This paper studies the relevant issues of innovative projects implementation, in particular, during the prospective development of coal reserves by geotechnology of underground gasification. To solve the objectives set in the work, an integrated approach is applied, which includes: critical analysis, generalization, systematization and synthesis to determine the phases and stages of the innovative project implementation; conducting econometric modeling to calculate the total effect from the implementation of innovations. The conducted research has proven that it is important to determine the phase and stage of an innovative project in order to increase the efficiency of its assessment. The prospect of introducing geotechnology for underground gasification has been revealed, which in conditions of "pre-investment"uncertainty is associated with the lack of reliable information on the choice of priority directions and methods of practical use of innovation (based on the experience of industrial research and the operation of closed coal gasification plants). An integrated system of indicators for assessing the effectiveness of innovative project at the stage of its implementation has been developed and an algorithm for determining the total effect from its implementation has been proposed.