The authors analyzed exploration wells of Mastahskoye gas-condensate field and Nedzhelinskaya area of Yakutgazprom JSC. Possible reasons of low cement up to the surface at high permeability of sandstones of Lower and Middle Jurassic are considered. The practical application of cementing intermediate columns in two stages was studied and taken apart as well as direct and reverse cementing of columns with OD 324mm in abnormal geological conditions. When cementing surface casings in permafrost zones it is necessary to consider low cement up to the surface due to the presence interpermafrost aquifers with low formation pressure and high permeability and tight contact between rock and casing.
When cementing the long conductor and surface casings it is absolutely necessary to add cement setting accelerators. To prevent freezing cement slurry must be entered when mixing with special additives reducing setting time. Based on the price to quality ratio the most effective and wide spread cement setting accelerator is calcium chloride. The amount of accelerator is received within 5-10% depending on the cement period of storing. The most rational way to deal with low cement up to the surface is the usage of lightweight cement.
Surface casing cementing in permafrost zone without additives of cement setting accelerators does not provide a reliable contact between the casing and the walls of the well. Surface casing cementing in permafrost zone is recommended to do with the addition of calcium chloride and 10% of dry cement weight. In order to lift the cement slurry for the technical and operational columns to the wellhead in the presence of cementing, absorption should be carried out in two or more stages. To run in hole of intermediate columns must be divided into sections. While cementing production casings cementing collars must be used. During the run in hole production casing with OD 146mm cementing collars must be installed above the intermediate shoe string. It is recommended to use the cement slurry with a specific weight of 1.25-1.30 kg/m3.
References
1. Makogon N.R., Kolushev N.R., Teplofizicheskie kharakteristiki glinistogo rastvora i tsementnogo kamnya pri burenii skvazhin Mastakhskoy NES (Thermophysical characteristics of clay mortar and cement stone during drilling of wells at the Mastakh Scientific-Experimental Station), Moscow: Publ. of VNIIGAZ, 1979, pp. 53–56.
2. Medvedskiy R.I., Stroitel'stvo i ekspluatatsiya skvazhin na neft' i gaz v vechnomerzlykh porodakh (Construction and operation of wells for oil and gas in permafrost rocks), Moscow: Nedra Publ, 1987, pp. 186–192.
3. Balobaev V.T., Kolushev N.R., Eksperimental'nye i teoreticheskie issledovaniya vzaimodeystviya skvazhin s mnogoletnemerzlymi porodami (Experimental and theoretical studies of the interaction of wells with permafrost rocks), Moscow: Publ. of VNIIGAZ, 1979, pp. 42–52.
4. Blinov B.M., Razrabotka tekhnologii upravleniya gidravlicheskimi razryvami plastov pri kombinirovannom sposobe krepleniya v razvedochnykh skvazhinakh Severa Zapadnoy Sibiri (Development of technology for reservoir fracturing control in combined method of exploratory well casing of the North of Western Siberia): thesis of candidate of technical science, Moscow, 1984, 189 р.
