posted on 2023-02-24, 14:07authored byZhiqi Zhao, Xue Xia, Yanan Li, Daiwei Liu, Wei Cai, Chuanxian Li, Guangyu Sun, Bo Yao, Fei Yang
Dodecylbenzenesulfonic
acid (DBSA) is injected into wellbores as
an asphaltene dispersant to alleviate asphaltene deposition problems.
The addition of DBSA will change the dispersion of asphaltenes in
the crude oil, affecting the wax precipitation property of the crude
oil as well as the adsorption behavior of asphaltenes at the oil–water
interface, thus significantly altering the W/O emulsion’s stability.
In order to provide better theoretical guidance for oil–water
separation in oilfield gathering and production processes, in the
paper, the effects of DBSA concentration (from 0 to 500 ppm) on the
emulsions’ stability containing both asphaltenes and paraffin
wax and the mechanism were systematically investigated at two different
temperatures (30 and 15 °C) based on the wax precipitation and
rheological properties of the model crude oil, the oil–water
interface adsorption properties, and the macroscopic and microscopic
properties of the emulsion. The outcomes demonstrated that the test
temperature had a highly substantial impact on the model emulsion.
The main element affecting the stability of the emulsion at 30 °C
(above the wax appearance temperature (WAT)) was the interfacial structure’s
strength. The low-temperature flowability of the oil phase primarily
controlled the process of emulsion stabilization at 15 °C (below
the WAT). Furthermore, we speculate that the wax crystals could precipitate
on the surface of the emulsified droplets, which also facilitated
emulsion stability at 15 °C. Combining the above experimental
observations, the mechanism of DBSA concentration affecting the emulsion
stability was proposed, which would contribute to solving the issues
in the emulsion breaking and dewatering process of crude oil emulsions.