Viscoelastic surfactants (VES) are essential components in self-diverting acid systems. Their low thermal stability limits their application at elevated temperatures. The industry introduced new VES chemistries with modified hydrophilic functional groups, which enhances their thermal stability. These new chemistries are still challenged by the lack of compatibility with corrosion inhibitors (CI). This work aims to study the nature and the mechanism of the interaction between the VES and the corrosion inhibitors, which affects both the rheological and corrosion inhibition characteristics of the self-diverting acid system.
This study is based on rheology and corrosion inhibition tests, where combinations of VES and corrosion inhibitors are tested and complemented with chemical and microscopic analysis. Negatively charged thiourea and positively charged quaternary ammonium corrosion inhibitors were selected to study their impact on both cationic and zwitterionic VES systems. Each mixture of the corrosion inhibitor and the VES was blended in a 15 and 20 wt% HCl acid mixture, then assessed for its viscosity at different shear rates, CI concentrations, and temperatures up to 280°F in live and spent acid conditions. Each acid solution was assessed using Fourier-Transform-Infra-Red (FTIR) before and after each rheology and corrosion test to track the changes of the mixture functional groups. Each mixture was examined under a polarizing microscope to assess its colloidal nature. The corrosion inhibition effectiveness of selected acid mixtures was evaluated. N-80 steel coupons were immersed statically in the acid mixture for 6 hours at 150°F and 1,000 psi. The corrosion rate was evaluated by using metal coupon weight loss analysis followed by optical microscope examination for the metal surface.
The interaction between the CI and the VES surface charges and molecular geometries dictates both the rheological and the inhibitive properties of the acid mixtures. The use of a small molecular structure anionic CI with a cationic VES, results in a fine monodispersed CI particles in the VES-acid system. The opposite charges between the CI and the VES results in electrostatic attraction forces. Both the fine dispersion and the electrostatic attraction enhances the rheological performance of the mixture and packs the corrosion-inhibiting layer. The addition of a bulk and similarly charged CI with the VES results in a coarse polydispersed CI particles with repulsive nature with the VES. These properties increase the shear-induced structures and lower the packing of the inhibition layer deposited on the metal coupons, which decrease the rheological performance of the acid mixture and increase its corrosion rate. The FTIR analysis shows that there is no chemical reaction between the CIs and the VESs tested.
This work investigates the interactions between the corrosion inhibitors and the viscoelastic surfactants. It explains the impact of the surface charge of both corrosion inhibitors and VES on their rheological and corrosion inhibition characteristics. It adds a selection criterion for compatible VES and corrosion inhibitors.
Yang, Zhen (College of Petroleum Engineering, China University of Petroleum) | Wang, Yefei (College of Petroleum Engineering, China University of Petroleum) | Wang, Renzhuo (College of Petroleum Engineering, China University of Petroleum) | Chen, Wuhua (College of Petroleum Engineering, China University of Petroleum) | Ding, Mingchen (College of Petroleum Engineering, China University of Petroleum) | Zhan, Fengtao (College of Science, China University of Petroleum) | Hou, Baofeng (School of Petroleum Engineering, Yangtze University)
Propargyl alcohol, at great expense and with high toxicity, is often used as an essential synergistic component of corrosion inhibitors for acidizing; however, in our recent work, a novel indolizine derivative was found to exhibit effective protection performance without the synergism of propargyl alcohol. These indolizine derivatives were easily prepared from quinoline, pyridine, and several halide compounds via 1,3-dipolar cycloaddition reaction. The derivative could prohibit the corrosion of metal at an extremely low concentration and fulfills the requirements of increasingly stringent environmental standards. The inhibition performance of the indolizine derivatives to N80 steel was investigated in 15 wt.% HCl and 20 wt.% HCl by weight loss measurements, potentiodynamic polarization method (Tafel curves), and electrochemical impedance spectroscopy (EIS).
In the absence of propargyl alcohol, when the dosage of indolizine derivatives in 15 wt.% HCl is 0.1 wt.%, the inhibition efficiency of N80 steel increases to approximately 99% at 90 °C. The indolizine derivative shows a superior anti-corrosion performance at a much lower concentration than that of benzyl quinolinium chloride (BQC, a commonly used compound in current acidizing corrosion inhibitors), which serves as the precursor to indolizine derivatives. More importantly, these protective indolizine compounds behave better than the synergistic inhibitor propargyl alcohol. The reinforced active adsorption groups in indolizine derivatives could provide extra adsorption sites and fasten the inhibitive molecule to the steel surface, thus augmenting the protective effect. Here, a new inhibitive indolizine derivative is presented as an acidizing inhibitor that may also offer a low-pollution technique for corrosion prevention.
Wang, Renzhuo (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Yang, Zhen (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Chen, Wuhua (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Wang, Yefei (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Ding, Mingchen (Key Laboratory of Unconventional Oil & Gas Development, Shandong Key Laboratory of Oilfield Chemistry, School of Petroleum Engineering, School of Petroleum Engineering ,China University of Petroleum, East China, Ministry of Education) | Zhan, Fengtao (College of Science, China University of Petroleum)
Among the numerous corrosion inhibitors for acidizing, the propargyl alcohol, with great expense and high toxicity, is often added as an important synergistic component. In this work, novel indolizine derivative high-effective inhibitor for acidizing was introduced. The indolizine derivative could exhibit an excellent protection performance at a much lower concentration without the synergism of the poisonous propargyl alcohol. The two inhibitive indolizine derivatives in this paper were synthesized easily from Benzyl Quinolinium Chloride (BQC, known as the a commonly used key component of acidizing inhibitor) via 1,3-dipolar cycloaddition reaction. The indolizine derivatives were purified by the column chromatography and the structure were characterized by NMR and elementary analysis etc.
The inhibition performance of the BQC, propargyl alcohol and the indolizine derivatives in 15 wt.% HCl and 20 wt.% HCl for N80 steel was investigated by weight loss test and potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The conclusion obtained from the electrochemical tests is in accordance with the results of gravimetric test. It is amazing to notice that the derivative could exhibit a much better anti-corrosion performance than its precursor BQC and propargyl alcohol in the abserence of the poisonous propargyl alcohol.
Compared with BQC, the active adsorption sites are reinforced and strengthed in indolizine derivatives, and therefore, the inhibitor would fasten the steel surface more stronger. The firmly adsorbed inhibitors would prohibit the steel from the contact of acid. Indolizine derivative is presented as a new concept of effective acidizing inhibitor for the first time in this paper. It may offer a new method for the corrosion prevention in acidification engineering.
This updated NACE International standard practice provides the most current technology and industry practices for material requirements and the use of tape coatings for external mainline coating, coating repair, coating rehabilitation, and coating weld joints on buried metal pipelines. The standard is applicable to underground metal pipelines in the oil and gas gathering, distribution, and transmission industries, as well as water and wastewater pipelines. This standard is intended for use by corrosion control personnel, design engineers, project managers, purchasing personnel, and construction engineers and managers.
This NACE International standard practice provides the most current technology and industry practices for material requirements and the use of tape coatings for external mainline coating, coating repair, coating rehabilitation, and coating weld joints on buried metal pipelines. This standard is intended for use by corrosion control personnel, design engineers, project managers, purchasing personnel, and construction engineers and managers. It is applicable to underground metal pipelines in the oil and gas gathering, distribution, and transmission industries, as well as water and wastewater pipelines.
This standard was prepared in 2009 and revised in 2019 by NACE Task Group (TG) 251, “Coatings, Tape for External Repair, Rehabilitations, and Weld Joints on Pipelines.” This TG is administered by Specific Technology Group (STG) 03, “Coatings and Linings, Protective: Immersion and Buried Service.” It is sponsored by STG 04, “Coatings and Linings, Protective: Surface Preparation,” and STG 35, “Pipelines, Tanks, and Well Casings.” This standard is issued by NACE International under the auspices of STG 03.
Furnishes guidelines that provide corrosion control personnel, owners, operators, designers, manufacturers, and contractors information on corrosion control of prestressed concrete cylinder pipe (PCCP) and mortar-coated steel pipelines for water or waste water service through the application of cathodic protection. The guidelines presented are applicable to new or existing buried pipelines with or without a supplemental coating.
The purpose of this standard practice is to furnish guidelines that provide corrosion control personnel, owners, operators, designers, manufacturers, and contractors with information on controlling external corrosion of embedded steel in concrete pressure pipelines and mortar-coated steel pipelines for water or waste water service through the application of cathodic protection (CP). The guidelines presented are applicable to new or existing buried pipelines with or without a supplemental coating.
The provisions of this standard should be applied under the direction of competent persons who are qualified to engage in the practice of corrosion control on buried or submerged metallic pipelines. Such persons may be licensed professional engineers or persons recognized as Corrosion Specialists or CP Specialists by NACE. The professional experience of such persons should include suitable experience in CP of prestressed concrete structures, if protection of that type of structure is being planned.
This standard was originally prepared in 2000 by NACE Task Group T-10A-28, a component of Unit Committee T-10A on Cathodic Protection. To provide the necessary expertise on all aspects of the subject and to receive input from all interested parties, Task Group T-10A-28 was composed of corrosion consultants, consulting engineers, architect-engineers, CP engineers, researchers, pipeline owners, and representatives from both industry and government. The standard was reaffirmed in 2004 by Specific Technology Group (STG) 05, “Cathodic/Anodic Protection” and revised in 2008 and 2014 by Task Group (TG) 019, “Mortar-Coated Pipes: Cathodic Protection Criteria.” It was reaffirmed with editorial changes in 2019 by TG 019. This standard is issued by NACE under the auspices of STG 05.
In this work we aim to enhance the sour-gas loading in acid-gas removal (AGR) systems, maximizing oil-production rate at the tertiary phase and enhanced oil recovery (EOR), and mitigating vented carbon dioxide (CO2) with minimal modification to the existing systems. We conducted a simulation study on the basis of a real natural-gas liquids (NGLs) plant and Qatari oil wells with a 390-MMscf/D feed of sour gas using HYSYS and ProMax process simulation tools to evaluate the novel configurations compared with a conventional AGR system.
The results show that the acid-gas loading improved from 0.48 to 0.81, and the amine circulation rate decreased by 40%, while maintaining the treated-gas quality specifications (4 ppm H2S, 1 mol% CO2). The required CO2 compression power for CO2-EOR decreased by 15.49%, and the oil production was enhanced by 1,360 B/D. In addition, 13.6 MMscf/D of CO2 is mitigated and used rather than vented.
Langé, Stefano (TOTAL S.A. 2 Place Jean Millier) | Zhao, Jing (TOTAL S.A. 2 Place Jean Millier) | Cadours, Renaud (TOTAL S.A. 2 Place Jean Millier) | Weiss, Claire (TOTAL S.A. 2 Place Jean Millier) | Bernadet, Mikael (SOBEGI Induslacq) | Caetano, Michel (SOBEGI Induslacq) | Layellon, Lise (SOBEGI Induslacq)
This paper presents how the optimization of the solvent composition provides significant OPEX reduction and simplifies process management.
Removing mercaptans from natural gas is becoming a tough work for operating companies due to the tightening of commercial specifications for sulfur-containing molecules in the final products. Beside this, about 40% of the known gas reserves are sour; some of them contain H2S and mercaptans. To commercialize these gas fields in a profitable way, smart process solutions focused on energy efficiency are needed. Classical gas sweetening units are based on chemical absorption by means of aqueous alkanolamines to remove CO2 and H2S from natural gas. These solvents have limited mercaptans removal capacity, requiring supplementary removal processes. This has a negative impact on the overall gas processing costs.
To face this challenge, TOTAL has developed a new series of hybrid solvents able to remove, in a one- step operation, CO2, H2S and mercaptans. Process performances can be improved without plant modification. The first solvent formulation was based on DiEthanolAmine (DEA) and was implemented in the sweetening units of the Lacq plant (France), demonstrating the benefits of the new hybrid solvents at industrial scale.
DEA solvent is a widely used and easy-to operate/monitor solvent. However, DEA has the drawback to be sensitive to chemical and thermal degradation. Moreover, DEA regeneration is quite energy demanding.
To overcome these problems, the amine components have been changed. The choice of new components is driven by following characteristics: good solvent stability, low regeneration energy demand, high CO2 and H2S removal efficiency.
A mixture of MethylDiEthanolamine and Piperazine (MDEA+PZ) has been adopted as the solution to replace the DEA based solvent. The choice has been made thanks to the good chemical stability of MDEA and the high performance of PZ as an activator to boost the rate of the absorption process.
This paper presents the operational feedback with this new formulation. The first benefit of the hybrid solvent formulated with MDEA+PZ is that it was implemented in the existing unit without plant modification. Other advantage is the improved chemical and thermal stability. This solvent swap allows to decrease the reboiler duty of the solvent regeneration, to reduce the chemicals consumption, while keeping the final product quality unchanged.
The benefits of the solvent swap will be supported by operating data collected before and after the solvent swap.
Sales, Daniella Guedes (Vallourec Research Center France) | Néel, Guillaume (Vallourec Oil & Gas France) | Oliveira, Jonathas (Vallourec Oil & Gas France) | Thébault, Florian (Vallourec Research Center France)
The limit of Sour Service (SS) grades regarding Sulfide Stress Cracking (SSC) resistance is defined by ANSI NACE MR0175 / ISO 15156 standard. For instance, API T95 grade is acceptable to be used in all regions of environmental severity and for all temperatures. As per Annex B of the same standard, SSC laboratory testing in accordance with NACE TM0177 Methods A and D in Solution A saturated by 1 bar H2S partial pressure (PH2S) qualify a material for all SSC regions, up to 10 bar PH2S. To evaluate this statement and verify if the existing NACE guidelines apply also for SS 110 ksi Specified Minimum Yield Strength (SMYS), a procedure to assess the SSC resistance in high H2S pressure was developed. This procedure was applied to enhanced SS 95 ksi and 110 ksi SMYS materials. The methodology consists in regular purging and filling of the gas phase in order to keep constant the PH2S and to remove hydrogen gas produced by generalized corrosion. Investigations combined NACE TM0177 Method A and D tests, characterizations of the iron sulfide scales and hydrogen electrochemical permeations. This methodology enables to give some insights on the corrosion mechanism and the influence of high partial pressure of H2S on the SSC resistance.
Anthony, J. (Nalco Champion an Ecolab Company) | Harrington, R. (Nalco Champion an Ecolab Company) | Durnell, C. (Nalco Champion an Ecolab Company) | Sanders, J. (Nederlandse Aardolie Maatschaapij B.V.) | Gerritsen, D. (Nederlandse Aardolie Maatschaapij B.V.) | de Vries, G. (Nederlandse Aardolie Maatschaapij B.V.) | Sonke, H. (Shell Global Solutions B.V.)
Measurement and interpretation of corrosion inhibitor residuals in a mature offshore gas/condensate field could not be reconciled with field data leading to the identification of a potential infrastructure integrity threat that mandated understanding. The field had recently transitioned from buffered pH operation to "natural" pH operation of the monoethylene glycol (MEG) loop (alongside addition of corrosion inhibitor) due to carbonate scaling caused by formation water influx. An investigation was initiated to determine the corrosion inhibitors behavior throughout the production system with focus on demonstrating the effectiveness of the inhibitor. The investigation included extensive laboratory corrosion testing using field and synthetic fluids, residual determination in field samples using liquid-chromatography mass-spectrometry (LC-MS), field implementation and confirmation of appropriate actions.
Upon completion of the investigation it was found that the intended corrosion inhibitor active components were not concentrating up in the MEG loop but were strongly partitioning to the natural gas condensate phase. This was leaving the topside facilities "under-inhibited". Obscuring this conclusion was the concentration of other benign (not corrosion inhibitor) active components present in the inhibitor formulation at very low concentrations which were giving falsely high inhibitor residuals.
After changing the inhibitor injection philosophy from batch-wise to continuous, LC-MS residuals have continued to confirm the partitioning behavior in field operation without the introduction of an unmanageable secondary property concern due to the inhibitor. Further online and laboratory corrosion studies have confirmed the integrity of the production system as proof of the effectiveness of the inhibitor. These key lessons learned challenge operators and chemical vendors to consider the MEG circuit chemistry more carefully during chemical qualification to ensure that chemical behavior is understood both before field application and that it is confirmed once applied.
The oil and gas industry uses molecular sieving to dehydrate or separate contaminants from natural gas. Such process involves several operational challenges that put valves under severe strain, potentially causing damage and service disruptions. In response to the shortcomings of conventional valve designs for this type of service, rising stem (tilting) ball valves have gained popularity over the years. However, several users are now open to adopt a new, innovative product capable of reducing both capital and operational expenditure involved. Triple offset valves (TOVs) represent a tried and tested solution that compared to rising stem ball valves offers a significant weight and footprint reduction while minimizing the need for maintenance.