In this Bureau of Mines investigation, one- and two-dimensional gas reservoir simulators were combined in such a manner that pressure distributions, both in an induced vertical fracture and in the surrounding formation, could be determined as a function of time for any specified well production rate. The technique used consisted basically of the alternate use of one- and two-dimensional algorithms for obtaining new pressure distributions in the fracture and in the reservoir, respectively. The pressures at adjacent reservoir and fracture nodes were used to calculate flow rates from the formation into the fracture, which provided source terms for both algorithms. The combination model developed provides the only known means of simultaneously simulating transient gas flow in a vertical fracture and the surrounding formation. Thus, the technique developed would be useful in locating wells in a gas storage field in that the effects of both fracture length and conductivity could be considered prior to drilling and fracturing operations. In addition, it will be helpful in analyzing pressure drawdown tests in a vertically fractured gas well since the entire test can be readily simulated for a wide range of reservoir and fracture properties.