Abstract: The history of buried hill in Budate Group of Beier Depression researched by using 38 balanced cross sections shows that there are three types of buried hills such as palaeogeomorphology,epigenesist and syngenesis in Budate Group.Although the various formation and evolution of buried hills were caused by the deviation of fault activity,the core observation and logging explanation show that the fractures are the mainly effective accumulation spaces in the three types of buried hills.The formation and evolution history of faults were analyzed according to the growth index of faults in different direction and the analysis of the balanced cross section.There are four types of faults in this area,including early extensional fault system,mid-period extensional-twist fault system,early extensional and mid-period extensional-twist fault system,early extensional and mid-period open-twist and later reverse fault system.The later two types controlled the development and distribution of the effective fractures in the buried hills.The evolution characteristics of source rock and homogenization temperature of inclusions show that the main period for oil-gas accumulation is in the end of Yimin Formation,the early north-north-east and north-east-east extension fault systems become active under the action of extensive stress field,which provide good passage ways for oil migrating to buried hill.The main migration passage way for oil and gas may be the north-east-east fault with greater twist intensity.The fault activity made the early closed fractures open,and much new fractures could be produced,which provided the effective spaces for oil accumulation.Three main reservoirs of base rock weathering crust,fault damage zone and inner fracture zone in buried hills were generated.So the favorable target in Budate Group is the near-source buried hill controlled by the long-time inheritance fault.

Key words: Beier Depression, Budate Group, buried hill, fault system, fracture, oil-gas bearing property

摘要： 利用全区38条平衡剖面,对海拉尔盆地贝尔凹陷布达特群潜山形成及演化历史进行了分析。贝尔凹陷布达特群潜山主要有3种类型,即早期潜山、中期潜山和长期潜山。尽管断裂活动规律差异导致潜山的形成和演化历史不同,但3种类型潜山有效的储集空间都主要是裂缝。根据不同方向断裂生长指数并结合平衡剖面分析了断裂形成演化历史。该区主要有早期伸展、中期张扭、早期伸展中期张扭和早期伸展中期张扭晚期反转4种类型的断裂系统,其中后两种断裂系统控制着潜山有效裂缝的发育程度和分布规律。烃源岩演化和包裹体均一温度研究表明,布达特群潜山油气成藏主要时期为伊敏组沉积末期,早期北北东和北东东向伸展断裂系统在此时近东西向拉张应力场作用下张扭复活,为油气向潜山运移提供了良好通道,其中北东东向断裂扭动强度大,可能是油气运移的主要通道;同时,断裂活动使潜山早期闭合裂缝开启,并产生了大量的新生裂缝,为油气的聚集提供了有效的空间;主要发育基岩风化壳、断裂破碎带和潜山内部裂缝带3种油气藏类型。因此,受长期继承性活动断裂控制的近源潜山是布达特群勘探的有利目标。

关键词: 贝尔凹陷, 布达特群, 潜山, 断裂系统, 裂缝, 含油气性