不整合面上底砾岩控制油气运聚的流体证据

Fluid evidences for control of hydrocarbon migration by basal granule on unconformity surface

准噶尔盆地腹部地区侏罗系和白垩系清水河组之间存在区域不整合面,之前有关不整合面之上底(砾)砂岩对中浅层油气藏运移与聚集的影响的研究较少,缺乏流体方面的证据。为恢复盆地内清水河组油气充注过程,选取该盆地腹部地区莫索湾凸起盆参2井区的莫深1井为典型井,结合现有地质成果,对12个岩屑样品进行颗粒定量荧光实验(QFT)。结果表明:白垩纪受风城组和乌尔禾组成熟原油充注,清水河组底(砾)砂岩存在古油层,古近纪末,喜马拉雅构造运动使得古油藏泄漏,QGF-E和TSF波谱图显示异常也证明油气有明显被排替的痕迹,侏罗纪成熟烃源岩有可能再次向底(砾)砂岩充注油气;现今研究层段原油的成熟度变化范围大,清水河组底(砾)砂岩油藏是油气聚集、调整、再接受充注的综合体现。研究结果从动态角度恢复了盆参2井区的成藏过程,为底(砾)砂岩作为优质储层和优势运移通道提供了流体证据。

There are regional unconformity surfaces between Jurassic and Cretaceous Qingshuihe Formation in cen- tral parts of the Junggar Basin. Researches related to control of basal granule on unconformity surface over migration and accumulation of reservoirs in middle and shallower formations are quite limited. In addition, there are few fluid evidences related to such control. To restore the hydrocarbon charging processes in Qingshuihe Formation of the Ba- sin, the Well Moshen-1 in Pencan-2 Well Block of the Mosuowan Uplift in central parts of the Basin has been studied. With consideration to available geologic research results quantitative fluorescence test { QFT） for 12 rock samples have been performed. Research results show Cretaceous formations accepted charging of matured oil from the Fengcheng Formation and Wuerhe Formation. On the other hand, the Qingshuihe Formation contain palaeo oil reservoirs in basal granule. Himalaya tectonic movement at the end of Paleogene led to leaking of such reservoirs. Both QGF-E and TSF spectrums have abnormal features to verify obvious displacement of hydrocarbons. During Ju- rassic Period, high-maturity hydrocarbon source rocks may charge basal granule with hydrocarbons again. Crude oil contained in the concerned interval at present has maturities varied significantly. Basal granule reservoirs in the Qingshuihe Formation can be seen as comprehensive representation of hydrocarbon accumulation, modification and re-charging. Relevant researches may dynamically restore reservoir formation processes in the Pencan-2 Well Block to provide fluid evidences for basal granule as high-quality reservoir and preferred migration channels.