The article discusses the need of taking into account the thixotropic properties of oils when oil pipeline starts after a long stop, as well as to calculation of the time of its safe stop. To evaluate the parameters of thixotropy, it is proposed to use the results of laboratory experiments of oil samples on a rotary viscometer. Typical properties of the rheological flow curves of thixotropic oils for the starting flow mode are determined. The use of the wave equation of damped vibrations is proposed to describe the rheological flow curve of the forward course of measurements of a rotational viscometer, characterized by the presence of ascents and descents of shear stresses. This equation, supplemented by a model of nonlinear-visco-plastic liquids, allows accurately finding the areas of appearance of thixotropic properties of oils. The article presents the results of experimental studies of the manifestation of thixotropic properties of two oil samples at a lower temperature. The wave equation of damped vibrations allows describing mathematically the ascents and descents of shear stresses observed at low oil temperatures. Experiments have shown that the wave properties of thixotropic oil do not change with a decrease in temperature except for the amplitude of maximum vibrations and are invariant properties of the studied liquid. The presented explanation of the physical mechanism for the manifestation of wave properties based on the hardening of the supramolecular paraffin crystal lattice characteristic of thixotropic oils explains the invariance of the frequency change function and the attenuation coefficient during starting processes at the beginning of the movement of the movable cylinder of a rotary viscometer. The result of laboratory studies allows determining the nature of changes in the contours of the zones of manifestation of thixotropic properties of oil as a dependence on the temperature and shear rate.

References

1. Dyagterev V.N., Voprosy puska nefteprovoda s parafinistoy neft'yu posle ego dlitel'noy ostanovki. Obzornaya informatsiya (Issues of starting an oil pipeline with paraffin oil after a long stop. Overview Information), Seriya Transport i khranenie nefti i nefteproduktov (Series Transport and storage of oil and oil products), Moscow: Publ. of VNIIOENG, 1982, 61 p.

2. Armenskiy E.A., On the issue of oil pipeline shutdowns during the pumping of high-paraffin oils (In Russ.), In: Problemy nefti i gaza Tyumeni (Tyumen Oil and Gas Problems), 1977, V. 37, 60 p.

3. Abuzova F.F., Abramzon L.S., Pressure distribution in a pipeline with hardened oil or oil product (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1968, no. 3, pp. 64–66.

4. Abuzova F.F., Abramzon L.S., An approximate method for calculating the pressure distribution in a frozen oil pipeline (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1968, no. 5, pp. 55–56.

5. Abramzon L.S., On possible mechanisms of pressure propagation in solidified oil pipelines (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1968, no. 9, pp. 63–64.

6. Skripnikov Yu.A., Gubin V.E., Abramzon L.S., Features of the shift of a cooled thixotropic fluid (In Russ.), Transport nefti i nefteproduktov, 1966, no. 7, pp. 3–6.

7. Gubin V.E., Skripnikov Yu.V., Abramzon L.S., On the static shear stress of viscoplastic oils (In Russ.), Transport vysokovyazkikh neftey i nefteproduktov po truboprovodam, 1970, no. ?, pp. 39–50.

8. Tugunov P.I., Novoselov V.F., Gol'yanov A.I., Cooling of oil and oil products in underground pipelines (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 1968, no. 3, pp. 15-18.

9. Tyan V.K., Pimenov A.V., Comprehensive study of solidified paraffin oil shear process in a pipeline (In Russ.), Vestnik Samarskogo gosudarstvennogo tekhnicheskogo universiteta, 2013, no. 4(40), pp. 218–221.

10. Tyan V.K., Degtyarev V.N., Tyan P.V., Pimenov A.V., Mathematical modeling of congelation paraffin oil in transit on pipes (In Russ.), Izvestiya Samarskogo nauchnogo tsentra RAN, 2009, V. 11 (27), no. 5 (2), pp. 358–361.

11. Tyan V.K., Reduction of synthesis process of many-dimensional linear control systems to synthesis of one-demensional linear control systems with standart (In Russ.), Novye tekhnologii, mekhatronika, avtomatizatsiya, upravlenie, 2008, no. 4(85), pp. 2–7.

12. Nikolaev A.K., Zaripova N.A., Deminin E.S., Tiksotropiya: izuchenie yavleniya na primere nefti Vostochno-Birlinskogo mestorozhdeniya (In Russ.), Delovoy zhurnal NEFTEGAZ.RU, 2018, no. 2, pp. 92–95.

13. Kondrasheva N.K., Baytalov F.D., Boytsova A.A., Comparative assessment of structural-mechanical properties of heavy oils of timano-pechorskaya province (In Russ.), Zapiski Gornogo instituta, 2017, V. 225, pp. 320–329.

14. Tashbulatov R., Karimov R., Valeev A. et al., The asymptotic rheological model of anomalously viscous oil, Journal of Engineering and Applied Sciences, 2018, V. 13, no. 7, pp. 5502–5506, DOI: 10.3923/jeasci.2018.5502.5506

15. Tashbulatov R.R., Karimov R.M., Valeev A.R., Mastobaev B.N., Asymptotic model for describing the rheological curve of the non-Newtonian flow of oil mixtures (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 2017, no. 5, pp. 14–23.

16. Tashbulatov R., Karimov R., Valeev A. et al., Modeling rheological properties in blending of anomalously viscous oils, Journal of Engineering and Applied Sciences, 2018, V. 13, no. 5, pp. 4728–4762, DOI: 10.3923/jeasci.2018.4728.4732

17. Tashbulatov R.R., Karimov R.M., Valeev A.R., Mastobaev B.N., Approximation of the rheological curve in the low-temperature zones of the anomalous flow of non-Newtonian oils using the asymptotic model (In Russ.), Truboprovodnyy transport: teoriya i praktika, 2017, no. 4, pp. 19–24.The article discusses the need of taking into account the thixotropic properties of oils when oil pipeline starts after a long stop, as well as to calculation of the time of its safe stop. To evaluate the parameters of thixotropy, it is proposed to use the results of laboratory experiments of oil samples on a rotary viscometer. Typical properties of the rheological flow curves of thixotropic oils for the starting flow mode are determined. The use of the wave equation of damped vibrations is proposed to describe the rheological flow curve of the forward course of measurements of a rotational viscometer, characterized by the presence of ascents and descents of shear stresses. This equation, supplemented by a model of nonlinear-visco-plastic liquids, allows accurately finding the areas of appearance of thixotropic properties of oils. The article presents the results of experimental studies of the manifestation of thixotropic properties of two oil samples at a lower temperature. The wave equation of damped vibrations allows describing mathematically the ascents and descents of shear stresses observed at low oil temperatures. Experiments have shown that the wave properties of thixotropic oil do not change with a decrease in temperature except for the amplitude of maximum vibrations and are invariant properties of the studied liquid. The presented explanation of the physical mechanism for the manifestation of wave properties based on the hardening of the supramolecular paraffin crystal lattice characteristic of thixotropic oils explains the invariance of the frequency change function and the attenuation coefficient during starting processes at the beginning of the movement of the movable cylinder of a rotary viscometer. The result of laboratory studies allows determining the nature of changes in the contours of the zones of manifestation of thixotropic properties of oil as a dependence on the temperature and shear rate.

References

1. Dyagterev V.N., Voprosy puska nefteprovoda s parafinistoy neft'yu posle ego dlitel'noy ostanovki. Obzornaya informatsiya (Issues of starting an oil pipeline with paraffin oil after a long stop. Overview Information), Seriya Transport i khranenie nefti i nefteproduktov (Series Transport and storage of oil and oil products), Moscow: Publ. of VNIIOENG, 1982, 61 p.

2. Armenskiy E.A., On the issue of oil pipeline shutdowns during the pumping of high-paraffin oils (In Russ.), In: Problemy nefti i gaza Tyumeni (Tyumen Oil and Gas Problems), 1977, V. 37, 60 p.

3. Abuzova F.F., Abramzon L.S., Pressure distribution in a pipeline with hardened oil or oil product (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1968, no. 3, pp. 64–66.

4. Abuzova F.F., Abramzon L.S., An approximate method for calculating the pressure distribution in a frozen oil pipeline (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1968, no. 5, pp. 55–56.

5. Abramzon L.S., On possible mechanisms of pressure propagation in solidified oil pipelines (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1968, no. 9, pp. 63–64.

6. Skripnikov Yu.A., Gubin V.E., Abramzon L.S., Features of the shift of a cooled thixotropic fluid (In Russ.), Transport nefti i nefteproduktov, 1966, no. 7, pp. 3–6.

7. Gubin V.E., Skripnikov Yu.V., Abramzon L.S., On the static shear stress of viscoplastic oils (In Russ.), Transport vysokovyazkikh neftey i nefteproduktov po truboprovodam, 1970, no. ?, pp. 39–50.

8. Tugunov P.I., Novoselov V.F., Gol'yanov A.I., Cooling of oil and oil products in underground pipelines (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 1968, no. 3, pp. 15-18.

9. Tyan V.K., Pimenov A.V., Comprehensive study of solidified paraffin oil shear process in a pipeline (In Russ.), Vestnik Samarskogo gosudarstvennogo tekhnicheskogo universiteta, 2013, no. 4(40), pp. 218–221.

10. Tyan V.K., Degtyarev V.N., Tyan P.V., Pimenov A.V., Mathematical modeling of congelation paraffin oil in transit on pipes (In Russ.), Izvestiya Samarskogo nauchnogo tsentra RAN, 2009, V. 11 (27), no. 5 (2), pp. 358–361.

11. Tyan V.K., Reduction of synthesis process of many-dimensional linear control systems to synthesis of one-demensional linear control systems with standart (In Russ.), Novye tekhnologii, mekhatronika, avtomatizatsiya, upravlenie, 2008, no. 4(85), pp. 2–7.

12. Nikolaev A.K., Zaripova N.A., Deminin E.S., Tiksotropiya: izuchenie yavleniya na primere nefti Vostochno-Birlinskogo mestorozhdeniya (In Russ.), Delovoy zhurnal NEFTEGAZ.RU, 2018, no. 2, pp. 92–95.

13. Kondrasheva N.K., Baytalov F.D., Boytsova A.A., Comparative assessment of structural-mechanical properties of heavy oils of timano-pechorskaya province (In Russ.), Zapiski Gornogo instituta, 2017, V. 225, pp. 320–329.

14. Tashbulatov R., Karimov R., Valeev A. et al., The asymptotic rheological model of anomalously viscous oil, Journal of Engineering and Applied Sciences, 2018, V. 13, no. 7, pp. 5502–5506, DOI: 10.3923/jeasci.2018.5502.5506

15. Tashbulatov R.R., Karimov R.M., Valeev A.R., Mastobaev B.N., Asymptotic model for describing the rheological curve of the non-Newtonian flow of oil mixtures (In Russ.), Transport i khranenie nefteproduktov i uglevodorodnogo syr'ya, 2017, no. 5, pp. 14–23.

16. Tashbulatov R., Karimov R., Valeev A. et al., Modeling rheological properties in blending of anomalously viscous oils, Journal of Engineering and Applied Sciences, 2018, V. 13, no. 5, pp. 4728–4762, DOI: 10.3923/jeasci.2018.4728.4732

17. Tashbulatov R.R., Karimov R.M., Valeev A.R., Mastobaev B.N., Approximation of the rheological curve in the low-temperature zones of the anomalous flow of non-Newtonian oils using the asymptotic model (In Russ.), Truboprovodnyy transport: teoriya i praktika, 2017, no. 4, pp. 19–24.