川东北飞仙关鲕滩气藏储层流体包裹体与成藏特征

The Fluid Inclusions and Reservoir-Forming Characteristics of the Oolitic Beach Gas Reservoirs in the Feixianguan Formation of the Northeastern Sichuan

对川东北地区飞仙关组储层成岩作用特征、流体包裹体均一温度、盐度和阴离子的分析表明,海槽区、鲕粒坝相区和澙湖区等不同沉积相带的成岩作用类型和特征存在较大差别。多数井区至少发生了两次溶蚀作用,晚期胶结作用和包裹体欠发育。孔隙胶结物和裂缝方解石脉中包裹体的发育在时间序列上均不完整。HCO3-与SO24-含量总体呈互为消长的关系,表明富HCO3-和富SO24-代表不同溶蚀作用期次的流体。断裂和裂缝在发育时间上具有阶段性和不连续性,体现在所记录的包裹体信息不具完整性。伴随成岩、成藏演化,总体上成岩流体盐度逐渐增大,即成岩演化阶段越高,流体盐度越高。

Based on the analyses of diagenetic characteristics of reservoir, homogenization temperatures, salinity and anion of fluid inclusions in the Feixianguan Formation of the northeastern Sichuan, it is shown that there are some quite big differences in the diagentic types and characteristics of sedimentary rocks among facies formed in trough and adjacent sea area, the oolitic limestone beach bar area and the lagoon area, respectively. At least two stages of dissolution were developed in the most of well area, though the late stage cementation and inclusions were not well developed. The inclusions in pore cements and fissure calcite veins have no integrality in time sequence. The anion analysis of inclusions indicated the characteristics variation of diagenetic fluids. The negative correlation between the contents of HCO3^- and SO4^2- indicates that there were two times of dissolution time and two stages of fluids rich in HCO3^- or SO4^2- respectively. The fissures and cracks were developed discontinuously in times, because the information recorded in inclusions is no completed. The salinity of diagenetic fluids is increased with the higher stage of diagenetic and reservoir-forming evolution. This means that the higher of the diagenetic evolution stage, the higher of the fluid salinity.