克拉玛依油田六区克下组冲积扇岩石相及储层质量差异

Lithofacies and reservoirs of allluvial fan in the Lower Keramay Formation in the block-6 of Karamay oilfield,the Junggar Basin

在准噶尔盆地克拉玛依油田六区11口取心井岩心描述的基础上,将该区克下组冲积扇岩石相划分为7种类型。结合沉积微相分析,应用岩心分析化验资料对冲积扇内部储层质量差异及其分布特征进行了研究。分析表明,研究区克下组储层以原生粒间孔隙为主,沉积组构对储层质量差异起控制作用;粗砂岩相和细砾岩相储层为研究区克下组冲积扇中最好的储层;各微相储层质量差异显著,辫流水道和流沟储层质量最好,砂砾坝次之,砾石坝和径流水道较差,漫洪砂体最差;流沟以窄条带状镶嵌于砾石坝和砂砾坝之中,为扇根和扇中内带储层中的高渗通道。

On the basis of core description of 11 wells in the block-6 of Keramay oilfield in the Junggar Basin, we recognize 7 types of lithofacies in the alluvial fan of the Lower Karamay Formation. In combination with sedimen- tary microfacies analysis, we study the quality differences and distribution of reservoirs within the alluvial fans by using core analysis and testing data. The pore space of the Lower Karamay Formation is dominated by primary intergranular pores. Depositional fabric controls the reservoir quality in the study area. The reservoirs of coarse sandstone facies and fine conglomerate facies are the best in the alluvial fans of the study area. The reservoirs of different microfacies are significant different in reservoir quality. The reservoirs of braided channel and gulley microfacies are the highest in quality, followed by the sandy gravel bars. The reservoirs of gravel bar and runoff channel microfacies are fair. The reservoirs of sheetflood microfacies are the worst. Gulley microfacies occur as narrow bands within gravel bars and sandy gravel bars, and act as the high transmissibility pathways for reservoirs in the root fan and inner-middle fan.