流体包裹体PVTx模拟研究油气充注期次和古压力恢复:以西湖凹陷平湖构造带为例

Application of PVTxSimulation of Fluid Inclusions to Estimate Petroleum Charge Stages and Restore Pressure:Using Pinghu Structural Belt in Xihu Depression as an Example

传统流体包裹体PVTx模拟应用包裹体组分、气液比和均一温度,结合模拟软件可以恢复包裹体被捕获时的古流体压力,然而组分参数受多因素影响而难以确定,导致精度有限。介绍了Ping等2011年提出的一种改进PVTx模拟法,以西湖凹陷平湖构造带为例,应用显微荧光、显微测温和激光共聚焦扫描显微镜等分析,划分了油气充注期次并恢复了古压力,简化了依靠传统模拟软件获取捕获压力的步骤。研究结果表明：平湖构造带存在两期油气充注,第一期距今16.8~13.2 Ma,即中新世早期,主要充注发橙黄色荧光的原油,古流体压力为25.00~28.86MPa;第二期为主成藏期,距今10.0~0Ma,即中新世中后期至今,主要充注天然气和发蓝绿色、蓝白色多种荧光颜色的原油,古流体压力为38.60~44.31 MPa。研究结果有助于深化勘探区油气成藏规律的认识。

Conventional PVTxsimulation of reservoir fluid inclusions has been applied to restore trapping pressures by inclusions component,gas liquid ratio and homogenization temperature,combined by simulation software such as VTflinc,PVTsim,and PIT.However,inclusions component influenced by multifactor were not easily acquired.Taking Pinghu structural belt as an example,based on microscopic fluorescent,microthermometry and confocal laser scanning microscope,this paper introduces and applies the revised PVTxsimulation to estimate petroleum charge stages and restore pressure.There were two stages in Pinghu structural belt.The first charging occurred in 16.8-13.2Ma,with the oil charged mostly low mature with orange fluorescence color.The second occurred in 10.00-0.0 Ma,with the charged gas and oil with blue-green and light blue fluorescence color.Two stage pressure respectively is 25.00-28.86 MPa and 38.60-44.31 MPa.These are helpful to deepen the understanding oil and gas accumulation patterns of exploration area.