低渗透砂砾岩储层不同孔隙类型下的水驱油特征——以二连盆地阿尔凹陷腾一下段储层为例

Characteristics of water flooding under different porosity types in low permeability sandstone and conglomerate reservoirs

以二连盆地阿尔凹陷腾一下段储层低渗透砂砾岩储层为例,利用铸体薄片、扫描电镜、高压压汞、恒速压汞、核磁共振、油水相渗实验等测试方法,对研究例区不同孔隙类型下的水驱油特征进行探讨。结果表明,阿尔凹陷腾一下段储层孔隙类型以粒间孔、长石溶孔为主;排驱压力小于1 MPa,孔隙组合类型为溶孔-粒间孔型,T2谱形态为左低右高峰,水驱效率为67. 8%;排驱压力介于1～2 MPa,孔隙组合类型粒间孔-溶孔型,T2谱形态为左高右低峰,水驱效率为49. 7%;排驱压力大于2 MPa,孔隙组合类型晶间孔-溶孔型,T2谱形态为单峰状,水驱效率为35. 8%。研究后认为,研究区不同孔隙类型的储集能力及水驱油特征差异明显,其影响因素主要为渗透率、喉道分布、孔喉比、分选系数、黏土矿物含量。当渗透率小于3×10^(-3)μm^2,喉道半径小于2μm时,储层水驱油效率受渗透率、喉道半径控制明显。

The heterogeneity of the micro-pore structure of low-permeability glutenite reservoirs restricts the efficient development of reservoirs.This paper takes the low-permeability glutenite reservoir of the Tengcai section of the Alzhao basin in the Erlian Basin as an example,using cast thin sheets and scanning electron microscopy.The high-pressure mercury,constant-pressure mercury,nuclear magnetic resonance,oil-water phase infiltration experiments and other test methods,the characteristics of water flooding under different pore types in the study area.The results show that the pore type of the reservoir in the sag of the Al sag is dominated by intergranular pores and feldspar dissolved pores;the displacement pressure is less than1MPa,the pore combination type is dissolved pore-intergranular pore type,and the T2spectrum is left low right peak.The water flooding efficiency is67.8%;the displacement pressure is between1and2MPa,the pore combination type is intergranular pore-dissolved pore type,the T2spectrum is left high right and low peak,the water flooding efficiency is49.7%;2MPa,pore combination type intercrystalline pore-dissolved pore type,the T2spectrum is monomodal,and the water flooding efficiency is35.8%.After the study,it is believed that the reservoir capacity and water flooding characteristics of different pore types in the study area are significantly different.The main influencing factors are permeability,throat distribution,pore throat ratio,sorting coefficient and clay mineral content.When the permeability is less than3×10-3μm2and the throat radius is less than2μm,the reservoir water flooding efficiency is controlled by the permeability and throat radius.