Study of wax deposition reasons in non-isothermal main pipelines for hot pumping of high-viscosity waxy oil

UDK: 658.5:622.692.4
DOI: 10.24887/0028-2448-2021-1-87-91
Key words: wax deposition, waxy oil, main pipeline, hot pumping efficiency, heat treatment, depressant additive, temperature gradient
Authors: R.M. Karimov (Ufa State Petroleum Technological University, RF, Ufa), R.Z. Sunagatullin (The Pipeline Transport Institute LLC, RF, Moscow), R.R. Tashbulatov (Ufa State Petroleum Technological University, RF, Ufa), M.E. Dmitriev (Ufa State Petroleum Technological University, RF, Ufa)

The paper discusses the issues and peculiarities of wax deposition in non-isothermal main pipelines for ‘hot’ pumping of oil, characterized by an increased content of paraffins - positive fluid loss temperatures, risks of congelation and intensification of wax deposition. Problems of pumping waxy oils are solved by thermochemical methods aimed at eliminating the risks of blocking the section at low ambient temperatures and long downtime of the linear part for the period of regular scheduled and emergency repair work. If the issue of determining the permissible safe shutdown time and start-up modes has been given a fairly large number of scientific works both in domestic and foreign literature, then the tasks of optimizing the operating costs associated with determining the required frequency of pigging, dosages of chemical reagents, today, remain unresolved and require rational solutions that are necessary and sufficient in order to maintain energy efficiency and system reliability. At the same time, the issues of ecology, especially for Arctic oil and gas regions, dictate new more stringent requirements for the special pumping methods, developed decades ago. 

This article presents the results of the performed analysis of the influence of various factors on the efficiency of hot oil pumping, substantiates the shortcomings of the equipment and chemical reagents used, caused by an insufficient level of preheating of oil due to a number of technological limitations adopted decades ago. The results of experimental studies of the dependence of the intensity of wax deposition on the temperature gradient in the near-wall zone are presented, confirming the advantages of low-temperature pipeline transportation of preliminarily heat-treated oil in comparison with a preheating scheme characterized by shock dosages of chemical reagents, on the one hand, partially solving the problem of extending the permissible safe shutdown time, and with the other, leading to the intensification of wax depositions on the inner surface of the walls of a non-insulated oil pipeline.

References

1. Tugunov P.I. et al., Tipovye raschety pri proektirovanii i ekspluatatsiy neftebaz i nefteprovodov (Typical calculations in the design and operation of tank farms and oil pipelines), Ufa: Dizain-PoligrafServis Publ., 2002, 658 p.

2. Karimov R.M., Mastobaev B.N., Change of technology of swapping of oil on the oil pipeline "Uzen-Atyrau-Samara" with development of petrotransport system of the western Kazakhstan (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 2010, no. 2, pp. 9–14.

3. Karimov R.M., Mastobaev B.N., Rheologikal features of the West Kazakhstan oil blend (In Russ.), Transport i khranenine nefteproduktov i uglevodorodnogo sur’ya, 2011, no. 2, pp. 3–7.

4. Karimov R.M., Mastobaev B.N., Joint transportation of high-viscosity and highly solidifying oils from Western Kazakhstan via the Uzen-Atyrau-Samara oil pipeline (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 2012, no. 1, pp. 3–6.

5. Karimov R.M., Bakhtizin R.N., Mastobaev B.N., The effect of high-molecular components on flow properties, depending on the structural-group and fractional oil content (In Russ.), Socar Proceedings, 2016, no. 1, pp. 42-50. 

6. Sunagatullin R.Z., Karimov R.M., Mastobaev B.N., Vliyanie temperaturnogo gradienta na granitse razdela “potok-stenka” na intensivnost' parafinootlozheniy (Influence of the temperature gradient at the “flow-wall” interface on the intensity of paraffin deposition), Proceedings of XIV International educational, scientific and practical conference "Pipeline transport - 2019", Ufa: Publ. of USPTU, 2019, pp. 132–133.

7. Revel'-Muroz P.A., Bakhtizin R.N., Karimov R.M., Mastobaev B.N., Joint usage of thermal and chemical stimulation technique for transportation of high viscosity and congealing oils (In Russ.), Socar Proceedings (Nauchnye trudy), 2017, no. 2, pp. 49–55.

8. Revel'-Muroz P.A., Bakhtizin R.N., Karimov R.M., Mastobaev B.N., Joint transportation of heavy and wax oil blended (In Russ.), Socar Proceedings, 2018, no. 2, pp. 65–70.

9. Armenskiy E.A., Novoselov V.F., Tugunov P.I., Study of thermal phenomena and dynamics of wax deposition in oil pipelines (In Russ.), Neft' i gaz, 1969, no. 10, pp. 77–80.

10. Tronov V.P., Teoreticheskaya otsenka vliyaniya fizicheskikh svoystv poverkhnostey kachestva obrabotki i drugikh faktorov na intensivnost' otlozheniy parafina (Theoretical assessment of the influence of the physical properties of surfaces, processing quality and other factors on the intensity of wax deposits), Proceedings of TatNIPI, 1962, V. 4, pp. 400–412.

11. Denisov E.F., Karimov R.M., Makarenko O.A., K voprosu o primenenii khimicheskikh reagentov dlya ochistki ot asfal'to-smoloparafinovykh otlozheniy (On the question of the use of chemicals for cleaning from asphalt-resin-paraffin deposits), Proceedings of International scientific and technical conference dedicated to the memory of academician A.Kh. Mirzajanzade, Ufa: Publ. of USPTU, 2016, 314 p.

12. Karimov R.M., Zaplatin A.V., Tashbulatov R.R., The use of twisted heat exchangers from coils of small bend radius for heating and heat treatment of oil (In Russ.), Delovoy zhurnal Neftegaz.ru, 2018, no. 12, pp. 45–49.

13. URL: https://asgard-service.com /works/ochistka-teploobmennikov-nps-chikshino 

14. URL: https://asgard-service.com/works/ochistka-mezhtrubnogo-prostranstva-teploobmennika-t-506-kozhuhotrub....

15. URL: https://asgard-service.com/works/ochistka-teploobmennikov-podogreva-nefti-na-knpz.

16. Karimov R.M., Tashbulatov R.R., Zaplatin A.V., Coiled heat exchanger with small radius bent tubes for controlled heat treatment of high viscosity waxy oil, IOP Conf. Series: Earth and Environmental Science, 2019, V. 272, pp. 022193, doi:10.1088/1755-1315/272/2/022193.

The paper discusses the issues and peculiarities of wax deposition in non-isothermal main pipelines for ‘hot’ pumping of oil, characterized by an increased content of paraffins - positive fluid loss temperatures, risks of congelation and intensification of wax deposition. Problems of pumping waxy oils are solved by thermochemical methods aimed at eliminating the risks of blocking the section at low ambient temperatures and long downtime of the linear part for the period of regular scheduled and emergency repair work. If the issue of determining the permissible safe shutdown time and start-up modes has been given a fairly large number of scientific works both in domestic and foreign literature, then the tasks of optimizing the operating costs associated with determining the required frequency of pigging, dosages of chemical reagents, today, remain unresolved and require rational solutions that are necessary and sufficient in order to maintain energy efficiency and system reliability. At the same time, the issues of ecology, especially for Arctic oil and gas regions, dictate new more stringent requirements for the special pumping methods, developed decades ago. 

This article presents the results of the performed analysis of the influence of various factors on the efficiency of hot oil pumping, substantiates the shortcomings of the equipment and chemical reagents used, caused by an insufficient level of preheating of oil due to a number of technological limitations adopted decades ago. The results of experimental studies of the dependence of the intensity of wax deposition on the temperature gradient in the near-wall zone are presented, confirming the advantages of low-temperature pipeline transportation of preliminarily heat-treated oil in comparison with a preheating scheme characterized by shock dosages of chemical reagents, on the one hand, partially solving the problem of extending the permissible safe shutdown time, and with the other, leading to the intensification of wax depositions on the inner surface of the walls of a non-insulated oil pipeline.

References

1. Tugunov P.I. et al., Tipovye raschety pri proektirovanii i ekspluatatsiy neftebaz i nefteprovodov (Typical calculations in the design and operation of tank farms and oil pipelines), Ufa: Dizain-PoligrafServis Publ., 2002, 658 p.

2. Karimov R.M., Mastobaev B.N., Change of technology of swapping of oil on the oil pipeline "Uzen-Atyrau-Samara" with development of petrotransport system of the western Kazakhstan (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 2010, no. 2, pp. 9–14.

3. Karimov R.M., Mastobaev B.N., Rheologikal features of the West Kazakhstan oil blend (In Russ.), Transport i khranenine nefteproduktov i uglevodorodnogo sur’ya, 2011, no. 2, pp. 3–7.

4. Karimov R.M., Mastobaev B.N., Joint transportation of high-viscosity and highly solidifying oils from Western Kazakhstan via the Uzen-Atyrau-Samara oil pipeline (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 2012, no. 1, pp. 3–6.

5. Karimov R.M., Bakhtizin R.N., Mastobaev B.N., The effect of high-molecular components on flow properties, depending on the structural-group and fractional oil content (In Russ.), Socar Proceedings, 2016, no. 1, pp. 42-50. 

6. Sunagatullin R.Z., Karimov R.M., Mastobaev B.N., Vliyanie temperaturnogo gradienta na granitse razdela “potok-stenka” na intensivnost' parafinootlozheniy (Influence of the temperature gradient at the “flow-wall” interface on the intensity of paraffin deposition), Proceedings of XIV International educational, scientific and practical conference "Pipeline transport - 2019", Ufa: Publ. of USPTU, 2019, pp. 132–133.

7. Revel'-Muroz P.A., Bakhtizin R.N., Karimov R.M., Mastobaev B.N., Joint usage of thermal and chemical stimulation technique for transportation of high viscosity and congealing oils (In Russ.), Socar Proceedings (Nauchnye trudy), 2017, no. 2, pp. 49–55.

8. Revel'-Muroz P.A., Bakhtizin R.N., Karimov R.M., Mastobaev B.N., Joint transportation of heavy and wax oil blended (In Russ.), Socar Proceedings, 2018, no. 2, pp. 65–70.

9. Armenskiy E.A., Novoselov V.F., Tugunov P.I., Study of thermal phenomena and dynamics of wax deposition in oil pipelines (In Russ.), Neft' i gaz, 1969, no. 10, pp. 77–80.

10. Tronov V.P., Teoreticheskaya otsenka vliyaniya fizicheskikh svoystv poverkhnostey kachestva obrabotki i drugikh faktorov na intensivnost' otlozheniy parafina (Theoretical assessment of the influence of the physical properties of surfaces, processing quality and other factors on the intensity of wax deposits), Proceedings of TatNIPI, 1962, V. 4, pp. 400–412.

11. Denisov E.F., Karimov R.M., Makarenko O.A., K voprosu o primenenii khimicheskikh reagentov dlya ochistki ot asfal'to-smoloparafinovykh otlozheniy (On the question of the use of chemicals for cleaning from asphalt-resin-paraffin deposits), Proceedings of International scientific and technical conference dedicated to the memory of academician A.Kh. Mirzajanzade, Ufa: Publ. of USPTU, 2016, 314 p.

12. Karimov R.M., Zaplatin A.V., Tashbulatov R.R., The use of twisted heat exchangers from coils of small bend radius for heating and heat treatment of oil (In Russ.), Delovoy zhurnal Neftegaz.ru, 2018, no. 12, pp. 45–49.

13. URL: https://asgard-service.com /works/ochistka-teploobmennikov-nps-chikshino 

14. URL: https://asgard-service.com/works/ochistka-mezhtrubnogo-prostranstva-teploobmennika-t-506-kozhuhotrub....

15. URL: https://asgard-service.com/works/ochistka-teploobmennikov-podogreva-nefti-na-knpz.

16. Karimov R.M., Tashbulatov R.R., Zaplatin A.V., Coiled heat exchanger with small radius bent tubes for controlled heat treatment of high viscosity waxy oil, IOP Conf. Series: Earth and Environmental Science, 2019, V. 272, pp. 022193, doi:10.1088/1755-1315/272/2/022193.


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