The global energy transition needs innovative solutions for decarbonizing oil&gas sector, with green hydrogen emerging as a pivotal energy carrier. This master's thesis presents a comprehensive techno-economic analysis of two distinct strategies for integrating green hydrogen into an existing offshore oil and gas platform. The primary objective is to evaluate their technical feasibility and economic viability. Scenario 1 encompasses a complex system integrating green hydrogen production via electrolysis, biomethanation (Power-to-Gas, P2G) utilizing captured CO₂, direct blending with natural gas, and flare for surplus H₂. Scenario 2, conversely, adopts a much more simple approach, focusing only on direct blending of green hydrogen with natural gas, with flaring as the only alternative for excess H₂.