Study on the early structural strength of a hardened GGBFS-based plugging slurry activated by alkali

The occurrence of repeated loss circulation and sealing failures using hardened slag -based plugging slurry after plugging treatment in the oilfields is a severe engineering problem, and the early strength properties of the plugging slurry play a crucial role in the plugging effect. Therefore, this paper adopts the response surface methodology (RSM), SEM, and computed tomography (CT) scanning to investigate the interaction among the addition of alkali, curing temperature, and curing age on early strength of slag -based hardened body (SHB). The early strength model of slag -based plugging slurry is established by RSM with high prediction accuracy. The results indicate that alkali activator dosage, curing time, and curing temperature have significant effects on the early strength development, with the amount of alkali having the greatest effect. In addition, SEM and CT scan analysis revealed that the prone -cracking hydration products and the induced microcracks caused by uneven thermal stress at low dosages of alkali activator are the main causes of the early strength retrogression of the SHB. Increasing the alkali proportion can effectively suppress the strength retrogression and both the porosity and permeability of the SHB are reduced. Therefore, the addition of an alkali activator should not be less than 5% to obtain a better early strength performance when designing the formula for slag -based plugging slurry. This study provides a theoretical and experimental basis for the further popularization and application of the hardened slag -based plugging technology in oil fields.