The construction of wells under conditions of abnormally low reservoir pressures (ALRP) requires the use of low-density process fluids. In ALRP conditions with anomaly coefficient of 0,6-0,8 drilling fluids with a density of 1,00 g/cm3 or less are typically used. The use of low-density drilling fluids is especially important when drilling wells in old fields at a late stage of development, in conditions of loss of circulation, when drilling in underbalanced conditions, etc. The practice of using light flushing agents - hydrocarbon liquids, aerated and foam systems - revealed their significant disadvantages, and therefore their use is limited. Gazprom VNIIGAZ LLC developed a technology for increasing the resistance of a surfactant emulsifier to temperature, which consists of condensing a polyelectrolyte complex (PEC) on the interface. The developed emulsion drilling fluid is a Pickering emulsion, with the difference that the protective layer, instead of solid particles, is represented by condensed PEC with viscoelastic properties from oppositely charged emulsifier and polymer. Emulsion solutions showed exceptional stability during testing and are recommended for drilling sidetracks in the Astrakhan gas condensate field. The developed technology makes it possible to create a line of emulsion drilling fluids with condensable PEC. Having in an arsenal a sufficiently number of oppositely charged surfactant emulsifiers and polyelectrolytes of polymers, it is possible to use various combinations of them to carry out PEC condensation reactions at the interfacial surface.
References
1. Kister E.G., Emul’sionnye glinistye rastvory (Emulsion clay solutions), Moscow: Publ. of GOSINTI, 1958, 60 p.
2. Kister E.G., Khimicheskaya obrabotka burovykh rastvorov (Chemical treatment of drilling fluids), Moscow: Nedra Publ., 1972, 392 p.
3. Kurbanov Ya.M., Gaydarov M.M.-R., Lightened process liquids (In Russ.), Izvestiya vuzov. Neft’ i gaz, 2008, no. 4, pp. 15-21.
4. Gaydarov A.M., Khubbatov A.A., Norov A.D. et al., Development and preparation of lightweight clathrate emulsions for well completions at Astrakhan gas-condensate field (In Russ.), Stroitel’stvo neftyanykh i gazovykh skvazhin na sushe i na more, 2015, no. 6, pp. 25-32.
5. Gaydarov A.M., Khubbatov A.A., Khrabrov D.V. et al., Comparative tests of polycationic drill fluid at wells No. 915 and 629 of Astrakhan gas condensate field (In Russ.), Gazovaya promyshlennost’, 2020, no. 1, pp. 36–44.
6. Gaydarov M.M-R., Khubbatov A.A., Gaydarov A.M. et al., “Katburr» polycationic drilling fluids and prospects for their use (In Russ.), Stroitel’stvo neftyanykh i gazovykh skvazhin na sushe i na more, 2019, no. 7, pp. 19–25.
