倾斜裂缝垂向封闭所需压力下限的确定方法及其应用

The minimum pressure on fracture surface required for sealing dipping fractures and its application

在倾斜裂缝垂向封闭机理研究的基础上,根据泥岩超压形成演化过程中裂缝封闭所需的压力下限,建立了确定倾斜裂缝垂向封闭所需压力下限的方法。以海拉尔盆地贝尔凹陷布达特群为例,利用新方法,对研究区不同角度的倾斜裂缝在主要成藏期——伊敏组沉积末期的古垂向封闭性进行了定量评价。结果表明,贝尔凹陷布达特群倾斜裂缝在主要成藏期均处于封闭状态,中部苏德尔特潜山构造带和敖瑙海洼槽布达特群倾斜裂缝处于开启状态。目前已发现的油藏主要分布在倾斜裂缝垂向开启区,这些开启的倾斜裂缝可成为油气向布达特群运移的主要输导通道,同时为油气在布达特群聚集提供了储集空间。应用结果表明,新方法确定的倾斜裂缝垂向封闭所需的压力下限用于研究倾斜裂缝垂向封闭性是可行的。

Based on the study of vertical sealing of dipping fractures,and the minimum pressure required for the sealing of dipping fractures during the process of overpressure occurrence and evolution of mudstone,the method to ascertain the minimum pressure required for the sealing of dipping fracture is proposed herein and validated in the Budate group,Beier depression,Hailaer basin.In the study area,the vertical sealing of dipping fractures with different tip angles in the main accumulation period,the end of K,y sedi-mentary period,was evaluated according to the minimum pressure on fracture surface established by the method.The result indi-cates that the dipping fractures in the south and north of depression were sealed,but in the middle of depression,Sudeerte buried hill structure zone and Aomaohai sag,were opened.The oil found hitherto was distributed in the area where dipping fracture is open in vertical direction.These open dipping fractures would have been main transporting pathways for oil and gas to migrate in buried hill of Budate group,as well as the reservoir spaces for hydrocarbon accumulation in buried hill of Budate group.It indi cates that the minimum pressure on fracture surface established by the method is feasible to evaluate the vertical sealing of dip-ping fractures.