青西油田沉凝灰岩储集特征

酒泉盆地青西油田的主要储集层下白垩统下沟组，由一套沉凝灰质碳酸盐岩和沉凝灰质砂砾岩组成。凝灰质的存在不但改善了储集层储集空间，而且有利于形成各类裂缝，为油气储集提供了场所。在溶解、交代及后生改造的作用下形成的次生孔洞晶间孔、基质微孔、次生粒砾内溶孔以及在压实作用下形成的泄水构造是油气储集的主要空间。裂缝对孔隙度的影响不大，但对渗透率、可动流体饱和度影响显著。

Bedded Tuff Reservoir in Qingxi Oilfield

Qingxi oilfield in Jiuquan basin is found in Xiagou reservoir of Lower Cretaceous, mainly composed of bedded-tuffaceouscarbonate and bedded tuffaceous glutenite.It is the tuffaceous presence that not only improve the reservoir spaces, but also in favor offorming various fractures which provide sites for hydrocarbon accumulation, The sites include secondary vuggy intercrystal pore, matrixmicropore and secondary intragranular dissolved pore that shaped by dissolution,matasomatism and epigenesis as well a8 drainagestructure shaped by compaction, in which the fracture has a great effect on permeability and movable fluid saturation rather than porosity