准噶尔盆地腹部地区侏罗系三工河组相对优质储集层的成因

在准噶尔盆地腹部地区侏罗系中,三工河组与八道湾组、西山窑组相比,在同等条件下具有更好的储集性能,特别是在莫索湾地区,三工河组埋深虽已达4500m,但仍具有较好的孔渗性。因此三工河组是准噶尔盆地腹部地区侏罗系的主力含油层段和勘探目的层,已发现多个油气藏。研究三工河组相对优质储集层的形成条件和控制因素,可为该区的油气勘探提供储集层依据。

The origin of favorable sandstone reservoirs of Sangonghe Formation, Lower Jurassic in central Junggar basin

The clastic reservoirs of Sangonghe Formation, Lower Jurassic in central Junggar basin mainly consist of lithic sandstone, whi ch is characterized by "two high and one low"(higher compositional maturity, h igher textual maturity and lower interstitial matter content). With increasing b urial depth, sandstone progressively loses porosity. Porosity was decreased main ly due to compaction and quartz cemen tation, but, at the same time, cements also protected grains from further compac tion. The quartz cementation is slight and dissolution is not obvious. The clast ic rocks are at late diagenesis stage (A1), all these make it possible that pore s types are mainly characterized by residual intergranular pores and partially b y intragranular solution pores. Middle compositional maturity, higher textual ma turity and lower interstitial matter content are the primary causes resulting in favorable physical properties of the reservoirs. It was also pointed out that s ubaqueous distributary channels, river mouth bars and beach bars, which are coar se and have lower interstitial matter content, are favorable for development of the reservoirs.