川东北地区白云岩储层地球化学特征对比研究

埋藏白云岩化是白云岩储层成因的主导模式，流体来源、交代过程、溶蚀期次和成因特征等一系列与其密切相关的白云岩化成岩系统，已成为当今碳酸盐岩领域最前沿的研究热点和困扰勘探实践的重要基础地质问题。以岩石学特征研究为基础，通过划分成岩阶段，对比各成岩阶段的微量元素与稳定同位素的地球化学特征，获得以下认识：埋藏白云岩化作用是控制川东北地区下三叠统飞仙关组和上二叠统长兴组优质白云岩储层分布的关键；飞仙关组和长兴组埋藏白云岩化过程具有相对应的多期次交代和多期次溶蚀特点；白云岩化流体来源于具有高含锶、高盐度热流体性质的飞仙关组海源地层水，飞仙关组和长兴组的埋藏白云岩为同源流体的白云岩化产物。进而得出结论：以不整合面和断裂为流体输导系统的飞仙关组和长兴组滩、礁相地层的埋藏白云岩化过程，在时空展布和演化过程中耦合关系密切，属于以同一流体和同一流体输导体系为主导因素的白云岩化成岩系统。

COMPARATIVE STUDY ON GEOCHEMICAL BEHAVIORS OF DOLOMITE RESERVOIRS IN NORTHEAST SICHUAN BASIN

Burial dolomitization is a critical model of dolostone reservoir genesis.Many issues involved in dolomitization diagenetic system,such as thermal fluid origin and its metasomatism process of burial dolomitization,later dissolution period and its process characteristics,have become the difficulties and frontier areas both for petroleum exploration and for scientific research in marine carbonate rock fields.Based on petrologic characteristics analysis,this study divided the process of diagenesis into different stages and compared their geochemical behaviors.This study leads to a conclusion that burial dolomitization is a critical factor of formation and evolvement for high quality dolostone reservoirs in the Changxing and Feixianguan formations of the northeastern Sichuan basin;the burial dolomitization of the Feixianguan and Changxing formation takes on corresponding multiple-stage metasomatism and multiple-stage dissolution;as the same source fluid of two formations,thermal brine water comes from marine closed water with high Sr concentrations and high salinity in the Feixianguan formation.Therefore,the same burial dolomitization of Feixianguan and Changxing reef-bank facies formations,using unconformity and faults as the same conduit system,takes on close relationship in space-time coupling for dolomitization diagenetic system.