Quantifying Methane Emissions Through Process Simulations Model and Beyond

Abstract

Methane concentration in the atmosphere is increasing steadily and this increment is driving climate change and continue to rise. Although the estimates of methane emissions are subject to a high degree of uncertainty, the energy sector is still one of the major sources of anthropogenic methane emissions. Focusing on the oil and gas industry, methane is emitted during normal operation, routine maintenance and system disruptions. However, globally more energy will be required in the future. Transitioning to a low carbon future requires an energy player in O&G to start managing methane emissions in the natural gas / liquefied natural gas value chain effectively. Many global methane management coalitions were established with common goals i.e. to reduce global methane emissions and to advance the abatement, recovery and use of methane as a valuable clean energy. One of it is Methane Guiding Principles (MGP) which focuses on priority areas for action across the natural gas supply chain, from production to the final consumer. Signatory members of MGP is to fulfill the expectations of the 5 principles in MGP that includes pursuing an accurate methane emissions quantification across its gas value chain. A baseline study was initiated to measure methane emissions for LNG plant, gas processing and gas transmission facilities, covering both intended and unintended releases. Methane emissions were quantified using a process simulation software that was developed by PETRONAS Group Technical Solutions, called iCON Emission, where the calculations applied in the software are aligned with API compendium, US EPA and IPCC. Methane emissions from unintended releases i.e. LOPC and fugitive leaks were quantified using the actual inputs from LDAR data (%LEL or concentration), stream compo, stream phase, device type and component correction factor to calculate methane emission rate. Meanwhile methane emissions from intended releases e.g. flaring, compressor seals, pneumatic devices, etc, were quantified using metered amount or designed leakage/vent rate. Further works on Fugitive emissions are currently developed by PETRONAS technologist using Inferential Modeling via machine learning approach. This approach is combining First Principle and Data Analytics to make Fugitive Emission as online information and accurate reporting. To provide further assurance to the results, PETRONAS had engaged a 3rd party to validate the results where it was concluded that methane emissions quantification using iCON tool is almost the same level of accuracy with Level 3 of OGMP 2.0 standard. This level of accuracy is at par with the practice of the other O&G peers. Based on the baseline identification & quantification of methane emissions, PETRONAS is able to take necessary mitigating action, operating its asset in a safe and sustainable manner protecting the environment while monetizing the methane emissions from LNG and gas processing facilities with approximate cost saving of RM 15 mil/year.