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综合利用薄片鉴定、氩离子抛光、聚焦双离子束扫描电镜、能谱、XRD、恒速压汞等技术手段,结合岩心观察,综合分析了准噶尔盆地吉木萨尔凹陷二叠系芦草沟组致密储层岩石学特征、物性特征、储集空间特征及其影响因素.认为储集空间特征受沉积作用、成岩作用、生烃作用及构造作用的共同控制,压实作用是导致储层致密化的主要原因,长石、岩屑和凝灰物质的溶蚀是形成“高孔高渗”储层的关键.研究结果表明:芦草沟组致密储层低成分和结构成熟度特点导致储层抗压能力弱,原生粒间孔空间变小,储层平均孔隙半径为124.5μm,平均喉道半径为0.3μm,平均孔喉半径比为339.1;生烃作用产生的有机酸导致次生溶孔发育,次生溶孔和原生粒间孔占总孔隙的80%以上;受沉积作用控制,储集空间类型组合由湖盆边缘的原生粒间孔+次生溶孔组合向湖盆中心的次生溶孔+原生粒间孔+晶间孔组合过渡;生烃产生的异常高压与构造作用可形成微裂缝,改善储层渗流能力.
In this paper, we comprehensively analyzed the tightness of the Lucaogou Formation in the Permian Lucaogou Formation in the Jimsar Sag of the Jiamusha Sag in the Junggar Basin by means of thin-slice identification, argon ion polishing, focused dual ion beam scanning electron microscopy, energy dispersive spectroscopy, XRD and constant pressure mercury injection Reservoir petrology, physical properties, reservoir space characteristics and their influencing factors.It is considered that the reservoir space characteristics are controlled by sedimentation, diagenesis, hydrocarbon generation and tectonism, and compaction results in densification of the reservoir The main reason is that the dissolution of feldspar, cuttings and tuff material is the key to the formation of “high porosity and permeability” reservoirs.The results show that the low composition and structural maturity of the tight reservoirs in Lucaogou Formation lead to the reservoir The compressive capacity is weak, the space between primary intergranular pores becomes smaller, the mean pore radius of reservoirs is 124.5μm, the average throat radius is 0.3μm and the average pore throat radius ratio is 339.1. The organic acids generated by hydrocarbon generation lead to secondary dissolution pores Secondary porosity and primary intergranular pores account for more than 80% of the total porosity. Sediment-controlled and reservoir-space combinations are dominated by primary intergranular pores and secondary pores dissolved in the edge of the lake basin, Slit pores + primary particles Hole + intergranular hole combination transition; abnormal high pressure generated by hydrocarbon generation and tectonic action can form micro-cracks, improve reservoir seepage ability.