基于流体包裹体的羌塘盆地鄂斯玛地区索瓦组地层古压力恢复

Restoration of the palaeo-fluid pressures from the Suowa Formation in the Esima area, Qiangtang Basin

关键词:  羌塘盆地  索瓦组  流体包裹体  古流体压力  热动力学模拟

Key words:  Qiangtang Basin  Suowa Formation  fluid inclusion  palaeo-fluid pressure  thermodynamic simulation

摘要:

对羌塘盆地鄂斯玛地区索瓦组储层中流体包裹体样品进行了详细的分析。研究区发生过3次油气充注事件,其中第2期油气充注是研究区最主要的成藏时期。结合埋藏史分析,确定了3期大规模油气生成聚集成藏发生的时间。运用流体包裹体PVT热动力学模拟(VTFLINC),获得了3期油气成藏时的古压力数据。对索瓦组地层的古压力恢复表明,区域构造和热史演化是古压力的主要控制因素。将古压力演化划分为3个发育阶段:油气藏形成初期的超压系统阶段、形成高峰期的正常压力系统阶段和萎缩期的低压系统阶段。

Abstract:

The restoration of the palaeo-fluid pressures is explored on the basis of the examination of the fluid inclusions samples from the Suowa Formation reservoirs, Esima area, Qiangtang Basin. There occurred three phases of hydrocarbon charging, of which the second phase of hydrocarbon charging is believed to be the main period for the accumulation in the study area. The timing of the three phases of hydrocarbon generation and accumulation is based on the burial history of the hydrocarbon reservoirs. The palaeo-fluid pressure data are obtained by using the PVT thermodynamic simulation of the fluid inclusions. The results of research for the stratigraphic evolution in the Suowa Formation show that the regional structures and geothermal evolution may be the main controlling factors for the palaeo-fluid pressures. The palaeo-fluid pressures have gone through three stages of evolution:the overpressure systems during the early stage of the hydrocarbon generation, normal hydrostatic pressure systems during the culmination, and low pressure systems during the decline of hydrocarbon generation.