温度对乙基己基延展型硫酸盐降低界面张力能力的影响

doi:10.3969/j.issn.2097-2806.2026.09.001

摘要/Abstract

摘要：

高温高盐油藏化学驱中，常规表面活性剂因界面活性衰减和盐析沉淀而失效，亟需开发兼具耐温抗盐性能的新型驱油剂。本文以乙基己基延展型硫酸盐（C₈P_xE_yS，x=10, 15；y=5, 10）为对象，在模拟地层水（总矿化度29 145 mg/L）中，采用旋转滴法测定30~86 ℃下体系与不同碳数正构烷烃间的界面张力，考察温度对亲水亲油平衡（HLB）及界面吸附膜结构的影响。结果表明，温度对界面张力的调控并非单调一致，而是取决于PO/EO嵌段长度：随温度升高，EO链段与水分子间氢键断裂导致分子水溶性降低、HLB向亲油端偏移；同时PO链段形成螺旋构象、EO链段由向水相伸展转为界面铺展，二者共同决定界面张力的变化趋势。C₈P₁₅E₁₀S在86 ℃下可将正癸烷界面张力降至10^-3 mN/m数量级，而C₈P₁₅E₅S因油溶性过强在高温下未能出现超低界面张力。研究提出了温度通过破坏水化层和诱导构象转变双重路径调控延展型硫酸盐界面活性的微观机制，为面向深层高温油藏的超低界面张力驱油体系设计提供了依据。

关键词: 延展型表面活性剂, 硫酸盐, 界面张力, 高温高盐油藏, 亲水亲油平衡

Abstract:

In chemical flooding of high-temperature and high-salinity reservoirs, conventional surfactants suffer from interfacial activity attenuation and salt-induced precipitation, necessitating novel agents with combined temperature and salt tolerance. This work investigates four ethylhexyl extended sulfates （C₈P_xE_yS, x=10,15; y=5,10） in simulated formation water （TDS 29 145 mg/L）. Interfacial tensions （IFT） against n-Alkanes with varying carbon numbers were measured by spinning drop method during 30-86 ℃, and the alkane carbon number （ACN） scanning curve was employed to evaluate temperature effects on hydrophilic-lipophilic balance （HLB） and interfacial adsorption film structure. Results demonstrate that temperature does not exert a monotonic effect on IFT; instead, the response depends on PO/EO block lengths. With rising temperature, hydrogen bonds of EO segments break, reducing hydrophilicity and shifting HLB toward lipophilicity; while PO segments adopt helical conformations and EO segments transform from water-extending to interfacial spreading. These dual pathways collectively determine IFT variation. C₈P₁₅E₁₀S achieves an ultralow IFT of 10^-3 mN/m against n-Decane at 86 ℃, whereas C₈P₁₅E₅S exhibits excessive lipophilicity and fails to reach an ultralow IFT at high temperature. This study elucidates the microscopic mechanism by which temperature regulates IFT reduction via dehydration and conformational transition, providing theoretical guidance for designing ultralow IFT flooding systems applicable to deep high-temperature reservoirs.

Key words: extended surfactants, sulfate, interfacial tension, high temperature and high salinity reservoir, hydrophilic-lipophilic balance

中图分类号:

TQ423

周朝辉, 李世祥, 滕旭东, 石蕾, 彭元奎, 樊剑. 温度对乙基己基延展型硫酸盐降低界面张力能力的影响[J]. 日用化学工业（中英文）, 2026, 56(9): 1125-1133.

Zhaohui Zhou, Shixiang Li, Xudong Teng, Lei Shi, Yuankui Peng, Jian Fan. Effect of temperature on the ability of ethylhexyl extended sulfate to reduce interfacial tension[J]. China Surfactant Detergent & Cosmetics, 2026, 56(9): 1125-1133.

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Type	ρ/ （mg/L）
Type	Cl^-	SO₄^2-	HCO₃^-	Na⁺+K⁺	Ca²⁺	Mg²⁺	TDS
Content	17 343	24	588	9 986	1 052	152	29 145