The Slag Influence on High Temperature Resistance of Aluminophosphate Cement for Heavy Oil Thermal Recovery

摘要

The sharp strength recession of silicate cement in high temperature is the crucial reason of casings damage and zonal isolation failure in heavy oil thermal recovery. Although aluminophosphate cement has a better high temperature resistance in comparison with silicate cement, its compressive strength recession in high temperature slightly recessed. The results show that adding slag into aluminophosphate cement can not only develop compressive strength of cement at low temperature, but it can also improve the high temperature resistance of the cement. After adding slag, the formation of C_2ASH_8 conduces to develop cement strength at low temperature, and C_3AS_2H_2 conduces to high temperature resistance. To increase temperature resistance of aluminophosphate cement, C_3ASH_4 generation and Al(OH)_3 decomposition should be avoided. Crystal structure of cement after high temperature is well developed with compactly and neatly arranged, allowing cement to maintain good mechanical properties to help protect the casing and improve zonal isolation performance.