超临界CO₂对疏松砂岩储层物性影响的实验研究

Influence of Supercritical CO₂ on the Physical Property of Unconsolidated Sandstone Reservoir

周琳淞 杜建芬 郭 平 汪周华

ZHOU Linsong DU Jianfen GUO Ping WANG Zhouhua

为了评价超临界CO2注入对绥中36-1油田疏松砂岩储层物性的影响，利用改进的实验装置在地层条件下测试了岩心在注气前后的孔隙度和渗透率。结果表明：在接触反应后，储层的孔隙度、气测渗透率和液测渗透率均降低。含气饱和度为30%、50%岩心的孔隙度分别由平均值55.36%、54.84%降至55.15%、54.59%，变化率分别为-0.4%、-0.5%；其气测渗透率分别由平均值5.019、5.060 μm2降至4.925、4.952 μm2，变化率分别为-1.9%、-2.1%；其液测渗透率分别由平均值2.417、2.426 μm2降至2.289、2.291 μm2，变化率分别为-5.3%、-5.6%。在地层条件下，溶蚀产物由于CO2分压的降低生成了碳酸盐沉淀。初始孔隙度和渗透率越大，储层物性降幅越小；含气饱和度对储层物性的影响不明显。图7表5参20

In order to evaluate the influence of supercritical CO2 on the physical property of unconsolidated sandstone reservoir in Suizhong 36-1 oilfield, under the reservoir condition, the core porosity and permeability before and after gas injection were tested by using improved test device. The results showed that the porosity, gas permeability and liquid permeability of reservoir all decreased after contact reaction. The core porosity in average with 30% and 50% gas saturation decreased from 55.36% and 54.84% to 55.15% and 54.59%, the change rate was -0.4% and -0.5%, respectively. The core gas permeability of that decreased from 5.019 and 5.060 μm2 to 4.925 and 4.952 μm2, the change rate was -1.9% and -2.1%. The core liquid permeability of that decreased from 2.417 and 2.426 μm2 to 2.289 and 2.291 μm2, the change rate was -5.3% and -5.6%. Under the reservoir condition, corrosion products changed into the precipitation of carbonate because of the decrease of CO2 partial pressure. The larger initial porosity and permeability, the smaller decrease degree of reservoir physical properties was. Gas saturation had little effect on the change of reservoir physical properties.