Influence of vugs in fractured-vuggy carbonate reservoirs on hydraulic fracture propagation based on laboratory experiments

Abstract

Abstract This study was conducted to examine the influence of vugs on hydraulic fracture propagation, which is very significant for hydraulic fracturing design in fractured-vuggy carbonate reservoirs. In this paper, a series of hydraulic fracturing physical simulation experiments were performed under true triaxial stress states and acoustic emission devices were used to monitor real-time hydraulic fracture propagation. Moreover, the key influencing factors and the typical fracturing curve characteristics of vug-hydraulic fracture interaction were studied and analyzed. The experimental results demonstrated that vugs exert an important effect on hydraulic fracture propagation. Three main vug-hydraulic fracture interaction modes were observed in our experiments: a) the hydraulic fractures directly crossed the vugs, which usually happened for small vugs. b) the vugs arrested the hydraulic fractures for further propagation when the hydraulic fractures tip reached the vugs that are in large size. c) the hydraulic fractures bypassed the vugs by propagating around it, which usually happened under low horizontal stress difference states. Furthermore, the fracturing curve response was obvious when the interaction between vugs and hydraulic fractures occurs. Our research findings provide a reliable basis for optimizing hydraulic fracturing design in fractured-vuggy carbonate reservoirs.