沉积学报2025，Vol.43Issue(5)：1679-1696,18.DOI:10.14027/j.issn.1000-0550.2025.044
川中古隆起灯影组多期盐水成岩流体活动与成储意义
Multiphase Saline Diagenetic Fluid Activity in the Dengying Formation of the Central Sichuan Paleo-Uplift:Implications for reservoir development
摘要
Abstract
[Objective]Pore fluids,particularly saline pore fluids,are widespread in sedimentary basins;however,their characteristics undergo substantial changes throughout the burial process.Such change has a significant influ-ence on the formation and modification of deep to ultra-deep petroleum reservoirs;thus,determining the variations of saline pore fluids during burial can help identify the formation mechanisms of these reservoirs.[Methods]The Deng-ying Formation of the central Sichuan paleo-uplift was studied.By integrating the δ13C,δ18O,87Sr/86Sr,clumped isotopes,and U-Pb age data of the main products formed by saline fluid activity,the genesis of these products,their fluid-charging sequences,and the influence of saline fluid activity on reservoir development were investigated.[Results]The results show that the Dengying Formation was characterized by the development of five product types associated with saline fluid activity:matrix dolomite(D1),fibrous or micrite to very fine-crystalline dolomite rim(D2),leaf or fine-crystalline dolomite(D3),medium to coarse crystalline dolomite(D4),and saddle or mega-crystalline dolomite(D5).These five types of dolomite display differences in δ13C,δ18O,87Sr/86Sr,T(Δ47),and U-Pb ages,corresponding to five phases of saline diagenetic fluid activity.[Conclusions]A comprehensive investigation shows that the general diagenetic sequence of these dolomite is as follows:(1)D1 formed by seawater dolomitiza-tion,(2)D2 generated by the reflux dolomitization of(evaporated)seawater,(3)D3 originated via the dissolution of early-formed D1 and D2 followed by reprecipitation,(4)D4 precipitated from the mixing of formation waters and hydrothermal fluids,and(5)D5 formed from by the influx of deep-sourced 87Sr-rich hydrothermal fluids.Early-stage saline diagenetic fluid activity(i.e.,1st and 2ed stages)enhances the ability of reservoir rocks to resist physicochemi-cal compaction,favoring reservoir formation;conversely,late-stage saline diagenetic fluid activity(i.e.,the later three stages)degrades petrophysical properties by precipitating abundant dolomite cements within void spaces.There-fore,saline diagenetic fluid activity controls the evolution of reservoirs through two-phase differential diagenesis.These findings may provide guidance for the petroleum exploration in deep to ultra-deep carbonate formations.关键词
成岩流体/成岩演化/白云石/成储效应/深层—超深层油气储层Key words
diagenetic fluids/diagenetic evolution/dolomite/reservoir formation/deep to ultra-deep petroleum reservoirs分类
天文与地球科学引用本文复制引用
文华国,罗连超,丁一,张晨..川中古隆起灯影组多期盐水成岩流体活动与成储意义[J].沉积学报,2025,43(5):1679-1696,18.基金项目
四川省天然气成藏物质基础青年科技创新团队基金项目(2022JDTD0004)Youth Science and Technology Innovation Team Fund Project of Natural Gas Reservoir Material Foundation,Sichuan Province,No.2022JDTD0004 （2022JDTD0004）
