Development of a Fugitive Methane Emissions Measurement and Attribution Methodology for the Nigerian Upstream Gas Sector

Accurate measurement and attribution of fugitive methane emissions from upstream oil and gas operations is increasingly critical for Nigeria's compliance with international climate commitments and its credibility in global voluntary carbon markets. However, no systematic measurement and attribution methodology adapted for the specific operational, environmental, and regulatory conditions of the Nigerian upstream sector currently exists. This study develops and validates an original fugitive methane emissions measurement and attribution methodology for the Nigerian upstream gas sector, integrating multiple measurement scales from component-level to facility-level and regional aerial survey approaches. The methodology development draws on the Oil and Gas Methane Partnership (OGMP) 2.0 framework, USEPA Measurement and Estimation Methods (MEM), and emerging satellite-based emission attribution techniques, adapted through a systematic field validation programme in the Niger Delta. Field validation is conducted at three onshore upstream facilities in Rivers and Delta states, applying simultaneous measurement using optical gas imaging (OGI), hi-flow sampling, tracer correlation methods, and vehicle-mounted mobile CRDS analysers, alongside a reference facility-level mass balance approach. The study's original contributions include: a Niger Delta facility equipment component emission factor database, a vegetation and surface water correction algorithm for CRDS mobile surveys in tropical swamp environments, and a superemitter identification algorithm adapted for Nigerian facility layouts. Validation results demonstrate that component-level bottom-up estimates systematically underestimate facility-level emissions by 35 to 55 percent, consistent with international super-emitter findings. The methodology is designed for cost-effective scalability to the entire Nigerian upstream sector. Recommendations include immediate adoption of OGMP 2.0 reporting requirements for all NUPRC-licensed operators and government investment in satellite methane monitoring subscriptions covering Nigerian production areas. Keywords: methane emissions, fugitive emissions, upstream Nigeria, OGMP, emission measurement.