LAUSR

Abstract Acid etched fracture length and conductivity affect the carbonate stimulation effect. In this paper, acid-etched experiments with large-scale rock plate (1000 mm × 100 mm × 15 mm) were performed to investigate the acid etched fracture length, pattern, and conductivity. The relayed rock plates were etched with spent acid, collected from the outlet of previous plates, to simulate acid flow and reaction in a long artificial fracture. The rock plates were scanned with laser profilometer before and after acid etching to study etch behavior. The acid-etched fracture conductivity was measured under different closure stresses. The effective acid-etched fracture length is the fracture position with residual acid concentration. The results showed that the effective acid-etched fracture lengths with retarded acid were much higher than conventional acid, and most of the acid is consumed near the fracture heel. The acid-etched fracture pattern of self-diverting acid shows stronger non-uniformity with higher acid concentration, and more uniformly with lower acid concentration. The acid-etched fracture conductivity distribution along the whole artificial fracture is obtained with several relayed large-scale rock plates. And the acid-etched fracture conductivity obtained from large-scale rock plate is much lower than that from an API (American Petroleum Institute) rock plate. This study provided an experimental measure for acid-etched fracture length and global fracture conductivity evaluation.