Long-term durability of rock-based geopolymers aged at downhole conditions for oil well cementing operations

Abstract

The long-term integrity of rock-based geopolymers was studied in corrosive environments. The geopolymers were cured for 7 days at ambient conditions. Afterwards, the geopolymers were exposed to crude oil, brine and H₂S in brine at 100 °C and elevated pressures. The compressive strength, tensile strength, weight and volume changes were measured prior and after 3, 6 and 12 months of exposure. The measurements showed a turning point after 6 months of ageing. Whereas the compressive strength and tensile strength started to increase when the specimens were exposed to crude oil and brine, the specimens that were exposed to H₂S experienced some degradation. Permeability of geopolymers before exposure and after 12 months of exposure to the crude oil and brine was very low. The permeability of the specimens which were exposed to H₂S was not measureable. Substantial volume changes were observed for the geopolymers which were exposed to H₂S and brine.

Keywords:

• geopolymer
• long-term
• durability
• brine
• crude oil
• hydrogen sulfide

Acknowledgements

The Research Council of Norway, ConocoPhillips, Det norske oljeselskap, Statoil, Wintershall and Lundin Norway AS is gratefully acknowledged for financing the work through the research center DrillWell – Drilling and Well Centre for Improved Recovery, a research cooperation between IRIS, NTNU, SINTEF and UiS.