Improving the method for estimating the deposit depth of asphalt-resin-paraffin oil components in the tubing of oil production wells

UDK: 622.276.72
DOI: 10.24887/0028-2448-2021-5-114-117
Key words: asphalt-resin-paraffin deposits, estimating the depth of tubing cleaning, gas-water-oil flows, volumetric oil and water contents in the liquid phase, temperature distribution of the produced fluid in the tubing, paraffin crystallization
Authors: M.G. Volkov (RN-BashNIPIneft LLC, RF, Ufa; Ufa State Petroleum Technological University, RF, Ufa), Yu.V. Zeigman (RN-BashNIPIneft LLC, RF, Ufa; Ufa State Petroleum Technological University, RF, Ufa)

Asphalt-resin-paraffin deposits (ARPD) are usually formed in submersible downhole equipment in fields characterized by a high content of paraffin and asphaltenes, and which are at the final stage of development. Such fields are characterized by deterioration of thermobaric reservoir conditions (decreasing the reservoir temperature), the weighting of oil due to high-carbon fractions and high water cut of the produced fluids (more than 80-90%). The process of wax crystallization in tubing most often occurs due to a decreasing temperature transported to the surface of the well product as a result of its intense heat exchange with the environment. ARPD on the inner surface of the tubing walls have a negative effect on the process of lifting the produced fluid to the surface, which is expressed in reducing the well flow rate by reducing the flow area of the tubing. It is necessary to reliably predict the interval of ARPD formation in the wellbore to improve efficiency when choosing technologies for tubing cleaning from deposits.

A method has been developed for estimating the depth of oil production wells tubing cleaning from ARPD, in which, in contrast to the known ones, the calculation of the temperature distribution in the wellbore is based on solving the equation of the heat balance of the produced fluid with the environment, not on empirical dependencies. The use of a three-phase one-dimensional gas-water-oil flow model for calculating the coefficients of the volumetric oil and water contents in the liquid phase in tubing, which takes into account not only the effect of phase slip between liquid and gas but also between water and oil, will improve the accuracy of calculating the thermal conductivity transported to the well product surface and will more reliably predict the depth of wellbore remediation. Practical application of the developed method will reduce the time required to determine the scope of remediation, and, as a result, reduce production costs by choosing the optimal remediation technology for tubing.

References

1. Akramov T.F., Yarkeeva N.R., Control deposits of paraffin, asphalt-resin components of oil (In Russ.), Neftegazovoe delo, 2017, V. 15, no. 4, pp. 67–72.

2. Khoshanov T., Shirdzhanov N., Prediction of wax deposition depth in the well (In Russ.), Neftepromyslovoe delo, 1981, no. 4, pp. 21 – 23.

3. Suchkov B.M., Khabibullin R.N., On the rational depth of running lift pipes with protective coatings into the well (In Russ.), Neftepromyslovoe delo, 1974, no. 7, pp. 19–22.

4. Suchkov B.M., Khabibullin R.N., Influence of the water cut of the well production on the temperature of the fluid flow and waxing of the riser pipes (In Russ.), Neftepromyslovoe delo, 1973, no. 10, pp. 28–30.

5. Volkov M.G., Oil-water-gas flow calculations in vertical wells (In Russ.), Problemy sbora, podgotovki i transporta nefti i nefteproduktov, 2017, no. 3(109), pp. 9–42.

6. Brill J.P., Mukherjee H., Multiphase flow in wells, SPE Monograph, Henry L. Dogherty Series, V. 17, 1999.

7. Hasan A.R., Kabir C.S., A simplified model for oil water flow in vertical and deviated wellbores, SPE-54131-PA, 1999, https://doi.org/10.2118/54131-PA.

8. Flores J.G., Oil-water flow in vertical and deviated wells, Oklahoma: The University of Tulsa, 1997.

9. Ansari A.M., Sylvester A.D., Sarica C. et al., A comprehensive mechanistic model for upward two-phase flow in wellbores, SPE-20630-PA, 1994, https://doi.org/10.2118/20630-PA.

Asphalt-resin-paraffin deposits (ARPD) are usually formed in submersible downhole equipment in fields characterized by a high content of paraffin and asphaltenes, and which are at the final stage of development. Such fields are characterized by deterioration of thermobaric reservoir conditions (decreasing the reservoir temperature), the weighting of oil due to high-carbon fractions and high water cut of the produced fluids (more than 80-90%). The process of wax crystallization in tubing most often occurs due to a decreasing temperature transported to the surface of the well product as a result of its intense heat exchange with the environment. ARPD on the inner surface of the tubing walls have a negative effect on the process of lifting the produced fluid to the surface, which is expressed in reducing the well flow rate by reducing the flow area of the tubing. It is necessary to reliably predict the interval of ARPD formation in the wellbore to improve efficiency when choosing technologies for tubing cleaning from deposits.

A method has been developed for estimating the depth of oil production wells tubing cleaning from ARPD, in which, in contrast to the known ones, the calculation of the temperature distribution in the wellbore is based on solving the equation of the heat balance of the produced fluid with the environment, not on empirical dependencies. The use of a three-phase one-dimensional gas-water-oil flow model for calculating the coefficients of the volumetric oil and water contents in the liquid phase in tubing, which takes into account not only the effect of phase slip between liquid and gas but also between water and oil, will improve the accuracy of calculating the thermal conductivity transported to the well product surface and will more reliably predict the depth of wellbore remediation. Practical application of the developed method will reduce the time required to determine the scope of remediation, and, as a result, reduce production costs by choosing the optimal remediation technology for tubing.

References

1. Akramov T.F., Yarkeeva N.R., Control deposits of paraffin, asphalt-resin components of oil (In Russ.), Neftegazovoe delo, 2017, V. 15, no. 4, pp. 67–72.

2. Khoshanov T., Shirdzhanov N., Prediction of wax deposition depth in the well (In Russ.), Neftepromyslovoe delo, 1981, no. 4, pp. 21 – 23.

3. Suchkov B.M., Khabibullin R.N., On the rational depth of running lift pipes with protective coatings into the well (In Russ.), Neftepromyslovoe delo, 1974, no. 7, pp. 19–22.

4. Suchkov B.M., Khabibullin R.N., Influence of the water cut of the well production on the temperature of the fluid flow and waxing of the riser pipes (In Russ.), Neftepromyslovoe delo, 1973, no. 10, pp. 28–30.

5. Volkov M.G., Oil-water-gas flow calculations in vertical wells (In Russ.), Problemy sbora, podgotovki i transporta nefti i nefteproduktov, 2017, no. 3(109), pp. 9–42.

6. Brill J.P., Mukherjee H., Multiphase flow in wells, SPE Monograph, Henry L. Dogherty Series, V. 17, 1999.

7. Hasan A.R., Kabir C.S., A simplified model for oil water flow in vertical and deviated wellbores, SPE-54131-PA, 1999, https://doi.org/10.2118/54131-PA.

8. Flores J.G., Oil-water flow in vertical and deviated wells, Oklahoma: The University of Tulsa, 1997.

9. Ansari A.M., Sylvester A.D., Sarica C. et al., A comprehensive mechanistic model for upward two-phase flow in wellbores, SPE-20630-PA, 1994, https://doi.org/10.2118/20630-PA.


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