The regional forecast of reservoir hydrocarbon systems for gas fields of the Outer Zone of Pre-Carpathian Depression has been made. The dependences of the distribution of different types of hydrocarbon systems have been established, which give one the opportunity to predict them at great depths in the region of high temperatures and pressures at the initial stages of exploration works. According to the results of the carried-out analyses, there is a significant discrepancy in the composition of free gases, which makes the application of classical statistical processing of available materials inefficient. However, the dominant array of points can determine the individual component trends of the gas content, which in total characterize the full (100% by volume) composition of fluid at different levels of deposit depths for two parts of the Outer Zone – northwest and southeast. In relation to the deposits’ depth the graphs have been constructed and the regression equations of expected parameters have been established. The graphs and equations are included in the formula for calculating hydrocarbon reserves by the volumetric method. The regression equations for prediction have been derived; laboratory studies of thermobaric conditions (pressure and temperature) with depth have been conducted, because information about the latter is needed to calculate individual parameters of hydrocarbon systems