千米桥潜山构造高蜡凝析油气藏的蜡质来源研究

千米桥古潜山奥陶系凝析油以高含蜡为特征。为探讨凝析油气藏中的高蜡成因机理 ,对黄骅坳陷近3 0年来 3 3 0 0多个第三系原油油样含蜡量的时空分布特征进行了研究。发现原油含蜡量的垂向分布主要受自下而上运移过程中的“地色层效应”所控制 ,对最接近油藏原始蜡质保存条件的试油含蜡量的层位分布统计研究也支持上述观点 ,说明无论是初次运移还是二次运移 ,随距离的增加含蜡量逐渐降低 ,亦即含蜡量较高的原油更靠近烃源岩。板桥油田和港东部分地区沙三段产层 (凝析油烃源层 )的含蜡量平面分布研究 ,表明千米桥古潜山奥陶系高蜡凝析油的蜡质来源于歧口凹陷方向的白水头地区 ,与白水头地区原油高分子量蜡馏分的指纹对比及含氮化合物、成熟度等多项指标也证实了上述结论

WAX SOURCE ANALYSIS OF HIGHLY WAXY CONDENSATE OIL AND GAS POOL IN QIANMIQIAO BURIED-HILL ZONE,HUANGHUA DEPRESSION

The newly prospected Ordovician condensate-associated oil and gas pool in the Qianmiqiao buried-hill zone is characterized by high wax content. To make a thorough going study of the origin and forming mechanism of wax, the space-time distribution characteristics of wax in crude oils in the Huanghua Depression were studied in terms of more than 3300 wax content data from Tertiary crude oils. It can be concluded that the vertical distribution of wax in Tertiary crude oils controlled mainly by geochromatographic effect in the process of migration from the bottom upwards. And this viewpoint is supported by the statistical study of the wax content in the horizons, which are nearest to the wax preservation conditions of primary reservoirs. So we can conclude that the wax content would be deduced in the process of migration. On the contrary, crude oils with a higher wax content should be near to the hydrocarbon source rocks. As a result, the wax of highly waxy condensate oil in the Qianmiqiao buried-hill reservoir was derived from the Baishuitou region, as indicated by the plane contour diagram of wax contents. Based on the correlation of C35+ high molecular weight chemical composition fingerprints between condensate-associated oil with some Tertiary cure oils in the Baishuitou region and some migration and fill indices, we still can withdraw the above conclusion.