缅甸伊洛瓦底盆地D区块P-1油气藏特征及其成因分析

An Analysis of Oil and Gas Characteristics and Genesis in P-1 Reservoir of Block D in Irrawaddy Basin of Myanmar

利用有机地化方法研究缅甸伊洛瓦底盆地D区块P-1油气藏产出的原油和天然气的性质及其成因。原油具高密度、高黏度、高含蜡量和高凝固点的特点;族组分具有高饱和烃、高饱芳比、低非烃和沥青质的特征;正构烷烃受轻烃含量影响较大,具有姥鲛烷优势,甾烷C_(27)-C_(29)ααα(20R)分布指示母源为Ⅱ2~Ⅲ型干酪根。天然气为Ⅲ型干酪根形成的煤成气。油气是在异常高压条件下由成熟的煤系腐殖型母质为主形成的高蜡凝析气藏。由于反凝析作用,随着轻烃组分不同程度散失,原油的物理化学性质发生明显改变。

The organic geochemical method was used to study the oil-gas characteristics and genesis of the crude oil and natural gas in P-1 oil/gas reservoir of Block D in Irrawaddy Basin of Myanmar.The crude oil is characterized by high density,high viscosity,high wax content and high condensation point,and with high saturated hydrocarbon content and high ratio of saturation and aromatics,low non-hydrocarbon and asphaltene.The n-alkanes were greatly influenced by light hydrocarbon content and had pristine advantage.C_(27)-C_(29) ααα(20 R)of steranen indicated that organic matter was TypeⅡ2~Ⅲ.The natural gas was the coal formed gas of TypeⅢ kerogen.Oil and gas was high waxy condensates generated by mature coal humic kerogen in abnormal high pressure.Because of retrograde condensate phenomenon,the physical properties and geochemical characteristics of crude oil can change obviously with the different degrees of loses of light hydrocarbon.