Emmanuel Obanijesu

Modelling the Natural Gas Pipeline Internal Corrosion Rate Resulting from Hydrate Formation

Abstract Hydrate formation along a long natural gas pipeline has recently been established to initiate different types of internal corrosion along the pipe-length based on the formation stage and point. These corrosions may lead to disintegration of the pipes properties and eventually result into the pipes leakage or full-bore rupture. Apart from the enormous economic implications on the operating company, the conveyed fluid upon escape to the environment poses the risk of fire, reduction of air quality and other health hazards. This article develops a predictive model on internal corrosion rate resulting from hydrate formation along a natural gas pipeline based on the thermodynamics properties of the transported fluid with H 2 O being 90% of the clathrates and the predictive rates were plotted against different operating conditions. The model clearly showed that the corrosion rate increases with temperature, wall shear stress, superficial velocity, fluid fugacity and acidity. Since the result trends agree with those of existing models, then, this model can be said to be reliable. To minimize the problems, some predictive and corrective management options are recommended on hydrate formation.

Hydrate Formation and its Influence on Natural Gas Pipeline Internal Corrosion Rate

This study establishes the ability of hydrate formation to initiate internal corrosions along natural gaspipelines. The identified corrosion types, which are cavitations, erosion and corrosions by chemicalreactions,arecapabletoindividuallyorcollectivelyinitiatepittingandstresscracking corrosionswhicharealso dangerous to gas pipelines. The impacts of these corrosion types are classified to economics,environmental and human loss with the economic loss as much as US

Modeling the Contribution of Gas Hydrate to Corrosion Rate Along the Subsea Pipelines

3 trillion depending on thepipe-length, location, sea depth, wave function, climatic conditions and political situations.Various predictive measures to minimize hydrate formations are finally recommended.

Effectiveness of Imidazoline in Mitigating Transport Pipeline Corrosion

This study developed a corrosion predictive model along the deepwater gas pipelines with hydrate as the corroding agent. The model was developed and simulated with primary focus on the thermodynamic properties of each component of the gas mixture and a solution algorithm written with Matlab 6.5 (The MathWorks, Natick, MA) code. The model was validated by comparing the generated results with the outputs of already established laboratory and mathematical corrosion studies; the trends of the results obtained comparatively agreed with these studies to confirm its reliability. The model correctly predicted the relationships between corrosion rate and other thermodynamic parameters such as temperature, pressure, wall shear stress, velocity loss, and pH. This study showed that hydrates can initiate galvanic corrosion, stress cracking corrosion, and erosion-corrosion amongst others. Furthermore, the resulting corrosion rate from the hydrates could be as high as 174 mm/year (0.48 mm/day). This is extremely alarming compared to the industrys aim to operate below 2 mm/year. At this rate, an underwater pipeline would be subjected to full bore rupture within some days if corrective measures are not quickly taken; hence, the need for further studies.

Potential Impacts and Modelling of the Heat Loss Due to Copper Chelation in Natural Gas Processing and Transport

The detrimental effects of corrosion in transportation pipelines have been a primary issue for the oil and gas industry for many years. Every year, millions of dollars are invested into corrosion inhibitors in order to minimise corrosions implication on flow assurance. Imidazoline and its derivatives have been a prevalent corrosion inhibitor owing to its good adsorption characteristics and film forming capabilities; however, there remains some uncertainty in literature pertaining to the effect of temperature on its performance. GULP simulation software was used to study the effect of temperature on the thermodynamic properties of imidazoline in carbon steel pipelines. Entropy, heat capacity, Helmholtz free energy, entropy and Gibbs free energy were influenced by changes in temperature. An optimal operating range was found to exist between 298K and 333K. Within this range, spontaneous chemisorption was occurring and the imidazoline molecules possessed enough kinetic energy to displace any bound water on the metal surface to permit the preferential adsorption of the imidazoline head group. However, beyond 333K, the kinetic energy of the system hindered the steady formation of the protective barrier, reducing its inhibitive potential. This study agrees with previous literature on the effect of temperature on the ability of imidazoline as a corrosion inhibitor, however further studies into the effect of pipeline conditions and imidazoline molecular structure are needed in order to affirm the optimal applicability of imidazoline as a corrosion inhibitor.

The influence of corrosion inhibitors on hydrate formation temperature along the subsea natural gas pipelines

Abstract Natural Gas at clients (downstream) terminals often burns with discolorations, with reduction in heat value and potential health hazard implications. One of the sources for the observed discolorations is a result of chelates (metallic compounds) formed from process fluids due to equipment corrosion and erosion during the Natural Gas processing and transportation either through the pipeline or as LNG. This is of particular interest in Alkanolamine-based gas sweetening processes transported over aging/aged pipelines. With possible sources of ligands having available bonding sites, and the solubilised metallic central atoms in the processing and transport equipments, attainable formation and stability conditions all strongly suggest the imminence of chelation in Natural Gas/LPG processing and transportation. This work applied the Channiwala and Parikh correlations to model the chelate formation using Copper (Cu) as a base case, but also presents summary results for Iron (Fe) and Nickel (Ni) in Ethanolamine (MEA), Diethanolamine (DEA) and Ethylenediethanolamine (EDTA) based gas processing systems. All the Chelates considered were found to be thermodynamically within formation and stability bounds, resulting in a 0.5MJ/kg (0.42MJ/m 3 ) heat loss at just 1.44 wt%, 1.55 wt%, 1.33 wt% and 1.40 wt% chelate to gas product for Cu-MEA, Cu-DEA, Fe-EDTA, and Ni-MEA respectively. This represents the lowest possible limit. In addition to the potential health hazards which include cancer and memory loss, this is a significant value loss when compared to the recommended 37.73MJ/m 3 for sales gas.