Multisourced CO_(2) Injection in Fan Delta Conglomerates and Its Influence on Reservoir Quality: Evidence from Carbonate Cements of the Baikouquan Formation of Mahu Sag, Junggar Basin, Northwestern China  

作　　者：Ning Zhu Yingchang Cao Kelai Xi Songtao Wu Rukai Zhu Miaomiao Yan Shunkang Ning 

机构地区：[1]School of Geosciences,China University of Petroleum,Qingdao 266580,China [2]Research Institute of Petroleum Exploration and Development,CNPC,Beijing 100083,China [3]Key Laboratory of Oil and Gas Reservoirs,CNPC,Beijing 100083,China [4]National Energy Tight Oil and Gas R&D Center,Beijing 100083,China [5]Wenliu Oil Recovery Plant of Zhongyuan Oilfield Branch,Puyang 457000,China

出　　处：《Journal of Earth Science》2021年第4期901-918,共18页地球科学学刊（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.U1762217,41702141);the Science and Technology Project of China National Petroleum Corporation(No.2016B-03).

摘　　要：Sandy-conglomerate reservoir has gradually become a major target of oil and gas exploration.Complex diagenetic process and diagenetic fluid play a significant role in affecting reservoir heterogeneity.Carbonate cements form at various stages of the diagenesis process and record various geological fluid information.Recently,one-billion-ton sandy conglomerate oil field was exposed in Triassic Baikouquan Formation,Mahu sag,Junggar Basin.Therefore,an integrated study applying casting thin sections,cathodeluminescence,fluorescence,carbon and oxygen stable isotopes,electronic probe microanalysis and aqueous fluid inclusions measurements was performed in order to identify the types of carbonate mineral and its representative diagenetic environment and discuss the influences of different CO_(2) injections on reservoir quality.The main findings are as follows:The reservoir is mainly composed of 70.33%conglomerate and 16.06%coarse-grained sandstone.They are characterized by low compositional maturity and abundant lithic debris.Four types carbonate cements are identified according to the petrological and geochemical characteristics,including two types of Mn-rich calcite,ferroan calcite,siderite and dawsonite.They display an unusual broad spectrum ofδ^(13)C values(-54.99‰to+8.8‰),suggesting both organic and inorganic CO_(2) injections.The δ^(13)C values of siderite are close to 0,and its formation is related to meteoric water.Theδ^(13)C values of ferroan calcite and the occurrence of dawsonite indicate the trace of inorganic mantle-derived magmatic fluids.Theδ^(13)C values and trace elements of Mn-rich calcite record the information of hydrocarbon-bearing fluids.The fluid inclusions measurement data and reservoir properties and oil-test data show that the oil content of reservoir is not only affected by the formation time of different cements,but also by the relative content of dissolution and cementation.For these reservoirs altered by carbonate cements,it does not cause poor oil-bearing due to blockage of secondary

关 键 词：carbonate cement CO_(2)fluid carbon and oxygen isotope RESERVOIR Mahu sag Junggar Basin 

分 类 号：P618.13[天文地球—矿床学]