西湖凹陷苏堤构造带花港组储层特征

HUAGANG FORMATION RESERVOIR FEATURES ON SUDI STRUCTURAL BELT IN XIHU DEPRESSION

西湖凹陷苏堤构造带花港组油层储集岩主要为岩屑长石砂岩、长石岩屑砂岩、长石石英砂岩 ,岩屑含量较少 ,岩石成分成熟度和结构成熟度均较高。孔隙度在 2 .2 7%～ 30 .89%之间 ,平均 19.2 6 %。渗透率在 ( 1.6～16 98.13)× 10 -3 μm2 之间 ,平均 318.2 8× 10 -3 μm2 。花港组砂岩储集岩的储集空间主要为孔隙 ,仅见少量裂缝。孔隙结构可以划分为 3类 ,Ⅰ类孔隙结构储层毛细管压力曲线具有较明显的平直段 ,孔喉较粗 ,为良好储层 ;Ⅱ类孔隙结构储层毛细管压力曲线基本为斜线 ,歪度略偏细 ,属较好的储集岩 ;Ⅲ类孔隙结构储层毛细管压力曲线基本为直线 ,孔隙度、渗透率较小 ,为极差或非储层。主要的成岩作用有机械压实、胶结、溶蚀等 ,大部分储集岩的变化发生在晚成岩作用阶段 ,对油气生成。

The reservoir lithology of oil bearing Huagang formation on Sudi structural belt in Xihu depression is mainly lithic arkose, feldspathic litharenite and feldspathic quartzitic sandstone. The content of the lithic fragment is relatively low due to their high compositional and textural maturity. The porosity of them is 2.27 % ∼ 30.89 % with an averge value 19. 26 %, and the permeability of theirs, varies between 1.6 × 10 -3. μm to 1 698.13 × 10-3 μm with an average value 318.28 × 10-3 μm. The main space of Huagang formation reservoir is pore, while fracture is only a little. In the light of the pore textures, the reservoir can be divided into 3 types: the 1st, showing an obvious straight horizontal segment in its capillary pressure curve and with wide pore throat, is excellent; the 2nd, displaying a oblique curve, is relatively good; the 3rd, almost with a straight line, is bad because of its low porosity and permeability. The main lithogenetic processes are mechanic compaction, cementation and corrosion. The lithogenesis commonly occurred at late stage, which had little effect on oil generation and accumulation.