Influence of silica fume on the physical properties of oil-well cement stone

The aim of the study has been to define the changes in the physical-mechanical properties of cement stone when adding different-concentration silica fume (SF) of different grades, and to experimentally compare the obtained values with the state standard (GOST) permissible values. Different-concentration cement slurry was mixed, with a 48-hour interval for thickening and solidification before the test. The obtained cement stone was tested for compressive and flexural strength using a hydraulic press; besides, its water separation and spreadability measurements were taken. Based on the experimental data analysis, the dependence of the cement stone’s strength properties on silica fume admixture was defined, and conclusions were drawn on the permissible amount of SF in the cement slurry. With the SF concentration exceeding 8%, the cement slurry no longer meets the standard values and becomes low workable and highly viscous. The article discusses the possibility of improving the cement stone properties in well construction for hydrocarbon deposits development. A series of experiments have been carried out with the purpose to modify the cement of PCT - 1-50 grade with silica fume admixtures of MK-65 and MK-85 grades. The reagent was chosen due to its ability to influence the strength and permeability of the cement stone, as well as the water separation, sulfate resistance, and density of the cement slurry. On the basis of the study done, it has been concluded that the above admixtures do influence the strength properties of the stone; though to increase the flowability of the cement slurry, further experiments are needed. A properly selected admixture can reduce the cement slurry’s viscosity, thereby making it possible to achieve the consistency meeting the production requirements.

portland cement, cement stone, silica fume, strength characteristics, spreadability, ultimate strength

1. Kruglitskii N.N., Grankovskii I.G., Vagner G.R., Detkov V.P. Fiziko-khimicheskaya mekhanika tamponazhnykh rastvorov [Physicochemical mechanics of cement slurries]. Kiev: Naukova dumka Publ., 1974, 291 p. (In Russ.).

2. Samsonenko N.V., Simonyants S.L., Samsonenko V.A. The effect of volume changes of grouting mortars- stones on the quality of casing strings primary cementing in wells. Stroitel'stvo neftyanykh i gazovykh skvazhin na sushe i na more, 2017, no. 4, pp. 19–24. (In Russ.).

3. Bulatov A.I., Ryabchenko V.I., Sibirko I.A., Sidorov N.A. Gazoproyavleniya v skvazhinakh i bor'ba s nimi [Gas show control in wells]. Moscow: Nedra Publ., 1969, 287 p. (In Russ.).

4. Vavrzhin F. Vliyanie khimicheskikh dobavok na protsessy gidratatsii i tverdeniya tsementa [Effect of chemical admixtures on cement hydration and hardening]. Doklady VI Mezhdunar. kongressa po khimii tsementa [Materials of 4th International Сongress on Сement Сhemistry]. Moscow: Stroiizdat Publ., 1976, 34 p. (In Russ.).

5. Karimov N.Kh., Danyushevskii V.S., Rakhimbaev Sh.M. Razrabotka retseptur i primenenie rasshiryayushchikhsya tamponazhnykh tsementov [Formulation and application of expanding cement cements]. Moscow: All-Russian Research Institute of Organization, Management and Economics of Oil and Gas Industry Publ., 1980, 51 p. (In Russ.).

6. Shakirova E.V., Averkina E.V., Sabirov T.R., Peryshkina K.O. Use of oil as lubricant additive in drilling mud fluid (on the example of the Yaraktinsky oil-gas condensate field). Neftegazovoe delo [Petroleum Engineering], 2018, vol. 16, no. 2, pp. 12–19. (In Russ.).

7. Bayasi Zing, Zhou Jing. Properties of silica fume concrete and mortar. ACI Materials Journal, 1993, vol. 90 (4), pp. 349–356.

8. Bhikshma V., Nitturkar K., Venkatesham Y. Investigations on mechanical properties of high strength silica fume concrete. Asian Journal of Civil Engineering (Building and Housing), 2009, vol. 10 (3), pp. 335–346.

9. Venkatesh Babu D.L, Nateshan S.C. Investigations on silica fume concrete. Indian Concrete Journal, 2004, рр. 57–60.

10. Ivanov F.M. Effektivnost' ispol'zovaniya superplastifikatorov [Superplastisizers usage efficiecy]. Betony s effektivnymi modifitsiruyushchimi dobavkami [Concretes with Effective Modifying Admixtures]. Moscow: Research, Design and Technology Institute of Concrete and Reinforced Concrete n.a. A.A. Gvozdev Publ., 1985, pp. 3–7. (In Russ.).

11. Yamada K.A. Summary of important characteristics of cement and superplasticizers. Proceedings of 9th CANMET/ACI International Conference “Superplasticizers and Other Chemical Admixtures in Concrete”. Seville, 2009, рр. 29–58.

12. Prince W., Espagne M., Aı̈tcin P.C. Ettringite formation: a crucial step in cement superplasticizer compatibility. Cement and Concrete Research, 2003, vol. 33, iss. 5, pp. 635–641.

13. Grabiec A.M., Piasta Z. Study on compatibility of cement-superplasticiser assisted by multicriteria statistical optimization. Journal of Materials Processing Technology, 2004, vol. 152, pp. 197–203.

14. Holland T.C. Technical Report no. FHWAIF-05-016. Silica Fume. User's Manual, 2005, April, 183 p.