Reservoir Gas Analysis Software (ResGAS) computes critical pressures and temperatures and specific gravities and heating values of a gas stream. The application works with the Reservoir Solutions Modules program. The computation of gas properties includes corrections for contaminants and adjustments for condensate content. ResGAS also calculates wet gas in place and recoverable wet-, dry- and sales-gas volumes as well as recoverable condensate volumes. ResGAS computes the estimated recovery of propane, butane and sulfur and approximates the BTU content of separator and gas sales. A user must enter separator-gas component percentages derived from laboratory analysis and other data input, including well and reservoir parameters and recovery factors.