PicoGC: a new microGC device for analysing natural gas

Micronit GmbH has teamed up with Pollution analytical equipment in a project called PicoGC. The aim of this project is to develop a new MEMS-based device that integrates all the analytical functions of gas chromatography, showing a better performance than current microGC devices.

Miniaturised gas chromatography (microGC) systems hold the potential for fast analysis of organic samples in a compact and low power demanding unit. PicoGC integrates, on a chip level, all vital parts of gas chromatography devices, being the injector, the analytical column and the detector. Note that all these parts, together forming the vital heart of the device, are solely fabricated of glass and silicon. In this process, the latest etching and bonding techniques are used. This micro gas chromatography device will be specifically implemented in the natural gas field and will enclose applications as Lower Heating Value calculations, odorants detection and mud logging analysis. High-performance separation columns and excellent overall engineering allows a vast increase of sensitivity and linearity in this new device. 

Higher sensitivity in measuring the composition of natural gas

The varying composition of natural gas can lead to an uncertain heat transfer capacity. Prevalence of for instance water in gas will lead to inefficiencies in the combustion process. Because of the high temperatures involved during combustion, water transforms into steam. The energy required to vaporise the water is not released as heat. In other words: the steam stores a small fraction of the available energy. This slightly reduces the heat transfer capacity of the gas and increases energy consumption. The total amount of heat liberated during combustion of a unit of fuel is called the Higher Heating Value (HHV). The amount of energy that remains after subtracting the ‘lost’ heat as a consequence of water vaporisation, is called the Lower Heating Value (LHV). By analysing the composition of the gas, the LHV can be calculated. PicoGC is striving towards a more precise control in real-time of the LHV.

From a more organic point of view, water vapour and sulphur components in the gas may cause corrosion or condensation problems in the pipelines. PicoGC performs real-time measurement of sulphur compounds and water, which is of great importance to ensure adequate levels of gas quality and energy efficiency. This way, precise determination of the gas composition is not only allowing a more efficient combustion process, but is also valuable in terms of pipeline integrity. 

More precise odorants analysis

As natural gas by itself is odourless and obviously has a combustible nature, odorants are injected into the gas, ensuring it can be perceived by any person with a normal sense of smell. The types of odorant and the amounts used, vary from country to country, depending on local regulations. For distributors and transporters, an important feature of PicoGC will be the ability to detect any type of odorant used in gas, even at very low levels. This is a major step forward because currently, none of the measuring systems has the adequate sensitivity level to do so. Furthermore, PicoGC enables online analyses of odorants, abolishing the need for analyses in external laboratories.

Real-time mud logging analysis

For exploration and production service companies, the main advantage of the PicoGC is to be found in the analysis of the natural gas composition in mud logging. Mud logging companies create a detailed record of a borehole by examining the cuttings of rock brought to the surface by the drilling device. This way, the geology of gas formations is evaluated, as a result of which the total organic content of the rock can be determined. This helps geologists locate the most productive strata and avoids drilling in the wrong spot. Mud logging is currently performed at rig-site at surface level. Current analysis time is several minutes. PicoGC promises a vast decrease in analysis time. This reduction in analysis time is possible due to the thinner and shorter analytical column. Further improvements of the device are its great precision, its robustness and its small size. 

How did Micronit GmbH contribute to the development of the PicoGC?

In the development process of this device, a very broad range of processes available at Micronit GmbH could be used. This includes PECVD, dry etching of silicon and oxide, wet etching of silicon and glass, different bonding techniques (anodic, direct and adhesive), lift-off, powder blasting and dicing. Besides, Micronit was able to use and combine very different materials available to fabricate chips, including glass, silicon and polymer. Certain challenges had to be overcome in this process, such as:

-creating layer combinations with low stress

-dry etching of different channel geometries on the same wafer

-handling very fragile structures.

For future commercial manufacturing purposes, Micronit will be also responsible for upscaling the fabrication process of the chips.

The PicoGC project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 756439.

For further information, check the project’s website: http://picogc-project.eu/

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