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Corrosion Inhibitor Selection for High Temperature Sweet Gas Wells

CO2 is well recognized to be a major factor accelerating the corrosion process. When CO2 dissolves in water, it forms carbonic acid which is a weak acid and it dissociates only slightly to form bicarbonate ion followed by further dissociation to form carbonate ions (Figure 1). At pH levels lower than 5.5, the bicarbonate ions (HCO3-) are the main carbonic species in solution.

Product Number: MECC23-20111-SG
Author: Anas S. Rushaid; Ali A. Jabran; Hassan A. Ajwad; Waleed A. Ghamdi
Publication Date: 2023
$20.00
$20.00
$20.00

Corrosion protection of production tubulars in high-pressure, high-temperature (HPHT) sweet gas wells is among the challenges encountered by corrosion engineers. Corrosion control by inhibitors in these wells has always been a challenge for the developers of oilfield chemicals. This is mainly due to the poor stability of the chemicals at elevated temperatures. The inhibitor components tend to degrade at high temperatures, losing the corrosion control function and, in some cases, these degraded products can pose adverse effects by promoting higher corrosion rates. This paper will focus on a laboratory study on various inhibitor chemistries under simulated HPHT sweet gas wells conditions. As part of the investigation, the corrosion behavior of the tubular carbon steel materials along the well depth at various temperatures was studied to measure the inhibitor capacity to protect the entire production tubulars from top to bottom sections. The study confirmed that temperature in a CO2 environment was the main factor controlling the corrosion process with significantly higher rates at the upper sections of the wells. None of the investigated inhibitor chemistries exhibited adequate corrosion control efficiency.

Corrosion protection of production tubulars in high-pressure, high-temperature (HPHT) sweet gas wells is among the challenges encountered by corrosion engineers. Corrosion control by inhibitors in these wells has always been a challenge for the developers of oilfield chemicals. This is mainly due to the poor stability of the chemicals at elevated temperatures. The inhibitor components tend to degrade at high temperatures, losing the corrosion control function and, in some cases, these degraded products can pose adverse effects by promoting higher corrosion rates. This paper will focus on a laboratory study on various inhibitor chemistries under simulated HPHT sweet gas wells conditions. As part of the investigation, the corrosion behavior of the tubular carbon steel materials along the well depth at various temperatures was studied to measure the inhibitor capacity to protect the entire production tubulars from top to bottom sections. The study confirmed that temperature in a CO2 environment was the main factor controlling the corrosion process with significantly higher rates at the upper sections of the wells. None of the investigated inhibitor chemistries exhibited adequate corrosion control efficiency.