轮南地区奥陶系原油特征及其控制因素

轮南地区油气相态分布非常复杂,奥陶系油气藏平面上具有西油东气的特点。西部轮古西油田、塔河油田和轮南1井区油族成熟度略低且有生物降解痕迹,主要以重油形式分布;东部地区油族成熟度略高,主要以轻质油、凝析油形式存在;中间地段桑塔木断垒带、中部平台区和轮南断垒带发生混合作用形成了中一高蜡油。各地区油气在垂向上变化很大,东部地区奥陶系和石炭系为凝析油气,三叠系又为正常油分布区;西部地区奥陶系为稠油,三叠系为正常油。轮南地区奥陶系在纵向上可能受控于岩溶和储层的发育程度,横向上受控于断裂作用。轮南地区油气成藏时间较早,不同物性的原油都是古油藏多期供油的结果。

Characteristics and Controlling Factors of Ordovician Oil in Lunnan Area,Tarim Basin

Phase states of hydrocarbon are complicated in distribution in Lunnan area. In lateral, the Ordovician oil reservoirs are located in the western part and the gas ones in the eastern part in plane. Analysis result shows that in the western part, the oils from Lunguxi and Tahe Oil Fields and Well LN-1(Lunnan Oil Field) are mostly heavy oil with appreciably low maturity and biodegradation mark and in the eastern part, the oils are light and condensate with relatively high maturity. The oils are moderately to high wax-bearing crude due to mixing in the middle area including Sangtamu faulting belt, Middle platform and Lunnan faulting belt. In longitudinal, distribution of hydrocarbon is obviously different in different areas. In the eastern part, condensate exist in Ordovician and Carboniferous reservoirs and common oil and gas are present in Triassic reservoirs and in the western part, viscous oil is in the Ordovician reservoirs and common oil are in the Triassic reservoirs. It is concluded that the development of Ordovician reservoirs are likely to be controlled with karstification in longitudinal and fracturing in lateral in Lunnan area. Owing to early hydrocarbon accumulation and migration, the hydrocarbons of different states are supplied to these reservoirs during several stages.