Gas-water separation via PDMS membrane
Methane gas monitoring and recovery from natural gas hydrates
The quest for new energy sources such as that of gas hydrate deposits requires the use of new tools for exploration and gas production. So far, several options have been discussed and tested for effective and efficient gas hydrate decomposition and gas release but few attempts have been made in terms of gas collection and reliable monitoring equipment. Envisaging the real scenario of gas production from hydrate deposits, membrane separation techniques are promising tools for gas hydrate exploration and gas production/extraction from decomposed hydrate deposits.
In the framework of production tests on the large scale reservoir simulator (LARS), an experimental setup is realized which explores the options of using a membrane for analytical purposes and gas recovery. For this application, a polydimethylsiloxane (PDMS) membrane was selected due to their thermal stability and high gas permeability. Two types of PDMS membranes are currently being tested (Fig. 1).
The following two concepts for the application of a membrane are currently being realized:
1. PDMS membrane as an analytical tool for monitoring and measuring the gas concentration (see Fig. 2). Preliminary experiments have shown that the monitoring of hydrate decomposition and gas release within the LARS is difficult. Even if the heat front continuesradially upon thermal stimulation, internal movements of gas bubbles, convection, or re-formation of hydrates away from the heat source cause a heterogeneous distribution of gases. The use of PDMS membranes at defined locations, at different distances from the heat source will provide detailed information about internal processes in the LARS. On the permeate side a continuous flow of argon is passed to a quadrupole mass spectrometer. The methane concentration which is measured within the argon is dependent on the concentration of dissolved or free methane gas in the LARS at the certain membrane location. This allows the observation of the temporal and spatial distribution of free and dissolved gas in the course in the course of an hydrate formation or decomposition experiment.
2. PDMS-membrane as a tool for the recovery of methane in the course of decomposition of gas hydrate (see Fig. 3). The design of an optimized PDMS membrane is aspired to deliver the required amount of methane for catalytic combustion in the heating element directly from decomposed hydrate.
