延长气田延气2井区山2段微观孔隙结构特征及其对气水渗流规律的影响

Characteristics of Micro-pore Structure and Its Influence on Gas-water Seepage of P1s2 Formation in Yanqi 2 Block,Yanchang Gas Field

储层微观孔隙结构特征控制着气水渗流特征,影响着气井的生产能力。延气2井区山2段砂岩储层气井产量差异明显,微观孔隙结构和气水渗流特征复杂。通过铸体薄片、扫描电镜、高压压汞、气水相渗等实验,对山2段储层的孔隙类型、孔隙组合类型、孔隙结构特征和气水两相渗流特征进行了描述,并在此基础上对影响气水相渗特征的因素进行了探讨。储层的孔隙类型主要为粒间孔、岩屑溶孔、晶间孔。根据毛管压力曲线形态特征,结合排驱压力、孔喉分选性、进汞饱和度、中值压力等参数,将研究区毛管压力分为四类:粒间孔类,粒间孔-岩屑溶孔类,岩屑溶孔-晶间微孔类和晶间微孔-微裂缝类;4类孔隙结构有着不同的气水渗流规律,应采取不同的开发策略。

Gas production capacity is affected by gas-water flowing characteristics,which is determined by micro-pore structure of reservoir.Because the complexity of micro-pore structure and gas-water seepage,gas-well production of P1s2 sandstone reservoir hase a significant difference in Yanqi 2 block,to study the affecting factors to gas-water relative permeability,four aspect characteristics of P1s2 reservoir,such as pore types,pore combination types,micro-pore features and gas-water two phases flowing,are described,by the experiments of casting thin sections,SEM,high-pressure mercury injection and gas-water relative permeability.The research shows that pore types mainly include intergranular pore,cutting solution pore and intracrystalline pore;the pore structure can be divided into four types,intergranular pore,intergranular-cutting solution pore,cutting solution-intracrystalline pore and intracrystalline-microcrack pore.Different pore structure type has different gas-water flowing characteristics and different exploitation strategy should be adopted.