摘要
基于测井、岩心、薄片、地球化学分析,重建鄂尔多斯盆地奥陶系马家沟组一段—三段(简称马一段—马三段)构造-岩相古地理格局,探讨构造沉积演变特征及其油气地质意义。研究表明:①马家沟组底部稳定发育一套穿时的、高自然伽马值段、边缘相泥质白云岩,分布于怀远运动期构造不整合面之上,具有与早奥陶世弗洛期全球海侵可对比的δ13C正漂移特征;②奥陶系马一段—马二段沉积期全球海平面上升、古陆淹没为水下隆起,形成一隆两坳构造格局,中央隆起首次接受沉积;随后马三段沉积期盆外俯冲挤压、盆内隆坳分异,乌审旗—靖边凸起活化;③构造格局演变对沉积古环境产生显著影响,马一段沉积期向西超覆,东部坳陷内海侵封隔形成大规模盐质蒸发潟湖;马二段沉积期持续海侵并沟通广海,环东部坳陷发育大规模颗粒滩,晚期干化收缩形成小规模蒸发潟湖;马三段沉积期受高地封隔影响,向东侧水体渐次分异分别形成云膏质和盐质蒸发潟湖,同时颗粒滩环凹沿高地展布;④马家沟组底部发育烃源岩,马二段和马三段滩相储层环坡展布,源储配置良好,有利于天然气成藏,具有一定勘探潜力。
Based on logging,core,thin section and geochemical analysis,the tectonic-lithofacies paleogeographic pattern of first member to third member of Ordovician Majiagou Formation(O1m1–O1m3 for short)in Ordos Basin is reconstructed,and the tectono-sedimentary evolution characteristics and oil-gas geological significance are discussed.The results are obtained in four aspects.First,a set of marginal argillaceous dolomites with high gamma ray value developed steadily and diachronously at the bottom of Majiagou Formation,which distributed over the Huaiyuan Movement unconformity,withδ13C values positive drift characteristics comparable to global transgression of the Early Ordovician Floplian.Second,the global sea level rose and the ancient land was submerged into the underwater uplift in O1m1 to O1m2,and the central uplift was deposited for the first time in the Ordovician,forming a tectonic pattern of“one uplift and two depressions”.Subsequently,the subduction and extrusion outside the basin and the differentiation of uplift and depression in the basin of O1m3 resulted in the activation of the Wushenqi–Jingbian bulge.Third,the evolution of the tectonic pattern had a significant impact on the sedimentary paleoenvironment.The O1m1 overlaps westward,and saline lagoon is formed in eastern depression and influenced by the transgression.The transgression continued in O1m2 and resulted in communication with the wide sea,and the large-scale grain shoal developed around eastern depression,and the late dry shrinkage formed a small scale evaporite lagoon in upper part.Under the influence of highland sealing in O1m3,the water body gradually differentiated into dolomitic gypsum and saline lagoons to the east,and the grain shoal spread along the highs around sag.Fourth,the source rocks developed diachronously at the bottom of Majiagou Formation form a favorable source-reservoir assemblage with the shoal facies reservoir distributed around the slope of O1m2–O1m3,and they have certain exploration potential for natural gas.
作者
钟寿康
谭秀成
魏柳斌
许杰
王前平
熊鹰
武春英
杜健笙
ZHONG Shoukang;TAN Xiucheng;WEI Liubin;XU Jie;WANG Qianping;XIONG Ying;WU Chunying;DU Jiansheng(Sichuan Key Laboratory of Natural Gas Geology,Southwest Petroleum University,Chengdu 610500,China;CNPC Key Laboratory of Carbonate Reservoirs Southwest Petroleum University Division,Chengdu 610500,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610500,China;Exploration and Development Research Institute,PetroChina Changqing Oilfield Company,Xi’an 710018,China;The Fourth Gas Production Plant,PetroChina Changqing Oilfield Company,Xi’an 710016,China)
出处
《石油勘探与开发》
EI
CAS
CSCD
北大核心
2024年第5期1040-1052,共13页
Petroleum Exploration and Development
基金
国家自然科学基金青年科学基金项目(42302139)
西南石油大学研究生科研创新基金项目(2022KYCX032)。
关键词
鄂尔多斯盆地
奥陶系
马家沟组
构造演化
构造格局
古地貌
构造沉积分异
岩相古地理
源储配置
Ordos Basin
Ordovician
Majiagou Formation
tectonic evolution
tectonic pattern
palaeogeomorphology
tectono-sedimentary differentiation
lithofacies paleogeography
source-reservoir assemblage
