A STUDY OF ACETIC ACID ROLE IN C02 CORROSION

In order to understand and determine the mechanism and corrosion reaction of C02
~orrosion in presence of acetic acid, HAc studies and experiments about the matter has been
ione. This report will document all information and data collected from experiments done
throughout the project. In major oilfield, C02 corrosion is considered as major problems that cost
million of dollars to the industry. C02 corrosion caused by carbonic acid that formed when C02
gas dissolved in the water or brine that accompanies oil production at high pressures common in
~nderground oil and gas reservoirs. Usually, COz corrosion problems are manageable and under
~ontrol. However, when small amount of organic acid that dominated by acetic acid is present in
the system, the corrosion rate changes drastically. In this project, Electrochemical Impedance
Spectroscopy ( EIS ) and Linear Polarization Resistance ( LPR ) was the measurement technique
that being used in the project. EIS is a technique employed to study the mechanisme of C02
corrosion in presence of acetic acid, while LPR is a technique to determine the corrosion rate. All
experiments were conducted in a 3% NaCl solution of pH 5.5 and temperature 60°C.Based from
results that was gathered from the experiment, LPR shows that corrosion rate for lOOOppm and
2000ppm of acetic acid increased significantly compared to blank C02. Meanwhile for 4000ppm,
the corrosion rate decreased. This phenomenon was due to excessive non ionized acetic acid
HAc. The carbonate ions from the iron carbonate could not dissolve the excessive amount of
acetate leaving the iron ions to reacts with it and form iron acetate. Formation of FeC03 that
decrease the corrosion rate can be proven from the trend of the data collection that shows
significant decrease with time. It is correct to claim that in presence of acetic acid, the corrosion
rate could increase significantly.