The Influence of Admixtures on the Hydration Process of Soundless Cracking Demolition Agents (SCDA) for Fragmentation of Saturated Deep Geological Reservoir Rock Formations

Abstract

Alternative fragmentation technologies such as soundless cracking demolition agents (SCDAs) can minimize adverse environmental impacts associated with conventional rock fracturing methods used in mining and energy industries. However, application of SCDA in deep underground environments is limited due to (1) inability of SCDA to react in saturated rock masses as a result of dilution and mass washout effects, and (2) slow expansive pressure generation in SCDA, which delays post-fracturing operations. This study addresses the first issue by modifying a generic SCDA using a viscosity-enhancing admixture (VEA), namely welan gum, to produce a hydrophobic SCDA for direct application in submerged conditions. The effect of the VEA, on the mechanical, microstructural and mineralogical morphology of hydrating SCDA was also investigated. According to the findings, adding just 0.1% of VEA by weight to the SCDA in combination with a water-reducing admixture significantly improves the washout resistance without compromising the fluidity of SCDA, however, at the expense of rapid expansive pressure generation rates. The reduction in expansive pressure, which is unfavourable for mining and energy engineering applications is caused by the interaction of VEA with the hydrating SCDA. This is evident in the SEM and XRD results observed. This urges the consideration of both positive and negative effects of welan gum in SCDA: enhancement of washout resistance and reduction of expansive pressure development prior to any field application.