Research on Downhole Gas Separation Method Based on a PDMS Separation Membrane

Safe and efficient deep drilling is a fundamental requirement for the development of oil and gas resources. In this regard, the application of membrane separation technology for drilling fluid gas separation and monitoring is highly significant. In this study, several commonly used permeable membrane materials were analyzed, and a PDMS separation membrane was preliminarily selected as a suitable material for downhole gas separation. We designed an experimental setup to investigate the separation performance of PDMS membranes. The effects of the separation pressure difference, operating temperature, and membrane thickness on the performance of PDMS membranes were analyzed, and the microstructure changes in the PDMS membrane under high temperature and pressure were observed using a scanning electron microscopy. The experimental results showed that PDMS membranes with a thickness of 150–200 μm can work stably and maintain good strength and permeability at a separation pressure difference of 1.1 MPa and a temperature of 150 °C. The SEM observations revealed that the PDMS separation membrane had a smooth surface and uniform microstructure after continuous operations for 15 h under the temperature and pressure conditions, without any cracks, demonstrating high temperature and pressure resistance. These research results provide an important reference for the application of PDMS separation membranes in downhole gas separation technology.