孔隙介质中泡沫生成机制和转向能力研究

Foam Generation Mechanism and Deflecting Ability in Porous Media

为了明确泡沫在地层中的生成、运移等行为并考察其在油气田开发中的应用基础,通过利用微观刻蚀玻璃模型开展可视化实验的方法研究了泡沫在孔隙介质中的生成机制以及转向能力。结果表明:排驱过程中易发生颈部卡断,吸吮过程中易发生颈前卡断、直线卡断;气液混注时随含水饱和度变化,会使吸吮和排驱过程交替出现,而导致生泡方式发生改变;发现颈前卡断生成的泡沫直径略小于生泡孔隙喉道的直径,直线卡断生成的泡沫直径约为生泡孔隙喉道直径的2倍,颈部卡断生成的泡沫直径与孔隙体直径大致相当;泡沫在不同渗透率级差模型中运移转向能力差异较大,一般非均质地层注泡沫转向的渗透率级差极限为6∶1,单纯注泡沫难以波及高渗透率级差模型中的低渗区域。上述研究结果能对泡沫在提高采收率中的应用提供一定的指导作用。

In order to clarify the behavior of foam generation and migration in the formation and to examine the basis of its application in oil and gas field development,microscopically etched glass models were used to investigate foam generation mechanism and deflecting ability in porous media by means of visualization experiments.The results show that the neck is easily snapped-off during displacement,anterior neck and straight neck are easily snapped-off during sucking.When gas-liquid injection is mixed with water saturation,the process of sucking and displacement will appear alternately,resulting in the change of foam generation mode.It is found that the diameter of foam generated by neck snap-off is slightly smaller than that of the pore throat of the generating bubble.The diameter of foam generated by the linear snap-off is about twice that of the pore throat of the generating bubble.The diameter of foam generated by neck snap-off is roughly equivalent to that of the pore body.The migration and deflecting ability of foam varies greatly in models with different permeability levels.Generally,the limit of the permeability level difference of foam injection in heterogeneous layers is 6∶1,and it is difficult for foam injection alone to affect the low permeability area in models with high permeability levels.It is concluded that the results of the above study can provide some guidance for the application of foam in recovery enhancement.