Enhancing CO2 Removal and Mitigating Methane Emissions Through Higher-Selectivity Membranes

Abstract Nestled within Field R, Platform X serves as a cornerstone in the critical task of CO2 removal from high-CO2 feed gas, ensuring compliance with stringent sales gas specifications. The current process utilizes membrane technology and features a two-stage membrane separation system. While this technology effectively separates CO2 from natural gas, continuous venting primarily consisting of CO2 occurs at the membrane skids to meet sales gas specifications. This venting contributes to greenhouse gas emissions, particularly due to the methane content in the vent stream, which has a high global warming potential. The main objective of this paper is to showcase the success of implementing higher selectivity membranes at Platform X, specifically aimed at abating methane in the vent stream and effectively reducing greenhouse gas emissions associated with continuous venting during CO2 removal. A systematic approach was employed to achieve these objectives. The process began with a comprehensive desktop simulation study on both the primary and secondary membrane skids. The simulation results, along with field trials, detailed technical justification and economic evaluation, informed the decision regarding the optimal placement of the higher selectivity membranes. Following a thorough engineering and economic analysis, it was determined that installing the advanced membranes at the secondary membrane skid would yield the most significant results. The implementation phase involved a gradual membrane changeout campaign, incorporating condition-based monitoring for real-time performance assessment. Post-changeout, sampling results were collected to evaluate improvements in vent CO2 purity, hydrocarbon recovery, and greenhouse gas emission reduction. This methodical approach ensured that each stage was thoroughly analyzed and optimized for maximum impact. Our initial simulations and strategic decisions have been validated, showing a remarkable 3% increase in CO2 purity within the vent stream, now reaching 96%. Additionally, hydrocarbon recovery has surged by 3%, achieving 97.5%, and we have successfully reclaimed approximately 4 MMscfd of hydrocarbon from the vent stream. This translates to a significant reduction of 840 ktCO2e per year. A crucial takeaway from this development is that the enhanced CO2 purity in the vent stream serves as a vital precursor for Carbon Capture and Storage (CCS) injection. Elevated CO2 purity ensures compliance with injection standards and improves the efficiency of subsequent capture processes. This positions Platform X among the innovative practices in the petroleum industry, facilitating sustainable carbon management solutions that reduce environmental impact and support the transition to a low-carbon future. By utilizing advanced membrane technology, we enhance operational performance while contributing to global efforts to lower greenhouse gas emissions.