冀北坳陷龙潭沟古油藏下马岭组辉绿岩侵入定量评价

Evaluation on Diabase Intrusion of Longtangou Paleo-reservoir in Maling Formation of Jibei Depression

冀北坳陷龙潭沟古油藏发育大规模的辉绿岩侵入体,并有与下马岭组底部沥青砂岩并存现象,两者有明显的成因联系。以实测固体沥青反射率作为约束,采用层状侵入体热传导模型定量计算了侵入体对围岩及油藏的影响程度。定量计算结果表明,侵入体冷却速度很快,完全冷却时间仅为0.1Ma;侵入体对上覆和下伏地层影响范围与其侵入体厚度有关,对下伏地层影响范围极其有限,对围岩影响最大的βμ1辉绿岩侵入体影响范围也仅有50m左右,基本限于下马岭组地层本身。模拟结果从正演角度很好地解释了下马岭组固体沥青的热蚀变成因,也确定了下马岭组底砂岩固体沥青不可能来源于洪水庄组烃源岩,而可能与高于庄组烃源岩有亲缘关系。

A large scale of diabase intrusion body was developed in Longtangou Paleo-reservoir in Jibei Depression of North China and bituminous sandstone was developed in Xiamaling Formation.There was an obvious genetic relationship between them.The effect of the intrusion on the surrounding rock and the reservoir was calculated quantitatively with the thermal conduction model by taking the measured reflectance of solid bitumen as the constraint.The result shows that the cooling time of intrusion is only 0.1 Ma,and the effect of intrusion on the surrounding rock is directly related to its thickness.The effect of diabase intrusion on underlying strata is extremely limited,and the effect of βμ1 intrusion on Lower Maling Formation is only about 50m and its effect is only on Maling Formation itself.The genesis of hydrothermal alterations of initial oil is explained very well by the modeling consequences.So the bituminous sandstone is not possibly generated from source rocks in Hongshuizhuang Area but is related with source rocks in Gaoyuzhuang Formation.