砂岩油藏油-气-水不混溶包裹体特征及成因

Characteristics and genesis of oil-gas-water immiscible inclusions in sandstone reservoirs

对多个砂岩油藏中流体包裹体进行研究后发现,石英颗粒中普遍发育一类油-气-水不混溶包裹体。这类包裹体非均一捕获了油-水两相,表现出油-气-水三相共存、均一温度异常高、同一组合内包裹体气/液比和均一温度分布离散且无规律、气泡紧靠包裹体内壁、降温后不共结等特征。因镜下特征与盐水包裹体相近,其异常高的均一温度易对测试结果造成严重影响,仔细观察包裹体的荧光特征和降温后的共结现象能够准确地进行识别。包裹体内油相组分以沥青质为主且吸附在包裹体内壁上,反映这类包裹体的普遍发育与矿物颗粒对原油沥青质中极性组分的选择性吸附作用有密切关系。

A study of fluid inclusions found that a special kind of three phase（oil-gas-water）immiscible inclusions developed widely in sandstone reservoirs.This type of inclusions trapped oil and water in an inclusion at the same time.Consequently,these inclusions showed five marked characteristics：（1）gas-oil-water three phase coexistence;（2）abnormal high homogenization temperature;（3）variable liquid-vapor ratios and homogenization temperatures in the same inclusion assemblage;（4）bubble closing to the inner wall of inclusion;（5）extremely low freezing point.There is only a shade of difference in appearance between these inclusions and aqueous inclusions,and their abnormal high homogenization temperatures could easily affect the testing result of homogenization temperatures.So,more attention to the fluorescence features and the phase transition during cooling process of fluid inclusions should be paid.The oil in these inclusions was dominated by asphaltic components and was adsorbed on the inclusion inner wall,which indicated that the formation of these inclusions was closely associated with the selective sorption of polar components in asphaltic by quartz grain surface.