Lightweight unshrinkable mixture of cement slurry for casing of low-temperature wells

UDK: 622.245.42. (075)
DOI: 10.24887/0028-2448-2019-1-24-27
Key words: well, cement, cementing, zeolite, synthetic zeolite, grouting mixture, frozen rocks, facilitating additive, low temperature well, hydraulic fracturing, water content, density, strength
Authors: V.G Kuznetsov (Tyumen Industrial University, RF, Tyumen), E.G. Grechin (Tyumen Industrial University, RF, Tyumen), G.A. Kuliabin (Tyumen Industrial University, RF, Tyumen), D.A. Rechapov (Tyumen Branch of Gazprom Proektirovanye LLC, RF, Tyumen)

The majority of natural hydrocarbon oilfields of the Far North are distinguished by frozen rocks and reservoirs with low pressures of hydraulic fracturing in their geological section. It makes complicate well construction. The height of frozen rocks can exceed 500 meters, and their natural temperature varies from 0 to -100 °C. The application of regular grouting mixtures in such geological conditions doesn’t provide a reliable cementing of the casing columns and formation isolation, as long as they harden for a long time, partially freeze, which adversely affects the working properties of cement stone. There is a risk of absorption of the grouting mixture, of the failure of the cement stone on exposure to cyclic freeze-thaw temperature. Therefore the main objective of grouting mixture formulation development for casing cementing in frozen rocks bedding interval – ensuring their freeze-proof properties, fast hardening without shrinkage strain. There is no serial production of the low density grouting mixtures for the low-temperature wells in the national industry. At the present time there are proposed various lightweight additives, among which zeolite is especially important. The paper reviews the problems of well cementing in the conditions of low reservoir pressure and temperature. The authors had developed and researched cement-zeolite grouting mixtures CZTS-1 (density of 1600-1610 kg/m3) and CZTS-2 (density of 1700-1720 kg/m3). The formulation contains binding material PCT I-50 (RF State Standard GOST 1581-96), synthetic zeolite of type NaA and NaX for CZTS-1 and CZTS-2 correspondingly (Technical Specification 2163-003-15285215-2006), stabilizing agent MK-85 under (Technical Specification TU 1714-457-05785388-2011), Natrosol 250EXR (TU 0799-001-99126491-2013), plasticizing agent SP-1 (TU 5870-005-58042865-2005). Process water was used as grouting fluid, 4 % solution of calcium chloride and 4% solution of mineralizing agent “Karnamin” were used for speeding up the setting time. We present the results of laboratory tests of basic working properties of cement-zeolite grouting mixture and stone at the temperatures ((20±2 and 5±2) °C. Optimal values of water-solid ratio for obtaining the grouting mixture of density 1600–1720 kg/m3 is 0.65-0.55.

References

1. Ovchinnikov P.V., Kuznetsov V.G., Frolov A.A., et al., Spetsial’nye tamponazhnye materialy dlya nizkotemperaturnykh skvazhin (Special cement slurry for low-temperature wells), Moscow: Nedra-Biznestsentr Publ., 2002, 115 p.

2. Oreshkin D.V., Frolov A.A., Ippolitov V.V., Problemy teploizolyatsionnykh tamponazhnykh materialov dlya usloviy mnogoletnikh merzlykh porod (Problems of thermal insulation cement slurry for permafrost conditions), Moscow: Nedra Publ., 2004, 232 p.

3. Beley I.I., Korostelev A.S., Karmatskikh S.A. et al., Cement mixtures for casing cementing in permafrost sections (In Russ.), Burenie i neft', 2014, no. 11, pp. 30–34.

4. Ovchinnikov V.P., Kuznetsov V.G., Frolov A.A., Gazgireev Yu.O., Lightweight grouting cement for low temperature wells (In Russ.), Burenie i neft', 2004, no. 5, pp. 32–33.

5. Ovchinnikov V.P., Kuznetsov V.G., Smyslov V.K. et al., Oblegchennyy tamponazhnyy rastvor dlya tsementirovaniya skvazhin v kriolitozone (Lightweight cement slurry for cementing wells in the permafrost zone), Proceedings of All-Russian Scientific and Technical Conference “Problemy sovershenstvovaniya tekhnologii stroitel'stva skvazhin i podgotovki kadrov dlya Zapadno-Sibirskogo neftedobyvayushchego kompleksa” (Problems of improving the technology of well construction and training for the West Siberian oil-producing complex), Tyumen': Publ. of TOSGU, 2000, pp. 56–57.

6. Oreshkin D.V., Belousov G.A., Efficiency of application of grouting materials with hollow glass microspheres (In Russ.), Vestnik Assotsiatsii burovykh podryadchikov, 2007, no 4, pp. 33–41.

7. Metodicheskie ukazaniya po ispytaniyu tamponazhnykh materialov dlya usloviy mnogoletnemerzlykh porod (Guidelines for testing cement materials for permafrost conditions), Moscow: Publ. of VNIIGAZ, 1982, 31 p.

8. Kubasov A.A., Zeolites - boiling stones (In Russ.), Sorosovskiy obrazovatel'nyy zhurnal, 1998, no. 7, pp. 70–76.

The majority of natural hydrocarbon oilfields of the Far North are distinguished by frozen rocks and reservoirs with low pressures of hydraulic fracturing in their geological section. It makes complicate well construction. The height of frozen rocks can exceed 500 meters, and their natural temperature varies from 0 to -100 °C. The application of regular grouting mixtures in such geological conditions doesn’t provide a reliable cementing of the casing columns and formation isolation, as long as they harden for a long time, partially freeze, which adversely affects the working properties of cement stone. There is a risk of absorption of the grouting mixture, of the failure of the cement stone on exposure to cyclic freeze-thaw temperature. Therefore the main objective of grouting mixture formulation development for casing cementing in frozen rocks bedding interval – ensuring their freeze-proof properties, fast hardening without shrinkage strain. There is no serial production of the low density grouting mixtures for the low-temperature wells in the national industry. At the present time there are proposed various lightweight additives, among which zeolite is especially important. The paper reviews the problems of well cementing in the conditions of low reservoir pressure and temperature. The authors had developed and researched cement-zeolite grouting mixtures CZTS-1 (density of 1600-1610 kg/m3) and CZTS-2 (density of 1700-1720 kg/m3). The formulation contains binding material PCT I-50 (RF State Standard GOST 1581-96), synthetic zeolite of type NaA and NaX for CZTS-1 and CZTS-2 correspondingly (Technical Specification 2163-003-15285215-2006), stabilizing agent MK-85 under (Technical Specification TU 1714-457-05785388-2011), Natrosol 250EXR (TU 0799-001-99126491-2013), plasticizing agent SP-1 (TU 5870-005-58042865-2005). Process water was used as grouting fluid, 4 % solution of calcium chloride and 4% solution of mineralizing agent “Karnamin” were used for speeding up the setting time. We present the results of laboratory tests of basic working properties of cement-zeolite grouting mixture and stone at the temperatures ((20±2 and 5±2) °C. Optimal values of water-solid ratio for obtaining the grouting mixture of density 1600–1720 kg/m3 is 0.65-0.55.

References

1. Ovchinnikov P.V., Kuznetsov V.G., Frolov A.A., et al., Spetsial’nye tamponazhnye materialy dlya nizkotemperaturnykh skvazhin (Special cement slurry for low-temperature wells), Moscow: Nedra-Biznestsentr Publ., 2002, 115 p.

2. Oreshkin D.V., Frolov A.A., Ippolitov V.V., Problemy teploizolyatsionnykh tamponazhnykh materialov dlya usloviy mnogoletnikh merzlykh porod (Problems of thermal insulation cement slurry for permafrost conditions), Moscow: Nedra Publ., 2004, 232 p.

3. Beley I.I., Korostelev A.S., Karmatskikh S.A. et al., Cement mixtures for casing cementing in permafrost sections (In Russ.), Burenie i neft', 2014, no. 11, pp. 30–34.

4. Ovchinnikov V.P., Kuznetsov V.G., Frolov A.A., Gazgireev Yu.O., Lightweight grouting cement for low temperature wells (In Russ.), Burenie i neft', 2004, no. 5, pp. 32–33.

5. Ovchinnikov V.P., Kuznetsov V.G., Smyslov V.K. et al., Oblegchennyy tamponazhnyy rastvor dlya tsementirovaniya skvazhin v kriolitozone (Lightweight cement slurry for cementing wells in the permafrost zone), Proceedings of All-Russian Scientific and Technical Conference “Problemy sovershenstvovaniya tekhnologii stroitel'stva skvazhin i podgotovki kadrov dlya Zapadno-Sibirskogo neftedobyvayushchego kompleksa” (Problems of improving the technology of well construction and training for the West Siberian oil-producing complex), Tyumen': Publ. of TOSGU, 2000, pp. 56–57.

6. Oreshkin D.V., Belousov G.A., Efficiency of application of grouting materials with hollow glass microspheres (In Russ.), Vestnik Assotsiatsii burovykh podryadchikov, 2007, no 4, pp. 33–41.

7. Metodicheskie ukazaniya po ispytaniyu tamponazhnykh materialov dlya usloviy mnogoletnemerzlykh porod (Guidelines for testing cement materials for permafrost conditions), Moscow: Publ. of VNIIGAZ, 1982, 31 p.

8. Kubasov A.A., Zeolites - boiling stones (In Russ.), Sorosovskiy obrazovatel'nyy zhurnal, 1998, no. 7, pp. 70–76.



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