Based on pressure-thermal experiments of kerogen degrading/cracking and oil cracking with source rocks and oil samples of Dongpu Depression,the componential differences between kerogen-degraded/cracked gas and oil-cracked gas were identified,and a genesis identification chart to distinguish the two different types of gas was generated.Using this chart,and combining the data of natural gas component and carbon isotope in the northern Dongpu Depression,the genesis of the oiltype gas in the study area was studied,and the distribution characteristics of these two types were discussed.The oil type gas found in Paleogene of the northern Dongpu Depression can be clearly identified with two origins,kerogen-degraded/cracked origin and oil-cracked origin.The kerogen-degraded/cracked gas has relative high value of C1/C2 and low value of C2/C3;while the oil-cracked gas has relative low value of C1/C2 but high value of C2/C3.There are significant differences in the distribution of the two types of gas in the northern Dongpu Depression,the kerogen-degraded/cracked gas occur more widely than oil-cracked gases in depression,while the latter is found near sag center.The distribution differences between kerogendegraded/cracked gas and oil-cracked gas are related to their generation and accumulation condition differences.In terms of the oil type gas identification and their distribution,a conclusion is made that there are favorable formation conditions for the gas types in deep and central sag area,suggesting that there are good oil type gas potentials for exploration in the deep and central sag in the northern Dongpu Depression.%以热压模拟实验模拟东濮凹陷干酪根热裂解和原油热裂解过程,分析干酪根热裂解气和原油裂解气组分特征的差异,以此建立干酪根热裂解成因气和原油裂解成因气的判识方法;结合东濮凹陷北部地区天然气碳同位素及天然气组分数据,对研究区油型气进行划分,进而探讨干酪根热裂解气与原油裂解气的分布特征.结果表明,研究区古近系油型气分为干酪根热裂解气与原油裂解气,干酪根热裂解气具有相对较高的C1/C2值和较低的C2/C3值特征,而原油裂解气则与之相反.干酪根热裂解气和原油裂解气的分布存在明显差异:前者分布范围更广,后者更近于洼陷中心分布,两者分布的差异性与其生成及成藏条件差异有关.根据干酪根热裂解气与原油裂解气分布特点,推测在邻近洼陷中心区具有良好的干酪根裂解成气及原油裂解成气的条件和油型气勘探前景.
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