东濮凹陷北部地区油气相态演化主控因素及充注模式

以油气藏气油比统计、热压模拟实验等资料为基础,结合成藏条件分析,探讨了东濮凹陷北部地区油气相态分布及相态演化的主控因素,并建立了油气充注模式。研究表明,研究区由浅至深依次出现液态烃、含凝析油的气态烃和气态烃,但不同地区油气相态的分布区间、区分度及不同时期的充注特征均具有明显差异。油气相态演化主要受源岩有机质类型、生烃演化阶段与运聚过程中温压环境控制。深层天然气主要为原油裂解成气,中浅层天然气主要为油溶天然气出溶气。油气来源有"单洼单源"、"单洼多源"和"多洼多源"3种类型,相应的相态演化有"早油相晚气相"、"早混相晚气相"、"侧向多期油相"和"垂向多期油相"4种形式,从而造成不同洼陷的油气充注模式各具特色。

Main controlling factors of phase evolution and charging pattern of hydrocarbons in northern Dongpu Sag

Base on statistics of gas oil ratios in reservoirs, thermal-pressure simulation experiments, and analysis of oil/gas accmulation conditions, the distribution and controlling factors of hydrocarbon phases in the northern Dongpu Sag were analyzed. From shallow to deep formations in the study area, liquid hydrocarbon, gaseous hydrocarbon containing gas condensate, and gaseous hydrocarbon were found in turn. The vertical distribution and dipartite degree of hydrocarbon phase varied among different regions, and the charging characteristics during different periods were distinctive. The evolution of hydrocarbon phase was controlled by the type of organic matter in the source rock, the thermal evolution degree of the source rock, and temperature-pressure environment of hydrocarbon migration and accumulation. In the deep formations, gases generated mainly form crude oil cracking. The majority of middle and shallow gas were evaporated from oils. There were three types of oil and gas source, including "single sag and single source", "single sag and multiple sources", and "multiple sags and multiple sources", and the corresponding phase evolution patterns were defined as "early oil phase and late gas phase", "early mixed phase and late oil phase", and "horizontal oil phase in multiple stages", "verticaloil phase in multiple stages". These contributed to various oil and gas charging patterns in different sags.