Study on cement slurry system in ultra-high temperature well

Abstract:

Aiming at the strength of set cement with sand degradation leads to the annular seal failure at 200℃， rich silica-aluminum material with hydration activity was developed， and when the adding amount for 30% to 70% of cement ，the compressive strength of cement are stable at 200℃×20.7MPa×30d. Based on the rich silica-aluminum material as a high temperature stabilizer， selecting matching additives， the rich silica-aluminum ultra-high temperature cement slurry was developed， the API water loss is less than 50mL at 100~200℃， the thickening time can be adjustable between 150~500min， the comprehensive performance is good. Compressive strength of set cement cured for 10d， 60d， 120d， 180d under 200℃×20.7MPa are all greater than 26MPa， and high temperature strength decline was not observed. The ultrasonic strength curve shows that the strength of set cement grows steady within 600h. The SEM and XRD shows that， the rich silica-aluminum material participate in the cement hydration reaction， and eliminate the calcium hydroxide， and generate aluminum-oxide tetrahedron and silica-oxide tetrahedron inter-bonding three-dimensional network structure with good high temperature performance， and together with tobermolite calcium silicate bauxite to maintain the stability of the high temperature strength of cement stone. The cement slurry system has been applied in hot dry rock cementing for 1 well， and the cementing quality is good. As so far， the cement ring has been well sealed for 1000 days.

Key words:ultra-high temperature well;cementing;rich silica-aluminum material;cement slurry;high-temperature strength