Productivity Model Considering Tree-shaped Fracture Characteristics for Fractured Horizontal Wells in Tight Gas Reservoirs
In fractured tight gas reservoirs,hydraulically induced fractures are usually simplified into straight-shaped fractures for predicting productivity of horizontal wells.Whereas,actual fractures are so complex that accurate prediction productivity becomes challenging work.In this case,considering tree-shaped fractures better fitting with actual fractures and gas slippage effect,a new productivity model was proposed for fractured horizontal well and the contributing factors was examined to productivity.The results demonstrate that in comparison with the straight-shaped fracture,the present model in terms of the tree-shaped fracture predicts higher productivity which is positively associated with its length ratio and branching level whereas negatively correlated with its branching angle and almost unaffected by its width ratio.Furthermore,well productivity decreases with the Knudsen number and boundary radius of reservoir,whereas increases with the fracture spacing and length and is almost unaffected by the fracture permeability.Fracture productivity is positively associated with its spacing and unrelated to its permeability.While,increasing fracture length can increase fracture productivity in the toe and foot ends of horizontal well whereas decrease fracture productivity in the center.These findings contributes to design and development of horizontal wells in tight gas reservoirs.
tight gas reservoirfractured horizontal welltree-shaped fractureproductivity prediction
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