成油环境中的流体包裹体：分析步骤与PTX重建

Fluid inclusions in petroleum environments:analytical procedure for PTX reconstruction

石油盆地内的古流体以流体包裹体的形式保存在成岩矿物中,它们代表了初始石油或气相的组成并记录了流体捕获时的温度和压力条件.在储集层中卤水通常以不混溶相的形式与石油共存.一般利用单个包裹体分析法对水溶液和石油包裹体进行研究,利用显微测温法来确定相转变的温度,利用拉曼光谱定量来分析水溶液包裹体中溶解甲烷的含量.石油包裹体中CH4和CO2的含量可以利用傅立叶变换红外光谱分析来估算,通过共聚焦扫描激光显微镜来重建石油包裹体的体积.利用Duan和Peng-Robinson方程可进行热力学模拟,并分别应用于水溶液和石油包裹体体系.两类流体体系等容线的交点可用来确定流体捕获时的实际温度和压力条件,从而利用流体压力对具有不同地球动力学背景的源区流体动力学演化进行重建.

Fossil fluids from petroleum basins are present in diagenetic minerals as fluid inclusions. They are the witnesses of the original oil or gas composition and the memory of the pressure and temperature conditions at the time of fluid emplacement. Brines are always present as non-miscible phase at equilinrium with oils in reservoir. The analytical procedure is based on the individual analysis of both aqueous and petroleum inclusions. Temperature of phase transitions is measured by microthermometry, dissolved methane contenl of aqueous inclusions is quantified by Raman spectrometry, CH_4 and CO_2 content of petroleum inclusions is approximated by Fouriet transform infrared spectrometry and the volume of petroleum inclusions is reconstructed by confocal scanning laser microscopy. Thermodynamic models are based on Duan and Peng-Robinson equations of state and are applied to aqueous and petroleum inclusions respectivzly. The intersection of the isochores of the two fluid systems gives the tree pressure and temperature conditions of fluid trapping. The knowledge of the fluid pressure allows us to reconstruct the hydrodynamic evolution of reservoirs in various geodynamic regimes.