川东北地区飞仙关组和长兴组白云岩成因与成岩-成藏系统

通过沉积相剖面、岩石结构和多项地球化学指标、油气源岩性质对比及流体非均质性与运移路径分析等新技术方法,运用流体-岩石相互作用和流体成藏动力学新理论,研究了川东北地区飞仙关组和长兴组白云岩成因和成藏特征,确定此2个层位的优质生物礁相和鲕滩相白云岩储层成因主要与成岩期的埋藏白云岩化作用有关,都属于同源流体和同一流体输导体系控制的多期次、多阶段埋藏白云岩化与连续的重结晶作用产物,论证了飞仙关组和长兴组与埋藏白云岩化作用及多期次油气运移、充注和成藏过程也受同一流体输导体系和同一油气源控制。依据埋藏白云岩化过程的成岩系统划分与成藏过程在时空上的耦合匹配关系,提出以通源断裂/裂隙带为核心的,由断裂/裂隙带、不整合面和优质礁、滩相白云岩储层构成的复合输导体系为主控因素的统一"成岩-成藏系统"概念。

Dolomite genesis and diagenetic-reservoir system of Feixianguan and Changxing Formation in northeast Sichuan Basin,China

On the basis of comprehensive studies of sedimentary facies,rock textures,a series of geochemical index, source rock properties, the heterogeneity and migration path of the fluid, combined with the application of new theories of fluid-rock interaction and fluid accumulation dynamics,the genesis of dolomite and the reservoir characteristics of the Feixianguan and Changxing Formation in the northeast Sichuan are studied.It shows that the quality reef and oolitic dolomite reservoirs are mainly related with the diagenetic burial dolomitization and resulted from multi-stage burial dolomitization and recrystallization controlled by same homologous fluid and passage system. The burial dolomitization,multi-stage hydrocarbon migration,filling and accumulation process are also controlled by the same fluid passage system and the same source of oil and gas.A unified concept of “diagenesis and reservoir system”is proposed on the basis of coupling relationship between the diagenetic system division of the burial dolomitization and accumulation process in time and space. The core of concept is the complex transport system composed of the fault/fracture zone, unconformity,quality reef and shoal dolomite reservoirs.