Explosive fracturing mechanism in low-permeability sandstone-type uranium deposits considering different acidification reactions

To clarify the effect and mechanism of reservoir composite stimulation technology of blasting and acidification for low permeability characteristic of sandstone-type uranium deposits, the influence of acidification reaction on macroscopic and microscopic mechanical properties of samples was first explored, the blasting fracturing effect of acidified samples was then analyzed by the discrete element method, the compatibility and suggestion of acidification and blasting technology were finally proposed. Results show that the acidification reaction possesses a mechanical weakening effect for sandstone, manifested in the reduction of major macroscopic and microscopic mechanical parameters. Acidification reactions contribute to the initiation, extension, and connection of blasting fractures, with the fragmentation zone, fracture extension zone and fracture network zone all larger after acidification reaction than in unreacted samples. It is recommended to use the TNT-B and CO2-PCB for the reservoir stimulation of original ore layer and ore layers reacted with medium concentration acid, and EPB for the reservoir stimulation of ore layers reacted with low and high concentration acid. It is suggested to adopt the CO2-PCB and EPB for reservoir stimulation of ore layers with acidification time less than and greater than 45 d, respectively.