摘要:
冀北坳陷中上元古界一下古生界是一套以碳酸盐岩为主的海相沉积岩系,其内广泛发育有结晶、重结晶作用形成的方解石、萤石、石英、重晶石等矿物。通过对这些矿物中流体包裹体特征的系统研究,划分出六类有机(烃)包裹体和三类水溶液包裹体。这些流体包裹体分别是由油气和油田水两种不混溶流体所形成;在这两种不混溶流体运移过程中,油田水以连续相形式存在,而油气以分散相(珠滴、气泡)形式悬浮于其中。按地层层序,各地层流体包裹体的均一温度表现出在上、下高,而中间低的特点。同一地层在坳陷不同部位,其均一温度也明显不同,但油气是由高温区向低温区运移。另外,据各地层中有机包裹体发育的类型和数量,推测此坳陷内油气主要储集层是中上元古界的铁岭组、雾迷山组,以及下古生界的奥陶系。
Abstract:
There is a set of marine-facies sedimentary series which are mainly composed of carbonate rock for middle-upper Proterozoic and lower Palaeo-zoic sub-erathem of libel depression. The sedimentary formation have many minerals which are formed by crystallization and recrystallization such ascalcite, fluorite, quartz, barite ect. Through making a systematic study to fluid inclusions characteristics in these minerals, there are six types hy-drocarbon inclusions and three kinds aqueous inclusions have been differentiated. These fluid inclusions separately formed by two immiscible fluid oil-gas and oil field water. During the two immiscible fluid migration, oil field water exist within it妙continuou-v phase, and oil-gas妙dispersed phase(drop, bubble). In these fluid inclusions, the vapor volume of vapor-liquid aqueous inclusions are between 1-10%.and it's salinity between I.73-9.86%( NaCI), and average is 4. 72 % ( NaCl), showing that it came from paleo-seawater. The homogenization temperature of the aqueous inclusions is inthe range 47-173 C，and the homogenized phase is liquid phase which represents the lowerest formation temperature for oil-gas migration and re-servior in the depression. The hydrocarbon inclusions are the direct sign of oil-gas primary and secondary migration, in which the vapor volume ofoil-gas hydrocarbon inclusions is in the range 2-10%，and its homogenization temperature is between 41-186℃ with the oil homogenized phaseshowing that oil-gas migration and reservoir was in oil phase. When forming temperature is lower, the homogenization temperature of hydrocarboninclusion is lower than aqueous inclusion. But when the temperature is higher, the homogenization temperature of aqueous inclusion is lower than hy-drocarbon inclusion. According to the strata sequence of middle-upper Proterozoic and lower Palaeozoic sub-erathem in Jibei depression, the mean homogenizationtemperature of fluid inclusion is higher in the top and bottom of strata, and lower in the middle strata. This is because that there are giant thick-bed-ed volcanic rock covering it. The homogenization temperature of the same foramtion are obviously different in the different parts of the depression,but the direction of oil-gas migration show that is from high temperature to low temperature. In addtion, according to the type and quantity of hydrocarbon inclusions in the different layers, we deduce that the main oil-gas reservoir are Tieling formation, Wumishan formation of middle-upper Proterozoic suberathem and Ordovician system.
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