气田采出水乳化规律及其与界面张力的关系研究

为了得到不同影响因素对气田采出水乳化的作用规律，以及乳化规律与界面张力的关系，首先研究了气田采出水的矿化度和主要无机盐（CaCl₂、NaCl）浓度对其乳化规律和界面张力的影响。研究发现：静置初始乳化程度、乳化稳定性和界面张力均随矿化度或无机盐浓度的增加而逐渐降低；增加相同质量浓度的CaCl₂或NaCl时，CaCl₂对乳化程度和界面张力的影响更大。其次，通过研究不同泡排剂含量下的乳化规律，发现增加微量泡排剂就可大幅提升静置初始乳化程度和乳化稳定性：泡排剂质量分数从0仅提升至1‰，静置初始浊度即提高1倍，静置48 h后浊度的降低幅度从94%降至43%。此外，增加矿化度和泡排剂含量均会使油/水界面张力降低，不过二者对静置初始乳化程度的变化趋势影响相反，说明仅凭界面张力的变化无法判断初始乳化程度上升或下降的变化趋势。但对比不同影响因素下界面张力的变化幅度和静置初始乳化程度的变化幅度发现，在单因素实验中，当界面张力的变化幅度越大时，气田采出水静置初始乳化程度的变化幅度也越大。

Emulsification regularity for water produced in a gas field and its relationship with interfacial tension

Gas fields contain oil/water (O/W) emulsions with high salinity. Emulsification of the water produced in gas fields results in great difficulties in subsequent sewage treatment. The bubble discharge agent is a surfactant and its adsorption at the oil-water interface inevitably leads to a change in the interfacial tension. In order to obtain the effect of different factors on the emulsification of produced water in gas fields, and the relationship between emulsification regularity and the interfacial tension, we have studied the influence of mineralization degree and the main inorganic salt components CaCl₂ and NaCl on the emulsification law and interfacial tension using single factor experiments. It was found that the standing initial emulsification degree, interfacial tension and emulsion stability all gradually decreased as the degree of mineralization or inorganic salt concentration was increased. Furthermore, addition of CaCl₂ resulted in a larger decrease in both emulsification degree and interfacial tension than the same concentration of NaCl. By studying the emulsification behavior with different contents of foaming agents, it was found that adding a microscale foaming agent greatly improves the initial degree of emulsification and emulsion stability:the mass concentration of the foaming agent only increased from 0 to 1‰, the initial turbidity was doubled. After standing for 48 hours, the content of the bubbling agent increased from 0 to 1‰, and turbidity was reduced from 94% to 43%. Furthermore, addition of a very small amount of foaming agent will greatly reduce the oil-water interfacial tension. Increasing the degree of salinity and the buffer content also reduces the oil-water interfacial tension in each case, but has opposite effects on the degree of emulsification. The results show that the variation in the degree of emulsification cannot be judged by the interfacial tension alone. However, by comparing the variation in the degree of initial emulsification and interfacial tension under the above three conditions using single factor experiments, it was found that when the variation of interfacial tension is larger, the variation of initial emulsification degree is also larger under single factor experiment.