CO₂ detection using graphene based micro sensors

Oil and gas industry encounters challenges whenever EOR/EGR is being introduced; numerous methodologies have been looked upon at an early stage of analyzing the recovery solution. Generally, there are numerous types of pipelines used in the oil industry; and each has its associated operational issues. There are certain mitigation plans for the oil production pipelines that have to be adopted, especially after implementing the CO2 injection as an EOR methodology into selected depleted reservoirs. CO₂ injection is used to enhance oil recovery (EOR); henceforth it is consequently commingled with other gases like the H₂S. Such commingled gases are considered corrosive and may lead to cracks and fractures to the pipelines. The thermodynamic property of CO2, influenced by the temperature and pressure during pipeline transportation, with the existence of other gases (such as H2S), makes the presence of CO₂ to be a coorosion driver in the pipeline. Therefore, such pipeline operation is considered to be more complicated than any other service pipelines. This paper will represent the joint research conducted in Masdar Institute and ADCO, which deals with the fabrication of graphene micro sensors. These micro sensors are based on graphene as active material for the transistor like sensor systems. Graphene has unique sensing/electronic properties along with physical and chemical stability in corrosive and hostile environments required for the oil and gas application. The graphene films are synthesized and optimized using Chemical Vapor Deposition (CVD) reactor in various substrates with different surface finishes. Three different types of architectures of micro sensors are fabricated and will be reported, which are Kelvin, Backgated and Memberane. The response of each of these architectures helps triangulate and identify the presence (and concentration) of each of the targeted gases. For example, the membrane device will detect the presence of any physical precipitation in the oil/gas mix. While the backgated device allows for detection of ionic and polar species. This will help to give a high-level assessment and early warning for the pipeline integrity. Our current delegated results include the fabrication of the three sensor types in Masdar's clean room. This included the development of the various processing steps, design and fabrication of test devices and structures. This was followed up with development and characterization of the performance in various environments (gaseous and liquefied). These results have demonstrated the capability of graphene, as an active sensor material, to sense and determine the concentration of gases within different pressures, down to the 100's of ppm level. Additional characterization assessments in different gaseous mixtures are ongoing and the results will be reported in the final paper.