In the context of the global energy transition and a strengthening climate agenda, this study provides a comparative assessment of sustainable development strategies adopted by leading national oil and gas companies in China and Russia, focusing on their contribution to decarbonisation and SDG 7 and SDG 13. The study combines content analysis of corporate ESG reporting with a quantitative assessment of key environmental indicators. The analysis covers Gazprom, Rosneft, Lukoil, Novatek and Tatneft (Russia), and CNPC (PetroChina), Sinopec and CNOOC (China) over 2020–2024. The quantitative assessment includes Scope 1–2 greenhouse gas emissions, emissions intensity per unit of energy produced, operational energy consumption, renewable energy share, water intensity and green capital expenditures. The results reveal differences in national adaptation models: Chinese companies follow a centralised, state-driven approach integrated into strategic planning and five-year programmes, while Russian companies demonstrate a more fragmented, corporate-oriented model focused on technological modernisation. The strongest divergence is observed in governance integration and low-carbon investment structures, while emissions intensity trends remain gradual in both cases. Based on these findings, recommendations are proposed to strengthen sustainability and climate governance in Russian and Chinese oil and gas companies. The findings rely on self-reported ESG data, which involve differences in reporting boundaries and calculation methodologies.

Decarbonization requires oil and gas companies to combine gas-monetization projects with measures to improve operational efficiency and reduce emissions. This study develops a scenario-based approach to portfolio selection for a gas-condensate asset, accounting for economic value, risk, net gas-resource requirements, and carbon effects. Projects are evaluated relative to baseline pipeline gas sales. Within-scenario uncertainty is represented using triangular distributions and Latin hypercube sampling. Feasible portfolios are generated by exhaustive enumeration, followed by Pareto selection and risk-adjusted ranking. The synthetic model-based application considers six project solutions, generating 63 nonempty combinations. Under the specified assumptions, the number of feasible portfolios decreases from 37 in the inertial scenario to 19 in the moderate scenario and 2 in the stringent scenario. The mere presence of a decarbonization component does not determine project priority. Operational projects gain portfolio significance when they improve resource use and carbon performance. The capital-intensive project combining value-added gas processing with CCUS plays a different role: for the project set considered, it becomes necessary only when the minimum portfolio carbon requirement exceeds 1.90 but does not exceed 2.40 million t CO₂e/year. Above this level, no feasible portfolio can be formed. This threshold interval is case-specific. These results reveal how decarbonization can affect both project ranking and portfolio feasibility, highlighting an asset-level energy–environment–economy trade-off.