Effects of Surfactants and Alkalis on the Stability of Heavy-Oil-in-Water Emulsions

Abstract

In this work, the effects of combining a surfactant/alkali on the stability of heavy-oil-in-water emulsions are analyzed by use of bottle testing, spinning-drop interfacial-tension (IFT) meters, microscopes, conductivity meters, zeta-potential analyzer Turbiscan laboratory expert stabilizer, and Anton Paar rheometer. The experimental results showed that the formulated surfactant (BS-12 and OP-10) had an optimal mass ratio (1:2), and the water-separation rates initially decreased sharply as the concentrations of the surfactant increased, before decreasing moderately until reaching a minimum value. The formulated alkali solution exerted a positive synergistic effect in tandem with the surfactant at low alkali concentrations. In this way, an increasing number of petroleum soaps are produced by reactions between the alkali solutions and the active components in heavy crude oil. However, the effect was reversed at high alkali concentrations, where the compression of the alkali on the electric double layer was more significant. Images of the emulsions taken with a microscope showed that the sizes of the oil droplets were the smallest when the alkali concentration was 0.2% and mass ratio of NaOH and TEA (triethanolamine) was 1:1, which indicated that the amount of petroleum soap produced reached the maximum at this point. In addition, TEA, as a type of surface-active molecule, can form cross-multiple adsorption and hydrogen-bonding structure with surfactant and petroleum soap at the water/oil interface. When the oil/water ratio was 7:3, the water-separation rate reached its lowest point 5.33% for 3 hours. In addition, the emulsion stabilized by the surfactant and the compositional alkali possesses salt tolerance and temperature resistance. When the concentration of the bivalent salt (CaCl 2 and MgCl 2 ) increased to 0.01molÁL À1 , the water-separation rate was less than 20%, and when the temperature increased from 30 to 60 C, the growth of back-scattering (BS) value was less than 2%.

Agentes emulsificantes aplicados à estabilização de emulsões o/a com intuito de melhorar o transporte de óleos pesados através das tubulações: Um estudo bibliométrico

“…O interesse crescente da comunidade científica nesta área de estudo pode estar relacionado à necessidade de se explorar reservatórios de óleos pesados e extrapesados, haja vista que as reservas de óleos leves têm diminuído gradativamente por conta do aumento da demanda energética. Considerando que óleos pesados apresentam baixa fluidez e que o transporte convencional não é adequado para escoar estes tipos de óleos (Sun et al, 2016), o aumento na quantidade de publicações ao longo dos 10 anos analisados é justificado pela necessidade de desenvolvimento de rotas alternativas, com fins de contornar os problemas resultantes da alta viscosidade destes óleos. Após a inclusão do critério "tipo de trabalhoartigo científico", o total de publicações foi reduzido para 155, sendo 113 do Science Direct, 18 do One Petro e 25 do Web of Science.…”

“…Por definição, o petróleo pesado é todo óleo cru que possui densidade igual ou inferior a 20 ºAPI, enquanto o petróleo extrapesado é aquele que apresenta densidade menor ou igual a 10 ºAPI (Sharma et al, 2018). A considerável atenção dada pela comunidade científica e pela indústria do petróleo à exploração de óleos não convencionais está pautada em previsões que apontam que, em breve, os óleos pesados vão ocupar o lugar de destaque no cenário energético mundial, substituindo óleos convencionais e tornando-se a principal fonte de energia fóssil (Sun et al, 2016).…”

Emulsion Characterization of the Heavy Oil-Alkaline Water System in Alkaline Flooding Mechanism Investigation Using a Combination of Modified Bottle Test and Sandpack Flooding

“…It is worth noting that water:oil volume ratio has a big influence on the emulsion type generation. As studied, when water:oil ratio is lower than 1:9, phase inversion occurred and only water in oil emulsion will be formed (Sun et al, 2017). In this study, there is no intention in preparation of specific type of emulsion.…”

“…On the contrary, there is a significant deviation of the two concentrations in Figure 15B for the Na2CO3 case. This is because weak alkali introduced surfactants are more hydrophilic (Sun et al, 2017) so most of them stay in the aqueous phase rather than adhering to the interface. Such a fact explains the incapability of the IFT spinning drop test to predict the optimum weak alkali concentration when O/W emulsion is dominant.…”

“…the operating alkaline concentration, salinity, and temperature of heavy oil alkaline flooding are relatively rough. These preliminary screening methods mainly include bottle test and dynamic IFT measurement (Acevedo et al, 2001;Dehghan et al, 2013;Sun et al, 2017) while both tests have their limitations. The spinning drop IFT test is a convenient way to quantify the emulsification process because the IFT is directly proportional to the amount of surfactants adhering to the fluids' contact.…”