The relevance of the study is based on the theoretical and practical importance of the problem of formation of an effective system of risk management amid economic growth and technological hazards in modern society as the most important factor for the competitiveness and profitability of a business. Currently, the risk-based approach to capital management is gaining wide acceptance in various industries, but the mechanisms of applying this approach for high-tech companies in the oil and gas business are poorly understood. The competitiveness of a high-tech business largely depends on its ability to operate stably, to generate cash flows, and to assess the specific risks accompanying the project. The issue of risk management is is of key importance here, being a necessary condition for long-term sustainability of high-tech companies. The problem becomes particularly relevant in terms of implementation of investment projects that can increase the efficiency and scale of the business or lead the company to collapse. The article presents the concept of a risk management system in oil and gas companies in the course of implementation of investment projects. A rating model is proposed for risk assessment of investment projects that takes into account multiple factors. The capital management model, which is a widely accepted and recognized in risk management, is the basis for the proposed approach to risk management of oil and gas companies. A method for estimating economic capital is developed that is based on the Merton-Vasicek model which makes it possible to set operational guidelines for managing long-term sustainability of oil and gas companies in terms of investment risk. The authors propose a comprehensive methodological approach to the assessment of the economic capital of an oil and gas company that allows you to quickly and efficiently identify the most dangerous factors in the implementation of investment projects, and develop a management program for long-term financial sustainability of high-tech companies. The results of the study can be used by the management of oil and gas companies, investors and analysts in the process of financial decision-making in the context of multiple criteria and uncertainty.