车排子地区火山岩油藏流体包裹体特征与成藏期次

Characteristics of fluid inclusions and time frame of hydrocarbon accumulation for volcanic reservoirs in Chepaizi Uplift

为了深入认识车排子地区石炭系火山岩油藏的形成过程,文中对8口探井28块样品进行了流体包裹体与盆地模拟分析。流体包裹体岩相学、热力学分析表明:该区石炭系火山岩储层发育2类烃类包裹体,第1类充填于方解石、方沸石脉中成群分布,伴生盐水包裹体均一温度主峰值为80~90℃,具有高盐度、低主频均一温度特征;第2类充填于石英颗粒斑晶和切穿石英颗粒的微裂隙中成带分布,伴生盐水包裹体均一温度主峰值为120~130℃,具有低盐度、高主频均一温度特征。结合红车断裂带启闭性演化及烃源岩热演化史,明确了石炭系具有2期成藏过程,成藏时间分别为古近纪末和新近纪末,均为早期形成的油藏调整改造与再次运移聚集而形成。

In order to understand the petroleum migration and accumulation processes of the Carboniferous volcanic reservoir in Chepaizi Uplift, 28 samples obtained from 8 exploration wells were investigated through fluid inclusions and basin modeling.Petrography and thermodynamics analysis of fluid inclusions shows that the Carboniferous volcanic reservoirs in Chepaizi Uplift have two types of hydrocarbon-bearing inclusions. The first type is hosted in the calcite-analcime veins and distributed in groups. The accompanied brine inclusions are characterized by high salinity and low main frequency homogenization temperature(80-90 ℃);the second type is distributed in quartz grain phenocrysts and the microcracks that cut through quartz grains with zonal distribution. The accompanied brine inclusions are characterized by low salinity and high main frequency homogeneous temperature(120-130 ℃).Combined with the opening and sealing evolution of Hongche fault zone and the thermal evolution of the source rocks, it is determined that the Carboniferous volcanic reservoirs in Chepaizi Uplift experienced two periods of hydrocarbon accumulation at the end of Paleogene and Neogene respectively, which were all formed by adjustment, transformation, re-migration and accumulation of the early reservoirs.