贝尔断陷南一段泥岩盖层和对成藏的控制作用

Evaluation on mudstone caprock in Nantun Formation and its effect on oil accumulation in Beier rift-subsidence basin

康德江 付广 吕延防

Kang Dejiang Fu Guang Lu Yanfang

大庆石油学院 地球科学学院, 黑龙江 大庆 163318

Geoscience College of Daqing Petrolum Institute, Daqing 163318, China

在全面分析了海拉尔盆地贝尔断陷南一段泥岩盖层宏观发育特征及地球物理信息所反映的微观封闭特征的基础上,选取排替压力、盖层厚度、泥岩单层厚度、泥地比、异常孔隙流体压力和沉积环境作为评价参数,对贝尔断陷南一段泥岩盖层进行了综合评价。结果表明,研究区内南-段泥岩盖层发育程度较好,横向连续性好,可作为下覆油气藏的区域性盖层;盖层具有较强的封闭能力作用;盖层封闭能力好~中等以上的区域主要分布在该区的中部和北部;该区南一段泥岩盖层是古潜山多源一储和新生古储成藏模式的主控因素之一,同时控制着油气藏的空间分布。

Based on the analysis of development and microcosmic sealing characteristics of mudstone caprock reflected by the earth physical information of the lower part of Nantun Formation in Beier rift-subsidence basin,this paper chooses displacement pressure, thinckness of caprock, thinckness ratio of mudstone and stratum, monolayer thinckness of mudstone,abnormal pore liquid pressure and sedimentary environment as parameters to evaluate comprehensively the sealing abilities of mudstone caprock of the lower part of Nantun Formation in Beier rift-subsidence basin. It indicated that mudstone caprock of the lower part of Nantun Formation in Beier rift-subsidence basin developed well,and the diatropic continuity was good so that it can serves as caprock for the underlying oil reservoir. The caprock has the strong seal abilities,and in which the north and middle part have good or medium sealing abilities. Two conclusions are drawn:the first is the lower part of Nantun Formation mudstone caprock is one of the main controlling factors of the model of oil accumulation, where reservoirs accumulated in old buried hills and its oil mixed by many origions, the second is in Beier the distribution of oil in space was controlled by the mudstone caprock.