Detection of gas leaks in the subsurface environment

Leaking valves, connections and distribution pipelines are significant sources of fugitive gas and volatile chemical emissions in chemical manufacturing, gas production, transmission, and oil refineries. A gas leak detection method has been developed based on continuous monitoring of the oxygen concentration surrounding a natural gas pipeline. The method utilizes optical fibers coated with an oxygen permeable polymeric film containing a luminescent sensor molecule. When the specialty fiber is illuminated by a light source that excites the luminophor, the functional cladding compound has the ability to detect and quantify leaks by measuring small changes in oxygen concentrations in the surrounding environment. Key features of the technology include long-term performance based on well understood platinum porphyrin chemistry, in addition to the capability of distributed sensing using fiber optic evanescent field spectroscopy. Results of leak detection in various environments namely atmospheric conditions, dry sand as well as saturated sand is reported, along with test results on long term system performance.