Methane Emissions from the Global Oil and Gas Industry: A Scoping Review to Characterize Research Trends, Knowledge Gaps, and Priorities
Creators: name: Vollrath, Coleman
Publisher: name: Arts
Year: 2022
Subjects: subject: methane emissions
subject: oil and gas
subject: review
subject: measurement
subject: detection
subject: quantification
subject: Geography

description: This thesis presents a scoping review – following the Preferred Reporting Items for Systematic Reviews and Meta Analyses extension for Scoping Reviews (PRISMA-ScR) methodology – to document major research trends, knowledge gaps, and priorities involving methane (CH4) emissions measurements from the oil and gas (O&amp;G) sector. The motivation for this thesis is the opportunity to organize and synthesize a rapidly growing body of literature to inform mitigation, policies, regulations, and guide future research directions. A total of 211 peer-reviewed journal articles were identified and reviewed using the PRISMA-ScR methodology to document four major research themes regarding CH4 emissions measurements from land-based O&amp;G sources: geography, measurement scales and methods, emissions sources, and emissions profiles. The majority of articles (73%) focused on the U.S. O&amp;G sector and the upstream supply chain segment, while other major O&amp;G-producing countries like Saudi Arabia, Russia, and China were under-represented. The global knowledge base is therefore derived primarily from research focused on the U.S. Approximately 43% of the articles included in the review reported site-level measurements, mostly focusing on the upstream segment of the O&amp;G supply chain, which precludes identification of equipment and component sources. Of the remaining articles that measured or identified equipment-level sources (16%), the highest emitters were tanks, flares, and compressors. The most common site-level measurement methods included vehicle systems and aircraft. A marked increase in the use of satellites was noted in articles published since 2019. Regardless of the measurement scales and methods used, emissions profiles reveal a consistent heavy-tail distribution, but profiles differ in that those derived with direct measurements are smaller than those derived with aircraft and satellites. This is related to the common finding that bottom-up (BU) estimates of emissions under-estimate measurements of emissions with top-down (TD) methods, suggesting a method-based bias on the size of emissions measured and the resulting emissions profiles. Based on the major research themes, the following research priorities are recommended: geography - more studies in other countries using diverse methods, reconciliation of multi-scale measurements, improve inventories with updated emissions factors (EF's) and statistical techniques, improve understanding of the root causes of emissions, more dedicated research on the temporal variability of CH4, more testing to document the accuracy of measurement-based emissions estimates and the limitations of each method, and clarify the link between measurements of CH4 and emissions mitigation through work practices. In addressing these priorities this thesis proposes that policy developers, regulators, and industry will make better informed decisions on how to cut emissions and improve reporting to track progress and demonstrate reductions.