Abstract

Fluids incorporating carbon dioxide (CO₂) microbubbles have been utilized to promote enhanced oil recovery from hydrocarbon reservoirs. The performance of such fluids in porous media is greatly affected by both the bubble size and stability. On this basis, the present study evaluated the effects of varying the concentrations of a xanthan gum (XG) polymer, a surfactant (sodium dodecyl sulfate: SDS) and sodium chloride (NaCl) on both the stability and bubble size distribution (BSD) of CO₂ microbubbles. CO₂ microbubble dispersions were prepared using a high-speed homogenizer in conjunction with the diffusion of gaseous CO₂ through aqueous solutions. The stability of each dispersion was ascertained using a drainage test, while the BSD was determined by optical microscopy and fitted to either normal, log-normal or Weibull functions. The results showed that a Weibull distribution gave the most accurate fit for all experimental data. Increases in either the SDS or XG polymer concentration were found to decrease the microbubble size. However, these same changes increased the microbubble stability as a consequence of structural enhancement. The addition of NaCl up to a concentration of 10 g/L (10 g/1000g) decreased the average bubble size by approximately 2.7%. Stability was also reduced as the NaCl concentration was increased because of the gravitational effect and coalescence.

摘要

掺入二氧化碳(CO ₂ )微泡的流体已被用于促进从烃类储层中提高石油采收率。这种流体在多孔介质中的性能受气泡大小和稳定性的影响很大。在此基础上，本研究评估了不同浓度的黄原胶 (XG) 聚合物、表面活性剂（十二烷基硫酸钠：SDS）和氯化钠 (NaCl) 的稳定性和气泡尺寸分布 (BSD) 的影响。 CO ₂微气泡。使用高速均化器结合气态 CO ₂的扩散制备CO _{2微泡分散体}通过水溶液。每种分散体的稳定性通过排水试验确定，而 BSD 通过光学显微镜确定并拟合为正态、对数正态或 Weibull 函数。结果表明，威布尔分布对所有实验数据给出了最准确的拟合。发现 SDS 或 XG 聚合物浓度的增加会降低微泡尺寸。然而，由于结构增强，这些相同的变化增加了微泡稳定性。添加浓度高达 10 g/L (10 g/1000g) 的 NaCl 会使平均气泡尺寸降低约 2.7%。由于重力效应和聚结，稳定性也随着 NaCl 浓度的增加而降低。