Relevance. Formation and accumulation of gas hydrates in gas gathering and processing system is one of the complicating factors in gas field operations. A more accurate determination of hydrate formation conditions will allow for more effective prediction of the necessary hydrate inhibitor supply, which will reduce operating costs while maintaining the level of reliability of the field. Aim. Improving the accuracy of hydrate formation prediction and efficiency of calculation of optimal inhibitor concentration for conditions of Turonian-Cenomanian deposits of Western Siberian fields. Methods. Mathematical modeling, laboratory research of hydrate formation by the rocking cell method. Results and conclusions. The authors have reviewed the works on experimental studies of thermobaric conditions of formation and decomposition of high-purity methane hydrates with distilled water. The generalized dependence is revealed and the coefficients correcting the existing methodology for calculation of equilibrium conditions of hydrate formation are specified in relation to the conditions of Turonian and Cenomanian deposits of Western Siberia. The paper demonstrates the results of laboratory studies of thermobaric conditions of formation and decomposition of hydrates of mixtures characteristic for the fields of Western Siberia. The paper considers the existing methods of hydrate formation modeling with different gas compositions, water mineralization and amount of injected inhibitor, estimats their error and conditions of application. The authors developed the model of hydrate formation for the conditions of Turonian and Cenomanian deposits of Western Siberian fields, including a “base curve” and coefficients that take into account the effect of water mineralization, gas composition and hydrate formation inhibitor concentration. The error of the existing methods for predicting the conditions of hydrate formation in relation to the parameters of Turonian and Cenomanian deposits of Western Siberian fields amounted to 0.5–1.2°C. The average error of the proposed method amounted to 0.28°C (maximum 0.88°C). This allows considerably increasing the efficiency of forecasting and accuracy of calculation of optimal concentration of methanol-based inhibitor.