Letteratura scientifica selezionata sul tema "Anti-agglomerant additive"

Dans le cadre de la production pétrolière, la formation d’hydrates de gaz peut conduire à la formation de dépôts, au bouchage des lignes et à l’interruption de la production du pétrole et/ou du gaz. La formation d’hydrate peut donc avoir un impact économique fort. Pour assurer la production sans risque d’arrêt de production, différentes stratégies sont adoptées. Une stratégie courante implique la production hors zone hydrates par injection d’additifs thermodynamiques (THIs) par exemple. Cependant, le déplacement des conditions de stabilité des hydrates par les THIs nécessitent l’injection de doses massives d’additif avec un coût environnemental et économique élevés. Une autre stratégie de production, en zone hydrate, consiste à injecter des additifs dits à faible doses (LDHI) : les inhibiteurs cinétiques (KHIs) ou les anti-agglomérants (AAs). Pour les champs pétroliers sous-marins profonds (deep offshore), seule l’injection d’additifs anti-agglomérants (AAs) est pertinente. Ces additifs ne bloquent pas la formation des hydrates mais évitent leur agglomération et dispersent les cristaux formés dans les fluides de production. Le développement des AAs et la validation de leurs applications sur des champs de production nécessitent une investigation approfondie de leurs impacts sur les systèmes réels de production (dispersion des cristaux dans les conduites, la taille des cristaux dans la phase continue, la transportabilité des suspensions, etc…).êPour apporter une meilleure compréhension de l’impact des additifs anti-agglomérants commerciaux (AAs) sur la formation d’hydrates une approche pluridisciplinaire et multi-échelles a été adoptée. La formation d’hydrates de gaz naturel a tout d’abord été réalisée au laboratoire en reproduisant les conditions de production pétrolière avec des systèmes industriels dans des conditions opérationnelles avec trois AA différents. À l’échelle macroscopique, les suspensions de cristaux réalisées sous agitation dans les réacteurs mettent en évidence des effets dépendants de l’AA utilisé. Ils impactent différemment la cinétique de formation des hydrates, le taux et la vitesse de croissance des cristaux ainsi que leur état de dispersion. Sans agitation, ces additifs AAs affectent la morphologie et contrôlent la croissance des cristaux et la phase dans laquelle ils vont croître. Ensuite, une cellule de transfert d’hydrates a été conçue pour prélever des échantillons de suspensions d’hydrates formés dans les réacteurs dans des conditions proches de la réalité industrielle (avec agitation, pression élevée, faible température). Les suspensions d’hydrates transférées ont ensuite été analysées par microtomographie à rayons X à l’aide d’une méthode développée au cours de ce travail. À l’échelle microscopique, l’état de dispersion des grains d’hydrates a été évalué pour l’ensemble des échantillons transférés et des informations ont été obtenues sur la taille des grains d’hydrates dispersés, leur forme et leur sédimentation dans la phase organique. À l’échelle moléculaire des analyses in-situ ont été réalisées par spectroscopie Raman sur des hydrates de méthane formés en présence des additifs AA. Ces essais ont mis en évidence la distribution des hydrates dans les phases organiques (gaz et condensat). Les observations par microscopie optique révèlent des morphologies d’hydrates comparables à celles obtenues en présence des additifs AAs dans les réacteurs
In the context of oil production, the formation of gas hydrates can lead to the formation of deposits, the clogging of lines and the interruption of oil and/or gas production. Hydrate formation can therefore have a strong economic impact. To ensure production without the risk of production shutdown, different strategies are adopted. A common strategy involves the production outside the hydrate zone by injection of thermodynamic additives (THIs), for example. However, the displacement of hydrate stability conditions by THIs requires the injection of massive doses of additive with high environmental and economic costs. Another production strategy, in the hydrate zone, consists of injecting so-called low dose inhibitors (LDHI): kinetic inhibitors (KHIs) or anti-agglomerant additives (AAs). For deep offshore oil fields, only the injection of AAs is relevant. These additives do not block the formation of hydrates but prevent their agglomeration and disperse the crystals formed in the production fluids. The development of AAs and the validation of their applications on production fields require an in-depth investigation of their impacts on real production systems (dispersion of crystals in pipes, the size of crystals in the continuous phase, the transportability of slurries, etc…).êTo provide a better understanding of the impact of commercial AAs on the formation of hydrates, a multidisciplinary and multi-scale approach was adopted. The formation of natural gas hydrates was first carried out in the laboratory by reproducing oil production conditions with industrial systems under operational conditions with three different AAs. On the macroscopic scale, the slurries of crystals produced under stirring in the reactors highlight effects dependent on the AA used. They impact differently the kinetics of hydrate formation, the rate and speed of crystal growth as well as their state of dispersion. Without stirring, these AAs additives affect the morphology and control the growth of crystals and the phase in which they will grow. A hydrate transfer cell was then designed to sample of hydrate slurries formed in the reactors under conditions close to industrial reality (with stirring, high pressure, low temperature). The transferred hydrate slurries were then analyzed by X-ray microtomography using a method developed during this work. On the microscopic scale, the state of dispersion of the hydrate grains was assessed for all transferred samples and information was obtained on the size of the dispersed hydrate grains, their shape and their sedimentation in the organic phase. At the molecular scale, in-situ analyzes were carried out by Raman spectroscopy on methane hydrates formed in the presence of the three AA additives. These tests highlighted the distribution of hydrates in the organic phases (gas and condensate). Observations by optical microscopy reveal hydrate morphologies comparable to those obtained in the presence of AAs additives in the reactors

La cristallisation des hydrates pendant la production de pétrole est une source de risques, surtout liés au bouchage des lignes de production dû à l’agglomération des hydrates. Pendant l'extraction de pétrole, l'huile et l'eau circulent dans le pipeline et forment une émulsion instable. La phase eau se combine avec les composants d'hydrocarbures légers et peut former des hydrates. La cristallisation des hydrates a été intensivement étudiée, principalement à faible fraction d’eau. Cependant, lorsque le champ de pétrole devient mature, la fraction d’eau augmente et peut devenir la phase dominante, un système peu étudié concernant à la formation d'hydrates. Plusieurs techniques peuvent être combinées pour éviter ou remédier la formation d'hydrates. Récemment, une nouvelle classe d'additifs a commencé à être étudiée : Inhibiteurs d'Hydrates à Bas Dosage (LDHI), divisés en Inhibiteurs Cinétiques (KHI-LDHI) et anti-agglomérants (AA-LDHI).Ce travail est une étude paramétrique de la formation d'hydrates à partir de l'émulsion, en variant la fraction d’eau, le débit, en absence et en présence d’AA-LDHI. Les expériences ont été réalisées sur la boucle d'écoulement Archimède, qui est en mesure de reproduire les conditions de la mer profonde. L'objectif de cette étude est d'améliorer la compréhension de la formation d'hydrate et de comprendre comment l'additif dispersant évite l'agglomération. Pour ce faire, un modèle comportemental de la cristallisation pour les systèmes sans et avec additif a été développé. Il a également été proposé une technique pour déterminer la phase continue du système et un mécanisme d'action pour l'anti-agglomérant a été suggéré
Crystallization of hydrates during oil production is a major source of hazards, mainly related to flow lines plugging after hydrate agglomeration. During the petroleum extraction, oil and water circulate in the flow line, forming an unstable emulsion. The water phase in combination with light hydrocarbon components can form hydrates. The crystallization of hydrates has been extensively studied, mainly at low water content systems. However, as the oil field matures, the water fraction increases and can become the dominant phase, a system less known in what concerns hydrate formation. Actually, several techniques can be combined to avoid or remediate hydrate formation. Recently, a new class of additives called Low Dosage Hydrate Inhibitor (LDHI) started to be studied, they are classified as Kinetic Hydrate Inhibitors (KHI-LDHI) and Anti-Agglomerants (AA-LDHI).This work is a parametric study about hydrate formation from emulsion systems ranging from low to high water content, where different flow rates and the anti-agglomerant presence were investigated. The experiments were performed at the Archimède flow loop, which is able to reproduce deep sea conditions. The goal of this study is enhancing the knowledge in hydrate formation and comprehending how the dispersant additive acts to avoid agglomeration. For this matter, it was developed a crystallization topological model for the systems without and with additive. A technique to determine the system continuous phase and a mechanism of the anti-agglomerant action from the chord length measurements were also proposed

In normal operation, a gas condensate field can be operated in pressure and temperature conditions where hydrates are stable. To mitigate the formation and deposition of hydrates, Mono Ethylene Glycol (MEG) is injected in the subsea flowline at high concentration (30 to 60% vol. versus water) (Yong Bai, 2019). MEG is then separated from water in the MEG Recovery Unit (MRU) and reinjected in the flowline while the water is discharged to environment or reinjected in the reservoir. When wells are aging, the water production is increasing and consequently the MEG flow rate. The increase of the liquid holdup (Water + MEG + condensate) in the production lines leads to a pressure buildup and increases the frequency of pigging outages for liquid removal. Therefore, finding a Low Dosage Hydrate Inhibitor (LDHI) could help to lower the volume of liquid (MEG) and consequently decrease the backpressure. (Bhajan Lal, 2020). This type of additive has shown that they can bring significant benefits in terms of additional production, HSE improvements and OPEX savings. (A. Singh; 2006; Orlin Lavallie, 2009) This study is assessing the feasibility to replace MEG injection in the production lines to prevent hydrates formation by a Low Dosage Hydrate Inhibitor (LDHI), in this study Anti-Agglomerant (AA) because the subcooling is higher than 10°C. AA does not inhibit hydrates formation but prevents their agglomeration in the condensate phase. A viscous slurry, composed of condensate and hydrates will be transported to the surface installation. These last years, chemical suppliers have developed "green" AA to limit environmental impact when discharged to environment. These products efficiency will be evaluated during the study.

Abstract Objectives/Scope Anti-agglomerant low dose hydrate inhibitors (AA-LDHIs) have the potential to exhibit corrosion inhibition due to their phase-boundary association and surfactant properties as well as containing similar functional groups as corrosion inhibitors (CI). However, it is often found that AA-LDHI molecules, on their own, do not possess the corrosion inhibition efficacy to meet commonly used industry standard corrosion rate criteria of less than 4 mpy general corrosion and minimal localized corrosion, even when dosed at typical AA-LDHI treatment rates (at the percentage level). For offshore applications, where an operator may have limited umbilicals for production chemical delivery and are conscious of capital expenditure, a combination chemical product would be the preferred option. In the search for such a single umbilical combination product to provide both corrosion and hydrate protection, a highly effective AA-LDHI/CI combination product was formulated. Methods, Procedures, Process The newly developed AA-LDHI/CI product was first evaluated in the laboratory under field simulated environments: rotating cage autoclave (RCA) to test corrosion inhibitor performance and visual sapphire hydrate rocking cells to test anti-agglomerant performance before being taken to the field. Results, Observations, Conclusions The corrosion inhibitor performance testing was conducted under sweet conditions using RCA at a temperature of 158 °F and a shear rate of 40 pascals. The post-test coupons were further evaluated for pitting corrosion performance using Vertical Scan Interferometer and coupon surface features were measured. After a 7-day test, the AA-LDHI/CI reduced the general corrosion rate to <4mpy whilst localized corrosion features were no greater than what was already present on the surface before exposure. The product was also tested for AA-LDHI performance utilizing visual sapphire hydrate rocking cells at 2,000 psi and 40 °F under shut-in/restart conditions which showed no impacts on performance when compared with the AA-LDHI chemistry by itself at the same dosage. Novel/Additive Information The paper describes the development and laboratory testing of new AA-LDHI/CI combination products that showed exceptional corrosion inhibition performance while also maintaining hydrate inhibition metrics with no change to secondary properties and with positive sustainability impacts. After laboratory development and testing, the new product was then field deployed. Preliminary data from an ongoing field trial is also shared.

The hydrate is an important issue that the flow assurance has to face in the oil and gas industry, especially in the deepwater area. With high pressure and low temperature, the hydrate formation is easily happened and leads to plug in the pipeline. In addition to the traditional thermodynamic inhibitor, the low dosage hydrate inhibitors (LDHI) has been increasing used as a costly effective technology for gas hydrate control. The LDHI include kinetic hydrate inhibitor (KHI) and anti-agglomerant (AA), the former can inhibit the hydrate formation in the pipeline, and the latter can prevent the agglomeration and plug of hydrate particles. According to the properties of oil and gas of South China Sea, a new KHI and AA were developed, a field test of the KHI has been undertaken and the results indicate that it can prevent the hydrate formation and plug in the pipeline well, the lab evaluation of the developed AA is in progress and the field test will be performed by the next year.