Study on Multi-scale Fracture-Vug Characteristics and Modeling Method of Jurassic Fractured-Vuggy Carbonate Reservoir on the Right Bank of Amu Darya: A Case from EH Gas Field, Amu Darya Basin

In the east of Amu Darya Basin, the structure is complex with tectonic reverse faults, extrusion folds, fracture-vug systems developed, and the spatial relationship between fractures and vugs is diverse. And the heterogeneity of fracture-vug development is the most fundamental factor of difference production between each well. However, the understanding of fracture-vug configuration is still insufficient, and it is urgent to form an effective prediction technology. Taking EH gas field as an example in this paper, the fractures in the gas field are divided into three types: micro-scale fractures, medium-scale fractures and large-scale fractures-vug system. The micro-scale fractures are stress response fractures, and the ratio of fracture porosity to total porosity is used for modeling. The medium-scale fractures, which are modeling by well-seismic combined discrete fracture modeling method, are mainly tensional fractures developed in the high position and steep wing of the structure. The large-scale fracture-vug system, concentrated in the fault and fault anticline structural turning zone, is transformed by dissolved medium-scale fractures. And it can be identified by seismic coherence attribute body. The multi-scale fracture distribution model is realized by multi-scale fracture step-by-step sampling method and multi-scale fracture permeability is realized by distance weighted geometric average method. The results show that the EH gas field is dominated by large-scale fractures and medium-scale fractures. The fractures at the turning end of the fault anticline are more developed than those at the two wings, and the fractures at the steep wings are more developed than those at the gentle wings. The application of multi-scale fracture modeling results has achieved good results, which can be used as a reference for efficient development of carbonate fractured-vuggy reservoirs.