The relevance of the work is caused by the fact that, taking into account external uncertainties such as risk, change in the value of money over time depending on the alternative cost of capital, lost profit, cost of deferred consumption and expectation of return on capital when calculating the efficiency of investment projects, the quality of the economic feasibility assessment of projects is improving. Analyzing the research of domestic scientists and experience of leading companies in oil and gas industry, it should be noted that the considering the current market situation and based on the risk nature of most investment projects, the problems of unjustified or hasty planning are not isolated, and come from inefficient forecasting tool for implementing project for exploration, production and transportation of geo-resources. There is a real opportunity to analyze the scenario and prospects of realization of the idea in changing market trends, predict and plan the actions and resources using more sophisticated financial and economic analytical tools. Scientifically based and validated model of investment evaluation can have a crucial influence on creation, preservation and development of the innovative advantages of developing oil production in the competitive struggle. The main aim of the study is to solve the problem of erroneous results in the field of forecasting and assessment of investment projects for exploration, production and transportation of geo-resources. The results are associated with a decrease in the estimated expenditure with the existence of negative cash flows over the life cycle and inadequate considering the risk and loss of profit, with understatement of the value of net discounted income and internal rate of return, profitability index of discounted costs and with overstating the value of the discounted payback period when using geometric progression and the discounted value of net income, not accrued amounts. The methods used in the study: methods of observation and collection of facts on modern problems of functioning of oil and gas companies and evaluation of investment projects efficiency of oil production; analysis of individual elements of the evaluation tool; comparative analysis of financial mathematics and project-investment approaches; synthesis of the final result of evaluating the economic efficiency of the project. The results. As a result of qualitative transformation of evaluation methods for economic efficiency of investment projects, the authors have solved first of all the problem of discounting negative cash flows by applying this operation subject to the requirements and the laws of financial mathematics to the accrued amount of capital, not net income, which, in accordance with the basic principles of financial calculations discounting is unacceptable. Secondly, the authors solved the issue of accounting the opportunity cost and risk as a negative factor in the structure of the mathematical apparatus, methods of valuation of efficiency of investment projects. Third, the economic inadvisability of using the geometric progression mechanism when discounting cash flows of a real investment project is justified, as the capital gain in a real investment project does not have geometric progression, as in the case with a complex interest in financial mathematics, as well as the future cash outflows associated with the risk, does not grow geometrically.