三角洲前缘厚层砂岩孔隙结构及微观渗流特征——以吴仓堡地区长6储层为例

Reservoir characteristics of thick sandstone and micro-anisotropy of delta front micro-facies: A case study of Chang 6 reservoir in Wucangbu area

依据薄片、压汞、扫描电镜、物性分析及油水驱替实验资料,对吴仓堡地区三角洲前缘亚相长6厚层砂岩储层的岩石学特征、孔渗特征、孔隙结构特征、成岩作用、微观渗流特征等进行深入研究,分析影响储层储集性能的主控因素。结果表明,受东北物源控制的长6厚层砂岩储层具有成分成熟度中等、结构成熟度较好的特点,储集空间主要为残余粒间孔和粒间溶孔、粒内溶孔,为典型中低孔、特低渗储集层;储层储集性能主要受沉积微相和成岩作用控制。对储层发育影响最大的成岩期位于中成岩A期,中等压实-粘土膜胶结残余粒间孔发育成岩相和弱压实-残余粒间孔+溶蚀孔隙发育成岩相是最有利储层发育的成岩相带。根据微观渗流特征,可划分出4种驱油类型,微观孔隙结构比宏观物性更能反映储层的本质特征。

Based on data obtained from cast slice, mercury injection test, SEM, physical properties, and oil/water micro-displace-ment experiment, the authors made a thorough study of the petrological characteristics, porosity and permeability characteristics,pore structure characteristics, diagenesis and micro-anisotropy of Chang 6 reservoir in Wucangbu area, and analyzed the main influ-encing factors. The results show that the sedimentary environment of the Chang 6 thick sandstones reservoir is a delta front derivedfrom the provenance in the northeast. In addition, the reservoir is characterized by medium compositional maturity and high textualmaturity. The reservoir space includes residual intergrantilar pores, intergranular emposieu and intragranular emposieu. The sedimen-tary micro-facies and diagenesis constitute the main factors controlling the reservoir properties. The diagenetic period affecting reser-voir development is stage A ofmiddie diagenesis. The middle compaction, clay film cementation, residual intergranular pore diagen-esis facies with weaker compaction and the secondary dissolution pore diagenesis facies are favorable diagenetic facies belts for reser-voir development. Four oil displacement types are distinguished by studying reservoir microscopic heterogeneity, and the microscop-ic pore structures can more really reflect the reservoir＇s essential characteristics than the macroscopically physical properties.