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Method for assessing the hydrate formation from a mixture of natural gas flows of varying degrees of moisture content

Iskandarov Elman Kh., Baghirov Alovsat N., Shikhiyeva Lala M.

Nafta-Gaz

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2024

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R. 80, nr 1

39--44

EN

The article deals with the issues of assessing the conditions of hydrate formation when mixing natural gas flows of various standards. An urgent problem of operation, especially of offshore subsea gas pipelines, is the prediction of the time, place and expected intensity of hydrate formation. Depending on the changing operating mode of the gas pipeline, dispatch service specialists must be able to adjust the process control tactics on their own, as quickly as possible. The predisposition of a particular gas pipeline to hydrate is also important for the dispatching service. Changes in the volumes of gas entering the region under consideration from different sources, due to the constant change in gas production, create the need to mix gases of different standards and pump them into subsea gas pipeline. To avoid hydrate formation, it is important to predict the thermobaric conditions that will be formed in the gas pipeline by considering the characteristics such as a volume in the mixture and the moisture content of the gas. The processes of hydrate formation proceed quickly and if the beginning of the process is overlooked, the problem of significant or complete blockage of the gas pipeline might appear. The paper gives a systematization of the risk of hydrate formation depending on several infrastructural factors – the presence of a preliminary gas drying system and a system for starting and receiving cleaning pistons. A method is proposed for estimating the moisture content and dew point temperature of a natural gas mixture by the condition and the proportion of primary flows. It has been shown that the addition of a small volume of undried gas to the main dried gas significantly increases the risk of hydrate formation. A formula is given for calculations for a mixture of multiple natural gas flows. The advantage of this method is the quick calculations, and the absence of the need for huge mathematical calculations and laboratory studies. This is an important element in the activities of the dispatch service, limited by a lack of time in the process of preventing hydrate formation.

PL

W artykule podjęto problematykę oceny warunków powstawania hydratów podczas mieszania strumieni gazu ziemnego o różnych standardach. Istotnym problemem eksploatacji, zwłaszcza w gazociągach podmorskich, jest określenie czasu, miejsca i przewidywanej intensywności powstawania hydratów. W zależności od zmieniającego się trybu pracy gazociągu specjaliści służb dyspozytorskich muszą potrafić jak najszybciej samodzielnie dostosować taktykę sterowania procesem. Dla służby dyspozytorskiej istotne znaczenie ma także predyspozycja danego gazociągu do powstawania hydratów. Zmiany objętości gazu docierającego do rozpatrywanego regionu z różnych źródeł, w związku z ciągłą zmianą wydobycia gazu, powodują konieczność mieszania gazów o różnych standardach i wtłaczania ich do gazociągu podmorskiego. Aby uniknąć tworzenia się hydratów, istotne jest przewidywanie warunków termobarycznych, jakie będą panować w gazociągu, biorąc pod uwagę takie cechy jak objętość mieszaniny i zawartość wilgoci w gazie. Procesy powstawania hydratów przebiegają szybko i jeśli zostanie przeoczony początek tego procesu, może pojawić się problem znacznego lub całkowitego zablokowania gazociągu. W pracy usystematyzowano ryzyko powstawania hydratów w zależności od kilku czynników infrastrukturalnych – obecności układu wstępnego osuszania gazu oraz układu startu i odbioru tłoków czyszczących. Zaproponowano metodę szacowania zawartości wilgoci i temperatury punktu rosy mieszaniny gazu ziemnego na podstawie stanu i proporcji natężenia przepływów pierwotnych. Wykazano, że dodatek niewielkiej ilości nieosuszonego gazu do głównej partii gazu osuszonego znacznie zwiększa ryzyko powstania hydratów. Podano wzór do obliczeń w przypadku mieszaniny wielu strumieni gazu ziemnego. Zaletą tej metody jest szybkość obliczeń, brak konieczności wykonywania obszernych obliczeń matematycznych i badań laboratoryjnych. Jest to ważny element w działalności służby spedycyjnej, ograniczonej brakiem czasu w procesie zapobiegania tworzeniu się hydratów.

2

Development of methods for predicting hydrate formation in gas storage facilities and measures for their prevention and elimination

Volovetskyi V. B., Doroshenko Ya. V., Matkivskyi S. V., Raiter P. M., Shchyrba O. M., Stetsiuk S. M., Protsiuk H. Ya.

Journal of Achievements in Materials and Manufacturing Engineering

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2023

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Vol. 117, nr 1

25--41

EN

Purpose: The purpose of this work is to study the processes of hydrate formation during the operation of wells and underground gas storage facilities. Development of a set of measures aimed at the prediction and timely prevention of hydrate formation in wells and technological equipment of gas storage facilities under different geological and technological conditions. Design/methodology/approach: The prediction of hydrate formation processes was carried out using a neural network that is a software product with weight factors calculated in MATLAB environment and the ability to adapt parameters of the network specified to updated and supplemented input data during its operation. So, within the MATLAB software environment, a software module of a two-layer artificial neural network with a random set of weight factors is created at the first stage. In the second stage, the neural network is trained using experimental field input/output data set, output data. In the third stage, an artificial neural network is used as a means of predicting hydrate formation with the ability to refine weight factors during its operation subject to obtaining additional updated data, as an input set, for modifying the coefficients and, accordingly, improving the algorithm for predicting of an artificial neural network. In the absence of new data for the additional training of an artificial neural network, it is used as a computing tool that, on the basis of input data about the current above-mentioned selected technological parameters of fluid in the pipeline, ensures the output values in the range from 0 to 1 (or from 0 to 100%), that indicates the probability of hydrates formation in the controlled section of the pipeline. Application of such an approach makes it possible to teach; additionally that is, to improve the neural network; therefore this means of predicting hydrate formations objectively increases reliability of results obtained in the process of predicting and functioning of the system. The authors of the work recommend to carry out an integrated approach to ensure clear control over the operation mode of wells and gas collection points. Findings: According to the results of experimental studies, the places of the most likely deposition of hydrates in underground gas storage facilities were identified, in particular, in the inside space of the flowline in places of accumulation of liquid contaminants (lowered pipeline sections) and an adjustable choke of the gas collection point. The available methods used to prevent and eliminate hydrate formation both in wells and at gas field equipment were analyzed. Such an analysis made it possible to put together a list of methods that are most appropriate for the conditions of gas storage facilities in Ukraine. The method of predicting hydrate formation in certain sections of pipelines based on algorithms of artificial neural networks is proposed. The developed methodology based on data on values of temperatures and pressures in certain sections of pipelines allows us to predict the beginning of the hydrate formation process at certain points with high accuracy and take appropriate measures. Research limitations/implications: To increase the efficiency of solving the problem of hydrate formation in gas storage facilities, it is expedient to introduce new approaches to timely predict complications, in particular, the use of neural networks and diverse measures. Practical implications: Implementation of the developed predicting methodology and methods and measures to prevent and eliminate hydrate formation in wells and technological equipment in underground gas storage facilities will increase the operation efficiency of underground gas storage facilities. Originality/value: The use of artificial intelligence to predict hydrate formations in flowlines of wells and technological equipment of underground gas storage facilities is proposed. Using this approach to predict and function the system as a whole ensures high reliability of the results obtained due to adaptation of the system to the specified control conditions.

3

Developing measures to eliminate of hydrate formation in underground gas storages

Volovetskyi V. B., Doroshenko Ya. V., Bugai A. O., Kogut G. M., Raiter P. M., Femiak Y. M., Bondarenko R. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 111, nr 2

64--77

EN

Purpose: The objective of this article is the analysys of methods for preventing and eliminating hydrates formations, classifying them and choosing the best ones for use in underground gas storage facilities. Comprehensive measures for the stable operation of gas storage facilities in the presence of conditions for the occurrence of hydrates formations were developed. Zones, being potentially prone to the hydrates formation during the gas storage facilities operation were identified. Design/methodology/approach: The operational parameters of gas storage wells during gas withdrawal are analyzed. The identified wells were operated under difficult conditions due to the deposition of hydrates on the wellheads, in flowlines and process equipment of gas storage facilities. The places of the highest hydrates accumulation on underground gas storages were determined: from the bottomhole of wells to the gas purification unit of the gas gathering station. Hydrate-prone zones were identified by computational fluid dynamic (CFD) modeling at the location of regulating choke installations in underground gas storage facilities. Findings: The zones of the greatest hydrates accumulation on underground gas storages were determined: from the bottomhole of wells to the gas purification unit of the gas gathering station. The analysis of the methods used in gas storage facilities of Ukraine to prevent and eliminate hydrates formation was out. A set of measures was proposed to prevent the hydrates formation in storage facilities to ensure their stable operation. Based on the Euler approach (Mixture model) by CFD modeling, zones prone to hydrates formation were determined at the installation site of regulating chokes in underground gas storages. The influence of the degree of fittings opening on the location of potential zones prone to hydrates formation was estimated. The gas-dynamic processes in the internal cavity of the gas pipeline at the installation site of the control fittings were studied and their influence on the distribution of bulk particles of the gaseous and liquid phases was established. Based on the studies performed, it was recommended to change periodically the mode of well operation for a certain time by opening or closing the regulating choke under favorable conditions for the formation of hydrates, especially at low ambient temperatures. Research limitations/implications: The obtained results of experimental studies and calculations showed that in order to solve the problem of hydrates formation at gas storage facilities, it is advisable to use diverse measures through the introduction of modern intelligent systems for monitoring and controlling the technological process. Further refinement of the algorithm of the proposed monitoring and control system with its approbation in production was provided. Practical implications: The results of the experimental studies and CFD modeling carried out allowed providing a more reasonable approach to the application of various available methods and measures to prevent hydrates formation in underground gas storage facilities. This approach made it possible to develop new effective ways and measures to prevent such complication. Originality/value: Based on the conducted experimental studies and modeling, the major zones prone to hydrates formation in underground gas storages were determined. The developed measures will allow timely detection and prevention of hydrates formation at gas storage facilities are original.

4

Influence of hydrate formation and concentration of salts on the corrosion of steel 20 pipelines

Poberezhny Lubomyr, Chudyk Ihor, Hrytsanchuk Andrii, Mandryk Oleg, Kalyn Tetyana, Hrytsuliak Halyna, Yakymechko Yaroslav

Management Systems in Production Engineering

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2020

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nr 3 (28)

141--147

EN

One of the ways to increase natural gas production is to conserve and/or intensify existing wells with their subsequent development. They are characterized by a high content of highly mineralized water, which leads to an increased risk of hydrate formation and internal corrosion. The issue of the formation of gas hydrates in industrial pipelines, which is a major problem for the exploitation of industrial gas pipelines, requires considerable attention to be made to exclude emergency situations. The main task of the study – to determine the effect of hydrates on the corrosion of the pipeline in order to prevent emergencies. A technique for studying the effect of hydration on the corrosion of pipelines has been developed. The combined analysis of the corrosion behavior of pipe material in aggressive media of chloride type was done. According to the results of corrosion-mechanical tests, regularities of joint action of mechanical stresses, concentration of chlorides and hydrate formation on the speed and localization of corrosion processes are established.