The Simultaneous Effect of Brine Salinity and Dispersed Carbonate Particles on Asphaltene and Emulsion Stability

Abstract

The oil recovery improvement by low-salinity waterflooding (LSWF) must be achieved with minimal formation damage. The asphaltic fractions of crude oil can be destabilized when in contact with incompatible injection brines resulting in organic formation damage. Due to the lack of fundamental understanding about the potential effect of rock presence on this phenomenon, in this study, the simultaneous effect of brine salinity and calcite rock presence on asphaltene instability in an emulsified system was investigated by developing a new experimental protocol. In this method, calcite rock is dispersed in different brines with total salinity ranging from 0−189,365 ppm and then mixed with oil to find the rock and brine effect on asphaltene and emulsion stability. UV−vis spectroscopy is performed on the supernatant oil phase before and after contact with brine to assess quantitatively asphaltene instability. Oil/water IFT measurements before and after contact and microscopic analysis of the water droplet size were conducted to evaluate the water/oil interface behavior. Besides, the zeta-potential for suspended calcite particles in different brines was measured to evaluate the electrokinetics of rock-oil interaction. The results show increased asphaltene instability when oil makes contact with the brine in an emulsified system. This highly depends on the brine type, and the maximum precipitation occurred at an intermediate salinity with two-times diluted seawater. While the trend of before-contact IFT and the water-in-oil emulsion size at different salinities is consistent, the UV−vis absorbance of bulk oil shows a reverse tendency with the after-contact IFT. Asphaltene deposition generally increased when solid calcite particles were present in the emulsified system, and at higher salinities, more asphaltene adsorption on the rock surface occurred due to a larger attractive force between rock and asphaltene. This trend is consistent with the results of the zeta-potential measurements. These novel findings can help avoid unrepresentative results regarding organic damage in LSWF.

n-C7 Asphaltenes Characterization as Surfactants and Polar Oil from the HLDN Model Perspective

“…(iii) large droplet size of the dispersed phase (oil) due to several variables, such as the concentration and type of salt (NaCl) in the brine , and the energy applied during the emulsification process.…”

“…At this respect, some researchers have demonstrated that at low concentrations (C A < 100 ppm) asphaltenes have small negative charges capable of producing electrical repulsions between drops of oil. 93 Nevertheless, the low stability of the O/W emulsions obtained in this work could be due to several factors, such as (i) little amount of asphaltenes adsorbed at the oil− brine interface (C A < CNAC), (ii) repulsion−attractive interactions produced by the asphaltene polar groups and aromatic rings oriented toward the aqueous phase, 98,99 (iii) large droplet size of the dispersed phase (oil) due to several variables, such as the concentration and type of salt (NaCl) in the brine 100,101 and the energy applied during the emulsification process.…”

Study of Interfacial Phenomena of High Asphaltene Crude Oil with Different Salinity Water and ZrO2 Nanoparticles

“…This technology has been shown to enhance the recovery rate by an additional 5–20%; thus, its efficacy relies on complementary technology. , Presently, research on low-salinity waterflooding primarily examines its impact from three aspects: crude oil, rock, and brine. Natural surface-active substances such asphaltenes and colloids in crude oil, as well as clay minerals in sandstone or hard gypsum in carbonate rock, CaCO 3 , and Ca 2+ , as well as Mg 2+ and SO 4 2– in brine, play roles in the oil displacement process. − …”

Water/oil emulsion and asphaltene instability in different formations during low-salinity waterflooding: an experimental study

“…Our recent studies indicate that the presence of calcite rock affects asphaltene behavior, prompting further investigation on the impact of different rock types on asphaltene instability during LSWF [39]. This comprehensive approach aims to understand factors influencing asphaltene deposition, crucial because unstable asphaltene can lead to pore plugging and formation damage.…”

“…To investigate asphaltene performance and its impact on emulsion stability, we followed the modified indirect method outlined by Balavi et al [39]. This involved measuring the UV-Vis absorbance of the oil phase before and after contact with the aqueous phase and evaluating water droplet size distribution.…”