Methodology for estimating downhole pressure using multivariate model

UDK: 622.276.2.001.57
DOI: 10.24887/0028-2448-2019-1-40-43
Key words: oil producing well, bottomhole pressure, bottomhole pressure monitoring, deep gauge, method reliability, multidimensional mathematical model
Authors: V.I. Galkin (Perm National Research Polytechnic University, RF, Perm), I.N. Ponomareva (Perm National Research Polytechnic University, RF, Perm), I.A. Chernykh (Perm National Research Polytechnic University, RF, Perm), E.V. Filippov (LUKOIL-PERM LLC, RF, Perm), G.N. Chumakov (LUKOIL-PERM LLC, RF, Perm)

The calculation of bottomhole pressure is the most important task of monitoring the operation of oil producing wells. When it is impossible to directly measure it, in practice, calculation methods are used, including methods for recalculating wellhead parameters (annular pressure, dynamic level, etc.). For this purpose, LUKOIL-PERM uses two methods for recalculating wellhead parameters into bottomhole pressure: one is fully analytical, and another is analytical with address correlations. The article presents the results of assessing the reliability of determining bottomhole pressure using these methods. The material was used for two fields of the Perm Territory - Magovskoye and Shershnevskoye, including the results of parallel wellhead and deep measurements. Comparison of actual and calculated by existing methods values of downhole pressure showed a low reliability of their application. The main reason for the low reliability of the applied methods should be considered the need to use the characteristics of the gas-liquid mixture in the wellbore and the annulus space, which cannot be determined accurately enough due to the complex nature of multiphase flow. The article proposes a fundamentally different approach, consisting in the construction of multivariate mathematical models based on statistical processing of the accumulated material of parallel wellhead and depth measurements. For this purpose, data from 235 wells surveys from the fields under consideration are involved. As the initial data in the developed method, it is proposed to use well performance indicators, the definition of which is not accompanied by difficulties: oil and liquid flow rate, water content, dynamic level, annular pressure, pump depth and its immersion under dynamic level, distance to water-oil contact. Multidimensional mathematical models are built for both fields under consideration. To assess the reliability of the developed methodology based on the use of multivariate models, the tools of mathematical statistics were used. The developed technique has demonstrated its high accuracy compared to the currently used methods for determining bottomhole pressure when recalculated from wellhead parameters.

References

1. Chernykh I.A., Razrabotka metodiki monitoringa zaboynogo davleniya po dannym promyslovo-geofizicheskikh issledovaniy skvazhin (Development of a bottomhole pressure monitoring method based on field geophysical well data): thesis of candidate of technical science, Permʹ, 2018.

2. Chernykh I.A., Determination of bottomhole pressure by using multivariate statistical models (on example of formation TL-BB Yurchukskoie field) (In Russ.), Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo, 2016, V. 15, no. 21, pp. 320–328, DOI: 10.15593/2224-9923/2016.21.3.

3. Galkin V.I., Ponomareva I.N., Cherepanov S.S., Development of the methodology for evaluation of possibilities to determine reservoir types based on pressure build-up curves, geological and reservoir properties of the formation (case study of famen deposits of Ozernoe field) (In Russ.), Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo = Perm Journal of Petroleum and Mining Engineering, 2015, no. 17, pp. 32–40, DOI: 10.15593/2224-9923/2015.17.4.

4. Bikbulatov S.M., Pashali A.A., Analysis and selection of methods for calculating the pressure gradient in the wellbore (In Russ.), Ehlektronnyy nauchnyy zhurnal “Neftegazovoe delo”, 2005, no. 2, URL: http://ogbus.ru/files/ogbus/authors/Bikbulatov/Bikbulatov_1.pdf.

5. Venttselʹ E.S., Issledovanie operatsiy (Operations research), Moscow: Sovetskoe radio Publ., 1972, 407 p.

6. Galkin V.I., Ponomareva I.N., Koltyrin A.N., Development of probabilistic and statistical models for evaluation of the effectiveness of proppant hydraulic fracturing (on example of the Tl-Bb reservoir of the Batyrbayskoe field) (In Russ.), Vestnik Permskogo natsionalʹnogo issledovatelʹskogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo = Perm Journal of Petroleum and Mining Engineering, 2018, V. 17, no. 1, pp. 37–49, DOI: 10.15593/2224-9923/2018.1.4

7. Gladkikh E.A., Khizhnyak G.P., Galkin V.I., Popov N.A., Method for evaluation of oil displacement coefficient based on conventional core analysis (In Russ.), Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo = Perm Journal of Petroleum and Mining Engineering, 2017, V. 16, no. 3, pp. 225–237, DOI: 10.15593/2224-9923/2017.3.3.

The calculation of bottomhole pressure is the most important task of monitoring the operation of oil producing wells. When it is impossible to directly measure it, in practice, calculation methods are used, including methods for recalculating wellhead parameters (annular pressure, dynamic level, etc.). For this purpose, LUKOIL-PERM uses two methods for recalculating wellhead parameters into bottomhole pressure: one is fully analytical, and another is analytical with address correlations. The article presents the results of assessing the reliability of determining bottomhole pressure using these methods. The material was used for two fields of the Perm Territory - Magovskoye and Shershnevskoye, including the results of parallel wellhead and deep measurements. Comparison of actual and calculated by existing methods values of downhole pressure showed a low reliability of their application. The main reason for the low reliability of the applied methods should be considered the need to use the characteristics of the gas-liquid mixture in the wellbore and the annulus space, which cannot be determined accurately enough due to the complex nature of multiphase flow. The article proposes a fundamentally different approach, consisting in the construction of multivariate mathematical models based on statistical processing of the accumulated material of parallel wellhead and depth measurements. For this purpose, data from 235 wells surveys from the fields under consideration are involved. As the initial data in the developed method, it is proposed to use well performance indicators, the definition of which is not accompanied by difficulties: oil and liquid flow rate, water content, dynamic level, annular pressure, pump depth and its immersion under dynamic level, distance to water-oil contact. Multidimensional mathematical models are built for both fields under consideration. To assess the reliability of the developed methodology based on the use of multivariate models, the tools of mathematical statistics were used. The developed technique has demonstrated its high accuracy compared to the currently used methods for determining bottomhole pressure when recalculated from wellhead parameters.

References

1. Chernykh I.A., Razrabotka metodiki monitoringa zaboynogo davleniya po dannym promyslovo-geofizicheskikh issledovaniy skvazhin (Development of a bottomhole pressure monitoring method based on field geophysical well data): thesis of candidate of technical science, Permʹ, 2018.

2. Chernykh I.A., Determination of bottomhole pressure by using multivariate statistical models (on example of formation TL-BB Yurchukskoie field) (In Russ.), Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo, 2016, V. 15, no. 21, pp. 320–328, DOI: 10.15593/2224-9923/2016.21.3.

3. Galkin V.I., Ponomareva I.N., Cherepanov S.S., Development of the methodology for evaluation of possibilities to determine reservoir types based on pressure build-up curves, geological and reservoir properties of the formation (case study of famen deposits of Ozernoe field) (In Russ.), Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo = Perm Journal of Petroleum and Mining Engineering, 2015, no. 17, pp. 32–40, DOI: 10.15593/2224-9923/2015.17.4.

4. Bikbulatov S.M., Pashali A.A., Analysis and selection of methods for calculating the pressure gradient in the wellbore (In Russ.), Ehlektronnyy nauchnyy zhurnal “Neftegazovoe delo”, 2005, no. 2, URL: http://ogbus.ru/files/ogbus/authors/Bikbulatov/Bikbulatov_1.pdf.

5. Venttselʹ E.S., Issledovanie operatsiy (Operations research), Moscow: Sovetskoe radio Publ., 1972, 407 p.

6. Galkin V.I., Ponomareva I.N., Koltyrin A.N., Development of probabilistic and statistical models for evaluation of the effectiveness of proppant hydraulic fracturing (on example of the Tl-Bb reservoir of the Batyrbayskoe field) (In Russ.), Vestnik Permskogo natsionalʹnogo issledovatelʹskogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo = Perm Journal of Petroleum and Mining Engineering, 2018, V. 17, no. 1, pp. 37–49, DOI: 10.15593/2224-9923/2018.1.4

7. Gladkikh E.A., Khizhnyak G.P., Galkin V.I., Popov N.A., Method for evaluation of oil displacement coefficient based on conventional core analysis (In Russ.), Vestnik Permskogo natsional'nogo issledovatel'skogo politekhnicheskogo universiteta. Geologiya. Neftegazovoe i gornoe delo = Perm Journal of Petroleum and Mining Engineering, 2017, V. 16, no. 3, pp. 225–237, DOI: 10.15593/2224-9923/2017.3.3.



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