MODIFICATION OF COMMERCIAL DEFOAMERS FOR EFFICIENT FOAM MITIGATION UNDER SIMULATED ENHANCED WATER-ALTERNATING GAS (EWAG) TREATMENT

The excessive formation of foam caused by the injection of surfactant foams in
FAWAG application has led to significant problems in the oil well production and
separation facilities. Defoamer is introduced to break and destroy the foams produced
in the separator. Over the years, the development of defoamers has reached its fourth
generation, referring to modified silicone defoamers. Several studies have shown that
modified defoamer gives better performances under harsh conditions and have greater
solubility and efficiency. Besides, studies also reveal that a gemini-based modified
defoamer can give good antifoaming ability and remain active even when dissolved in
a solvent. Unfortunately, not all defoamer composition is suitable for every application
since different oilfields may have different treatment methods and conditions.
Consequently, several different compounds should be examined to determine the most
appropriate defoamer for specific treatment. For this reason, various commercially
available defoamers with different family types were screened under simulated EWAG
treatment to select the best chemicals with a short foam collapse time. These selected
commercial defoamers were then characterized to determine the best parent chain for
modification into gemini based chemicals. Four modified silicone-based defoamers
were successfully synthesized and characterized for high foam mitigation at a lower
temperature and pressure range. The performance of modified defoamers was evaluated
using TECLIS Foamscan under simulated EWAG treatment. Results show that all four
modified silicone-based defoamers, especially amide modified defoamer (S2), showed
excellent performance as a defoaming agent over other defoamers (S1, S3 and S4) to
mitigate foam in specific conditions. The study on the factor affecting the performance
of defoamers has proved that the best-case condition for the modified defoamer was at
high temperature (60°C), gas flow rate of 1.0 L/min, and low ratio concentration of
surfactant polymer-to-brine (30:70). The study on bubble counts and distributions using
KRÜSS Dynamic Foam Analyzer revealed that S2 excellently contributes to the
formation of unstable foams that can fasten foam destruction in the foaming system.