准噶尔盆地乌夏地区二叠系火山岩储层气孔充填机理及定量化预测方法

Pore Filling Mechanism and Quantitative Prediction Methods of the Permian Volcanic Reservoir in Wuxia Area,Junggar Basin

准噶尔盆地乌夏地区二叠系风城组底部发育火山岩储层,岩性为熔结角砾凝灰岩,储集空间以气孔为主,但气孔的充填程度不同,导致储层的非均质性较强。通过岩心、薄片观察和构造分析,深入研究了气孔的充填机理。应用基于模型正演的地震属性分析方法定量预测了气孔的充填程度。研究表明,强烈的构造运动导致断裂和裂缝发育,地表水沿断裂和裂缝渗入气孔中,所含SiO2等物质发生沉淀作用,使原生气孔被充填,据此建立了气孔充填的成因模式。模型正演的结果表明,气孔未充填的火山岩具有强振幅、高能量的地震响应特征,并且通过对多口井的正演模拟建立了定量解释图版,结合地震属性对气孔的充填程度进行了定量化预测。预测结果与钻探情况吻合,证明这种定量化预测的方法是有效的,值得在类似地区推广应用。

Volcanic reservoir is developed in the bottom of the Permian Fengcheng Formation in Wuxia area of Junggar Basin.The lithology is welded breccia tuff and the reservoir space is mainly pore.The different filling degree of pores causes strong anisotropy.Based on the observation of core,thin section and structural analysis,the filling mechanism of pores was further studied.The filling degree of pores was predicted by using seismic attributes analytic technique based on forward mode.The results show that the pores are filled with the precipitation of SiO2,owing to the surface water（containing SiO2）penetration along the faults and fissures,resulted from the strong tectonic movement.Accordingly,the genetic model of pore filling is established.The results of the forward modeling show that the seismic response characteristics of the unfilled pore volcanic are large amplitude and high energy.The qualitative interpretation chart is given by the results of the forward simulation in many wells.Finally,using the chart and the seismic attribute,the filling degree of pores is predicted quantitatively.The predication result consists with the drilling condition,showing that this method is effective and is worthy of promotion.