Method for predicting the range of effective operation of a submersible centrifugal gas separator for electric centrifugal pumps

UDK: 622.276.53.054
DOI: 10.24887/0028-2448-2021-6-94-97
Key words: electric centrifugal pumps (ESP) unit, submersible centrifugal gas separators, screw supercharger, flow and pressure characteristics, high gas content, viscosity of oil-water emulsions
Authors: M.G. Volkov (RN-BashNIPIneft LLC, RF, Ufa; Ufa State Petroleum Technological University, RF, Ufa)

To increase the efficiency of oil production from high gas content wells, submersible installations of electric centrifugal pumps (ESP) are equipped with centrifugal gas separators (CGS). When selecting a gas separator model for the specified field conditions, it is important to know that it is able to ensure effective separation of gas from well fluid. For this purpose, the developed method for evaluating the range of ESP feedings in which the CGS is able to effectively separate free gas from well fluid with high gas content and the formation of oil-water emulsions. The method is based on the calculation of the degree of degradation of the head capacity curve of the screw supercharger of the gas separator under the influence of complicating factors; mathematical modeling of hydraulic losses during the flow of the gas-liquid mixture in the inter-blade channels of the screw. Technique calculates the range of fluid flows through the CGS, at which the potential energy increase from the hydrodynamic action of the screw blades on the gas-liquid flow exceeds the loss of energy flow due to friction against the channel walls and impact in the front blade edges area. According to the developed method for the gas separator GSAON5A-500-5ME produced by RimeraAlnas LLC, the calculations showed that: with gas content increase from 0.1 to 0.5, the range of feeds corresponding to the effective operation of the gas separator decreases from 290 to 100 m3/day; with an increase in the viscosity of the extracted oil-water mixture from 0.001 to 0.5 Pa⋅s, with a volume gas content of 0.2, the feed range corresponding to the effective operation of the gas separator is reduced from 240 to 160 m3/day.

References

1. Volkov M.G., Mikhaylov V.G., Petrov P.V., The research of gaz-liquid mix structure influence on gazseparation process efficiency in the centrifugal gasseparator (In Russ.), Vestnik UGATU, 2012, v. 16, no. 5(50), pp. 93–99.

2. Volkov M.G., Calculation method to obtain operational characteristics of a rotary centrifugal gas-separator (In Russ.), Neftepromyslovoe delo, 2017, no. 12, pp. 57–62.

3. Alhanati F.J., Bottomhole gas separation efficiency in electrical submersible pump installations: Ph. D. Dissertation, Tulsa, Oklahoma: The University of Tulsa, 1993.

4. Chebaevskiy V.F., Petrov V.I., Kavitatsionnye kharakteristiki vysokooborotnykh shneko-tsentrobezhnykh nasosov (Cavitation characteristics of high-speed centrifugal screw pumps), Moscow: Stroyizdat Publ., 1970, 336 p.

5. San D., Modeling gas-liquid head performance of electrical submersible pumps: PhD dissertation, The University of Tulsa, Oklahoma, 2003.

6. Beggs H.D, Brill, J.P., A Study of two-phase flow in inclined pipes, Trans. AIME, 1973, v. 256, 607 r.

7. Dukler A.E. et al., Frictional pressure drop in two-phase flow B. An approach through similarity analysis, AIChE Journal, V. 10, no. 1, 1964, pp. 44-51, doi:10.1002/aic.690100118.

8.
Alkaya B., Oil-water flow patterns and pressure gradients in slightly inclined
pipes: PhD dissertation, Tulsa, Oklahoma: The University of Tulsa, 2000.

To increase the efficiency of oil production from high gas content wells, submersible installations of electric centrifugal pumps (ESP) are equipped with centrifugal gas separators (CGS). When selecting a gas separator model for the specified field conditions, it is important to know that it is able to ensure effective separation of gas from well fluid. For this purpose, the developed method for evaluating the range of ESP feedings in which the CGS is able to effectively separate free gas from well fluid with high gas content and the formation of oil-water emulsions. The method is based on the calculation of the degree of degradation of the head capacity curve of the screw supercharger of the gas separator under the influence of complicating factors; mathematical modeling of hydraulic losses during the flow of the gas-liquid mixture in the inter-blade channels of the screw. Technique calculates the range of fluid flows through the CGS, at which the potential energy increase from the hydrodynamic action of the screw blades on the gas-liquid flow exceeds the loss of energy flow due to friction against the channel walls and impact in the front blade edges area. According to the developed method for the gas separator GSAON5A-500-5ME produced by RimeraAlnas LLC, the calculations showed that: with gas content increase from 0.1 to 0.5, the range of feeds corresponding to the effective operation of the gas separator decreases from 290 to 100 m3/day; with an increase in the viscosity of the extracted oil-water mixture from 0.001 to 0.5 Pa⋅s, with a volume gas content of 0.2, the feed range corresponding to the effective operation of the gas separator is reduced from 240 to 160 m3/day.

References

1. Volkov M.G., Mikhaylov V.G., Petrov P.V., The research of gaz-liquid mix structure influence on gazseparation process efficiency in the centrifugal gasseparator (In Russ.), Vestnik UGATU, 2012, v. 16, no. 5(50), pp. 93–99.

2. Volkov M.G., Calculation method to obtain operational characteristics of a rotary centrifugal gas-separator (In Russ.), Neftepromyslovoe delo, 2017, no. 12, pp. 57–62.

3. Alhanati F.J., Bottomhole gas separation efficiency in electrical submersible pump installations: Ph. D. Dissertation, Tulsa, Oklahoma: The University of Tulsa, 1993.

4. Chebaevskiy V.F., Petrov V.I., Kavitatsionnye kharakteristiki vysokooborotnykh shneko-tsentrobezhnykh nasosov (Cavitation characteristics of high-speed centrifugal screw pumps), Moscow: Stroyizdat Publ., 1970, 336 p.

5. San D., Modeling gas-liquid head performance of electrical submersible pumps: PhD dissertation, The University of Tulsa, Oklahoma, 2003.

6. Beggs H.D, Brill, J.P., A Study of two-phase flow in inclined pipes, Trans. AIME, 1973, v. 256, 607 r.

7. Dukler A.E. et al., Frictional pressure drop in two-phase flow B. An approach through similarity analysis, AIChE Journal, V. 10, no. 1, 1964, pp. 44-51, doi:10.1002/aic.690100118.

8.
Alkaya B., Oil-water flow patterns and pressure gradients in slightly inclined
pipes: PhD dissertation, Tulsa, Oklahoma: The University of Tulsa, 2000.


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