盒8致密砂岩储层气水驱替特征及其形成机理

Gas-Water Displacement Characteristics and Formation Mechanism of Tight Sandstone Reservoir of He 8 in Yanchang Area

储层气水驱替效率是影响油气层开发的关键。盒8段储层样品束缚水饱和度普遍超过50%,原始含气饱和度低,气水驱替实验显示样品气驱效率差别大,粒度的差异影响了颗粒间孔隙充填情况,样品中亲水性矿物、钙质胶结物含量、孔喉结构都是影响样品中流体渗流能力的关键原因。C39-1样品中方解石胶结物少,主要孔喉半径相对较大,分布均匀,排驱压力低,两相相对渗透率大,使其气驱效率相对较高,当盒8气层含水饱和度高于32%的时候,就会出现气水同产。

Gas water displacement efficiency of reservoir is the key element to influence the development of oil and gas layer. The irreducible water saturation of He 8 reservoir samples are generally more than 50%,and the original gas saturation is low.The difference of particle size affected the intergranular pore filling by analyzing the reservoir characteristics,and hydrophilic minerals,content of calcium cement and pore throat structure are the key factors affecting the fluid seepage capacity of the samples.The calcite cement in the sample C39-1 is less,the radius of the main pore throat is relatively large,the distribution is uniform,the displacement pressure is low,and the relative permeability of the two phases is large,which makes the gas displacement efficiency relatively high.Meanwhile,when the water saturation of He 8 reservoir is higher than 32%,gas and water produce in the same formation,which causes the gas phase relative permeability decrease quickly.