鄂尔多斯盆地中南部侏罗系直罗组流体包裹体特征

Characteristics and indication of fluid inclusions of Jurassic Zhiluo Formation in south-central Ordos Basin

为了明确鄂尔多斯盆地中南部侏罗系直罗组流体包裹体特征及其指示意义,利用包裹体显微测温、显微荧光,结合埋藏史和热演化史模拟进行分析。结果表明:研究区直罗组主要发育2期油气包裹体,早期油气包裹体主要分布在石英颗粒表面溶蚀孔、石英早期裂隙,成熟度低,发橘黄色—黄绿色荧光,同期盐水包裹体均一温度为250~320℃;晚期油气包裹体主要分布在石英晚期裂隙中,成熟度高,发暗绿色荧光,测得同期盐水包裹体均一温度为120~180℃。结合埋藏史-热演化史研究,包裹体均一温度高于地层温度,分布范围大且2期温度间断明显,推测直罗组油气运聚成藏受构造热事件影响,是一个相对漫长且不连续的过程。研究成果对直罗组成藏机理研究及其油气勘探具有重要意义。

In order to clarify the characteristics of fluid inclusions and their indication of Jurassic Zhiluo Forma‐tion in south-central Ordos Basin,micro thermometry,micro fluorescence,burial history and thermal history simula tion of inclusions were applied to carry out the analysis.The results show that there are mainly two stages of oil and gas inclusions in Zhiluo Formation in the study area.The early stage of oil and gas inclusions are mainly distri buted in dissolved pores on the surface of quartz particles and the early fractures of quartz,with low maturity and orange-yellow-green fluorescence.The homogenization temperature of brine inclusions in the same period ranges from 250℃to 320℃.The late stage of oil and gas inclusions are mainly distributed in the late quartz fractures,with high maturity and dark green fluorescence.The homogenization temperature of brine inclusions in the same period is 120-180℃.Combined with the study of burial history and thermal history,the homogenization tempera‐ture of inclusions is higher than the formation temperature,the distribution range is large,and the temperature discontinuity is obvious in the two stages.It is speculated that the oil and gas migration and accumulation in Zhiluo Formation are affected by tectonic thermal events,which is a relatively long and discontinuous process.The research results are of great significance to the study of reservoir forming mechanism of Zhiluo Formation and are impor‐tant to the further breakthroughs of oil and gas exploration in the study area.