显示:本区的成岩矿物组合为石英次生加大边、方解石、白云石，铁白云石，微晶石英和自生高岭石.发育3期油气充注:第1期为低温高盐度的低成熟油气流体，以记录在石英愈合裂隙、长石解理和方解石胶结物中的黄褐色荧光包裹体为代表，充注时间为18 Ma；第2期为高温高盐度的高成熟油气流体，以记录在石英愈合裂隙和白云石胶结物中的黄白-蓝白色荧光包裹体为代表，充注时间为6 Ma；第3期为高温低盐度的天然气充注，以记录在石英愈合裂隙和铁白云石胶结物中的无荧光气烃包裹体为代表，充注时间4 Ma.本区储层中自生高岭石、微晶石英和储层沥青是晚期天然气充注对储层改造的结果. 

Characterization of Diagenesis and the Petroleum Charge in Kela 2 Gas Field,Kuqa Depression,Tarim Basin

The Kela-2 gas field is the most productive gas field in China. The lower Cretaceous Bashenjiqike Formation (K₁bs) are the dominated gas-bearing strata. Characterization of the diagenetic history, different fluid inclusion assemblages and the effects of oil emplacement on diagenetic processes of the K1bs in the Kuqa Depression, Tarim Basin have been studied using a combination of techniques such as polarizing microscope, cathode luminescence (CL), scanning electron microscope (SEM), CT three-dimensional reconstruction, X-ray diffraction (XRD), fluorescence spectroscopy, microthermometry, and Raman microspectroscopy. Diagenetic events identify include quartz overgrowths, early calcite cements, dolomite cements, ankerite cements, micro-quartz and authigenic kaolinite. Three episodes of oil emplacement are recorded by the diagenetic products in the K₁bs Formations. The first episode consists of the yellowish-brown fluorescent petroleum inclusions hosted in the transgranular fractures, cleavage plans of the feldspar and calcite cements, paired with low trapped temperature and relatively high salinity, forming around 18 Ma; the second episode consists of the yellow-white to blue-white petroleum inclusions located in the transgranular fractures, boundary of quartz particles and dolomite cements, paired with high trapped temperature and high salinity, forming around 6 Ma; the third episode consists of the CH₄-bearing vapour inclusions within the annealed microfractures and ankerite cements, having with high trapped temperature and low salinity, forming around 4 Ma. Authigenic kaolinite, micor-quartz and solid bitumen are the results transformed by the advanced natural gas charge.