松辽盆地敖古拉断裂的封烃泄水作用

敖古拉断裂位于齐家一古龙坳陷生油气区向西运移的指向上。且其走向与油气运移方向垂直。该断裂自基底一直断到第四系。具同生正断特征。通过封堵率计算研究表明,该断裂的侧向封烃能力在姚家组和泉头组地层中为中等,在嫩江组和青山口组地层中较好。通过断面压力计算发现,该断裂垂向封闭性在浅部差,深部好;在断裂走向上断裂中部差。向两端逐渐变好。通过地层水矿化度和变质系数等参数的分布规律及一系列折算水位剖面图的分析发现。该断裂对水是不封闭的,并且是盆地西缘大气渗入水向东流动(向心流)及齐家—古龙坳陷沉积压实水向西流动(离心流)的共同泄水带。所以,该断裂是一条封烃泄水断裂。敖古拉断裂封烃泄水的主要机理是毛细管压力作用。由于敖古拉断裂的封烃泄水作用,使其对齐家—古龙坳陷向西运移的油气起到了一定的屏障作用。

THE SEALING HYDROCARBONS AND SLUICING ACTION OF AOGULA FAULT IN SONGLIAO BASIN

Aogula fault is the direction that oil and gas in Qijia Gulsng depression migrate forward for west, and the fault strike and the migration direction of oil and gas meet at right angles. The fault faults from basemet to Quaternary system, and has the feature of contemporaneous and normal fault. The lateral seal of the fault is studied with calculating the seal ratio, it is medium in Yaojia group and Quantou group, fairly good in Nenjiang group and Qingshankou group. The vertical seal of the fault is studied with calculating the section pressure, it is poor in shallow and good in deep. It is found that the degree of mineralization and metamorphic coefficient and conversion potential of formation water, the fault is zone of sluicing of atmospheric infiltration water flowing from basin west margin to east (centripetal flow) and sedimentary compaction water flowing from Qija Gulong depression to west (centrifugal flow). The fault is a fault that is seal for hydrocarbons and is not seal for water. The mechanism of sealing for hydrocarbon and nonsealing for water is capillarity. Because of the effect sealing for hydrocarbon and nosealing for water, Aogula fault has hindered for hydrocarbon to migrate eontinue from east to west.