Integrated Approach to Maximize Production and Improve HSE

Slugging is an ongoing flow assurance risk in some of the ADNOC Onshore production systems, leading to difficulty in operations, inefficiencies, integrity and HSE concerns. For example stagnant water increases the risk of pipeline corrosion, especially with increased levels of H2S and CO2, potentially leading to leaks, pressure rating downgrading and reduction in the overall system capacity. With more reservoirs being under different schemes of secondary and tertiary recovery (WI, WAG, EOR – CO2, etc.), slugging in wells and transfer lines is expected to continue to be a challenge for the efficient and safe production operations across the entire ADNOC Onshore. This paper summarizes an integrated approach to understand the underlying causes of slugging in an onshore production system, reviews the current slug mitigation philosophy and proposes a stepwise approach to improve performance of the system, leading to production acceleration, improved profitability, efficiency and HSE performance. The system under investigation is experiencing slugging in the Transfer Line (TL) leading to liquid surges in the first stage separator (SEP) located at the Central Facilities. The slugging in the Transfer Line is attributable to a combination of wells and terrain induced slugging, and not so much to the hydrodynamic effects of the multiphase flow. In the current slug management philosophy, the pressure (RP) recorded at the TL receiver location is used in an algebraic formula to calculate a level set-point (LSP) that, in relation to the actual oil level in the separator (SEP), is used to act on the Surge Control Valve (SCV) located at the separator inlet. When the LSP is below the actual oil level in the separator, the SCV is tripped to 30% opening. The RP signal acts as a tell-tale sign of the incoming slug. In an initial phase, the system performance is evaluated using real time data available in the Control Room and offices. The initial data driven approach is complemented by complex dynamic multiphase modeling efforts. The models are used for further insights into the system behavior under different operational conditions, with a focus on identifying a more stable operating envelope, where the effects of slugging are mitigated while the production levels are maintained or increased. The focus on this paper is on the interface between the Transfer Line (TL) and inlet separator (SEP), including the Slug Control Valve (SCV). Results indicate a more stable flow regime is achieved at higher fluid velocities in the TL, where the RM pressure is increased to 35 barg from the current 29 barg. (N.B. The 35 barg is the maximum TL operating pressure, as identified in a separate study, and limited by the current HIPPS setpoints. The corresponding increase in production capacity is up to 10,000 bopd, thus accelerating the cumulative oil by up to 3.5 MMBBl / year, and accelerating revenue by up to USD 180 MM / year). However, in the current control scheme, operation at 35 bar is limited by the SCV characteristic and control scheme. To mitigate the problem, a staggered approach is proposed. A reduction in SCV tripping frequency is expected to be achieved in the short term, by modifying the algebraic equation that govern the SCV actions. A slight increase in the B factor by 2.5% is expected to reduce the SCV tripping frequency by up to 10%. Reduction in SCV tripping frequency will further reduce the mechanical stress on the valve and associated piping, thus reducing the risk of structural damage of the system. Also, it will allow for starting to increase the fluid velocities and move towards a more stable flow regime and reduced water holdup in the pipeline (reduced corrosion risk). Additional increase in fluid velocities appears to be limited by the SCV characteristic. In the current control scheme the pressure drop across the valve becomes sizeable at higher flowrates, leading to frequent tripping. As a longer term measure, increasing the SCV capacity is expected to facilitate operation of the system at higher fluid velocities, thus reducing the slugging, mechanical stress and corrosion risk in the TL. As slugging will continue to be a challenge to safe and efficient operations across ADNOC Onshore, it is important to develop in house the ability to understand the underlying causes for such flow instabilities, identify mitigation and optimization workflows. This paper demonstrates that a combination of data driven analytics and integrated physics based modeling, carried out in an integrated approach by a mixed team of subsurface and surface engineers, can help understanding the system behavior under slugging conditions and identify opportunities to improve production system efficiency and profitability, while operating within a safer envelope.

Non-Destructive Diagnostic Methods for Fire-Side Corrosion Risk Assessment of Industrial Scale Boilers, Burning Low Quality Solid Biofuels—A Mini Review

The use of low-emission combustion technologies in power boilers has contributed to a significant increase in the rate of high-temperature corrosion in boilers and increased risk of failure. The use of low quality biomass and waste, caused by the current policies pressing on the decarbonization of the energy generation sector, might exacerbate this problem. Additionally, all of the effects of the valorization techniques on the inorganic fraction of the solid fuel have become an additional uncertainty. As a result, fast and reliable corrosion diagnostic techniques are slowly becoming a necessity to maintain the security of the energy supply for the power grid. Non-destructive testing methods (NDT) are helpful in detecting these threats. The most important NDT methods, which can be used to assess the degree of corrosion of boiler tubes, detection of the tubes’ surface roughness and the internal structural defects, have been presented in the paper. The idea of the use of optical techniques in the initial diagnosis of boiler evaporators’ surface conditions has also been presented.

Online Modeling of CO2 Storage Systems

This paper discusses the development and deployment of a specialized online and offline integrated model to simulate the CO2 (Carbon Dioxide) Injection process. There is a very high level of CO2 in an LNG development and the CO2 must be removed in order to prepare the gas to be processed into LNG. To mitigate the global warming effects of this CO2, a large portion of the CO2 Rich Stream (98% purity) is injected back into a depleted oil field. To reduce costs, carbon steel flowlines are used but this introduces a risk of internal corrosion. The presence of free water increases the internal corrosion risk, and for this reason, a predictive model discussed in this paper is designed to help operations prevent free water dropout in the network in real time. A flow management tool (FMT) is used to monitor the current state of the system and helps look at the impact of future events (startup, shutdowns etc.). The tool models the flow of the CO2 rich stream from the outlet of the compressor trains, through the network pipeline and manifolds and then into the injection wells. System behavior during steady state and transient operation is captured and analyzed to check water content and the balance of trace chemicals along with temperature and pressure throughout the network helping operators estimate corrosion rates and monitor the overall integrity of the system. The system has been running online for 24/7 for 2 years. The model has been able to match events like startup/shutdown, cooldowns and blowdowns. During these events the prediction of temperature/pressure at several locations in the field matches measured data. The model is then able to forecasts events into the future to help operations plan how they will operate the field. The tool uses a specialized thermodynamic model to predict the dropout of water in the near critical region of CO2 mixtures which includes various impurities. The model is designed to model startup and shutdown as the CO2 mixture moves across the phase boundary from liquid to gas or gas to liquid during these operations.

Using the galvanostatic pulse method to estimate the corrosion of reinforcement in structural elements

ABSTRACT Early steel bars corrosion in reinforced concrete elements is difficult to detect because of the lack of visible changes on the concrete surface. To assess reinforcement corrosion risk level without structure damage some non-destructive diagnostic methods are applied. One of them is the galvanostatic pulse method. This semi-non-destructive electrochemical method allows to determine the corrosion areas and estimate the steel bars corrosion activity. Using this method it is possible to measure some electrical parameters (corrosion current density, stationary potential and reinforcement concrete cover resistivity) that allow to indirectly estimate the reinforcement corrosion progress in concrete. So far this method has been generally applied to bridges. The article presents results of studies in which the galvanostatic pulse method was used to determine reinforcement corrosion risk in structures elements different than bridges. Two types of reinforced concrete columns were tested under different environment conditions and two groups of laboratory specimens which were subjected to freezing and thawing cycles in NaCl solution or stayed in natural air–dry conditions. The apparatus GP-5000 GalvaPulseTM was used. Based on the obtained results the conclusions were drawn. The galvanostatic pulse method allows to assess the progress of the reinforcement corrosion process in tested elements. However, it is necessary to measure simultaneously all parameters and make their complex analysis. RESUMEN La corrosión temprana de las barras de acero en elementos de hormigón armado es difícil de detectar debido a la falta de cambios visibles en la superficie del hormigón. Para evaluar el nivel de riesgo de corrosión de la armadura sin dañar la estructura se aplican algunos métodos de diagnóstico no destructivos. Uno de ellos es el método del pulso galvanostático. Este método electroquímico semi no destructivo permite determinar las áreas de corrosión y estimar la actividad de corrosión de las barras de acero. Utilizando este método es posible medir algunos parámetros eléctricos (densidad de corriente de corrosión, potencial estacionario y resistividad de la cubierta del hormigón de la armadura) que permiten estimar indirectamente el progreso de la corrosión de la armadura en el hormigón. Hasta ahora este método se ha aplicado generalmente a los puentes. El artículo presenta los resultados de estudios en los que se utilizó el método de impulsos galvanostáticos para determinar el riesgo de corrosión de las armaduras en elementos de estructuras diferentes a los puentes. Se ensayaron dos tipos de columnas de hormigón armado en diferentes condiciones ambientales y dos grupos de probetas de laboratorio que se sometieron a ciclos de congelación y descongelación en solución de NaCl o permanecieron en condiciones naturales de secado al aire. Se utilizó el aparato GP-5000 GalvaPulseTM. A partir de los resultados obtenidos se extrajeron las siguientes conclusiones El método de impulsos galvanostáticos permite evaluar el progreso del proceso de corrosión de la armadura en los elementos ensayados. Sin embargo, es necesario medir simultáneamente todos los parámetros y realizar su complejo análisis.

TECHNOLOGY PROVIDING SECONDARY PROTECTION METAL STRUCTURES AGAINST CORROSION UNDER AGGRESSIVE IMPACT OF METALLURGICAL PRODUCTION

Research is aimed at the formation and development of innovative developments to increase the metal structures corrosion protection, as an important means of ensuring the quality and safety industrial facilities. The method determining the corrosion destruction signs, the procedure of monitoring and carrying out measures to diagnose the technical condition of lattice metal structures according to the level of corrosion hazard were adopted. The nomenclature indicators and control methods (conformity assessment) of determining parameters primary and secondary protection metal designs against corrosion is established. During this study, the lattice structures operational condition loader crane’s girder structure was considered. It is revealed that operation of the crane is carried out in difficult production conditions operating environment’s aggressive influence in combination with considerable dynamic loadings working operations loading technological process, unloading, sorting (averaging) of ore yard’s charge of blast furnace shop. Based on the study structures corrosion condition and operating conditions, measures have been developed to increase the durability ore-grab crane of the reloader. Based on the analysis of the principles of the ISO 9001 process approach, the development and implementation design solutions to extend the structures service life in aggressive environments of metallurgical production. It is proved that the procedure of making constructive and technological decisions, performance works on increase corrosion resistance promotes maintenance conditions of resource saving and technological safety industrial constructions. The principles process is offered to develop and implement design measures to extend the service life of structures in aggressive environments metallurgical production are proposed. Constructive and technological measures to ensure durability in accordance with the requirements of the building structure corrosion risk have been developed, which are determined by the critical indicators metal structures protection in the conditions corrosion influences within their limit values.

Corrosion Study on Single-Phase Liquid Cooling Cold Plates with Inhibited Propylene Glycol/Water Coolant for Data Centers

Single phase cold plate based liquid cooling attracts more and more attention to high-performance computing (HPC) and general computing data centers for thermal management of modern microprocessors due to liquid's inherent advantage of higher specific heat compared to air. Deionized (DI) water is usually used as coolant for liquid cooling in data centers. On the contrary, propylene glycol/water is recommended as coolant for one-phase cold plate liquid cooling in this study for following reasons. The inhibited propylene glycol-based fluids of 25+% vol. have the benefit of being biostatic and not requiring addition of biocides. They also offer freeze protection in the usage of data centers in cold climates. The cold plates made from copper is prone to oxide even under room temperature and the dissimilarity between brazing material and copper can also cause galvanic corrosion in the usage. In this paper, a study was carried out to investigate cold plate corrosion with inhibited propylene glycol/water using design of experiments (DOE) method. This study shows manufacturing process plays an important role on corrosion risk of copper based cold plates and the corrosion risk can be mitigated by enabling new manufacturing processes, including friction stir welding (FSW) and nickel plating to the inside surface of the cold plate in the manufacturing process.

Analysis of internal corrosion of supercritical CO2 pipeline

Carbon capture and storage (CCS) technology is considered to be one of the key technologies to reduce CO2 emissions. This paper reviews the industry corrosion accidents of CCS transportation system, in which the pipeline corrosion risk is analyzed, and the pipeline corrosion theory is summarized. Also, the effect of impurities on gas phase properties is discussed. We analyze the corrosion mechanism of multicomponent impurities on metals in a supercritical CO2 environment from the aspects of corrosion rate and corrosion products. We also describe the mechanism of pitting and stress corrosion of metals in a supercritical CO2 environment. Besides, the formation mechanism of FeCO3 protective layer and the research status of corrosion resistant alloys in supercritical CO2 are reviewed and analyzed. Finally, a series of shortcomings and prospects of the current research are put forward.