天然气工业2025，Vol.45Issue(11)：40-56,17.DOI:10.3787/j.issn.1000-0976.2025.11.004
塔里木盆地北部地区上寒武统超深层白云岩储层发育机理与成因模式
Development mechanisms and formation patterns of ultra-deep Upper Cambrian dolomite reservoirs in the northern Tarim Basin
摘要
Abstract
In the northern Tarim Basin,there are thick dolomite reservoirs developed in the ultra-deep(burial depth＞6 500 m)Upper Cambrian Xiaqiulitage Formation,which have considerable potential of oil and gas exploration and development.However,controversies remain regarding their sedimentary-diagenetic characteristics and reservoir development mechanisms under different burial conditions.Based on core observation,thin section analysis,logging,cathodoluminescence(CL),U-Pb dating,and micro-area geochemical analysis data of the ultra-deep Upper Cambrian dolomite in the northern Tarim Basin,this paper clarifies its sedimentary microfacies types and reservoir characteristics,and reveals its sedimentary-diagenetic characteristics,reservoir development mechanisms and formation patterns.The following results are obtained.First,eight types of sedimentary microfacies(MF1 to MF8)are totally identified in the Upper Cambrian dolomite reservoirs,and they constitute four types of microfacies assemblages(MA1 to MA4)representing different sedimentary environments,which correspond to shoal,microbial mound,tidal flat,and platform margin shoal,respectively.The overall sequence framework and sedimentary filling presents as a sedimentation and development pattern of restricted platform-marginal platform within the framework of rimmed carbonate platform.Second,the reservoir spaces in the dolomite reservoirs are dominated by intercrystalline dissolution pores,vugs,and intercrystalline pores.The porosity is mrainly less than 5％,and most reservoirs are incluoded in the scope of Grade Ⅲ.Third,formation and reworking of pores and vugs in dolomite reservoirs are influenced by multiple diagenetic processes.Atmospheric freshwater dissolution during;the penecontemporaneous period lays the foundation for the formationl of reservoir pores;recrystallization modifies the early pore structures;the tectonic-hydrothermal fluid filling process in the diagenesis stage is an important factor leading to the destruction of primary pores.Fourth,the ultra-deep dolomite reservoirs are classified into two types,namely platform margin shoal grain dolomite reservoir and intraplatform shoal grain dolomite reservoir.The reservoir development pattern takes the high-energy facies belts of platform margin beach and intraplatform shoal as the material basis.Due to the atmospheric freshwater dissolution induced by descending sea level,quality reservoir intervals are formed in the upper part of highstand system tract(HST).The porosity-preserving reworking process during the late diagenesis stage plays a crucial role in sustaining pore structures in ultra-deep reservoirs.In conclusion,this study summarizes the sedimentation and reservoir development patterns of the ultra-deep Upper Cambrian dolomite in the northern Tarim Basin,and the research results can provide reference and guidance for the ultra-deep reservoir study and oil and gas exploration in this area and the basins with similar structural settings.关键词
塔里木盆地北部地区/上寒武统白云岩储层/超深层/沉积-成岩作用/发育机理/成因模式/油气勘探Key words
Northern Tarim Basin/Upper Cambrian dolomite reservoir/Ultra-deep/Sedimentation-diagenesis/Development mechanism/Formation pattern/Oil and gas exploration分类
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李俊,石开波,刘波,何卿,王远翀,邓嘉铭,华健豪,门溪川..塔里木盆地北部地区上寒武统超深层白云岩储层发育机理与成因模式[J].天然气工业,2025,45(11):40-56,17.基金项目
国家自然科学基金企业创新发展联合基金集成项目"三大盆地深层—超深层海相油气高效勘探开发基础研究"(编号:U24B6001). （编号:U24B6001）
