Surfactant-induced flow behavior effects in gas condensate reservoirs
天然气占世界能源的四分之一，由于其储量丰富且对环境的影响较小，一直是主要的能源来源。随着更多的深层、高温高压气藏的勘探，凝析气藏在全球天然气产量中所占的份额正在增加。与这些储层相关的一个独特的生产挑战是凝析油堵塞问题，由于降到露点压力以下，导致井筒周围的凝析油液体饱和度增加。 解决这一问题需要深入了解液体和气体的多相流特性。表面活性剂在文献中因影响储层中的多相流特性而广为人知。它主要通过改变润湿性以及扩散系数来影响流动行为。本研究中，通过代表实际气藏反凝析现象的岩心实验来研究包含含和不含表面活性剂的气体凝析液的多相流动特征。 商用阴离子表面活性剂Alfoterra®123-4S，在表面活性剂浓度为2000 ppm下，其相对渗透率提高了17%以上，这也是流动条件下的最佳浓度。表面活性剂的效果是其浓度的非线性函数，主要归因于高于临界胶束浓度（CMC）值的平台效应。 采用Winprop进行了相关相态研究。
ABSTRACT
Natural gas, which accounts for a quarter of world’s energy, has been a major energy source because of its abundance and less impact on environment. With explorations at higher depth, pressure and temperature, the share of gas condensate reservoirs to global gas production is increasing. A unique production challenge associated with these reservoirs is the condensate blockage problem, which is the buildup of condensate liquid saturation around wellbore as a result of drawdown below dew point pressure. Mitigation of this problem requires in depth understanding of the multiphase flow of liquid and gas. Surfactants are well known in the literature for affecting such multiphase flow characteristics in reservoirs. They affect the flow behavior primarily by wettability alteration as well as spreading coefficient modification. In this study, multiphase flow characteristics of gas condensates, with and without surfactants were observed by running corefloods representing actual reservoir retrograde condensation phenomena. A commercial anionic surfactant, Alfoterra® 123-4S, was successfully shown to facilitate condensate removal with relative permeability enhancement of over 17 percent at a surfactant concentration of 2000 ppm, which was also the optimum concentration under the flowing conditions. The efficacy of surfactant was observed to be a non-linear function of its concentration and this is attributed mainly to the pleateauing effect above the critical micellar concentration (CMC) values.
