TSR-Derived Authigenic Calcites in Triassic Dolomite,NE Sichuan Basin,China-A Case Study of Well HB-1 and Well L-2

作     者：Sijing Huang Keke Huang Zhiming Li Ming Fan Ershe Xu Jie Lü 黄思静;黄可可;李志明;范明;徐二社;吕杰

作者机构：State Key Laboratory of Oil/Gas Reservoir Geology and ExploitationChengdu University of TechnologyChengdu 610059China Institute of Sedimentary GeologyChengdu University of TechnologyChengdu 610059China Wuxi Research Institute of Petroleum GeologySINOPECWuxi 214151China 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2012年第23卷第1期

页      面：88-96页

核心收录：

学科分类：081803[工学-地质工程] 08[工学] 0708[理学-地球物理学] 0818[工学-地质资源与地质工程] 0704[理学-天文学] 

基　　金：supported by the National Natural Science Foundation of China (Nos. 40839908 and 41172099) 

主　　题：NE Sichuan basin Triassic TSR,calcite cementation reservoir quality. 

摘      要：It has been proven that thermochemical sulfate reduction （TSR） took place extensively in the Lower Triassic carbonate reservoirs in Northeast （NE） Sichuan （四川） basin. We have carried out analyses on bulk rock compositions and isotope ratios together with petrography and fluid inclusions to assess the impact of TSR on diagenetic process of Triassic dolomites. In this article, TSR-related burial diagenesis is characterized by precipitation of calcite cement with negative 613C values and high ho- mogenization temperature. The light carbon isotopic compositions of this phase indicate that carbon incorporated in this cement was partly derived from oxidation of hydrocarbon. The high homogeniza- tion temperatures indicate that the thermochemical reduction of sulfates has been taking place in the deep part of NE Sichuan basin. Additional evidence supporting this interpretation is the high Sr values of this calcite cement. Moreover, the calcites have a 6180 of -8.51%o to -2.79%0 PDB and are interpreted to have precipitated from high salinity fluids with 6180 of ＋5%0 to ＋13%o SMOW. Under cathodolumi- nescence, these calcite cements appear dark brown or black, and both Mg concentrations and Mn/Sr ratios are low. It is therefore indicated that seawater was the principal agent of precipitation fluids. Finally, it should be noted that although H2S and CO2 increased as TSR continued, porosity has been ultimately destroyed by calcite cementation.