苏北盆地闵北地区阜宁组一、二段火山岩的储集特征

苏北盆地金湖凹陷闵北地区火山岩储集空间主要有原生孔隙和次生孔隙两类,原生孔隙包括粒间孔、晶间孔、气孔及原生节理,是在火山岩堆积、成岩时形成的,原生孔隙多处于孤立分布的状态,并且又多被充填。次生孔隙包括粒内溶孔、溶蚀孔、缝、洞等,是火山岩成岩之后,因风化、淋滤、溶蚀及构造应力作用形成,次生孔隙能大大改善储集性能,尤其是构造节理,对孤立分布的原生孔隙起到了很好的连通作用。通过对火山岩孔、渗测井曲线分析对比发现,在剖面上,一个岩流单元的孔、渗值由下往上呈变大的趋势;岩流组的孔、渗变化特点与岩流单元一致或表现为这一规律的若干次重复;研究区东西向孔、渗值变化较大,南北向相对平稳。阜宁组一段的Ⅵ～Ⅺ及阜二段的Ⅲ岩流组储集性能较好。

RESERVOIR CHARACTERISTICS FOR VOLCANIC ROCKS FROM MEMBER I,II OF FUNING FORMATION IN NORTHERN MINBEI REGION IN SUBEI BASIN

There are mainly two types of pores(primary and secondary) in the space of volcanic rock reservoirs in northern Mingqiao region of Jinhu depression in Subei basin. The primary pores consisting of intergranular pores,intercrystalline pores, gas pores and primary joints were formed during the accumulation of volcanic rocks and diagenesis. The distribution of the primary pores are mostly isolated and filled. The secondary pores including intraparticle dissolution pores, dissolution pores, seams and caves etc. were formed after the diagenesis of volcanic rocks caused by the effects of weathering, leaching, dissolution and structural stress. The secondary pores can improve reservoir quality greatly especially for structural joints and play very good rule in communicating isolated primary pores. The ratios of porosity and permeability of a rock flow unit in the profile are observed to have a trend of being enlarged gradually from downwards to upwards by analyzing volcanic rock porosity and well log of permeability. Variations of porosity and permeability in a rock flow group correspond to these in a rock flow unit or reveal several repetitions of the same regularity above. The ratio variations of porosity and permeability of east-west in the study area are quite big while ratio variations of south-north are relatively stable. Reservoir qualities of Ⅶ-Ⅺ rock flow group in 1st member of Funing formation and Ⅲ rock flow group in 2nd member of Funing Formation are quite good.