Unsteady Flow Model for Fractured Gas Reservoirs

Developing low permeability reservoirs is currently a big challenge to the industry. Because low permeability reservoirs are of low quality and are easily damaged, production from a single well is low, and there is unlikely to be any primary recovery. Therefore, in most cases, unconventional recovery methods are used for economic development of those reservoirs. Hydraulic fracturing has been an important means to develop low permeability gas reservoirs both at home and abroad. Correctly predicting fractured gas well's productivity can provide important guidance to formation sensitivity analysis and production plans for fractured wells. Taken into consideration the effects of the flows in artificially fractured cracks on formation as well as gas properties and real gas's equation of state, a partial differential initial boundary problem is established to describe the unstable flows in artificially fractured low permeability gas reservoir. We analyzed a concrete example, and the results show that the derived productivity formula can be used in practical engineering calculations and the model can be applied to multiple parallel fractures and other more complex conditions.