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Evaluation of well completion quality based on flow test result

UDK: 622.276.5.001.5
DOI: 10.24887/0028-2448-2020-7-33-35
Key words: well drilling, well completion, flow tests, evaluation of quality, skin-factor, bottomhole formation zone
Authors: V.А. Iktisanov (TatNIPIneft, RF, Bugulma), N.Kh. Musabirova (TatNIPIneft, RF, Bugulma), А.V. Baygushev (TatNIPIneft, RF, Bugulma), М.Kh. Bilalov (TatNIPIneft, RF, Bugulma), F.F. Akhmadishin (TatNIPIneft, RF, Bugulma)
Basically each major company repeatedly faces the issue of well completion quality. This is associated with low actual oil flow rates compared to expected production. Accordingly, a strong focus is placed on various drilling technologies, drilling mud formulations and completion tools, including underbalanced drilling. Thus, the purpose of this study is addressing the issue of well drilling and completion quality for the main types of reservoirs, wells, drilling mud and completion technologies applied in Tatnet PJSC. For this purpose, results of pressure build-up tests reflecting the fluid flow in situ were used. Mechanical skin-factor representing the changes in properties of the bottomhole zone or fracture was applied as the main comparison parameter. Results of flow tests performed in 396 wells have demonstrated that the average mechanical skin-factor ranges within 0.1-0.5, which is equivalent to well production decline of 1-5%, on the average. However, a number of wells exhibited better performance or greater formation damage. All this suggests that the problem of well completion quality is not the top priority issue for Tatnet PJSC. The total skin, which also considered well geometry, was about minus 4.0, which is attributable to extensive drilling of horizontal wells, bottomhole zone treatment jobs and hydraulic fracturing operations. For this reason, even negligible adverse effects from well drilling and completion are entirely offset due to the activities mentioned above. However, multiple operations conducted prior to flow tests (drilling, perforation, completion, stimulation) did not allow differentiation of various completion practices for selection of optimal technologies considering individual reservoir properties. References 1. Ibragimov N.G., Iktisanov V.A., Ibatullin R.R., Akhmadishin F.F., Estimation of technological efficiency of formations exposing in drawdown conditions (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2005, no. 4, pp. 108–111. 2. Khuzin R.R., Musin K.M., L'vova I.V., Laboratornoe modelirovanie na kernakh s tsel'yu otsenki vliyaniya na fil'tratsionnye svoystva plasta, primenyaemykh pri pervichnom vskrytii polimernykh burovykh rastvorov (Laboratory core modeling to assess the effect on the reservoir properties of the formation used in the initial opening of polymer drilling fluids), Collected papers “Metody uvelicheniya nefteotdachi trudnoizvlekaemykh zapasov. Problemy i resheniya” (Oil recovery enhancement methods for hard-to-recover reserves. Problems and solutions), Proceedings of NIInefteotdacha RS of RB, 2003, V. 4, pp. 153–159. 3. Ibatullin R.Kh., Khabibullin R.A., Rylov N.I., The technology of well completion in terrigenous sediments (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1987, no. 2, pp. 21–24. 4. Ovnatanov G.T., Vskrytie i obrabotka plasta (Sompletion and formation treatment), Moscow: Nedra Publ., 1970, 312 p. 5. Muslimov R.Kh., Mokhel' A.N., Kulinich Yu.V., Volkov Yu.A., O mekhanogennykh izmeneniyakh produktivnosti vertikal'nykh, gorizontal'nykh i naklonno-napravlennykh skvazhin (On mechanogenic changes in the productivity of vertical, horizontal and directional wells), Collected papers “Prirodnye rezervuary uglevodorodov i ikh deformatsii v protsesse razrabotki neftyanykh mestorozhdeniy” (Natural reservoirs of hydrocarbons and their deformation during the development of oil fields), Proceedings of All-Russian Scientific Conference, Kazan, 19–23 July 2000, Kazan: Publ. of Kazan University, 2000, 30 p.
Basically each major company repeatedly faces the issue of well completion quality. This is associated with low actual oil flow rates compared to expected production. Accordingly, a strong focus is placed on various drilling technologies, drilling mud formulations and completion tools, including underbalanced drilling. Thus, the purpose of this study is addressing the issue of well drilling and completion quality for the main types of reservoirs, wells, drilling mud and completion technologies applied in Tatnet PJSC. For this purpose, results of pressure build-up tests reflecting the fluid flow in situ were used. Mechanical skin-factor representing the changes in properties of the bottomhole zone or fracture was applied as the main comparison parameter. Results of flow tests performed in 396 wells have demonstrated that the average mechanical skin-factor ranges within 0.1-0.5, which is equivalent to well production decline of 1-5%, on the average. However, a number of wells exhibited better performance or greater formation damage. All this suggests that the problem of well completion quality is not the top priority issue for Tatnet PJSC. The total skin, which also considered well geometry, was about minus 4.0, which is attributable to extensive drilling of horizontal wells, bottomhole zone treatment jobs and hydraulic fracturing operations. For this reason, even negligible adverse effects from well drilling and completion are entirely offset due to the activities mentioned above. However, multiple operations conducted prior to flow tests (drilling, perforation, completion, stimulation) did not allow differentiation of various completion practices for selection of optimal technologies considering individual reservoir properties. References 1. Ibragimov N.G., Iktisanov V.A., Ibatullin R.R., Akhmadishin F.F., Estimation of technological efficiency of formations exposing in drawdown conditions (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2005, no. 4, pp. 108–111. 2. Khuzin R.R., Musin K.M., L'vova I.V., Laboratornoe modelirovanie na kernakh s tsel'yu otsenki vliyaniya na fil'tratsionnye svoystva plasta, primenyaemykh pri pervichnom vskrytii polimernykh burovykh rastvorov (Laboratory core modeling to assess the effect on the reservoir properties of the formation used in the initial opening of polymer drilling fluids), Collected papers “Metody uvelicheniya nefteotdachi trudnoizvlekaemykh zapasov. Problemy i resheniya” (Oil recovery enhancement methods for hard-to-recover reserves. Problems and solutions), Proceedings of NIInefteotdacha RS of RB, 2003, V. 4, pp. 153–159. 3. Ibatullin R.Kh., Khabibullin R.A., Rylov N.I., The technology of well completion in terrigenous sediments (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 1987, no. 2, pp. 21–24. 4. Ovnatanov G.T., Vskrytie i obrabotka plasta (Sompletion and formation treatment), Moscow: Nedra Publ., 1970, 312 p. 5. Muslimov R.Kh., Mokhel' A.N., Kulinich Yu.V., Volkov Yu.A., O mekhanogennykh izmeneniyakh produktivnosti vertikal'nykh, gorizontal'nykh i naklonno-napravlennykh skvazhin (On mechanogenic changes in the productivity of vertical, horizontal and directional wells), Collected papers “Prirodnye rezervuary uglevodorodov i ikh deformatsii v protsesse razrabotki neftyanykh mestorozhdeniy” (Natural reservoirs of hydrocarbons and their deformation during the development of oil fields), Proceedings of All-Russian Scientific Conference, Kazan, 19–23 July 2000, Kazan: Publ. of Kazan University, 2000, 30 p.


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