Investigation of the fracture performance of soundless cracking demolition agents (SCDA) in different reservoir rocks

Artificial fracture stimulation has been widely used to exploit unconventional energy and mineral resource to meet the growing energy consumption. To minimize possible severe environmental impacts caused by hydraulic fracturing, many have studied the feasibility of using Soundless Cracking Demolition Agents (SCDA) to fracture low-permeability rocks in energy and mining industries. However, the fracture performance of SCDA in common reservoir rocks (sandstone, siltstone and granite) has not been investigated or compared. Therefore, a series of SCDA charged fracturing experiments were performed to study the potential application of SCDA in these three reservoir rocks. Digital image correlation technology and computed tomography imaging were employed to identify the connected fracture network in tested samples. Moreover, acoustic emission technology was applied to monitor fracture propagation during the fracturing test. Mechanical properties of tested rocks were obtained by conducting mechanical strength tests before fracturing tests. Siltstone exhibits brittle fracture characteristics during mechanical strength tests and fracturing test. Furthermore, SCDA generates the largest connected fracture network in siltstone when the reaction period is 24h. This is probably because the continuous pores between cementing minerals and grain particles provide a path for fracture propagation. Therefore, SCDA can produce long-connected fractures in siltstone in a short period once the fracture initiates. In contrast, during the 48h reaction process, the largest connected fracture network which is the collection of localized cracks is produced in sandstone. Although granite has the highest value of fracture toughness, SCDA can generate single diametrical fracture in granite. Hence, it is concluded that SCDA is effective in producing fractures in three tested rocks.