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

Yu Zhichao; Liu Keyu; Zhao Mengjun; Liu Shaobo; Zhuo Qingong; Lu Xuesong

doi:10.3799/dqkx.2016.044

Abstract：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 mi-crospectroscopy.Diagenetic events identify include quartz overgrowths,early calcite cements,dolomite cements,ankerite ce-ments,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 trans-granular 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.