贝尔断陷布达特群泥岩盖层综合评价

Comprehensive e valuation on mudstone caprocks of Budate Group in Beier Rift

在全面分析了海拉尔盆地贝尔断陷布达特群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、单层厚度、泥地比、沉积环境和成岩程度等参数,对贝尔断陷布达特群泥岩盖层进行了综合评价。结果表明,该区布达特群泥岩盖层发育较差,单层厚度小,横向连续性差,多以叠合累加方式对潜山油藏起封盖作用;盖层不具有压力封闭能力,只具有较弱的烃浓度封闭作用;盖层封闭能力中等以上的区域主要分布在贝31—霍9井一线以北和德2—贝D2—贝46井所在的中部区域。该区布达特群泥岩盖层决定了“多源一储”和“新生古储”的成藏模式,不利于形成气藏;其主力油源位于上覆岩层,油藏应呈层状分布。

Based on the all - around analysis of macroscopic development character and microscopic sealing character reflected by the geophysical information of mudstone caprocks in Budate Croup of Beier Rift.Hailaer Basin,displacement pressure,caprock thickness, single layer thickness of mudstone,thickness ratio of mudstone and stratum,sedimentary environment and diagenetic level were chosen to comprehensively evaluate the mudstone caprocks of Budate Group in Beier Rift. The result indicates that the mudstone caprocks of Budate Group in the area developed poor,the single layer was thin and the lateral continuity was weak,the stacking mudstone layers take sealing effect for the buried hill oil reservoir,but the caprocks lack in the ability of pressure sealing and only has weak sealing ability of hydrocarbon concentration;the places with middle sealing abilities distributed in the north areas of line along Bei 31 to Huo 9 well and the central section along De2,Bei D2 to Bei8 well. The Budate group mudstone caprocks in these areas controll the model of oil reservoir forming, it is unfavorable to accumulate gas. Its main oil source lies in the overburden, and the reservoirs are layered in distribution.