CO2驱中岩石性质变化

 CO₂驱作为一种成熟而且具有广阔应用前景的提高原油采收率(EOR)技术,越来越受到各国重视。CO₂驱中,CO₂溶解于地层水后与岩石产生反应,改变岩石的孔隙结构、润湿性等。为确定CO₂驱后岩石的孔隙结构、润湿性的变化规律,本文针对大庆F油层实际情况,在模拟油藏条件下,通过实验方法对天然岩心展开CO₂驱中岩石性质变化的室内研究。结果表明,注入的CO₂改变岩石的孔隙结构、渗透率以及润湿性等。随着CO₂与岩石接触时间增加,岩石中小孔隙及大孔隙所占比例增加,中等孔隙所占比例减小,渗透率逐渐增大,亲水性逐渐变强。这是由于CO₂溶于水后显酸性,与岩石孔隙表面的矿物成分发生反应,改变了岩石孔隙表面矿物组成和岩石的孔隙结构。

Changes of Rock Properties in CO2 Flooding

CO₂ flooding that is a kind of developed EOR technology with widely prospect of application, becomes the focus of attention in many countries. In the CO₂ flooding, rock can react with CO₂ dissolved in the water, which changes the pore structure and wettability of rock, and so on. In order to determine the change rule on pore structure and wettability of rock treatment of CO₂ flooding, in this paper under the actual condition of daqing F reservoir, using the simulation of the actual reservoir conditions, the changes of rock properties for natural core treated by CO₂ flooding are studied by the experimental methods of indoor research. The results show that as CO₂ injected the rock is changed on pore structure, permeability and wettability, and so on. As the contact time of rock reacted with CO₂ increases, the percentage of small pore and big pore increases, but the proportion of secondary porosity decreases, meanwhile the permeability and the hydrophilicity gradually increase. This result is caused by the release of CO₂ that can lead to the acidifying effectreacting with the mineral composition on the pore surface of rock, and then change the rock pore structure and the mineral composition of the rock surface.