Impact of Fracture Network Connectivity on the Ultimate Recovery from Shale Gas Wells

The production decline of an unconventional gas well depends on the induced fracture network and its complexity that depends on the stimulation parameters. In this study, we investigate the effect of stimulation job size on the distribution of the induced fracture network. Further, we investigate the effect of fracture network complexity on the production rate decline and recovery factor of shale gas wells The complexity of the induced fracture network after hydrofracturing depends on (a) the permeability of the induced fracture network, k_f, in the stimulated reservoir volume (SRV) and (b) the fractal dimension, D, of the induced fracture network. We have simulated 3000 wells from Barnett and used the k_f - s - D fractal-SRV model to estimate k_f and D of a well under production. The relation between k_f and D, and its effect on the fracture network distribution was analyzed. Finally, the relation between induced fracture complexity was correlated with the onset of exponential production decline. We found an exponential relation between k_f and D for Barnett. The values of k_f and D control fracture distribution in the SRV, and the decay of fracture permeability away from the hydrofracture face. The results show that, as the stimulation job size increases, the induced fracture permeability, k_f, increases and vice-versa. However, this high k_f signature decays faster away from the hydrofracture face because of the higher value of D. Also, as the D of the induced fracture network increases, the onset of exponential production decline comes faster. Finally, we conclude that (a) fracture network is spread over a larger SRV volume for smaller stimulation jobs, (b) induced fracture permeability, k_f, in the SRV is relatively homogeneous for smaller stimulation jobs compared to the large ones, and (c) large-size stimulation job does not serve the economic and production objectives in the long run. Our study uses production data to extract induced fracture network parameters after hydrofracturing. The study offers novel insights into the fracture network signature with respect to the stimulation job size and its effect on the production economics. Our results are useful in the optimizations of fracking strategies to meet long-term production goals.