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Results
Electrochemical Investigation of the Evolution of Interfacial Electrodic Processes For Downhole Tubular Steels In CO2 Saturated Environments
Gavanluei, Arshad Bajvani (Cameron International Inc.) | Al-Abbas, Faisal (Saudi Aramco) | Elramady, Alyaa (Colorado School of Mines) | Mishra, Brajendra (Colorado School of Mines) | Olson, David L. (Colorado School of Mines)
ABSTRACT ABSTRACT CO2 corrosion behavior and atomic processes at the corroding interface of a high strength low alloy tempered martensite tubular steel were investigated for 177 h at 70 and 80 °C using electrochemical and surface evaluation techniques. Linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS) were applied to assess the corrosion rate and evolution of atomic processes and interfacial phenomena. The corrosion rate increased at the beginning to a maximum, then, it declined with time at both temperatures. Variation of pH was monitored for the test duration, and it changed from 3.78 at the beginning to 5.82 and 5.94 for 70 and 80 °C respectively. EIS measurements and equivalent circuit modeling demonstrated the formation of a porous scale upon beginning the experiments. Increase in charge transfer resistance with time indicated a decrease in porosity of scale, increasing its protectiveness. X-ray diffraction analysis did not detect formation of iron carbonate in these conditions. INTRODUCTION Extraction of oil and gas from geological formations is accompanied with impurities such as water, carbon dioxide and hydrogen sulfide, as well as various salts and organic acids. The combination of water and carbon dioxide in oil and gas provides a corrosive environment, which influences the integrity of the facilities. Dissolved carbon dioxide in water forms weak but corrosive carbonic acid. The presence of carbonic acid causes the corrosion of steel in downhole environments and hydrocarbon transportation pipeline. It has been reported that chemical and electrochemical reactions are responsible for the CO2 corrosion of steel. Chemical reactions take place in the solution, while three possible cathodic reactions, depending on the pH of the solution and the anodic reaction, take place on the surface of steel. Occurrence of these reactions release bicarbonate, carbonate and iron ions in the solution and exceeding the concentration of ions beyond their solubility limits leads to the precipitation of iron carbonate on the surface of steel as:
- Asia > Middle East > Saudi Arabia (0.46)
- North America > United States > Texas > Harris County > Houston (0.18)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Effects of Carbon Dioxide Partial Pressure And Strain Rate On the SCC Susceptibility of Low Alloy Tempered Martensite Tubular Steels Used In Downhole Environments
Gavanluei, Arshad Bajvani (Cameron International Inc. Subsea Systems) | Al-Abbas, Faisal (Saudi Aramco Midra Office Complex) | Mishra, Brajendra (Colorado School of Mines) | Olson, David L. (Colorado School of Mines)
ABSTRACT: Stress corrosion cracking (SCC) susceptibility of a tempered martensite downhole tubular steel were evaluated in CO2 partial pressures from 500-3000 kPa and different strain rates from 5×10-7-2 ×10-6 S-1 at 175°C in carbonate-bicarbonate environments. Constant extension rate tests coupled with a high temperature/high pressure autoclave were used. Results revealed the occurrence of SCC at CO2 partial pressure from 500-1500 kPa. However, at CO2 partial pressures greater than 1500 kPa, SCC susceptibility decreased and uniform corrosion was observed without cracking. In addition, increasing strain rate decreased SCC susceptibility. Corrosion products and cracks distribution were analyzed by X-ray diffraction and scanning electron microscopy. The occurrence of SCC was attributed to the formation of protective corrosion products mainly iron carbonate layer on the surface. INTRODUCTION The search for new oil and gas resources has forced the industry towards deeper, deviated wells and the use of extended reach drilling technology, horizontal wellbores and multiple lateral completions. Operational activities have moved toward harsher environments in deeper high pressure/high temperature wells and deep water for the exploration of new reserves of oil and gas. New project development and operations have faced increased challenges in which facilities integrity and accurate prediction of materials performance become important. Additionally, the economic incentive of multi-phase transportation through subsea completions and long infield flowlines causes increased risk of corrosion. As corrosion becomes a main operational hindrance to successful oil and gas production, management and control of corrosion becomes necessary for the cost effective design of facilities and their safe operations.1-2 Traditionally, carbon and low alloy steels are used for transportation pipelines as well as downhole tubing and casing. Even though these steels do not show appropriate performance for uniform CO2 corrosion, the industry still relies on the extended use of carbon and low alloy steels.
- Asia > Middle East > Saudi Arabia (0.68)
- North America > United States > Texas > Harris County > Houston (0.17)