Investigation of Nonlinear Flow Behavior Along a Rough-Walled Limestone Fracture With Acid Dissolution

Understanding the complex flow behavior along a rough-walled fracture under complex chemical conditions is of great significance to deep rock engineering in carbonate rocks. This study investigates the influence of acid dissolution on the nonlinear flow behavior of rough-walled limestone fractures. Fracture flow tests are performed under different flow rates to obtain the correlation between pressure gradients and flow rates before and after acidizing. The fitting results indicate that both the Forchheimer equation and the Izbash equation are suitable for characterizing the flow nonlinearity caused by inertial effects after acidizing. The generation of dominant etching channels is a key factor that influences the change in the nonlinear flow properties along the rough-walled fracture surface. The change rate of nonlinear coefficient B after the formation of the dominant etching channel is affected by the combined effect of the acid injection rate and the fracture roughness. For the acidized fracture without generating the dominant etching channel, the variation of microscale roughness after acidizing changes the local vortex area and the inertial resistance of the flow field, and thus influences the nonlinear flow behavior along the limestone fracture.