Effect of fracturing fluid flow and particle migration within fracture spaces on reservoir seepage capacity

China is rich in low-permeability oil and gas resources, offering significant potential for exploration and development. However, low-permeability reservoirs are characterized by poor reservoir properties, high seepage resistance, and limited effectiveness of enhancement measures. Therefore, understanding the key factors affecting seepage capacity during stimulation is crucial. This study focuses on low-permeability core samples from the South China Sea and investigates the mechanisms of seepage capacity damage in fractures under three conditions: fracturing fluid systems, solid particles within fractures, and displacement pressure differentials. A 3D scanner was used to visually capture changes in fracture surface roughness under different experimental conditions, and the extent of permeability changes in core samples was analyzed to evaluate fracture damage. Among the fracturing fluid types, guar gum fracturing fluid caused the most significant damage, extensively adsorbing onto fracture walls and reducing flow area within fractures. The permeability damage rate reached 41.54%, with roughness changes of 34.53%. Regarding solid particles, formation particles were prone to secondary fragmentation, generating more fines that easily blocked fracture channels. Formation particles caused the highest damage to fracture permeability, with a reduction rate of 59.51% and roughness changes of 35.12%. In contrast, proppant particles had the least impact. Higher displacement pressures exacerbated the exfoliation and transport of loose particles on fracture surfaces. The damage rate of fractures was positively correlated with pressure differential: greater pressure differentials resulted in larger reductions in permeability and greater changes in fracture wall roughness. Understanding these damage trends is crucial for improving production in low-permeability reservoirs.