ABSTRACT

Carbon capture utilization and storage (CCUS) are technologies aimed at capturing CO2 and preventing its subsequent emission. Though CO2 transport and injection for enhanced oil recovery (EOR) has been a common practice for the Oil and Gas industry for over 40 years, new challenges arise when the CO2 source is anthropogenic. Industrial CO2 stream composition will carry impurities such as NO2 (nitrogen oxides), SO2 (sulfur oxides), O2 (oxygen), H2S (hydrogen sulfide) that could affect material corrosion behavior.

A complete testing program was undertaken to assess the main corrosion risks associated to the application: Sulfide Stress Cracking (SSC), Stress Corrosion Cracking (SCC), crevice and mass loss resistance. The results confirm the effects of impurities such as SO2, NO2 and oxygen on corrosion behavior.

Carbon low alloyed steel (N80Q) material presented a higher corrosion rate, and it is not suitable for injection tubing but may be acceptable for casing materials when not permanently exposed to the CO2 stream. UNS S41426 (S13Cr) material needs special considerations for CCS application due the presence of some localized corrosion when exposed to a high saline water phase. UNS S31803 (22Cr) could be suitable for a less severe environment including additional testing, whilst UNS S32760 (25CrS) presented good corrosion behavior and is suitable for the application.

INTRODUCTION

CCUS (Carbon Capture, Utilization and Storage) is recognized as a key technology to achieve net zero targets. After its capture and transport, the carbon dioxide (CO2) stream is injected into one of several types of stable geological formations, such as depleted oil and gas reservoirs and saline aquifers, trapping and preventing its subsequent emission1,2.

The oil and gas industry has extensive experience injecting CO2 in oil fields to increase the oil production, this process is known as EOR (Enhanced Oil Recovery), the CO2 used on this process has two different sources, either from natural CO2 reservoirs or industrial sources with some impurities, such as argon (Ar), methane (CH2) and nitrogen (N2). A notable difference between the CO2 stream employed for EOR and industrial CO2 targeted for permanent storage is the composition of the gas stream. Industrial CO2 streams will carry impurities such as NO2, SO2, O2, and H2S. Their concentration depends on many factors, such as raw materials, fuel, capture technology, and the purification steps. These impurities increase the CO2 stream injection challenges by changing the fluids thermo-physical and chemical properties, water solubility, segregating CO2 into the aqueous phase, potentially lowering the solution pH, and affecting material corrosion3,4. Thus, there is a strong need from the industry to understand material behavior in CO2 streams from industrial sources to formulate a robust and cost-efficient materials selection strategy for the CCS injection wells.

Keywords:
corrosion management, geologist, riser corrosion, subsurface storage, geology, co 2, production chemistry, flowline corrosion, enhanced recovery, corrosion inhibition
Subjects:
Production Chemistry, Metallurgy and Biology, Pipelines, Flowlines and Risers, Improved and Enhanced Recovery, Storage Reservoir Engineering, Environment, Materials and corrosion, CO2 capture and sequestration, Climate change, Well Integrity, Subsurface corrosion (tubing, casing, completion equipment, conductor)
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