Transportation of hydrocarbons and water in long subsea flow lines from satellite fields to a platform or to an onshore facility presents new challenges in the control of gas hydrates, corrosion, and mineral scale. Gas hydrates form at high pressure and low temperature and are a common problem in offshore wet gas pipelines due to low seabed temperatures and elevated pressures in these remote subsea developments. Monoethylene glycol (MEG) is widely used as a thermodynamic hydrate inhibitor in these developments to manage the risk of hydrate formation during production and transportation of multiphase fluids from subsea wells. Due to large amounts of MEG required for effective hydrate control, it is necessary to recycle and re-use it. The main processes for recycling of MEG are regeneration and reclamation. Typical conditions of regeneration and reclamation processes are ambient to vacuum pressures and temperatures in the range of 120°C −150°C1. In addition to the use of MEG for hydrate control, corrosion inhibitors are also applied for corrosion control in the subsea pipelines and infrastructure. These corrosion inhibitors must be able to perform under high shear and highly corrosive environments without losing their effectiveness after having been subjected to the system conditions present in the MEG regeneration process. Inappropriate selection of corrosion inhibitors for MEG based applications can lead to severe fouling/formation of solids, emulsion and foaming issues in the receiving facilities. The corrosion inhibitors developed for use in facilities operating with glycol regeneration systems should remain active after multiple MEG Regeneration Unit (MRU) cycles without causing fouling/formation of solids, emulsion and foaming. The current paper presents MRU compatible corrosion inhibitors developed based on the stringent testing methods adopted from real time MRU process.

A dual functional kinetic hydrate inhibitor (KHI) and compatible corrosion inhibitor (CI) package was developed to simplify production chemistry demands for operation in wet gas mode. As these two classes of chemistries are both water soluble and contain surface active components, they have a tendency for interference reducing the efficacy of each inhibitor. Their pairing in a production scenario requires both comprehensive performance testing as well as extensive secondary properties evaluation. The KHI is to serve as a traditional KHI during steady-state operations while performing as a thermodynamic hydrate inhibitor (THI) during extended shut-ins and cold well restarts. This challenge required the development of a KHI which would retain performance upon significant dilution in a thermodynamic hydrate inhibitor solvent carrier (methanol, ethanol, monoethylene glycol, etc). Performance of this new KHI would be confirmed in blind rocking cell experiments, in the presence of the matched corrosion inhibitor, targeting a hold time of more than eight days at a subcooling of 8 ºC. The CI is targeted to reduce the general corrosion rate to less than 0.1 mmpy and prevent localized attack. Due to the surfactancy of this class of chemistry, the tendency to induce and stabilize emulsions is of high concern. A robust formulation amenable to modification and potential dilution is required to address the application of chemical over a vast subsea network containing wells of varying age, existing infrastructure, production profiles, and operating conditions. This paper describes the development, qualification process, related lessons learned, and field applications of this new KHI/CI package. Introduction The oil and gas industry often relies on chemical solutions to address challenges related to flow assurance and corrosion inhibition. The transport of produced fluids containing water and acid gases such as carbon dioxide and/or hydrogen sulfide in metal pipelines afford conditions susceptible both to gas hydrate formation and corrosion. Accordingly, production chemical strategies typically must consider a compatible corrosion inhibitor and low dosage hydrate inhibitor as a unified package. Standard chemical compatibility often includes the mixing of two neat production chemicals with exposure at various temperatures to examine for hazing, phase separation, precipitation, etc. This exercise provides operators insight in the event that chemicals are accidently mixed in storage tanks or may come into contact in delivery lines. Though, the performance compatibility of a KHI and a CI presents a more challenging case.

The microstructure and properties of heavy section forgings of the 8090 Al-Li alloy were investigated including the as-cast, homogenized, forged, and heat-treated conditions. The ingots, 305x965x2000-3600 mm in size, were cast by Alcan. Homogenization involved 24 to 48 h soaks at 545°C. Ingots were hand-forged by HDAF Ltd. to sizes up to 356x356x1524 mm, then solution-treated at 530°C for 6 h and water quenched. The material was aged at various times at temperatures of 150, 170, and 190°C. Microstructures were examined by TEM, CBED, SEM, AES, and optical microscopy. Mechanical properties were characterized by tensile, fracture toughness, and stress corrosion tests. A strong correlation was observed between grain boundary precipitation of a icosohedral (I) phase and certain mechanical properties. The I-phase has been tentatively identified as Al6CuLi3, historically called "T2". When the I-phase was predominant, the fracture toughness, SCC, and tensile ductility were invariably low. Factors identified as promoting the formation of I-phase were cooling rates from the solution treatment temperature slower than -10°C s-1, increased aging time, and increased aging temperatures in the range 150 to 190°C. Aging conditions which minimized the formation of the grain boundary I-phase and, consequently, improved the mechanical properties were determined. Three distinct constituent phases were found in cast ingots having only slightly different chemistries. Remnants of these constituent phases were present in every subsequent stage of thermal processing. One, AlLiSi, was discovered to promote surface pitting and to substantially lower the stress corrosion cracking resistance. This phase's reactivity with seawater appears to promote dissolution of the adjacent matrix. Material heat-treated to suppress the formation of the I-phase, but high in silicon, revealed low SCC resistance. In summary, many factors including composition, casting practice, metal-working, and heat-treatment, determine the mechanical properties of 8090 Al-Li in heavy section forgings, and which range from unacceptable to acceptable for high performance aerospace structures

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.

Railroad track inspections conducted in accordance with federal regulations and internal railway operating practices result in significant labor costs and occupy valuable network capacity. These factors, combined with advancements in the field of machine vision, have encouraged a transition from human visual inspections to machine-based alternatives. Commercial machine vision technologies for railway inspection currently exist, and automated analysis approaches—which deliver objective results—are available in some systems. However, they are limited to a “pass/fail” approach through the detection of components which fail to meet maintenance or geometry thresholds, as opposed to being able to detect subtle changes in track conditions to identify evolving problems. To overcome these limitations, this paper presents results from the field deployment and validation of a system that pairs three-dimensional (3D) machine vision with automated change detection technology. The change detection approach uses a deep convolution neural network (DCNN) to accurately characterize track conditions between repeat runs. Current automated track inspection technologies were studied, and the applicability of change detection is discussed. The paper presents the process for 3D image capture, DCNN training, and evaluation by comparing DCNN results to an expert human evaluator. Finally, it presents change detection results for fastener presence and spike height. Results indicate that this technology can successfully identify fasteners and spikes with percent accuracies greater than 98% and that it can successfully generate change detection results for comparison of track condition among runs.