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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 the vertical sealing mechanism of inclined fractures, a method of determining the lower limit of pressure required for the vertical sealing of inclined fractures is established according to the lower pressure limit required for the formation of fractures during evolution of mudstone overpressure. Taking the Budate Group in Beier Sag of Hailaer Basin as an example, the paleotyric sealing of the inclined fractures at different angles in the study area during the main reservoir-sedimentation period of Yimin Formation was quantitatively evaluated. The results show that the Budat Tertiary inclined fractures in the Beier sag are closed during the main hydrocarbon accumulation periods, and the oblique fractures of the Budate Group in the central Sudeertun buried hill and the central part of the Ao Nao Hai depression are open. The discovered reservoirs are mainly distributed in the vertical open area of the inclined fractures, and these open inclined fractures can be the main channel for the migration of oil and gas to the Budat Group. At the same time, reservoirs are provided for the accumulation of oil and gas in the Budat Group space. The application results show that it is feasible to study the vertical sealing ability of inclined fractures by using the new method to determine the lower limit of pressure required for vertical sealing of inclined fractures.