Natural gas leak dispersion studies using an infrared gas-imaging system

The Gas Research Institute (GRI) has been investigating improved methods for the detection of gas leaks, particularly from buried pipes. Detection of natural gas leaks by infrared remote sensing, using topographical targets, can provide a significantly improved method for gas leak surveys, where the remote sensing system is capable of scanning large areas for leaks. For any candidate remote sensing system, the performance goal of greatest interest is the detection limit (DL), which should be as low as possible. A method is described by means of which a realistic DL may be estimated before the start of any proposed R & D project. A key feature of this method is the ability to challenge candidate remote sensing systems with a realistic 3-D model of small turbulent plumes from ground level gas leaks. To obtain these 3-D models, a novel electro-optical technique was developed in which real-time infrared optical density distributions and fluctuations of gas leak plumes from controlled releases of methane were captured as video images. These optical density plume images may be used with the infrared beam geometry of the candidate remote sensing system to achieve realistic estimates of the DL.