低渗透油气藏用阳离子型乳液表面活性和润湿性研究

doi:10.3969/j.issn.1006-396X.2022.02.009

摘要/Abstract

摘要：

以自制的一种长链阳离子表面活性剂(SFC111)和低界面能物质(SFC115)构建出阳离子型乳液，研究其作为低渗透油气藏用表面活性剂性能。通过粒度仪考察乳液在水中的分散性，通过接触角测定仪考察经乳液处理前后岩心的接触角，通过旋转滴界面张力仪测试表面张力；通过计算得到乳液在20、70 ℃的热力学参数。结果表明，质量分数为0.5%的乳液在20 ℃时D₅₀=420.8 nm，70 ℃时D₅₀=728.0 nm；清水在岩心表面上的接触角从10°最大可增至120°；70 ℃下乳液可将清水的表面张力降至24 mN/m，表现出良好的防水锁性能。乳液符合langmuir吸附理论，其热力学结果表明，随着温度的升高，乳液表面吸附量降低，乳液表面分子所占面积减小，吸附层厚度降低。

关键词: 低渗透油藏, 乳液, 表面张力, 接触角, 热力学计算

Abstract:

A self?made long?chain cationic surfactant (SFC111) and a low interfacial energy substance (SFC115) were used to prepare a cationic emulsion for further application as surfactant for low permeability oil and gas reservoirs. The dispersion of the emulsion in water, the contact angle of the core before and after the emulsion treatment and the surface tension were investigated by particle size analyzer, contact angle meter, and rotating drop interfacial tension meter, respectively. The thermodynamic parameters of the emulsion at 20 ℃ and 70 ℃ were calculated. Particle size of 0.5% concentration emulsion is D₅₀=420.8 nm at 20 ℃, D₅₀=728.0 nm at 70 ℃.The contact angle of clear water on the surface of the core increases from 10° to 120°. The emulsion could reduce the surface tension of water to 24 mN/m at 70 ℃, indicating the good waterproof lock performance. The adsorption characteristic of emulsion conforms to the langmuir adsorption theory. The thermodynamic results show that as the temperature increases, the amount of adsorption on the surface of the emulsion decreases, the area occupied by the molecules on the surface of the emulsion goes down, and the thickness of the adsorption layer decreases.

Key words: Low permeability reservoir, Emulsion, Surface tension, Contact angle, Thermodynamic calculation

中图分类号:

TE258

刘淼, 罗根祥, 乔钰, 杨江. 低渗透油气藏用阳离子型乳液表面活性和润湿性研究[J]. 石油化工高等学校学报, 2022, 35(2): 56-61.

Miao Liu, Genxiang Luo, Yu Qiao, Jiang Yang. Study on the Surface Activity and Wettability of Cationic Emulsions for Low Permeability Oil and Gas Reservoirs[J]. Journal of Petrochemical Universities, 2022, 35(2): 56-61.

图/表 8

图1 20、70 ℃时SFC111和SFC115混合物质量分数为0.5%的乳液粒径分布

Fig.1 Particle size distribution of SFC111 and SFC115 at 20 °C and 70 °C with mass fraction of 0.5%

图2 岩石表面微观形貌（a）未处理（b）已处理

Fig.2 Micro?morphology of rock surface

图3 阳离子型乳液防水锁剂质量分数对岩心接触角的影响

Fig.3 The influence of the mass fraction of cationic emulsion waterproof lock agent on the core contact angle

表1 阳离子型乳液防水锁剂处理岩心前后接触角测量结果

Table 1 Contact angle measurement results before and after treatment of core with cationic emulsion waterproof lock agent

w（防水锁剂）/%	静态接触角/（°）			动态接触角/（°）
w（防水锁剂）/%	左	右	平均	左	右	前进角	后退角	差值
0	10.80	10.80	10.80	-	-	-	-	-
0.1	90.60	88.80	89.70	84.73	85.15	1.58	0.02	1.56
0.3	114.50	113.90	114.20	109.21	107.31	1.64	0.47	1.17
0.5	114.30	113.20	113.75	116.08	117.50	0.35	0.03	0.32
0.7	88.10	86.60	87.35	109.01	106.57	0.97	0.90	0.07

图4 阳离子型乳液防水锁剂在不同温度下的表面张力

Fig.4 Surface tension of cationic emulsion waterproof lock agent at different temperatures

图5 阳离子型乳液防水锁剂在20、70 ℃时的吸附曲线

Fig.5 The adsorption curve of cationic emulsion waterproof lock agent at 20 ℃ and 70 ℃

图6 阳离子型乳液防水锁剂在20、70 ℃时c/Γ?c曲线

Fig.6 c/Γ?c curve of cationic emulsion waterproof lock agent at 20 ℃ and 70 ℃

表2 阳离子型乳液防水锁剂吸附计算结果

Table 2 Calculation result of adsorption of cationic emulsion waterproof lock agent

t/℃

Г_max

× 106

/(mol

⋅

m^-2)

A_min

× 10 - 2

/nm²

ΔG^θ/

（kJ $⋅$ mol^-1）